M ystery Caves in the Middle and Upper Ordovician limestones near Etna. (Courtesy of Joe P etty.) 
UNIVERSITY OF MINNESOTA 
MINNESOTA GEOLOGICAL SURVEY 
WILLIAM H. EMMONS, DIRECTOR 
BULLETIN ~9 
THE PALEOZOIC AND RELATED ROCKS 
OF SOUTHEASTERN MINNESOTA 
BY 
CLINTON R. STAUFFER 
AND 
GEORGE A. THIEL 
MINNEAPOLIS· 1941 
THE UNIVERSITY OF MINNESOTA PRESS 
COPYRIGHT 1941 BY THE 
UNIVERSITY OF MINNESOTA 
All rights reserved. No part of this book may 
be reproduced in any form without the written 
permission of the publisher. Permission is 
hereby granted to reviewers to quote brief 
passages in a review to be printed in a 
magazine or newspaper. 
PRINTED IN THE UNITED STATES OF AMERICA 
FOREWORD 
The initial work on the stratigraphy of Minnesota was done by N. H. 
Winchell, who was ably assisted by Warren Upham, Charles Schuchert, 
E. O. Ulrich, U. S. Grant. .James E. Todd, M. W. Harrington, Horace V. 
Winchell, W. H. Scofield, .John M. Clarke, and others. Their field work 
was completed and the final reports published by 1900. While this was 
a pioneer task and the early reports quite naturally carried preliminary 
conclusions which occasionally proved erroneous. it is nevertheless a 
monumental study, characterized by thoroughness and completeness of 
detail. These final reports are the starting point for all subsequent work 
and a model for field and laboratory detail. 
The erroneous identification of certain formations, particularly the 
St. Lawrence and Jordan, which plagued the preliminary work was un-
fortunately carried through to the first of the final reports, hut was cor-
rected thereafter. The suhsequent confusion that has been perpetuated 
by student members of the geological profession is to be charged to lack 
of knowledge of the following volumes of the series or to a lack of experi-
ence in dealing with the preliminary statements and errors of others. 
Dr. F. W. Sardeson very carefully corrected the early volumes and puh-
lished a list of the revised statements so that it should be easy to a void 
errors in stratigraphy. 
The work covered by the present bulletin has been in progress over 
a period of years and has furnished the basis for various bulletins and 
papers that have appeared from time to time. covering such subjects as 
limestone and marl, building stone, and faunal zones. During this time 
a number of individuals have given their assistance to the project. The 
authors wish to mention particularly Dr. William Strunk. Dr. Eunice 
Peterson, Dr. Raymond .J. Leonard, Mr. Richard E. Gile. Dr. Harlan 
Bergquist, and Dr. Louise F. Bush. Several of these did extensive field 
work, while others were concerned chiefly with work on the collected 
materials in the laboratory. Dr. Christina Lochman very kindly identi-
fied some of the St. Croixian trilobites, and for the new forms suggested 
that we use G. O. Raasch's unpublished generic names. which are there-
fore given here in quotation marks. 
Dr. George M. Schwartz revised the physiography and stratigraphic 
geology of the Minneapolis and St. Paul metropolitan area in Bulletin 27 
of this survey. The authors have frequently conferred with him hoth 
during the preparation of that bulletin and while working on this one. 
Finally, Dr. W. H. Emmons has read and criticized the whole manuscript 
and contributed materially to its readability and clearness. Moreont'. 
his council and guidance have been available during the entire time 
spent in field work. If the bulletin has a ny merit. a measure of the credit 
must go to those who have thus shared in its production. 
C.R.S. and G.A.T. 
III 

CONTENTS 
PART ONE. STRATIGRAPHY 
I. INTRODUCTION ......................................... . " .) 
II. PRE-CAMBRIAN ......................................... 11 
Igneous and Metamorphic Rocks ..................... 11 
Keweenawan Sediments .............................. 11 
Lake Superior Series .............................. 1'2 
III. PALEOZOIC: CAMBRIAN .................................. '24 
St. Croixian Series ................................... q4 
Dresbach Formation .............................. , q9 
Franconia Formation .............................. 35 
St. Lawrence Formation ........................... 4'2 
.J ordan Sandstone ................................. 46 
IV. PALEOZOIC: ORDOVICIAN AND POST-ORDOVICIAN. . . . . . . . . . . .. 50 
Beekmantownian Series .............................. 5:3 
Kasota Sandstone ................................. 54 
Blue Earth Siltstone .............................. 54 
Oneota Dolomite .................................. 55 
Root Valley Sandstone . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 59 
Shakopee Dolomite ............................. . .. 63 
Chazyan Series ...................................... fi6 
St. Peter Sandstone ............................... 66 
Mohawkian Series ................................... 69 
Platteville Formation .............................. 70 
Galena Formation ................................. 8'2 
Cincinnatian Series .................................. 90 
Maquoketa Formation ............................. 90 
Post-Orcloyician Interval ............................. 9:) 
V. PALEOZOIC: DEVONIAN AND POST-DEVONIAN ............... 94 
Senecan Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 94 
Cedar Valley Limestone ........................... 94 
Post-Devonian Interval .............................. 97 
VI. MESOZOIC: CRETACEOUS ................................. 99 
Dakota Series ....................................... 99 
v 
VI PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Dakota Formation ................................ 99 
Colorado Series ...................................... 104 
Coleraine Formation ............................... 104 
VII. CENOZOIC .............................................. 107 
Pre-Pleistocene Erosion .............................. 107 
The Pleistocene ..................................... 107 
Glacial Drift ...................................... 107 
Pleistocene Drainage Changes ...................... 112 
PART TWO. COMPOSITION OF MINNESOTA LIMESTONES 
TABLE SHOWING CO:MPOSITION OF lYIINNESOTA LIMESTONES . . . . . . .. 115 
LOCALITIES FROlH 'WHICH SAlVIPLES 'WERE TAKEN ............... , 117 
PART THREE. SECTIONS AND WELL RECORDS .......... 121 
PART FOUR. FAUNAL LIST ................................ 225 
INDEX ................................................... ," 250 
LIST OF FIGURES 
Mystery Caves in the Middle and Upper Ordovician Limestones 
near Etna ........................................ Frontispiece 
L Geologic Map of Southeastern Minnesota ................... 4 
2. Half Dome, South of Winona. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 
3. Dakota Creek Valley from Cemetery Hill, Dakota, Minnesota. . 7 
4. Hinckley Sandstone along the Kettle River at Sandstone. . . . .. Q2 
5. The Dresbach Formation, Eau Claire Member, in the North 
Wall of the Old Tostevin Quarries at Dresbach. . . . . . . . . . . . . .. 31 
6. The Taylors Falls and Ironton Members of the Franconia For-
mation, at the South Edge of Taylors Falls. . . . . . . . . . . . . . . . .. 37 
7. The Galesville-Ironton Contact at Snake Creek, near Kellogg.. 38 
8. The Taylors Falls :Member of the Franconia Sandstone at 
Taylors Falls ............................................ ~38 
9. The Bad Axe Member of the Franconia Formation, Stockton 
Hill, Winona ............................................. 41 
10. The Nicollet Creek Member of the St. Lawrence Formation in 
the Olel Hewitt and Beason Quarries at St. Lawrence. . . . . . . .. 4Q 
LIST OF FIGURES VI! 
11. The Jordan Sandstone with Basal Oneota (Ordovician) at Red 
Wing .................................................. " 47 
12. Cross-bedding in the Jordan Sandstone, Red Wing .......... 48 
1:'1. The Jordan Sandstone in the River Bluff at Kasota. . . . . . . . . .. .50 
14. An Old Sink in the Oneota Dolomite (Ordovician) Partly Filled 
from Abovc, at Kasota. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .51 
1.5. The Blue Earth Siltstone at the Southwest Edge of Mankato.. .52 
16. The Oneota Dolomite at Lanesboro ........................ .5fi 
17. The Jordan-Oneota Contact, Stockton Hill, Winona. . . . . . . . . .. .56 
18. The Jordan Sandstone Capped by Oneota Dolomite in the Mis-
sissippi River Bluffs near Winona ......................... " 60 
Hl. The Root Valley Sandstone and the Overlying Shakopee Dolo-
mite at Whitewater State Park ............................ 61 
20. The Shakopee Dolomite near Lanesboro .................... 63 
21. The Platteville Limestone Overlying the St. Peter Sandstone at 
the Soldiers Home, Minneapolis ........................... 66 
22. Chimney Rock, Formed by Wind Erosion, "North of Cannon 
Falls .................................................... 67 
2S. Diagram Showing Relationship of the Ordovician Section of 
Minnesota to Those of Iowa and Illinois. . . . . . . . . . . . . . . . . . . .. 70 
24. The Platteville Limestone West of Spring Gro,'e, Houston 
County ..... ,............................................ 71 
25. Platteville Fornlation South,vest of Lanesboro. . . . . . . . . . . . . . .. 73 
26. The Platteville Capping the St. Peter, at the vVashington Avc-
nue Bridge, University of Minnesota Campus . . . . . . . . . . . . . . .. 76 
27. The Spechts Ferry Member of the Platteville Northwest of 
Chatfield ................................................ 80 
28. The Guttenberg Sub member of the Decorah Shale Northwest of 
Chatfield ................................................ 84 
29. The Guttenberg Submember of the Decorah Shale, Zumbrota.. 84 
SO. The Ion Submember of the Decorah Shale, Northwest of Chat-
field ..................................................... 8.5 
:n. The Prosser Limestone along Lost Creek, ,,"Vest of Cha tficld. .. 87 
:~2. The Stewartville Dolomite at Stewartville ....... . . . . . . . . . . .. 8D 
3:3. The Stewartville Dolomite and the Dubuque or Basal Member 
of the lVlaquoketa Formation in the Lime City Quarry, North of 
Spring Valley .................... ,....................... DI 
,iii PALEOZOIC AND HELATED HOCKS OF SOUTHEASTEHN MINNESOTA 
34. The Lower or Productella Beds of the Cedar Valley Limestone 
at Spring Valley. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 96 
~l.5. The Hard, Compact, High Calcium Beds (StromatoporcUa beds) 
of the Cedar Valley Limestone at Le Roy ................... U6 
~W. Gravel Pit in the Ostrander Member East of Ostrander. . . . . . .. 100 
~)7. Map of the North-Central United States, Showing the Distribu-
tion of Glacial Drift of the Successive Pleistocene Stages ....... I] I 
~38. :Map of Blue Earth County ............................... 1014 
~39. Map of Brown County ................................... 1019 
40. Map of Chisago County .................................. 13] 
41. Map of the St. Croix River in the Taylors Falls Region ....... 134 
40l. Map of Dakota County ................................... 136 
4~3. Map of Dodge County ................................... 141 
44. Map of Fillmore County .................................. 143 
4.5. Map of Goodhue County .................................. 1.56 
46. Map of Hennepin County. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 163 
47. Map of Houston County ................................. 167 
48. Map of Southeast Itasca County .......................... 173 
49. Map of Le Sueur County ................................. 17.5 
.50. Map of Western Morrison County ......................... 176 
.51. Map of Mower County ................................... 178 
.52. Map of Nicollet County .................................. 179 
.53. Map of Olmsted County .................................. 180 
.54. Map of Pine County ..................................... 18.5 
.5.5. Map of Ramsey County .................................. 187 
.56. Map of Rice County ..................................... 190 
.57. Map of Scott County .................................... 194 
.58. :Map of Western Stearns County ........................... lU6 
.59. Map of Steele County .................................... 197 
60. Map of Wabasha County ................................. 199 
61. ~Iap of Washington County ............................... 206 
60l. Map of Winona County ................................... 216 
PART ONE 
STRATIGRAPHY 

CHAPTER I 
INTRODUCTION 
The area covered by this report is mainly the southeastern part of 
Minnesota. (See Figure 1.) It includes that portion of the state lying 
along or bounded by the St. Croix, the Minnesota, and the Mississippi 
rivers from Pine County southward to the Iowa state line and from 
Brown County eastward to the Wisconsin state line. Adjoining areas 
are referred to at various points in the text, chiefly for correlative pur-
poses or in order to clarify the discussion. This area lies mostly within 
the hardwood timber section. Numerous towns and villages dot the 
region, which is part of the more thickly populated area of Minnesota, 
settled for over seventy-five years and first pioneered over one hundred 
years ago. Many of the old traders and missionaries traveled its navi-
gable waters early in the seventeenth century; and for untold centuries 
before that it was an important part of the great hunting ground of the 
American Indian. 
The state of Minnesota lies on the southern border of the great 
Canadian Shield, so that much of its surface is covered by the pre-
Cambrian rocks characteristic of that ancient land mass. '\There more 
recent sediments overlie these older rocks, they vary in age from Cam-
brian to Cretaceous and later, for the glacial drift and the recent non-
marine sediments may lie directly on the pre-Cambrian. 
The strand line of Paleozoic and late lVlesozoic time often passed 
through Minnesota; and the position of the ancient shore, varying from 
time to time, left many unconformities. The significance of some of these 
unconformities may not yet be fully appreciated, but they range from 
short breaks (diastems) in sedimentation, like those in the St. Croixian 
series, to great erosion intervals (disconformities) like that between the 
lVlaquoketa formation and the Cedar Valley limestone, where a whole 
system and fully half of another are wanting. It is evident, therefore, that 
during these long intervals diastrophism caused the land mass to the 
north to be extended beyond the boundaries of the state and that during 
such periods profound erosion lllnst have affected this area, removing 
an unknown amount of the sm'face, probably base-leveling it several 
times. 
Portions of the Laurentian and the Algoman mountains enter the 
state near the northeastern angle, the so-called Arrowhead district, and 
cross the state diagonally toward the southwest. One or both ranges pass 
beyond its borders near the southwest corner, perhaps to be represented 
again in the buried granite ridge of central Kansas. Although it is only in 
the structural sense that these ranges may now be referred to as llloun-
3 
4 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MI NESOTA 
~ CreJ'oceous ..5/7 <£ Ss 
ITIIlIII Cedor Vo//ey Ls 
§ Mo,wokeJ'o..5/> dr Ls 
= ';;o/eao. Pecoro/>. P/o/J'ev///e 
= (LeTTer P //JQ/coJ'<f!S P/o/T. Oa/y./ 
D Sr. Pe/er ..5s 
§I Shokopee, Roor Jlolley, Oneolo 
m2i] .57' Cro/;rian J"e/"/ es 
~ /IeJ.-V'eenoJ.'Von ..5eds. 
/r'eJ-'VeenO/4/on ~oV'o F/o;vs 
AJ,fomon qronite 
JlohJ, Lowe.r fluronion or Olde.r 
Mi/e.5 
o / 0 20 30 b /~ IZ~ Jot )0 I 
/1'/77 
FI GURE 1. - Geologic map of southeastern Minne ota. (After map by M inneso ta Geological 
Survey, 1932 .) 
ta ins, sin ce th ey have been eroded so deeply, yet this diagonal of th e 
sta te is even today a low ridge on the old pre-Cambrian floor. This is clu e 
to th e warping of th e ancient la nd surface long after peneplana tion.1 Th e 
sediments dip away from this ridge both to the north we t and to th e 
south east . The Cretaceo us seclimen ts, however, override th e ancient 
height of land , and it is probable tha t a large part of th e sta te, then 
much eroded or nearly base-leveled, was submerged beneath the Cre-
1 C. W. H all. O. E. Meinzer, and M . L . F uller, Geology and Underground Wal ers of 
South.ern M innesota (U. S. Geologica l Survey, Wa ter Supply P aper 25(j , 1911 ), p. 32. 
INTRODUCTION 5 
taceous sea. Along the Red River in the northwest part of the state the 
older sediments are deeply buried beneath heavy glacial drift and lacus-
trine deposits of Lake Agassiz. Deep wells in the region have revealed 
Middle and Upper Ordovician, and the stratigraphy of the adjacent por-
tion of Manitoba suggests that Silurian and Devonian may also be rep-
resented; however, so little is known of the deeply buried rocks of the 
northwest corner of Minnesota that it is impractical to treat its geology 
in detail. 
East of the ridge is a great structural basin" or geosyncline with its 
axis running nearly north and south along the ninety-third meridian, but 
variously modified hy secondary cross folds. This basin is of very ancient 
origin and probably was partially elevated above marine sedimentation 
throughout most of the Paleozoic, certainly through the middle and 
latter part of that era. The shallow marginal part of this trough extended 
eastward into the adjacent portion of Wisconsin, where it was limited by 
the central ridge of that state, the southern end of the Killarney Moun-
tains; to the south it continued into Iowa and opened into the main Mis-
sissippi embayment of the sea which frequently spread northward to 
include part of Minnesota. 
These adjacent mountainous areas and their rejuvenated land sur-
faces furnished the sediments accumulating in this region during the 
early part of the Paleozoic. During the late pre-Cambrian or early Cam-
brian great quantities of arkosic sand and sandy to argillaceous red muds 
were washed into this trough, especially in the northern part, accumu-
lating to a depth of a thousand feet or more. These are mostly unfos-
siliferous deposits and may be of nonmarine origin; but by late Cambrian 
time the sea spread into the southern part of the area, and typical marine 
sedimentation set in. The surface over which sedimentation took place 
in the late Cambrian was very irregular, and the advance of the sea was 
too rapid to penuit base-leveling or even peneplanation to take place. At 
some places the deeply weathered surfaces of ancient rocks that had de-
veloped during the long period succeeding the uplift and folding were 
not completely removed, and the Cambrian sediments rest unconform-
ably on thesc old accumulations of weathered material. 
With numerous interrruptions of more or less importance, this marine 
sedimentation continued through the Ordovician, until the basin was 
essentially filled, except in the extreme south, where the sea once more 
invaded it during the Devonian, and deposition probably completely 
filled the Minnesota portion of the basin. During this sedimentation, or 
subsequently, minor folds and faults a hundred or more feet in displace-
ment were also developed, and such structures as the Twin City basin, 
the Belle Plaine-Castle Rock anticline, and the Hastings faults may now 
'G. A. Thiel aud G. M. Scbmu·tz. "Subsurface Structure of tbe Paleozoic Rocks of 
Southeastern Minnesota," Bulletin of the Geological Society uf A.meriC{!. ;';'2: 49-60 (l9H). 
See especially the map, p. 50. 
"" 
FrGU RE 2. - Half Dome. south of Winona. A part of the Mississ ippi River bluff capped by Oneota dolomite. (Photograph by Cutler's S tudio.) 
INTROD UCTION 7 
FIGURE 3. - Dakota Creek Valle,Y from 'Cemetery Hill , Dakota, Minnesota . 
be observed along the three major treams already mentioned . It is the 
Minn esota portion of thi basin that is the principal area of discussion in 
this bulletin. 
The present drainage of southeas tern 'Minnesota was partly estab-
li shed by late Plei tocene time, although much of it is of pos tglacial origin. 
During th e late stage of the Pleistocene, when th e River Warren was 
the outlet of ancient Lake Agas iz, th e floor of the valley was at a 
lower level than that a t the present day . Thus the fill in the valley of 
River Warren at Fort Snelling (M endota Bridge) is about 90 feet, and a 
similar or greater change is evident along the Miss iss ippi River from Men-
dota downstream, so that at the R ed Wing Dam the alluvium is more than 
150 feet thick, and near Winona it reaches a thickness of nearly ~oo feet. 
As a result of this change in gradient and its effects upon tributary 
streams, man y excellent and stratigraphically valuable outcrops which 
must have existed along th e old river have been obliterated. The upper 
portions of some of these ancient outcrops now rise above flat-bottomed 
valleys and form th e most conspicuous features of a picturesque a nd en-
chanting landscape (see Figure ~) , especially as viewed from th e environ s 
of the rivers. The tops of these outcrops are bluffs , often sheer walls 
rising 500 to 600 feet above th e level of these rivers and affording an 
excellent opportunity to study the ancient sediments. 
Th e Pleistocene glaciers seems to have had little eros iona l effect. for 
in many localities they passed over soft sand tone and hale without 
removing them. However, large areas have been covered by a heavy 
mantle of glacial drift representing several different ice invasions. Others, 
such as th e so-called driftles area of the south eastern corner, have little 
or no drift but are heavily loess-covered . Undoubtedly many of the ir-
regularities antedate the ice age and have been modified only slightly by 
glacial action. (See Figure 3.) 
The formational divi sions of most of the Paleozoic and part of the 
pre-Cambrian of Minn esota have long been in use. With more intensive 
study, however, new interpretations are found necessary, particularly of 
the pre-Cambrian, on which work is not yet completed . For the Cam-
brian, various a uthor have suggested subdivisions and modifications. 
8 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
some of which should doubtless be recognized. This is especially true of 
such limited faunal zones as appear to have wide horizontal distribution 
over the United States. These zones, however, have not been recognized 
by the Minnesota Geological Survey as anything more than members of 
the formations of longer standing, and every attempt has been made in 
the survey to be consistent in the use of these older and newer terms. 
Any failure in this respect has been due to misinterpretation of well logs, 
faulty identification of outcrops, faulty identification of fossils, or too 
great haste, rather than to an attempt to change radically the existing 
classification or to fill the literature with a miscellaneous collection of 
formational subdivisions. 
A large percentage of the formational names in the Minnesota classifi-
cation have been borrowed from adjacent states; others, described first 
from outcrops within this state, are adhered to in accordance with the 
rules of priority. Certain writers on the stratigraphy of the Upper Mis-
sissippi Valley, however, have applied local names to these formations or 
have redefined the older formational names, changing the content so that 
they no longer refer to the horizons originally designated by the terms. 
This is especially true of the formations belonging to the St. Croixian 
series, where the variation in usage has been so great among different 
authors or in the different writings of the same author, that it is only 
with great difficulty that the literature is understandable at all. As will 
be noted later, an attempt has been made herein to bring the St. Croixian 
formational units of this state into harmony with the more feasible 
changes in classification suggested elsewhere. The following column of 
stratigraphic succession is based on the classification commonly used in 
Minnesota. 
GEOLOGICAL COLUMN OF MINNESOTA 
Cenozoic (Quaternary) 
Pleistocene 
Eldoran 
Recent (marl, peat, alluvium) 
Wisconsin drift 
Centralian 
Sangamon (loess deposits and soil) 
Illinoian drift 
Ottumwan 
Yarmouth (interglacial forest beds) 
Kansan drift 
Grandian 
Aftonian (old soils and erosion) 
Nebraskan drift 
Mesozoic 
Cretaceous 
Colorado series 
Coleraine (Benton) formation 
INTRODUCTION 
GEOLOGICAL COLUMN OF MIN:'<ESOTA - Continued 
Dakota series 
Dakota formation 
Ostrander mem ber 
Paleozoic 
Devonian 
Senecan series 
Cedar Valley limestone 
Ordovician 
Cincinnatian series 
Maquoketa formation 
Wykoff member 
Dubuque member 
Moha w kian series 
Galena formation 
Stewartville member 
Prosser member 
Decorah shale mem ber 
Ion submember 
Guttenberg submember 
Platteville formation 
Spechts Ferry member 
McGregor member 
Glenwood member 
Cha7.yan series 
St. Peter sandstone 
Beekmantownian series 
Shakopee dolomite 
Root Valley sandstone 
Oneota dolomite 
Blue Earth siltstone 
Kasota sandstone 
Cambrian 
St. Croixian series 
Jordan sandstone 
Van Oser member 
Norwalk member 
St. Lawrence formation 
Lodi member 
Nicollet Creek member 
Franconia formation 
Bad Axe member 
Hudson member 
Taylors Falls member 
Ironton member 
Dresbach formation 
Galesville member 
Eau Claire member 
Mt. Simon member 
9 
10 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
GEOLOGICAL COLUMN OF l\iINNESOTA - Co-n tin ued 
Proterozoic 
Keweenawan 
Upper Keweenawan 
Lake Superior series 
Hinckley sandstone (Devils Island) 
Fond du Lac beds (Orienta) 
Middle Keweenawan 
Keweenaw Point volcanics, Duluth gabbro, Beaver Bay complex, Logall 
sills, etc. 
Lower Keweenawan 
Puckwunge formation, consisting of sandstones and conglomerates 
Huronian (see U. S. Geol. Surv., Prof. Paper 184) 
Virginia and Rove slates 
Biwabik and Gunflint formations 
Pokegama and Sioux quartzites 
Algoman 
Giants Range, Vermilion, and other granites 
Temiskaming (sometimes called Lower Huronian) 
Knife Lake slates, including Agawa formation, Ogishke conglomerates, 
and other sediments 
Archeozoic 
Laurentian 
Saganaga and other granites 
Keewatin 
Soudan iron formation 
Ely greenstone 
CHAPTER II 
PRE-CAMBRIAN 
IGNEOUS AND METAMORPHIC HOCKS 
The Archeozoic and Proterozoic formations are of little importance as 
outcrops in southeastern :Minnesota and may be discussed under the term 
pre-Cambrian. They form the surface on which the younger formations lie, 
and are therefore penetrated occasionally by the deeper wells. From New 
Dim westward up the lVlinnesota Valley, however, these rocks are ex-
posed at many places or crop out along the river. At some places, such 
as Redwood Falls, pre-Cambrian gneisses are weathered to a depth of 80 
feet or more, and when it is recalled that the upper surface was scraped 
off by the glacier. it is apparent how extremely long must have been the 
interval during which these rocks were subjected to weathering processes 
in order to produce sllch deep alteration. It was undoubtedly similar 
weathered materials that furnished the sediments for the Paleozoic for-
mations lying on the flanks of this old pre-Cambrian ridge. 
At Taylors Falls the pre-Cambrian rocks may be seen in actual con-
tact with the Paleozoic formations. These basal rocks are part of the 
Keweenawan lava flows of the Lake Superior district, and Berkey 1 iden-
tified at least seven distinct flows. That other flows also reached this dis-
trict is probable, since neither the top nor the bottom of this series is 
shown at that locality. These flows are found as far south as Stillwater, 
where the deep city well penetrates about 340 feet of such rocks.2 Evi-
dently the lava cliffs, still observable at Taylors Falls, were cliffs on the 
shores of the Cambrian sea, for mingled with the boulders in the adjacent 
beds is an,abundance of Cambrian fossils. The endurance of these cliffs 
is also suggested by the fact that the boulder beds or conglomerates just 
mentioned range through the stratigraphic interval of the Dresbach for-
mation, which in this vicinity consists of 150 feet of sediments, and 
through most of the Taylors Falls member of the Franconia formation. 3 
KE'VEENA WAN SEDIMENTS 
In addition to the lava flows and other igneous rocks included in the 
Keweenawan. the thick sediments lying along the south shore of Lake 
Superior should probably be included in the series. They are mainly 
sandstones and shales with occasional important conglomerates, the 
whole of which lllay reach several thousand feet in thickness. These are 
''"Geology of thp St. Croix Dalles," American Geolo91~'t. 20: 3HO-82 (1897). 
'C. R. Stauffer. E. P. Burch. and G. :M. Schwartz, "A Reinterpretation of the Slillwater 
Deep-Well Records." jOllmal of Geology, 43:638 (1935). 
"C. P. Berkey. '"Geolog~' of the St. Croix Dalles," American Geologist, 20:374-77 (1897). 
11 
1't PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
the beds which Houghton! called the Lake Superior sandstone, part of 
which was designated by Irving ,', as the vVestel'l\ sandstone. Since this 
great deposit of arenaceous sediments has been dividcd into several for-
mations, the earlier term is used as a series name. Although these sand-
stones and shales have occasionally been considered Cambrian in age, 
their lack of fossils makes classification more or less indeterminate. They 
definitely lie below the St. Croix ian series and may be interbedded with 
Keweenawan lava flows." 
LAKE SUPERIOR SERIES 
Fond d1l Lac Beds. - The Fond du Lac or Red Clastic beds of south-
eastern l\1innesota probably were encountered first in the deep wells of 
Minneapolis and in the Bunker Hill well at Mankato. These beds were 
described by Winchell and Upham 7 as part of the Potsdam. and with the 
Hinckley sandstone were regarded as the equivalent of the red sand-
stones and shales cropping out along the St. Louis Rivcr at Fond dl! Lac 
near Duluth and along the south shore of Lake Superior. The name Red 
Clastic beds or series apparently was proposed by Hall or Meinzer.s They 
seem to have regarded it as a convenient term to cover those red beds of 
uncertain age penetrated in the deeper wells of southern "Minnesota 
rather than as a permanent name for a series or a formation. The term is 
still used in that same indefinite sense, because these red sandstones and 
shales are unfossiliferous and are known chiefly from well samples. There 
is little doubt. however, that they represent the similar beds of the Lake 
Superior district which Winchell" referred to as the Fond du Lac sand-
stone. In later years the lower beds of the Fond du Lac were called the 
Oronto series and the upper the Bayfield series by Thwaites,1° in both 
Wisconsin and Minnesota. though the older term is still largely used in 
this state. Since these beds are typically exposed along the St. Louis 
River at Fond du Lac, the name Fond du Lac seems most appropriate. 
Regarding the relationship of these red beds in the well at Mankato, 
4 Third Report of the Michigan Geological Suryey for 1839, (House Document No.8. 
1840), p. 13. 
o The Copper-bearing Rocks of Lake Superior (U. S. Geological Survey, Monograph .5. 
1883), pp. 1.53-.54 and 36.5-66. 
"N. H. Winchell. Geology of Minnesota (Final Report of the Geological and Natural 
History Survey of Minnesota J, Vol. 4 (1899), pp. 470-71; G. M. Schwartz, A Guidebook to 
Minnesota Trunk Highway No.1 (Minnesota Geological Survey, Bulletin 20. 192.5). pp. 67-
68; F. F. Grout. "Duluth Rocks and Structure," Guidebook\!?, Sixteenth International 
Geological Congress (1933), p. 68. 
, Geology of Minnesota (Final Report of the Geological and Natural History Survey of 
Minnesota), Vol. I (1884), pp. 422-'t4; Vol. 't (1888), pp. 't79-86. 
s C. W. Hall, O. E. Meinzer, and M. L. Fuller, Geology and Underground lVaters of 
Southern Minnesota (U. S. Geological Survey, Water Supply Paper 2.56, 1911), pp. 32-33. 
"N. H. Winchell, Preliminary List of Rocks (Tenth Annual Report of the Geological and 
Natural History Suryey of Minnesota, 1881), pp. 30-34; Geology of Minnesota (Final Report 
of the Geologi~al and Natural History Survey of Minnesota ), Vol. 4 (1899). pp . .567-71. 
1» Sandstones of the lViscomin COCL,t of Lake Superior (Wisconsin Geological and Natural 
History Sliney. Bulletin \1;;. 1912), pp. 2.5-tn. 70-78. and PI. 'iI;;. 
PRE-CAMBRIAN 13 
Winchell and Upham state that "this formation of sandstone and shales, 
thus shown to have a thickness of about 1,300 feet, appears to be strati-
graphically and lithologically the same with the nearly horizontal red 
sandstone, including frequent beds of shale, which borders thc south shore 
of Lake Superior almost continuously from Fond du Lac to Grand Island 
and again rises into view at the Falls of St. Mary." 11 Hall and :lVIeinzer 
eliminated part of Winchell's correlation and said that "its lithologic 
character, stratigraphic situation, and geographic relations" suggest that 
the Fond du Lac or Red Clastic is ;'the sedimentary extension of the 
Keweenawan rocks of the Lake Superior basin." J" A somewhat similar 
suggestion has been made more recently by Atwater and Clement J;, in a 
review and discussion of these beds in the central part of the state and 
the Lake Superior district. They regard the Fond du Lac or Red Clastic 
heds as definitely the Amnicon or upper part of the Oronto series. An 
examination of samples from the Stillwater deep well and a study of thc 
outcrops along the St. Louis River suggest, however, that they include 
much of the Orienta sandstone of the Vi'isconsin classifica tion, and the most 
recent study by Tyler, Marsden, Grout, and Thiel l± correlates the Fond 
du Lac or Red Clastic beds with the lower part of the Orienta formation 
of the Lake Superior sandstone series. 
The character of the sediments of the Fond du Lac beds is fairly well 
known from the northern outcrops and the numerous wells that pene-
trate them in southeastern :lVIinnesota. Also at :iVIora, Kanabec County, 
they crop out in typical form along the Snake River, where test pits were 
dug in 1892 in an attempt to utilize the argillaceous red shales in the 
manufacture of terra cotta. As a whole, these sediments are composed of 
dark red, argillaceous to arenaceous shales and red to brown arkosic sand-
stones, with occasional streaks of bluish or greenish shales and clear 
white sandstones in very minor amount. Pebble horizons are common, 
and these may become real conglomerates, as along the St. Louis River 
at Fond du Lac or along the Snake River at Mora. In east-central and 
southeastern :lVIinnesota the whole series ranges from several hundred to 
more than two thousand feet in thickness. It rests on the eroded surface 
of pre-Cambrian igneous and metamorphic rocks, and the lower portion 
may be of coarse, weathered material derived from the old land area and 
deposited on a surface made up of similar materials, thus making it diffi-
cult to draw a distinct basal contact by means of data obtained :rom 
well-cuttings. 
At Mora the beds consist of coarse gray to yellowish and red sand-
"N. H. Winchell and Warren Upham, Geology of Minnesota (Final Report of the Geo-
logical and Natural Histor~' Sur"e~' of :Minnesota). Vol. 1 (lR84). p. 4'o!5. 
"C. W. Hall, O. E. Meinzer, and lVI. L. Fuller, Geology and Undergrollnd 11' atns of 
Southern Minnesot<l (U. S. Geological Survey, Water Supply Paper 'o!56, 1911), p. 33. 
10) "Pre-Cambrian and C'Jmbrian Relations in the Upper 'Mississippi Valley." Bulletin of 
the Geological Society of Amuica. 46: 1673-74 (1935). 
11 "Studies of the Lake Superior Pre-Cambrian by the Accessory-Mineral Method," 
Bulletin of the Geological Society of A merica, .51: 1.514 (19'10). 
U PALEOZOIC AND RELATED ROCKS OF SOllTHEASTEHN MINNESOTA 
stone, together with conglomerates and argillaceous red shales. About 30 
feet have been exposed from time to time, fully half of which is red shale. 
The sandstones form a low cliff along the east bank of the Snake River 
about a mile north of the Mora cemetery gate. The greater part of the 
red shale lies still farther to the north, where scveral tcst pits were dug 
50 to 75 feet east of the river bank. 
At Fond du Lac, where these rocks are excellently shown in the bluff 
of the St. Louis River, the sandstones are red, gray, and mottled, often 
cross-bedded. and frequently ripple-marked. Some are fine-grained, oth-
ers coarse. There are even conglomerates with vein quartz and other 
pebbles, and quartz pebbles may be found scattered through the sano-
stone. Other conglomerates containing shale pebbles are locally devel-
oped. The associated red and mottled shales may be mud-cracked and 
interbedded with the sandstones or may occur as important members 25 
feet or more in thickness. :Microscopically, the rock shows angular quartz, 
biotite. unweathered feldspar, and glassy fragments. It was in part the 
latter that led 'Vinchell to correlate these beds with the volcanic rocks of 
the Lake Superior district, although similar beds occurring beneath the 
flows farther to the north may have contributed to his conclusions. 
The follmying section along the St. Louis River at the dam above 
Fond du Lac is believed to be typical. 
FOND DU LAC. CARLTON COUNTY 
Section along the St. Louis River. Downstream from the Po\\,crhouRe 
THICKXESS 
5. Drift. red c1a~' and stony gray. . . . . . . . . . . . . . . . . . . . . . . . . . .. . .... 
FOND DU LAC BEDS 
4. Sandstone. gray streaked with red, medium to coarse, arkosic, thin- to massi\'e-
(in feet) 
1,30 
bedded, ripple-marked.. . . . . . .. ........................ . . 75 
3. Shale. red to chocolate, often mottled or streaked with gray. Although argil-
laceous, it may be arenaceous, ripple-marked. and mud-cracked. . . . . . . . . . 't5 
'to Sandstone. red to gray, arkosic, fairly massive, although grading into thill-
bedded, gray-spotted, cross-bedded, and micaceous ........ " . . . . 60 
1. Shale, red to chocolate. sand~'; shaly sandstone, grading into the sandstones 
above. The shales are gray-streaked and micaceous and e"temj to the le\"el of 
the St. Louis River. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 
Downstream a quarter to a half mile. other quite similar beds OCC1ll', 
though they lie wholly below the beds by the dam. These carry con-
glomerates or thin pebble zones in the lower part, grading upward into 
sandstones, and are succeeded by red shales similar to those at the bottom 
of the section by the dam. Thus the sequence is repeated. 
All these excellent sediments, only slightly disturbed from their origi-
nal position and scarcely affected by metamorphism, give every hope of 
fossils. but diligent search has so far yielded nothing definite. A few in-
definite trails may be found in the shales along the St. Louis River at 
Fond elu Lac, but they are of no value for correlation purposes and prob-
ably are not of organic origin. Trilobites and brachiopods obtained from 
PRE-CAMBRIAN 1.5 
a well at Waconia were erroneously reported as occurring in this forma-
tion.'" These were later sent to various paleontologists to be checked, but 
in most cases without very satisfactory results. Dr. E. O. Ulrich, how-
ever, said that the specimens belong to an obscure Eau Claire (Dresbach) 
fauna, and Dr. Christina Lochman]n definitely placed them in the 
Aphelaspis zone of the Eau Claire member of the Dresbach formation. 
The beels carrying this fauna are said to be rather widely distributed 
over the United States, but are not known in any outcrop in the Missis-
sippi Valley except at Hudson, Wisconsin, anel the fauna is still largely 
undescribed. The probable explanation of the absence of this zone in 
Minnesota outcrops is either its transitory development or the fact that 
it has been overlooked in the loose, sandy shales of the upper part of the 
Eau Claire member. However, it is evident that the fossiliferous red 
shales in the Waconia well are not Red Clastic beels and must be red 
shales definitely within the St. Croixian series. This is the more probable 
since it has lately been found in other wells below the surface west of 
Minneapolis that the Dresbach contains much red shale. The 'Waconia 
well, therefore, did not penetrate the Hinckley sandstone," nor did it even 
reach the bottom of the St. Croixian series. The driller's log is faulty and 
the original interpretation incorrecU8 
Hinckley Sandstone. - The Hinckley sandstone was described by 
Winchell in his annual report for the year 1882,l!l but the name was not 
proposed until the final report co was published. This rock was formerly 
quarried by the Great Northern (St. Paul and Duluth) Railway at 
Hinckley and was used for bridge abutments. Later the quarrying in-
dustry was transferred to the village of Sandstone on the Kettle River, 
where a large amount of rock has been removed. 
The Hinckley sandstone is coarse to fine, usually medium-grained, 
yellowish to salmon pink and red or nearly white. The color is due to 
varying amounts of iron oxide, which may form part of the cementing 
material and which occurs as either limonite or hematite. The cementa-
tion of the sand grains varies much from place to place, but in the quar-
ries at Sandstone it is very complete and the material is chiefly silica; 
therefore, the rock is well indurated, hence suitable for building stone, 
curbing, paving blocks, and even crushed rock. 
A short distance east of Hinckley this sandstone crops out and ex-
tends almost continuously northward along the Kettle River for fifteen 
"C. R. Stauffer. "Age of the Red Clastic Series in Minnesota."' Bulletin of the Geological 
Society of A merica, 38: 47-J.-7:5 (19'27). 
J'J Persollal communication. January 30, 1936. 
17 G. M. Schwartz. Geology of the Minneapolis-St. Paul Jletropolitall Area (Minnesota 
Geological Sun·e,\'. Bulletin 27, 1936). p. 132. 
1< C. R. Stauffer. "Age of the Red Clastic Series ill Minnesota," Bulletin of the Geological 
Society of America. 38: 473-7.J, (1927). 
10 N. H. Winchell. Elafnth Ammal Report of the Geological and Natural History Survey 
of Minnesota (1884). pp. 12:5-'28. 
~. N. H. Winchell. Geology of Minnesota (Fillal Report of the Geological and Natural 
History Surwy of ]Vlinnesota). Vol. 'l (IHR8). pp. xxii. \186, and PI.:56. 
16 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
to twenty miles. It forms castellated bluffs as much as 50 to 100 feet in 
height above the valley. Here and there arc great towerlike masses of 
sandstone"' partly separated from the bluff ~ncl divided by yawning 
chasms. Some of these have toppled into the gorge below. where they 
are strewn about in great confusion. The river flows through this narrow 
valley, occasionally plunging in the turbulent form of rapids, which were 
especially well-developed at Sandstone and four miles farther to the 
north, but which have been more or less obliterated in recent years by 
rising water due to power dams. Potholes also occur, some of them 15 to 
'20 feet deep, rivaling those at Taylors Falls. Some of the tributaries have 
cascades or waterfalls which occasionally tumble 50 feet or more over the 
sandstone. Outside of the immediate river valley the rock soon passes 
beneath the drift, which is not cut through by the smaller streams. 
The strata vary from a few inches to several feet in thickness, al-
though occasionally more massive beds are encountered. This is especially 
true of the upper beds at Sandstone. The lower half of the quarry shows 
occasional beds of shale. Some of these shaly beds have been broken 
up and converted into pebbles, which are now packed together in intra-
formational conglomerates. The bedding is nearly horizontal at the old 
quarry or type locality at Hinckley, but dips of a few degrees may 
be found at selected places. At the quarries on the eastern edge of Sand-
stone the dip is "southeast at an angle of approximately three degrees.""" 
Ripple marks and cross-bedding are common in the Hinckley at Sand-
stone and more or less throughout the region of outcrop. North of Sand-
stone, in the vicinity of the upper falls, the cross-bedding is inclined 
southward"" at angles which vary from 10° to 45°, while in the vicinity 
of Hinckley it is inclined northward at angles varying from 10° to 15°. 
South of the Hinckley sandstone outcrops along the Kettle River in 
Pine County, the formation passes beneath the drift and beneath the 
Upper Cambrian sandstones. The latter are encountered above the 
Hinckley in the wells of southern Chisago County. The deep wells as far 
south as :lVIinneapolis, Faribault, Mankato, and Rochester encounter a 
sandstone similar to or identical with the Hinckley, which occurs be-
tween the Fond du Lac or Red Clastic beds and the lowest sandstones 
(Mt. Simon) of the St. Croixian series. The authors agree with Winchell,c4 
who stated that this sandstone is the same as that cropping out along 
Kettle River. lVloreover, a recent comparative study of samples from 
the Rosemount well and specimens from the quarries at Sandstone indi-
cates their identity. Other sedimentary analyses bear out this correla-
"N. H. Winchell, Eleventh Annual Report of the Geological and Natural History Survey 
of Minnesota (1884), pp. 125-516. 
"George A. Thiel and Carl E. Dutton, The Architectural., Structural, and Jl10llllmental 
Stones of Minnesota (Minnesota Geological Survey, Bulletin 25, 1935). p. 144. 
"" Warren Upham, Geology of Minnesota (Final Report of the Geological and Natural 
History Survey of Minnesota). Vol. 2 (1888), pp. 638-39. 
"' Ibid., p.'286. 
PRE-CAMBRIAN 17 
tion, although it is possible, of course, that some of the beds included in 
the Hinckley in recording the Mankato and Rochester wells should be 
referred to the St. Croixian series. 
The contact between the Hinckley sandstone and the Fond du Lac 
beds below does not come to the surface in east-central or southeastern 
Minnesota; hence it is known only from well samples and well drillers' 
logs. Apparently the red color of the sandstone grades downward into 
the red beds without very great or sudden change in character. The 
Federal Prison well at Sandstone illustrates this point. Here red sand-
stone occurs at least 350 feet above the base of the Hinckley. (See the 
log. page 186.) It is for this reason the Hinckley sandstone has been 
designated occasionally as the uppermost member of the red beds. 
Winchell, however, distinctly separated the two, although he recognize 1 
the character of the beds below. 
A petrographic study of a series of samples representing all exposed 
phases of both the Fond elu Lac or Reel Clastics and the Hinckley sand-
stone shows that the Red Clastics are uniformly high in feldspar anel that 
the Hinckley is uniformly very low. The basal Dresbach (Mt. Simon) 
that overlies the Hinckley has from two to four times as much feldspar 
as the Hinckley. but far less than the Reel Clastic beds. (See Table 1.) 
Furthermore. the assemblage of heavy accessory minerals in the Fond du 
Lac or Red Clastics is very different from that of the Hinckley. (See 
Tables £ and 3.) 
At Hinckley. the type locality, and at Sandstone. as at all other 
places along the Kettle River. the upper surface of the Hinckley sand-
stone is glaciated and was probably eroded in preglacial time. Therefore, 
the upper portion of the formation is not known in outcrop. The quarry 
at Sandstone and the cliffs along the river expose about 100 feet. and the 
Federal Prison well penetrates 465 feet which must be assigned to this 
formation. However. the distinction between the basal Dresbach and the 
top beds of the Hinckley as shown in well logs can now be quite definitely 
established by petrographic analyses, and it is found tha t the Hinckley 
becomes progressively thinner southward from its type locality. aver-
aging 150 feet in the region of Minneapolis and St. Paul. Schwartz has 
assigned "££0 feet as an average""5 for the Twin Cities region. but his 
figure included approximately 100 feet that should be classified as Mt. 
Simon (basal Dresbach). 
Both the Mt. Simon and the Hinckley have been penetrated by deep 
wells in or near St. Paul. Minneapolis. Rosemount. Glencoe, Faribault. 
Owatonna, and Rochester. and the Hinckley, at least, is present over the 
Red Clastics at Mankato. In the Bunker Hill well (Mankato) there is no 
sample representing the interval above the Hinckle~- that lllay be ]\lIt. 
'" Geology of the Minneapohs-St. Palll Metropolitan Area (Minnesota Geological Sur-
vey, Bulletin 27. 1936). p. '15. 
18 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
TABLE I.-PERCENTAGE (BY '''EIGHT) OF FELDSPAR IN THE UPPER KEWgENAWAN AND 
BASAL ST. CUOlXIAN SEDIMENTS * 
Sample Location Percentage of Feldspar 
BASAL DRESBACH 
Wisconsin) 
(MT. SIMON) SANDSTONg (at and near its type location at Eau Claire, 
MS I Type section 0-10 ft. below top ............................ . 
MS 2 Type section 10-20 ft. below top ........................... . 
MS 3 Type section 20-30 ft. below top ........................... . 
MS 4 Type section 30-40 ft. below top ........................... . 
MS 5 Type section 40-50 ft. below top ........................... . 
MS 12 Type section 1l0-20 ft. below top .......................... . 
MS 7 Basal conglomerate, Chippewa Falls, Wisconsin .............. . 
MS 8 1-10 ft. above MS 7 .............. , ....................... . 
MS 9 10-20 ft. above MS 8 ..................................... . 
MS 10 20-30 ft. above MS 9 ..................................... . 
MS II 30-45 ft. above MS 10 ...... " .............. '" ........... . 
HINCKLEY SANDSTONE (outcrop samples and well-cuttings) 
2.06 
2.18 
2.10 
2.27 
3.01 
4.03 
2.89 
3.88 
3.07 
3.18 
4.20 
I Type section at Hinckley. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.12 
2 Composite sample. quarry wall. Sandstone. .. . ... .. . . . . .. . ... 0.29 
3 Road cut west of Askov. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.26 
4 Outcrop along Willow River. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.26 
5 Outcrop southeast of Rutledge ... , .............. , ......... " 0.31 
6 Outcrops along Net River. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.18 
7 Drill-cuttings near top, Federal Prison well. Sandstone. .. . ... .. 0.30 
8 50 ft. below no. 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.24 
9 50 ft. below no. 8.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.21 
10 50 ft. below no. 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.28 
II 50 ft. below no. 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.27 
12 50 ft. below no. II. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.25 
13 50 ft. below no. 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.30 
14 50 ft. below no. 13 ....... , .. . .. .. .. .. .. .. . . .. ....... ... . .. 0.23 
1.5 Bottom of well, 465 ft. below surface ............... , ..... . ......... 0.28 
RED CLASTICS 
I 
2 
3 
4 
.5 
6 
7 
8 
9 
10 
II 
12 
13 
14 
(outcrop samples and well-cuttings) 
Mission Creek quarry wall, near Fond du Lac ................ . 
40 ft. below no. I ........................................ . 
Chambers Grove quarry wall .............................. . 
30 ft. below no. 3 ........................................ . 
10 ft. below no. 4 ...... , ................................. . 
Cliff along St. Louis River ................................ . 
Cliff along St. Louis River ................................ . 
Railroad cut near Chambers Grove ........................ . 
10 ft. below no. 8 ................. , ... , ........... , ...... . 
Deep well, Rosemount. 1,040 ft. below surface .............. . 
50 ft. below no. 10. " .................................... . 
Deep well, Manka to, 1,060 ft. below surface ................. . 
100 ft. below no. 12 ...... , " ............................ , . 
Deep well, Lake City, 700 ft. below surface ... , .............. . 
27.6 
31.4 
54.3 
36.8 
67.1 
41.6 
24.3 
68.3 
27.2 
4.5.1 
72.3 
21.3 
53.7 
47.4 
* A. J. Crowley and G. A. Thiel, "Pre-Cambrian and Cambrian Relations in East-
Central Minnesota," Bulletin of the American Association of Petroleum Geologists, 24: 744-
49 (1940). 
Simon; hence its presence or absence has not been determined. From 
Faribault eastward toward the Mississippi River the Hinckley pinches 
out against the westward sloping surface of the pre-Cambrian granites. 
In the region of Winona and northward along the river, the Mt. Simon 
TABLE :2. - HEAVY MINERALS OF THE FOND DU LAC BEDS, FOND DU LAC" 
Weight Relative Abundance before Acid Treatment Distribution (in Percentages) Per Cent (in Percentages) 
Sample 
Before After Earthy No. 
HCI HCI Car- Aggregates, Pyrite AIIAc- Apatite Garnet Zircon Tour- 0 Un- M' II .1. Treat- Treat- bonate Mainly cessories maline paques known lsce aneous I 
ment ment Leucoxene 
Mission Creek Quarry 
P402 ..... 3.0 :2.2 0-15 30-50 0-15 15-30 .56 pI' 20 17 3 3 Hornblende - pr 
P403 ..... 1.5 1.1 0-1.5 Over 50 0-15 30-50 .51 9 19 16 2 :2 ............... 
P404 ..... 1.3 1.1 0-15 30-50 0-15 15-30 48 7 16 :23 4 1 ............... 
P405 ..... 0.6 0.3 0-15 30-.50 0-1.5 15-30 50 7 13 Q3 4 Q Hornblende - pr 
Railroad Cut, North of Chambers Grove 
P406 ... " Q.l 1.9 0-1.5 30-50 30-.50 48 7 13 17 9 4 " ............. 
..... 
P407 ..... Q.1 1.8 15-30 30-.50 30-.50 54 3 10 Q4 6 4 Biotite-pr 
:0 P408 ..... 3.6 Q.3 0-15 15-30 0-15 15-30 30 Q 10 11 45 Q ............... 
P409 ..... :2.6 Q.O 0-15 30-50 0-15 15-30 5Q 5 19 17 5 3 Epidote-pr 
P41O ..... Over 50 1.5-30 15-30 53 Q 13 19 5 Biotite-4 
Old Quarry, West Bank of St. Louis River 
P411. .... 2.1 1.6 0-1.5 30-50 30-50 63 Q 13 9 3 3 Biotite- 6 
P412 ..... 1.8 1.4 0-1.5 15-30 0-15 30-.50 60 Q 14 8 13 4 Rutile-pI' 
P413 ..... 1.2 0.9 0-15 Over 50 0-1.5 1.5-30 40 6 17 29 Q 5 Rutile-l 
P414 ..... 0.4 0.2 0-15 30-50 0-15 15-30 42 (j Q6 21 3 2 Rutile-pr 
Old Quarry. Chambers Grove 
P415 ..... 2.4 1.8 15-30 30-.50 30-50 49 4 15 11 18 3 Biotite- pr 
P416 ..... :2.2 1.7 0-15 30-50 30-50 58 '2 1'2 19 7 2 Rutile -tr 
One Mile North of Mora 
P448 ..... 0.3 0.2 0-15 Over 50 30-50 5 2 17 9 5Q Rutile-14 
* S. A. Tyler, R. W. Marsden, F. F. Grout. and G. A. Thiel, "Studies of the Lake Superior Pre-Cambrian by the Accessory-Mineral Method," 
Bulletin of the Ueolog1(~al Society of America, .51: 1508 (1940). 
t pr = present (0.5-0.!1 per cent). 
tr = trace (less thall 0.5 per cent). 
TABLE 3. - HEAVY MINERALS OF THE HINCKLEY SANDSTONE * 
Geographic and Distribution (in Percentages) 
Stratigraphic 
Location of Samples 
Weight T Magnetite Epidote 
Thick- PerCent Zircon °frma- and Leucoxene Rutile Anatase and Unknown Miscellaneoust 
Sample ness me Ilmenite Zoisite 
No. (in ft.) 
Sandstone Quarry 
Top 
P433B ........... 10 .022 55 15 24 tr 2 2 Hornblende - tr 
P434B ........... 10 .039 55 11 pr 26 4 3 Garnet-tr ~ P435B ........... 10 .027 64 11 2 17 2 tr 3 Tremalite - 1 0 
P436B ........... lO .049 50 8 29 4 7 2 Hornblende - tr 
P437B ........... 10 .023 54 16 tr 23 1 2 1 Pyrite-2 
P438B ........... 10 .029 63 12 tr 18 2 2 3 tr ................ 
P439B ........... 10 .0lO 51 1.5 2 22 pr 3 5 tr ••.• ·•• •. ··.0·0. 
P440B ........... lO .013 47 13 2 34 tr tr 3 tr ••••••• ·0 •• 0.0·· 
P441B ........... 10 .038 64 8 1 22 2 2 1 ••••• 0 •• ' ••••••• 
Askov 
Top 
P442B ........... 6 .029 32 12 30 22 1 2 ................ 
P443B ........... 6 .019 35 19 23 15 1 1 4 Pyrite-pr 
P444B ........... 6 .073 47 4 27 17 2 2 2 Pyrite-tr 
P445B ........... 6 .015 39 17 20 20 pr 4 tr •••• '0 ••• 0 •••••• 
P446B ........... 6 .031 56 12 10 18 tr pr 1 Hornblende - 1 
Rutledge 
Top 
P429B ........... 10 .042 66 8 2 16 6 1 I · ....... ,- ..... , 
P430B ........... 10 .078 56 14 4 17 2 2 2 1 Pyrite-l 
Willow River 
Top 
P431B ........... 10 .023 28 40 pr 27 1 1 Pyrite-1 
P432B ........... 10 .02'1 48 23 2 22 pr 2 2 tr · -, ............. 
Net RiYer 
Top 
P417B ........... 6 .034 37 16 12 27 I 3 2 Pyrite-l 
P418B ........... 5 .04.5 45 15 16 18 4 2 tr · . . . . . . . . . . . . . . . 
P419B ........... 4 .021 18 14 35 28 3 2 \ Pyrite-1 
'" 
l Hornblende - tr 
..... P420B ........... 7 .067 31 14 30 19 3 1 2 ......... - ...... 
P421B ........... 10 .045 20 II 47 16 tr 5 f Garnet -tr l Hornblende - tr 
P422B ........... 4 .036 26 7 47 1.5 3 1 tr · ............... 
P423B ........... .5 .108 27 13 44 12 I 1 tr ............... . 
P424B ........... 6 .077 3.5 13 30 U) 1 I Pyrite-tr 
P42.5B ........... 6 .086 28 13 37 18 1 3 tr ....... '.- ...... 
P426B ........... 8 .074 33 II 39 12 2 3 pr ............... . 
P427B ........... 7 .146 32 II 26 23 I 6 1 ................ 
P428B ........... 5 .327 24 10 42 13 1 7 pr tr Pyrite-l 
* S. A. Tyler, R. W. Marsden. F. F. Grout. and G. A. Thiel, "Studies of the Lake Superior Pre-Cambrian by the Accessor~'-Mineral Method:' 
BIllletin of the Geological Society of America. 51: 1.512 (1940). 
t pr = present (0 . .5-0.9 per cent). 
tr = trace (less than 0.5 per cent). 
22 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
FIGURE 4. - Hinckley sandstone along the Kettle River at Sandstone. 
overlaps the Hinckley and rests directly on the granite, as it does over 
large areas in Wisconsin . At many places along the St. Croix Valley the 
Mt. Simon, where present, rest s directly on the K eweenawan basalts . 
Winchell regarded the Hinckley sandstone as the upper part of the 
Fond du Lac sandstone series that crops out along th e St. Louis River, 
although its nearest outcrop is at Holyoke. Recent petrographic studies 
by the junior author indicate, however, that it should be correlated with 
the Devils I sland formation of the Bayfield group of the Lake Superior 
sandstone of Wisconsin.26 
The type section of this formation at Hinckley exposed a ledge about 
9 feet high which extended for 250 feet or more along the east side of 
the railroad just north of the Grindstone River. This old railroad quarry 
was never a satisfactory type section; and now, since th e abandonment 
of the quarrying industry there, it is nearly valueless. The best exposures 
of the sandstone have always been along the Kettle River. In fac t at 
times, chiefly in the building trades, the formation has been called the 
K ettle River sand stone, a much more appropriate name in every way 
than the accepted one. Since the quarrying industry was transferred from 
Hinckley 2 7 to Sandstone and has flouri shed there for many years, the 
section in th e west bluff of Kettle River at that point (see Figure 4) has 
come to occupy the place of a type section and is regarded as a typical 
20 S. A. Tyler, R. W. Marsden, F. F. Grout, and G. A. Thiel, "Studies of the Lake Superior 
Pre-Cambrian by Accessory-Mineral Methods," Bulletin of the Geological Society of America, 
51: 1514 (1940). 
"N. H . Winchell , Geology of Minnesota (Fin al Report of the Geological and Natural 
History Survey of M innesota), Vol. 2 (1888), p . 645n . 
PRE-CAMBRIAN Q3 
development of the formation. The following section was measured and 
.qampled by Dr. Samuel Goldich during a study of pre-Cambrian heavy 
minerals undertaken by the Geological Society of America in 1935. For 
his purposes the section was divided into 10-foot intervals and channel 
samples were cut from each. As the section is here presented, some com-
binations have been made for simplicity, but the section is still essen-
tially that of Goldich. 
SANDSTONE, PINE COUNTY 
Section of quarries anJ Gorge, West Bank of Kettle River 
THICKNESS 
(in feet) 
11. Drift, Lhin co\'er, bedrock striated ... , ......................... , . . . . . . . . 0.7 
HINCKLEY SANDSTONE 
10. Sandstone, very coarse, light yellow to buff and brown, cross-bedded, massive 
or thick beds ......... , ..... , . , ..... , ............................. , , . . 10.0 
9. Sandstone, massive and coarse like that above, hilt with some fine-grained, 
thin beds. Good quarry stone ... , ......... ' ....... , " '" . . .. . . . .. . .. . . . 10.0 
8. Sandstone, salmon-colored to brown, thin-bedded, ripple-marked, massive, 
coarse, and cross-bedded at the base ... , .. , ..... '" .... , " ...... , . ,. . .. . 13.3 
7. Sandstone, thin-bedded, hard, fine-grained, red to yellow ........ , . . . . . . . . . '2.7 
6. Sandstone, massive, medium-grained, pink to buff and red. Good quarry stone 18.0 
5, Sandstone, fine to coarse. pink to reddish. A '2-foot and a 4-foot bed. . . . . . . . 6.0 
4. Sandstone, massive, cross-bedded, light yellow to pink ....... , . , . . . . . . . . . . . 10.0 
3. Sandstone, coarse-grained, well-cemented, pink ... , ........ , .... , .... , . . . . ].).0 
2. Sandstone, massive to thin-bedded, ripple-marked, pink to buff. , ..... , . . . . . S.O 
1. Sandstone, partly covered to level of Kettle River. , ......... , ...... , , . . . . . S.O 
Total,.", .......... " ... , ... , ........... . 101.7 
Tables ~ and 3 show the heavy mineral content of both Fond du Lac 
(Red Clastic) beds and the Hinckley sandstone. A comparison of heavy 
mineral and feldspar content is the best method of distinguishing the t\\"o 
formations and the safest means of identifying them. 
CHAPTER III 
PALEOZOIC: CAMBRIAN 
The period of prolonged erosion which immediately preceded the 
Paleozoic in North America has been called the Lipalian interval by 
Schuchert. Its rela tionship to the Keweenawan of the Lake Superior dis-
trict has never been satisfactorily determined because of the uncertain age 
of that series, but the erosion surface is certainly later than the youngest 
of the Upper Huronian. During this Lipalian interval in other parts of 
the continent, base-Ieyeling neared completion, and the same was prob-
ably true in the l\1innesota region. There are no sediments known to 
represent the interval, and the base-leveled surface lies either below the 
Fond du Lac (Red Clastic) beds or above the Hinckley sandstone, a 
point which cannot well be determined, although it is suspected that the 
surface lies above the Hinckley or at the contact between the supposed 
Proterozoic and the lowest known Cambrian of this region. If that is the 
propel' horizon, all of Minnesota was still a land mass suffering erosion 
at the beginning of the Paleozoic, for the entire Lower and Middle Cam-
brian are wanting, and the sedimentation of the era begins with the 
St. Croixian series or Upper Cambrian of other regions. 
ST. CROIXIAN SERIES 
The term St. Croix sandstone was introduced by Winchell 1 in 1872 
for the sandstone, shales, and sandy dolomites below the Oneota dolomite 
and above the sandstones of the 'Lake Superior district. The most im-
portant fossil horizons of this sandstone series had been recognized and 
tabulated by Owen," but no attempt was made to break it into forma-
tions until 1874, when 'Winche1l 3 described the Jordan sandstone and the 
St. Lawrence formation. Even then these formations were not recognized 
as parts of the St. Croix sandstone, but were regarded as subdivisions of 
the sediments referred to as the Lower :Magnesian series. 
The following tabulation is a condensation of Winchell's general sec-
tion of the St. Croix sandstone or series in Winona County." The forma-
tional names in parentheses have been inserted by the present authors 
to indicate the divisions according to the present classification. When 
this section was compiled, Winchell was still incorrect in his correlation 
of the beds cropping out in the Minnesota Valley with those along the 
1 First Annual Report of the Geological and Natural History Survey of Minnesota (1873), 
pp.68-80. 
, Report of a Geological SUT1'ey of Wisconsin, Iowa and Minnesota (185'l). pp. 5'l-53. 
3 Second Annual Report of the Geological and Natural History Survey of Minnesota 
(1874), pp. 147-55. 
"N. H. Winchell. Geology of Minnesota (Final Report of the Geological and Natural 
History Sur"",\' of Minnesota). Vol. I (1884). pp. 257-.58. 
24 
PALEOZOIC: CAMBHIAN 
Mississippi River, and thought the Jordan sandstone equivalent to the 
Root Valley sandstone. He therefore called the Oneota dolomite along 
the southeast line of the state St. Lawrence and did not intend to 
subdivide his St. Croix sandstone into formations. 
WINONA COUNTY, MINNESOTA 
Winchell's General Section of the St. Croixian Series 
THICKNESS 
(JORDAN SANDSTONE) (in feet) 
1. Argillaceous, siliceous rlolomitic beds generally fine-grainerl but including some 
thin strata of coarse, loo~e quartz sand. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 40- 50 
2. Sandstone, nodular to concretionary beds of medium Lo fine, well-cemented 
sand .......................................... , .. , ... ...... ...... ... 25- 30 
3. Sandstone, massiye. loosely cemented, more or less iron-stained. . . . . . . . . . . . .. 40- 50 
(ST. LAWRENCE FORMATION) 
4. Argillaceous, sandy, greenish calcareous beds containing trilobites and grapto-
lites ................................................................ 30- 40 
(FRANCONIA FORl\IATION) 
,5. Sandstone, loosely cemented .......................................... ,50 
6. Shales and shaly sandstone, often covered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 
(DRESBACH FORMATION) 
7. Sandstone, including the beds in the Toste"in Quarries. Contains at least one 
6-foot shale bed, in the lower part, which gives rise to springs ............... 120-150 
8. Shales and shaly sandstone, including a 4-inch conglomerate. Very fossiliferous. 
Extends down to river level at Dresbach ............................... " 10- 15 
O. Saudstone, gray, below leyel of Mississippi River in Winona Mining Co. shaft at 
Dresbach ........................................................... 20 
10. Shale and shaly sandstone. in the Da"is drill hole at Dresbach. all lower than 
the bottom of the shaft ............................................... 68 
Total known thickness in Winona County .......................... 488-558 
In the years that followed, Winchell discoyered some of the errors he 
had made along the Minnesota River. and the preliminary subdivisions 
of the St. Croixian series 5 were shown and corrected by him in 1888. In 
a still later publication G on the Minneapolis area Winchell gave his inter-
pretation of the sediments beneath the city as follows: 
FORMATIONS UNDERNEATH THE CITY OF MINNEAPOLIS 
1. Drift 
2. Trenton limestone .................................................. . 
3. St. Peter sandstone .................................................. . 
4. Shale in the St. Peter ................................................ . 
5. St. Peter sandstone .................................................. . 
6. Shakopee limestone, fissured .......................................... . 
7. New Richmond sandstone ............................................ . 
8. Oneota limestone .................................................... . 
9. Jordan sandstone '" ................................................. . 
1 O. St. Lawrence limestone and shale ..................................... . 
11. Dresbach sandstone and shale ........................................ . 
12. Hinckley sandstone .................................................. . 
5 Ibid., Vol. 2 (1888), p. xxii. 
THICKNESS 
(in feet) 
10- 2;; 
25- 30 
134-164 
1- 5 
38 
25 
2- 2;; 
100-150 
100-140 
100-125 
100-200 
175-'WO 
oN. H. Winchell. "Deep Wells as a Source of Waler Supply for Minneapolis." American 
Geologist, 35: 268 (1905). 
'26 PALEOZOIC AND HELATED HOCKS OF SOUTHEASTEHN MINNESOTA 
This classification, only slightly modified, was used by Winchell more or 
less consistently thereafter. Berkey introduced the name Franconia and 
others have sui)divided the formations into mcmbers and slightly sl~ifted 
the contacts, but the Winchell classification still remains the basis for 
study of the St. Croixian series in 1Vlinnesota. 
The formations constituting the St. Croixian series T have much in 
common throughout. It is distinctly a sandstone series, with a certain 
percentage of dolomite prevailing in the sandy beds at l1l11UerOUS horizons 
and occasionally forming layers of nearly pure dolomite. Glauconite also 
is common throughout the series, although it is rare in some parts and 
very much concentrated in others. Thus Berkey says that "an earchy. 
granular, bright green mineral occurs abundantly in the Dresbach forma-
tion. It is recognized as glauconite and is the same mineral that is so 
abundant in the St. Lawrence formation [Bad Axe member, now part of 
the Franconia] of many localities." S Intraformational conglomerates, 
cross-bedding, ripple marks, and mud cracks may be found at various 
horizons, indicating similarity in conditions of sedimentation. But the 
appearance of even such variations as these is marked by great irregu-
larity, so that sandstones grade into sandy shales and these into arena-
ceous dolomites. Conglomerates appear, disappear, and reappear, but not 
always at the same horizons. Two or perhaps three greensand horizons 
are fairly persistent, but probably the most continuous and uniform 
lithological unit in the series is the few feet of siltstone in the St. La w-
rence formation which carries the typical DikeloceJlhalus minlZesotensis 
fauna. Even this siltstone may be repeated several times at slightly dif-
ferent horizons, and comparable silts may be found in quite different 
forma tions. In many cases, therefore. it is practically impossible to corre-
late distant sections of the series on the basis of lithology alone. 
Sedimentary analyses 9 so far undertaken are suggestive but hardly 
reliable as means of correlation over wide areas and perhaps should 
be used only in conjunction with faunal evidence. The~l reveal heavy 
residuals and accessory minerals that help in the recognition of horizons. 
but their limits apply rather to zones or members and do not necessarily 
correspond to the contacts ordinarily set for the formational units. In-
deed, there is no safe guide to members of the series othcr than the 
fauna; and where the fauna is lacking, a horizon should be given or cor-
related only approximately by its relation to an identifiable fauna or to 
such well-marked changes in sedimentation as the .Iordan-Oncota con-
tact. Even this latter b~eak in sedimentation is not always satisfactory. 
7 F. W, Sardeson, "Cambric of the Upper Mississippi Region." Pan-American Geologist, 
65: 339-47 (1936). 
8 C. P. Berkey. "Geology of the St. Croix Dalles." American Geologist. '21: 153 (1898). 
'W. A. P. Graham, "Petrology of the Cambrian-Ordovician Contact in Minnesota," 
Journal of Geology. ·11: 468-86 (l933): W, G. Wilgus. "Heavy Minerals of the Dresbach Sand-
stone of Western Wisconsin," Journal of Sedimentary Petrology, 3: H3-91 (1933); S. A, Tyler. 
"Heavy Minerals of the St. Peler Sandstone in Wisconsin," ibid., 6: 77-79 (1936). 
PALEOZOIC: CAMBRIAN 27 
as may be seen at many places along the :Mississippi River where the 
Oneota begins with a sandy dolomite, the sand of which is largely de-
rived from the .Jordan and is therefore difficult to distinguish from the 
undisturbed layers bclow. 
The fauna of the St. Croixian series is rather large and varied and 
lends itself fairly well to zonal studies. Brachiopods are often so abun-
dant as to be crowded into a real coquina, but trilobites are the most 
conspicuous fossils of the series. These are usually mere molds of dismem-
bered or fragmentary carapaces, rendering identification difficult and 
often cxtremely uncertain. Some few species are very limited, others 
are much longer in their vertical range. A portion of the fauna is well 
known. but many species are still undescribed and others doubtless need 
revision. A study of a large number of specimens. particularly the trilo-
bites belonging to the Dikelocephalidae. seems to indicate that in some 
cases at least the described species are simply extremes in a variational 
series of forms showing a normal distribution curve, and hence would 
more properly be classed as varieties than as distinct species. In fact, the 
whole St. Croix ian fauna, and more especially the Brachiopoda, needs 
further study. 
The most important feature of the St. Croixian fauna as a whole is 
the concentration of groups of species into faunules at certain horizons 
where conditions of sedimentation favored their preservation. These 
groups constitute the faunal zones of Owen, Ulrich. Raasch. Bridge, and 
others; and being traceable over wide areas. they serve as the most satis-
factory guides to correlation. Although these assemblages are fairly COll-
stant, certain species are not entirely limited to the faunal zones to 
which they are usually attached. but grow fewer in number or gradually 
disappear as the succeeding beds become relatively unfossiliferous; hence, 
they leave the member and formational boundaries uncertain. Differ-
ences of opinion. supported by real evidence. are therefore to be expected 
among those working on the series; in this, at least. one is not disap-
pointed. 
It would appear that the conditions of sedimentation prevailing dur-
ing the deposition of the St. Croixian series were eminently suited to 
inhibiting the typical faunas in some places. whereas in others they flour-
ished so that their remains accumulated in abundance. Io It also seems 
possible that in the coarser sands. originally quite fossiliferous. all traces 
of such organisms may have been removed by the solution of calcareous 
or dolomitic ingredients and by the subsequent rearrangement of the 
sand grains. It seems probable. therefore. that many of the unfossiliferous 
beds occurring in certain localities at the horizons of well-known faunal 
zones may be of contemporaneous deposition with the typical fossilifer-
ous beds elsewhere. 
'" W. H. Twenhofel. "Sedimentation and Stratigraphy from Modern Points of View." 
JOUr/wi of Paleontology. 8: 461 (1934). 
l<l 
00 
OWEN 
1852 
Formation / 
r flower part) 
Formation Ie 
Formation I 
d (upper part) 
5th or Stillwater 
tnlobite bed 
rormation I 
d (main part) 
3rd and I-th 
tnlobite beds 
Formation! 
c (upper part) 
Formation I 
c (main part) 
Formation 1 
b - 1st and lnd 
trdobtte beds 
Formation I 
a (upper port) 
WINCHELL 
1886 -1d88 
Jordan 
sandstone 
St Lawrence 
/imeJtone 
.shales 
Dresbach 
sandrock. 
BERKEY WINCH£LL 
1897 1905 
Jordan Jordon 
sondstone sandstone 
St Lawrence St Lawrence. 
dolomites hmeston~ 
and shale; and shale 
Franconia 
./ond.stone 
Oresbach 
sandstone 
Oresbach ond ;hole 
shales 
TABLE 4. - CAMBRIAN CLASSIFICATIONS 
HALL, WALCOTT- ULRICH /1INNESOTA MEiNZER. ULRICH GEOLSUR~ 
end FULLER 1924 
/9/1 1914 1931. 
Jordon 
Jordan Jordan sandstone Jordan 
sandstone (Winchell Id74) sandJtone 
Norwalk .IS 
, member 
" ~~ Lodl shale 
"- member 
EO 
St. Lawrence St, Lawrence ~ St. Lawrence St Lawrence 
(Winchell ION) 'Is member ('ormation ('ormation 
Mazomanie 
"" 
Franconia Franconia Sf rranconio 
(BerAey 1393) sandstone 
Dresbach Dresbach Sf 
Oresbach (Winchell 1888) 
.Jandstone 
Dresbach 
£ou Claire, Eau Claire {'ormation 
(Ulrich NSS 19Ni shale 
Mt", Simon 
{Ulrich NSf 191? Nt. Simon ss 
TWENHOFEL. MINNESOTA 
R£SSEA RAASCH. .na BRIDGE GEOL. SURV. 
1933 THWAITES 1937 1939 1935 
l'1odf.fOn Mod/Jon !Jondstone) ~ Van Dsu Jordon member c: member 
sandstone ~ ·3 Jordon -ti member i: 
C) Jordan J f or ~ ~ ~o;!:~r § 6JJ ~rlCh ~ Nor,./oIA ~ <..:: meml;t. qflltJ/}( :::. JJ qf ~ member ~ ~ Ulrich 
Trempealeau ~ 
" ~ Ladi 
<>,) Ladl hlla/e. ~ c:: Lodi rormation ~ member [ on~~b~o;eJ ~-:3 member 
~ St Lawrence ~" ~ Jt. Lawrence 
.3 ~ VVicollet Cretif 
mem -bo.sal dolomite \-.ir:: member JrJond' cons. [member! 
"' ~ ~~~~:: < .~ 8adA..re. ~ Bod A.(e Mo..<'omanie .~ ~.~ ss}mem :c member ('ormation tJ e:5 I Hudson " § Hudson ~ ~1s § fludson 
eo': member ~~ {ssl mem. ~ member 
Fronconia .~ OoodenouJh .~ t:l-C:: IIiOOdtn"'ll .~ Tafjlors roILs {"ormation ~ member § .§~ {Sf} mem a member 
Ironton § Ironton g ~r.... l/ront;" § Ironton 
rormation ~ member L(: t.'.: Q (sJJmem ~ member 
GalesVIlle OuleHl/le Oolesvl/le [sandstone) 
member member member Eau Claire 0 ~ formation ~ ~ 
" " § 
Eau ClaIre ~ Eou Claire ~ ["au Claire ~ 
member <0..... [sandstone! ~ 
"5 <: member ] member ~ ~ 2 <> ~ 11t. Simon ~ !1t. Simon c:::. lit. Simon Mt. Simon 
{'ormatfon member [fondJtoneJ member 
m£mber 
PALEOZOIC: CAMBRIAN £9 
While the content of the St. Croixian is now seldom, if ever, ques-
tioned by the various authors who write on the Upper Cambrian, there 
has been a great deal of variation from the original definitions of the 
formations constituting the series. Winchell himself suggested the expan-
sion of the St. Lawrence to include the shales and greensands below, but 
the statement just made applies particularly to the Franconia sandstone, 
in which Berkey's "third trilobite bed of Owen," 11 or the Conaspis zone, 
and associated barren layers of the type locality ha ve come to represent 
only a minor part of the beds now included'" in that formation. Thus the 
Franconia has been extended slightly downward to include the Ironton 
member and expanded markedly upward to include sandstones and 
greensands of the Hudson and Bad Axe members, formerly regarded as 
part of the St. Lawrence formation. In addition to this, some new or dif-
ferent member names have been inserted, which for the most part agree 
with divisional names proposed for adjacent areas, although a few l\Iin-
nesota names are retained. 
In the outline of St. Croixian formations (see page SO), subdivisions 
and faunal zones are much as used by their original authors, with the ex-
ception of the changes noted above. In addition to the fossiliferous beds 
indicated, sparingly fossiliferous or barren beds are associated with the 
faunal zones of the different formations as parts of them, and thick 
masses of relatively barren rock may separate certain of the faunules 
mentioned, Aside from the adjustments in formational boundaries to 
conform to recent suggestions and the addition of member names, the 
outline represents only a minor change in the terminology used by the 
Minnesota Geological Survey for more than a score of years. :Most of 
the passing innovations in classification of the series have been avoided 
by the members of this survey, and an attempt has been made to prevent 
the ever changing use of terms which makes the literature confusing and 
difficult. (The relationship of this to various other classifications is shown 
in Ta ble 4.) 
DRESBACH FORMATION 
The term Dresbach sandstone was used by N. H. Winchell as part of 
his classification of :Minnesota formations in the second volume of final 
reports.'3 No adequate description of the rock is given with the term, 
11 C. P. Berkey, "Geology of the St. Croix Dalles," A merican Geologist, 21: 272 (1898). 
"E. O. Ulrich, "Notes on New Names in Table of Formations and on Pln'sical Evidence 
of Breaks between Paleozoic Systems ill Wisconsin," Transactions of the Wisconsin Academy 
of Sciences. Arts and Letters. 21: 90-94 (1934); A. C. Trowbridge ancl G. I. Atwater, "Strati-
graphic Problems ill the Upper Mississippi Valle~"" Bulletin of the Geological Society of 
America, 45: 45-50 (1934); W. H. Twenhofel, G. O. Raasch, and F. T. Tlmaites, "Cambrian 
Strata of Wisconsin," Bulletin of the Geological Society of A merica, 46: 1698-1706 (1935); 
W. H. Twenhofel, "The Greensands of Wisconsin," Ecol/omic Geology, 31: 473-7-1 (1936); 
C. R. Stanifer, G. M. Schwartz, and G. A. Thiel, "The St. Croixian Classification of Minne-
sota," Bulletin of the Geological Society of America, 50: 1227-44 (1939). 
13 N. H. Winchell, Geology of Jliinnesota (Final Report of the Geological and Natural 
Hislory Survey of rvrinncsota). Vo!' '! (18RR). p. xxii. 
MINNESOTA CAMBRIAN (ST. CROIXIAN SERIES) 
Stratigraphic Classification with Relationship to Beds Above and Below 
BEEKl\IANTOWNIAN SERIES 
Oneota Dolomite 
THICKNESS 
(in feet) 
ST. CROIXIA?>I SERIES 
.Jordan Sandstone (Winchell) 
Van Oser Member <,Yinchell) 
Coarse sand, massive beds, white to brown or reel. Sand grains often recon-
structed. Sparingly fossiliferous. Tellerina-Saukiella faunule ............. :20- 35 
Norwalk Member (Ulrich) 
.Medium to fine, white to yellow sand constituting the rock at the type 
locality. Usually unfossiliferous but at some places, such as Marine and the 
Osceola bridge, abundantly fossiliferous. Eurekia-Osceolia faunule 65- 85 
St. Lawrence Formation (Winchell) 
Lodi Member (Ulrich) 
Dolomitic shale and siltstone. Dike/ocephalus millnesotensis faunule. The 
Stillwater trilobite bed of Owen ......... . 
Nicollet Creek Member (Stauffer, Schwartz, and Thiel) 
Dolomite, sprinkled through with grains of glauconite. The quarry beds 
of this formation are along the Minnesota Ri\"er. Scaevogyra-Billillgsella 
10- 50 
faunule .......................................................... 0- 40 
Franconia Formation (Berkey) 
Bad Axe Member (Twenhofel. Raasch, and Thwaites) 
Dolomitic, vermicular, fine-grained sandstone and beds of sandy glauconite. 
Dikelocephalus postrectus faunule .... ............. . . . . . . . . . . .. 40- 65 
Hudson Member (Twenhofel. Raasch, and Thwaites) 
Sandstone and sandy glauconitic shales. Idahoia-Ptychaspis faunule. . . . .. 35- 70 
Taylors Falls Member (Stauffer, Schwartz, and Thid) 
Medium-grained gray to buff sandstone. Type of formation. May be abun-
dantl~' fossiliferous; several subfaunules can be distinguished. Conaspis 
faunule ........................................................... 15-100 
Ironton Member (Ulrich) 
Gray to yellow-brown sandstone. Reworked sands from the beds below. 
Camaraspis-Irvingella faunule .............. . 10- £:3 
Dresbach Formation (Winchell) 
Galesville Member (Trowbridge) 
JYfedium to coarse, nearly barren, yellow to white, friable sandstone 0- 50 
Eau Claire Member (Ulrich) 
Mostly a very fossiliferous gray to brownish sandstone with some shaly 
beds. This is Winchell's type of the formation. Crepicepha/lls faunule. First 
trilobite bed of Owen ............................................... 15-££5 
Mt. Simon Member (Ulrich) 
Coarse gray to white sandstone with quartz pebble zones. Crops out in Pine 
County and is penetrated in deep wells elsewhere 80-'100 
I"AKE SUPERIOR SERIES 
Hinckley Sandstone 
30 
PALEOZOIC: CAMBRIAN 3 1 
FJOURE 5 . - The Dresbach formation , Eau C laire member, in the north wall of the old 
T ostevin Quarrie a t Dresbach . 
but in his first volume of the same series he had used the name Dresbach 
stone 14 and had also given a general section of th e St. Croixian series for 
Winona County.' ;; This section gives a thickness of 130-165 feet of Dres-
bach formation exposed above the river level at the town of Dresbach. 
This, of course, includes much of the white sandstone above the Tostevin 
Quarries, ca lled Galesville by Trowbridge a nd in part included by Berke~' 
in th e Franconia sandstone. It is now called th e Dresbach formation 
rather than andstone because it a lso includes much shale. Undoubtedly, 
Winchell originally used the name chiefl y for the sandstone which was 
being worked in the Tostevin Quarries at Dresbach (see Figure 5) , but he 
included th e beds down to river level as well as those penetrated by the 
lead prospect shaft and those in the well drilled by D avis, giving a total 
of 88 feet below river level. Later he extended the Dresbach still further 
dO\vnward / 6 a nd in th e deep wells of the Minneapo lis region the forma-
tion thu s came to include all th e beds at lower levels down to the top of the 
Hinckley sandstone. 
The Dresbach formation is a white to gray and buff, fine to medium, 
even coarse-grained sandstone, occurring in thin to massive beds, some 
of which are cros -bedded. Glauconite is common but usually occurs as 
very fin e grains among the sand. Some of the sand tone la yers become 
thin or shaly and may contain mu ch clay or pas into a real shale, which 
is usually gray to bluish in color but may be red. Both ripple marks and 
mud cracks occur in th e shaly layers. Some of the thin beds of sandstone 
11 Ib id .. Vol. 1 (188+), p. 180. 
" Ibid., p . 258. 
10 N . H . Winchell . " Deep Wells as a Source of Water Supply for l\Iinneapoiis," American 
Geologist, 35: 268 (1905). 
3~ PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
in the lower quarry at Dresbach (now completely covered) are quite 
dolomitic. Several of these thin dolomitic layers have been broken up, 
and the fragments more or less rounded to form pebbles of an intrafor-
mational conglomerate. These pebbles are fossiliferous, carrying espe-
cially Dicello1nus politus, a'common fossil in the matrix and throughout 
the Tostevin Quarries. Deeper down, as shown by well records and more 
abundantly by outcrops to the east, extensive beds of sand occur. 
Whether these lower beds are fossiliferous and whether they are land or 
marine cannot be discovered from the drillings brought to the surface. 
The formation as exposed at Dresbach and at Taylors Falls is undoubt-
edly marine, since it contains an abundance of marine fossils. 
Outcrops at Winona combined with the record of city water well 
no. 2 indicate that the Dresbach formation may have a total thickness 
of more than 400 feet in Winona County. The sections at Taylors Falls, 
Chisago County, however, show only a small part of this great thick-
ness, although both top and bottom of the Dresbach formational rem-
nant are exposed. 
The following section, measured at Dresbach, includes the portion of 
the formation cropping out at the type locality and is one of the best in 
Minnesota. 
DRESBACH, WINONA COUNTY 
Type Section of the Dresbach Formation, Tostevin Quarries 
THICKNESS 
FRANCONIA FORMATION (in feet) 
Ironton Member 
DRESBACH FORMATION (top at 784.9 ft. A. T.) 
Galesville Member 
1 '2. Sandstone, coarse, yellow to white, massive. . . . . . . . . . . . . . . . . . . . . . . . . . . 24.0 
Eau Claire Member 
11. Sandstone with gray, shaly partings containing linguloid brachiopods. .. . 2.0 
10. Sandstone, gray to yellow. massive to thin-bedded. . . . . . . . . . . . . . . . . . . . 8.4 
9. Sandstone, massive, medium- to coarse-grained, gray, brown to reddish 
brown. Some beds are very hard, and some are crowded wit.h D-icellomus 
politus .......................................................... 21.3 
8. Sandstone, white to brown, cross-bedded, fine- to medium-grained. .. .. .. 26.6 
7. Sandstone. white to yellow, cross-bedded, fine- to medium-grained, thin 
to massive beds .................................................. 23.0 
6. Sandstone, partly covered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3 
5. Sandstone, gray to buff, massive ......... . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.'2 
4. Sandstone, quarry rock (Tostevin Quarries; top at 668.1 ft. A. T.). gray to 
buff, medium-grained, massive. Abundant fossils include D-icellomus poli-
tus. Lin(Julella phaon, Hyolithes primordialis, Crepicephalus iowensis, 
Lonchocephalus minor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.0 
3. Shale, sandy, gray, with mud cracks and shaly gray sandstone. Common 
fossils are D-icellomus politus, Lingulella ampla, Hyolithes primordialis, 
G-repiceph(du_y iowensi.y, Anomocarella? uJinona, Lonchocephalus minor, 
Dresbachia amata ................................................ 12.1 
2. Sandstone. gray, massive. with a few fossils, down to pool level at 639.0 £t. 
A. T. .... ...... ...... ... .......... ..... .... .... ...... ............ 3.0 
1. Shale, sandy, gray, mud-cracked, with irregular layers of gray sandstone. 
Dicellomus politus, Lingulella ampla, and others common. These beds are 
now below water level. (Mississippi River [oldllevel at 63'2.5 ft. A. T.). . . . 6.5 
PALEOZOIC: CAMBRIAN 33 
Mt. Simon Member. - The Dresbach formation is divided into three 
members. the lowest of which is usually a coarse white to pink and 
brown sandstone. with somc conglomerate or quartz pebble horizons. It 
is typically exposed in the hill, commonly called Mount Simon. near Eau 
Claire. Wisconsin, and was given the name Mt. Simon sandstone by 
Ulrich. '7 In Wisconsin this sandstone generally rests on the pre-Cam-
brian granites and related rocks; but. as already noted. over much of the 
adjacent part of Minnesota it lies on the Hinckley sandstone (see above, 
pages 17-2:3). Its Minnesota outcrops are confined to Pine County along 
the St. Croix River and its tributaries above the falls. but it is en-
countered frequently in deep wells in southeastern :l\1inncsota. It is ap-
parently without fossils exccpt for trails and burrows, although the 
rarity of outcrops in :l\1innesota docs not afford much opportunity to 
search for fossils. 
Eau Claire Member. - The middle portion of the Drcsbach forma-
tion has been named the Eau Claire member by Ulrich 18 from the out-
crops on Mount Washington near Eau Claire. Wisconsin. It is the highly 
fossiliferous portion of the formation occurring in the Tostcvin Quarries 
at Dresbach. Minnesota, which is Winchell's type section of the Dresbach 
formation. In general, the Eau Claire member is a medium- to fine-grained 
gray to buff sandstone with beds and partings of gray shale, but it may 
include conglomerates, and over large areas its shales may be red. Sev-
eral good outcrops occur in the immediate vicinity of Dresbach, particu-
larly at Mineral Bluff and at Dakota. A good outcrop also occurs at 
Taylors Falls, but in general the greater portion of this member is 
covered or lies below drainage level. 
The Eau Claire member carries a fauna characterized by Crepicep/wlus 
I:owensis. It is composed of a great many individuals but not a large number 
of species. In the shales Obolns matinalis and Linglilepis aCllminata are ex-
ceedingly abundant. The Cre picephalus zone is Owen's first trilobite bed. 
but two other faunal zones have been discovered in the Eau Claire. The 
lower has been designated the Cedaria zone by Twenhofel, Raasch, and 
ThwaitesY A few fossils representing this zone were collected from the 
lower beds, now mostly covered by the higher lenl of the water in the 
river pool at Dresbach. The upper is the Aphelaspis zone. which was found 
by Trowbridge and Powers cO near the upper limit of the member in Nigger 
Coulee about two miles north of Hudson. 'Visconsin. This upper faunule 
has been found in l\!Iinnesota only in the reel shale cuttings from the 
"Vaconia well, not recognized as Eau Claire at the time."' 
17 In C. D. Walcolt, "Dikelacephalus and Other Genera of the Dikelocephalinae:' Smith-
sonian Miscellaneous Col/ections, 57: 354 (1914). 
18 Ibid., p. 354. 
'0 "Cambrian Strata of Wisconsin," B1llletin of the Geological Society of America. 46: 
1694-95 (1935). 
'0 In G. O. Raasch, Guide Book of the Ninth Anllllal Field COllferellce (Kansas Geological 
Society. 1935), p. 306. 
"C. R. Stauffer. "Age of the Red ClasLie Series in Minnesota," Blll/elin of the Geulogical 
Society of America. 3il: 474-76 (] 9'27). 
3-l PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Galesl'ille JI ember. - The upper member of the Dresbach is also a 
sandstone and nearly as barren of fossils as the lower division. In W'iscon-
sin it bears certain marks which have suggested land or fresh-water sedi-
mentation. To this more or less barren sandstone, aggrcgating about 86 
feet at the t?pe locality (Galesville, Wisconsin), Trowbridge and Atwater"" 
ha ve given the name Galesville member. This member is not very well 
developed along the lVlississippi River, where it seldom exceeds 20 to 30 
feet, but it crops out abundantly along the lower portion of the Mississippi 
bluffs in lVIinnesota from Winona County southward. 
:Much of the Galesville is apparently without fossils, but in some re-
gions sandstones that appear to belong to this member contain fragments 
of oboloids, and the shaly partings carry Lingulella. Perhaps, in part, it 
grades laterally into fossiliferous beds not distinguishable from those 
belonging to the Eau Claire member. At the type locality it passes gradu-
ally downward into typical Eau Claire sandstones and often appears to 
grade upward with equal regularity into beds that must represent the 
Ironton member of the Franconia formation and which are certainly fossil-
iferous. Furthermore, numerous brachiopod fossils were found by the 
authors approximately 40 feet above the base of the Galesville member 
at its type locality. The fossils are preserved in thin grayish green layers 
of shale in the sandstone. Some of the beds at Galesville near the horizon 
at which the lower contact is drawn contain an abundance of fragmentary 
Dicello/llus shells, resembling those in the Galesville beds to the west of 
the Mississippi River; and the appearance of the intervening beds leads 
one to expect fossils even where they have not been found. In fact, this 
member does not seem much more barren than many another horizon within 
the St. Croixian series which happens to be poor in fossils. 
To the east of the type locality the Galesville is reported in part a 
fresh-water or even an eolian deposit."" It is quite possible that it may 
have a land phase, and part of it may even be a sand dune deposit on the 
shores of a sea which contained an abundant life and in whose accumu-
lating sediments of shallow water a highly fossiliferous formation was 
being deposited. Thus, to the west or offshore, the same horizon might 
ha ve become quite fossiliferous. This is also suggested by the eastward 
disappearance of the fossils in the main part of the Dresbach formation."" 
TwenhofeL Raasch, and Thwaites "5 give a section for Dresbach, Min-
nesota, suggesting 44 feet of sandstone and covered interval as the Gales-
ville. The section at that point varies somewhat in exposure from year 
to year, and part of that which at one time was covered has been found 
to be fossiliferous when later exposed. The above-mentioned authors have 
""Stratigraphic Problems in the Upper Mississippi Valley." Bulletin of the Geological 
Society of America. 45: 45 (1934). 
'" W. H. T\\'etlhofel. G. O. Raasch, and F. T. Thwailes, "Cambriall Strata of Wisconsin," 
Bulletin of the Geological Society of A merica, 46: 1697, 1714, 171,3 (193,3). 
" Ibid., pp. 1694. 1695. 
"" Ibid., p. 1736. 
PALEOZOIC: CAMBRIAN 35 
drawn the top of the Galesville 6 to 14 feet higher than members of this 
survey have placed the top of the Dresbach, but the Ironton member or 
basal portion of the Franconia sandstone is not typically developed there, 
and it might easily be questioned where the line marking its base should 
be drawn. Farther southward the same question arises as to the disposi-
tion of the sandstones in the cliffs along the highway. The upper part of 
these outcrops is certainly Franconia, but the lowcr part may be the Gales-
ville member of the Dresbach formation. The finer-grained portion is 
probably fossiliferous, and it is certain that some layers have abundant 
fragments of Dicellomus polihlS or a very similar form well up to the base 
of the Ironton. 
FHANCONIA FORMATION 
As defined by Berkey, the Franconia is a medium- to fine-grained white 
to yellow sandstone lying deep in the St. Croixian series. By the fauna it 
can be traced from Iowa northward to Taylors Falls on the St. Croix River, 
and remnants may occur farther to the north in Pine County. In discussing 
the geology of the St. Croix Dalles, Berkey adopted Norton's"G term, 
Basal Sandstone series, to include the "sandstones, shales, and conglomer-
ates between the base of the overlying St. Lawrence formation and the 
Keweenawan floor.""' That he employed the term St. Lawrence forma-
tion in its prevailing meaning is evidenced by his continual reference to 
the shales of that formation and to the abundance of its glauconite. He 
also illustrated a polished specimen showing "a splendid development of 
alternating bands of sand and green shale" which was "obtained at the 
foot of the falls at Osceola and belongs to the St. Lawrence formation." "8 
:Moreover, the faunal list "" which he gave for the St. Lawrence formation 
includes species that are known only in the shales and sandstones below 
the dolomitic beds cropping out at Judson or at the type locality at St. 
Lawrence. Winchell thought the sandstones occurring along the creek 
and in the village of Franconia were part of the Dresbach formation, but 
Berkey found them to be more fossiliferous here than in most localities 
and to carry a somewhat different fauna. This, together with the unusual 
thickness of the sandstone, led Berkey to consider it as a distinct strati-
graphic unit. 
When it came to naming the formation, Berkey said that "the upper-
most subdivision fof the Basal Sandstone series] is a sandstone exhibiting 
two phases: (a) an incoherent fine sand, which is underlain by (b) more 
compact and thick-bedded layers. Thin seams of green shale occasionally 
appear in this bed. Its thickness is about 100 feet at its most favol'abie 
exposure. Fossils are not well preserved within it, and they are not abun-
'" "Artesian "'ells or Iowa." Annual Report of the Iowa Geological SUrI'eyfor lS9G 
(1897). Vol. G, p. BO. . 
:: C. P. Berkey, "Geology or the St. Croix Dalles." A merican Geologist. '20: 372-73 (1897). 
-, lIJld .. '2I: 139. 
". /l;id., 21: ~271. 
36 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
dant except in one horizon. Because of the exceptionally fine exposures of 
this formation in the vicinity of the small village of Franconia, this upper-
most division of the series is called the Franconia sandstone.":JO More-
over, he further fixed the limits of the new formation by its description: 
"The uniform white color, varying locally to brown or yellow through 
ferric oxide stains, the rather angular character of the grains, the porous 
and friable nature of the stone, the development of minute micaceous 
flakes among the sand grains, the complex veining produced locally by 
infiltrated iron oxide, a thick-bedded structure exhibited by exposed bluffs, 
thin seams of greenish clay shale frequently magnifying the bedded ap-
pearance, and the general lack of calcareous matter are characteristics of 
the Franconia sandstone. The few fossils which occur in the limited hori-
zons are casts (molds) from which all traces of the original shells have 
been removed.":n The second subdivision, consisting of shales and green-
sand, he called the "Obolella polita" zone; this he definitely assigned to the 
Dresbach. As thus defined. the Franconia includes only the Oonaspis zone, 
with a thickness rarely exceeding 100 feet, or less than half of the beds 
now generally included within the formation. In fact, the rocks thus 
described are merely the Taylors Falls member 3" of the Franconia forma-
tion. 
Ulrich 33 expanded the use of the term Franconia to include all of 
the sandy, shaly glauconitic beds between the top of the Conaspis zone 
and the base of the conglomerate and shaly zone at the bottom of the 
typical dolomites of the St. Lawrence formation. He also included within 
the Franconia the "Obolella polita" zone, or the portion he called the Iron-
ton member."4 The Ironton member thus indicated, however, was con-
sidered by Berkey Xu to be the upper member of the Dresbach shales. 
This expansion of the Franconia formation suggested by Ulrich has been 
followed by the Wisconsin geologists 3<3 and by various other students 
of the Upper Cambrian.:" It has also been used by the United States 
Geological Survey 38 and has lately been accepted by members of the 
Minnesota Geological Survey."" The Franconia formation as thus defined 
30 Ibid., ~O: 373,377. 
31 Ibid., ~1: 140--41. 
32 C. R. Stauffer, G. M. Schwartz .. and G. A. Thiel, "The St. Croixian Classification of 
Minnesota," Bulletin of the Geological Society of America. 50: H!39 (1939). 
33 "Notes on New Names in Table of Formations and on Physical Evidence of Breaks 
between Paleozoic Systems in Wisconsin," Tmnsaction,y of the Wisconsin Academy of Sci-
ences, Arts and Letters, 21: 90--94 (1924). 
34 Ibid., pp. 93-94. 
"" "Geology of the St. Croix Dalles," American Geologist, ~O: 373, 374, 377 (1897). 
3(l W. H. Twenhofel, G. O. Raasch, and F. T. Thwaites. "Cambrian Strata of Wisconsin," 
Bulletin of the Geological Society of America, 46: 1697-1705 (1935). 
37 Guide Book of the Ninth Ann·lUtl Field Conference (Kansas Geological Society, 1935), 
Fig. 2 (facing p. 21); also pp. 4.54-f!5. ... . 
38 Josiah Bridge, The Correlatwn of the Upper Cambrian Sectwns of MUJSOUTl and Texas 
with the Section in the Upper Mississippi Valley (U. S. Geological Survey, Professional Paper 
186. 1937). p. 234. 
·30 C. R. Stauffer, G. M. Schwartz. and G. A. Thiel, "The St. Croixian Classification of 
Minnesota," Bulletin of the Geological Society of America, .50: 1~27-44 (1939). 
PALEOZOIC: CAMBRIAN 37 
FIGU RE 6. - The T aylors F all s and Ironton members of the Franconia formation o\'erl ying 
the Dresbach formation along the highway cut at the south edge of T ay lors F alls . 
includes sandstone, sandy hale, thick beds of sandy gla uconite, and 
at places sandy dolomitic beds of much importa nce. It is composed of 
four fairl y di stinct members, th e lowes t of which is the Ironton. 
honton M em beT. - The name Ironton \Va suggested by Ulrich 40 
for the 5 to 15 feet of medium to coarse brown sandstone cropping out 
in the vicinity of the town of Ironton, Wisconsin . As described by lrich, 
"the Ironton member is composed mainly of reworked. wa hed and rela-
tively coarse residual grains of Dresbach sa ndstone, th e surface of which 
had previously been subj ected to subaerial leaching and wear. The line 
of th e break between th e two formations - Dresbach and Franconia-
lies at th e undulating plane where washing a nd sorting of th e loose 
quartz grains of th e und erlying formation is first indicated . In other 
words, the Ironton sandston e member extends downward to the lowest 
plane, indicating reworking and red eposition of the weather-loosened top 
sands of the underlying Dresbach formation ." 4 1 
In Minnesota th e Ironton member i well developed at T aylors Falls 
(see Figure 6). but traced down th e St. Croix Valley it soon passes be-
neath river leveL D own th e Mississippi it ri es again a nd is easily traced 
from the vicinity of Kellogg southward. It nearly always begins abruptly 
with a coarse brown sandstone (see Figure 7) carrying an abundance of 
oboloid brachiopods and several trilobite, of which the most common is 
40 "Notes on New Names in T able of Formations and on Phys ical Evidence of Breaks 
between Paleozoic Systems in Wisconsin ," Transactions of t he Wisconsin Academy of Sci-
ences . Arts and Letters, 21: 93-94 (1924) . 
U Ibid ., p. 93. 
FIGURE 7. - The Galesvi lle-Ironton contact along U. S. Highway No. 61 at Snake Creek, 
three and one-hal f mile outhwes t of Kellogg. The Galesville here i sparingly fossiliferous. 
FIGURE 8. - The Taylors Falls member of the Franconia sandstone in the highway cut at 
Taylors Falls. 
38 
PALEOZOIC: CAMBRIAN so 
Ca-maraspis he·misphericus; its shore phase is a conglomerate carrying 
numerous species of the gastropod Hypseloconus. Its thickness varies 
from 1 to 15 or more feet. Occasionally it is almost impossible to draw 
the line between it and the underlying formation, and it may carry 
prominent beds of sandy glauconites. 
Taylors Falls Member. - Above the Ironton lies the Taylors Falls 
member of the Franconia formation. It is the original member of the forma-
tion and as such was described by Berkey as a medium- to fine-grained 
gray to buff sandstone about 100 feet thick. His type section is at Fran-
conia, Minnesota, but the fine rock cut along the highway just south 
of Taylors Falls is now considered the type section of the member. (See 
Figure 8.) The section exposed along Lawrence Creek at Franconia, 
Berkey's type locality, is as follows: 
FRANCONIA, CHISAGO COUNTY 
Type Section of the Franconia Sandstone, Lawrence Creek 
24. Drift, covered to Franconia railroad slation (915 ft. A. T.) .............. . 
FRANCO:\IA FOR;\IATION 
Taylors Falls Member 
23. Sandstone, white to yellow and brown, thick-bedded. medium-grained .. 
22. Sandston€', buff. fine-grained. massive to thin-bedded. lower part very 
ferruginous. Trilobites common in lower 4 feet are COllaspis perseus, 
Taenicephalus bipunctatus, and Jrilburnia sp ........................ . 
21. Sandstone, yellow to buff, partly covered ........................... . 
20. Sandstone. fine-grained. micaceous, buff to tan ...................... . 
19. Sandstone, fine-grained, thin-bedded to shaly, buff to brown ........... . 
18. Sandstone. fine-grained, massive, white to tan. Contains fragments of small 
brachiopods and trilobites ......................................... . 
17. Sandstone. fine-grained, thin-bedded. tan to white. showing glanconite 
and patches of brown iron slain .................................... . 
16. Sandstone. fine-grained. white to tan. massive. Parts micaceous and glau-
conitic. Brachiopod fragments common ............................. . 
15. Sandstone. fine-grained. shal~'. gray to buff, glauconitic. micaceous ..... . 
14. Sandstone, fine-grained, white to massh'e .......................... . 
13. Sandstone, mostly covered ........................................ . 
12. Sandstone. fine-grained, buff to tan. thin-bedded. micaceous ........... . 
II. Sandstone, mostly co\'ered ........................................ . 
10. Sandstone. fine- to medium-grained. thin-bedded, glauconitic. interstrati-
fied with thin layers of buff shale .................................. . 
Ironton Member 
9. Sandstone. medium-grained. white to gra~', massive. cross-bedded. glau-
conitic. with occasional thin layers of gray shale. Occasional quartz pebbles. 
Dicellomlls sp .. Camaraspis hemisphericlls, and frag111ents of other fossils 
8. Sandstone. fine-grained. white to gray. with much greenish shale and 
locally slreaks of iron stain ...................................... . 
7. Sandstone. fine- to medium-grained. friable. white to gray and brown. 
in part glauconitic. Gray-green shales alternate with thin. lenticular layers 
of sandstone. especiall~' in lower part. Dicellom ns abundant. especially in 
the upper part ................................................... . 
6. Sandstone. mostly cOYered ........................................ . 
5. Shales. gray to bluish gray. arenaceous. alternating with thin layers of 
sandstone ....................................................... . 
THICKNESS 
(in feet) 
78.5 
22.0 
8.S 
2.0 
3.0 
2.0 
2.5 
1.5 
4 .. 5 
0.5 
2.0 
2.0 
8.0 
17.0 
6.5 
11.7 
1.5 
.S.8 
3.5 
2.8 
40 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
4. Glauconite, sandy, green ........................................... 1.5 
3. Covered interval .................................................. 2.5 
2. Sandstone, medium to coarse, poorly sorted, fossiliferous . . . . . . . . . . . . . . . 6.0 
KEWEENAWAN 
1. Massi\'e diabase and flows to level of St. Croix RiYer. . . . . . . . . . . . . . . . . . 30.0 
The lower 5 or 10 feet of sandstone overlying the flows in this section 
have been referred to the upper Dresbach (Galesville) by Trowbridge.4 " 
The presence of Ironton fossils, however, in sandstone resting directly 
on the Keweenawan igneous rocks a few hundred feet east of Berkey's 
type section is evidence against such an interpretation. 
The Taylors Falls member does not carry a large fauna, but there 
are a large number of individuals in it, especially in the beds above the 
middle of the member, where the typical Conaspis trilobites are abund-
ant. It is quite possible to separate the fauna into several partially inde-
pendent faunules, as Raasch';3 has done in Wisconsin, but over large 
areas it is more difficult to identify the minor faunal divisions, and that 
has not seemed practicable in the present study. 
Hudson ~Mem.ber. - Immediately above the Taylors Falls member is 
the Hudson of Twenhofel, Raasch, and Thwaites!4 It is typically de-
veloped at Hudson, Wisconsin, but is often exposed in Minnesota, where 
it consists of gray to buff or pink sandstones and gray shales, all more 
or less glauconitic. The member is really an expansion of Wooster's Hud-
son trilobite bed!5 which marks the lower portion of this member. The 
upper half is particularly fossiliferous, with two faunules that are easily 
distinguishable but still carry parts of a common fauna. The lower of 
these is especially characterized by Ptychaspis gmllulosa and Idahoia 
wisconsinensis, the upper by Idahoia hamulus. 
Bad Axe 1U ember. - The top member of the Franconia formation, as 
now generally recognized, is the Bad Axe. It is a sandy mudstone and 
sandy glauconite, in :Minnesota often full of worm trails and burrows 
which obliterate any other forms that may have been present and would 
otherwise have left fossil remains. The Bad Axe member was named by 
Twenhofel, Raasch, and Thwaites 46 from the Bad Axe Valley, south of 
La Crosse, where several good sections are reported; the Victory section 
is particularly mentioned. This member is more or less characterized by 
a few Dikelocephalus sp., Saukiella sp., and others that suggest forms 
found higher in the series. This is Ulrich's Dikelocephalus postrectu8 
fauna, which he evidently includes in the upper part of his Mazomanie 
.2 Guide Book of the Ninth Annual Field Conference (Kansas Geological Society, 1935), 
p.199 . 
.. Ibid., p. 409 . 
.. "Cambrian Strata of Wisconsin," Bulletin of the Geological Society of America, 46: 
1701. 1704 (I935). 
"L. C. Wooster. Geology of wi,'consin, Vol. 4 (188'i). pp. 109. llO. 112. and PI. 6 . 
• 0 "Cambrian Strata of Wisconsin." Bulletin of the Geological Society of A merica, 46: 
1702, 1703, 1705, 1733-36 (1935). 
PALEOZOIC: CAMBRIAN 41 
formation ." Th e Bad Axe member is well shown at numerous places 
a long th e Minnesota side of the Mississippi River from Frontenac and 
Lake City outh eas tward to the Iowa line. It is especially well exposed 
and carries the characteristic fauna in Stockton Hill (see Figure 9) along 
U. S. Highway No. 14 at th e western edge of Winona. However, Bad Axe 
FIGU RE 9. - The Bad Axe member of the Franconia [ormation, Stockton Hill , Gilmore 
Valley, Winona. 
foss il s are exceedingly rare and poorly preserved in Minnesota, and al-
though th e Bad Axe lith ology is fairl y characteristic, the place of this mem-
ber in th e formation must usually be inferred from th e interval between 
the excellent fossiliferous horizons of the Hud son member and the con-
glomerate zone generally marking th e ba e of the 1 ico llet Creek member 
of the St. Lawrence. 
The lower members of th e Franconia formation are well developed and 
also well shown a t Franconia and Taylors Falls. The upper members are 
fairly well shown along the bluffs southward from the vi llage of Franconia. 
but better at Marine and in the bluff still farth er to the outh. 
<7 E. O. Ulrich, "The Cambrian of the Upper Mississ ippi Valley," Bulletin of the Public 
lI1usewIn of Milwaukee, 12: 52 (1930). 
4'2 PALEOZOIC A D RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
FrGURE 10. - The Nicollet Creek member of the St. Lawrence formation in the old Hewitt 
and Beason Quarries at St. Lawrence. 
ST. LAWRENCE FORMATION 
The name St. Lawrence limes tone was used first by Alexander Win-
chell 4 8 in his report on the Belle Plaine region of Minnesota, but th e 
formation was described by N. H . Winchell 40 from th e quarries in Sec-
tion 28, St. La wrence Township, Scott County, Minnesota. Th ese quar-
rie were opened about 1865 in the remnant of an old rock terrace about 
45 feet above the present level of th e Minnesota River . Th e stone was 
used as the building material for a hotel and two or three local hou ses 
but never found a wide market. R ecently it has been exploited for the 
manufacture of rock woo!. Winchell described the quarry rock as a buff 
to reddi sh or yellowish gray arenaceous dolomite sprinkled with grains 
of glauconite; Shumard 50 had referred to it as a "salmon-colored magne-
sian limestone," probably from weathered outcrops which usually show 
reds and browns owing to altered glauconite. 
Although the original description covers chiefly the quarry beds as 
shown at St. Lawrence (Figure 10). Winchell gradually expanded his 
original definition to include the shaly beds above and below the quarry 
rock. Both th ese horizons are sandy, shaly dolomites which approach the 
appearance of the beds in the quarry at th e type section . Such beds occur 
.. R eport of a Geological Survey of the Vicinity of Belle Plaine, Scott County, Minne-
sota (Senate Document. St. Paul , 1872), p. 10 . 
•• Second Annual Report of the Geological and Natural History Survey of Minnesota 
(1874), pp. 152-55. 
,. In D . D . Owen, Report of a Geological Smvey of Wisconsin, Io wa and Minnesota 
(18.52), p. 483. 
PALEOZOIC: CAMBRIAN 43 
in the bottom of Sand Creek at .Jordan and were encountered at much 
lower levels in the wells drilled in that vicinity. Dolomitic beds are likely 
to occur at other horizons within the series, cven within the Dresbach 
formation; hence their presence is not of importance in fixing the limits 
of forma tional divisions of the St. Croixian series. 
As a whole, this formation consists of gray to brown or buff dolomitic 
sandstones, dolomitic shales and siltstones, and beds of dolomitic lime-
stone, persistent over large areas. The sandy dolomitic beds may alter-
nate with sandy greenish shale, or such shale may constitute a very 
important part of the formation. Glauconite is a common constituent. 
especially of the more dolomitic beds and of the lower part of the forma-
tion. At some places this material is so abundant that the rock appears 
green, and near .Judson it may constitute the greater part of the dolomite. 
The following section of the Hewitt and Beason Quarries is that given 
by N. H. Winchell/,J and is essentially the same as that gn'en by Alex-
ander Winchell in his report of the previous year. 
ST. LAWRENCE, SCOTT COUNTY 
'Vinchell's Type Section of the St. Lawrence Formation. Hewitt and 
Beason Quarries 
1. Beds 2 to 4 inches. with shaly partings and green specks ................. . 
2. Beds 14 to 18 inches. hard. siliceous. occasionally porous from crystallization. 
specked with green. showing crystals of brown spar. A good building stone ... . 
3. Somewhat ferruginous. hard. and crystalline; less porous than no. 'i ......... . 
4. Beds irregular. specked with green. and showing green surfaces ........... . 
.5. Band of greenish shale. sandy ......................................... . 
6. Beds 2 to 4 inches; magnesian limestone; seen about 1 ft. ................. . 
Total ............................................................ . 
THICKNESS 
(in feet) 
3 
4 
0.5 
14.5 
Along the creek below the old Hewitt and Beason Quarries there are 
about 17 feet of arenaceous gray shale and thin-bedded, sandy dolomite 
continuing the section to a lower level. This may be the Bad Axe mem-
ber, but it has not been found to be fossiliferous. hence its correlation is 
doubtful. Winchell identified the arenaceous dolomite and the dolomitic 
shales in the bottom of Sand Creek at .Jordan as the upper part of the 
St. Lawrence formation and stated that '·the well of the lower brewerv 
... was dug 6 feet in sandstone and then 5 feet in this yery hard lim~­
stone. Below this it was drilled 25 feet, all the way in lillle~tone, which 
was thought to grow harder .... All these exposures of St. Lawrence 
limestone in the Minnesota Valley probably exhibit its upper portion." .-,c 
The log of the Minneapolis and St. Louis Railway well at .Jordan 
continues the section down through the Franconia san(lstone. After pass-
ing through 112 feet of alluvium, this well penetrates 98 feet of shale and 
,1 Second Annual Report of the Geological (Lnd Natural History Sun'ey of llIil1llesuta 
(1874). pp. 15'2-55. 
G2 N. H. Winchell. Eighth Annual Rf)>ort of the Geological and Natural History 81lrl'ey 
of Minnesota (1880). pp. ]04-5. 
44 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
dolomite referred by Hall. "Meinzer. and Fuller"' to the St. Lawrence 
formation. As the elevation of this well location is at or near the St. 
Lawrence-Jordan contact in the nearby Sand Creek. it follows that 100 
feet or more of rock have been removed at the railroad well location by 
the erosion of River Warren. and that the total thickness of rock as-
signed by Hall and his associates to the St. Lawrence is about 200 feet; 
this includes. however, the Bad Axe and Hudson members of the Fran-
conia. as the latter is now defined. The records of deep wells to the south 
show essentially the same thickness :'. of dolomitic beds at this horizon, 
but it is not very clear what thickness should be assigned to the St. 
Lawrence formation to the southwest in Iowa. 
In commenting on the formation at its type locality, Winchell says 
that "the St. Lawrence limestone was so named in the report of prog-
ress for 1873. It is the same that Professor Irving named, in 1875, the 
'Mendota limestone.' This limestone is unfavorably exposed in the Min-
nesota Valley. Its greatest thickness, known there, is only about 15 feet, 
but it seems to extend, with some shaly components, distinctly over a 
thickness of about 30 feet in the Mississippi Valley; while, if the shaly 
beds with which it is associated and into which it seems to graduate, be 
included under this term, it will include beds to the amount of nearly 
200 feet. This is the chiefly fossiliferous portion of the St. Croix forma-
tion [series]." ;,;, This expansion of the formation by Winchell to cover great-
FARIBAULT, RICE COUNTY 
City Waterworks Well No.1 (Drilled in 1910)'* 
THICKNESS 
(in feet) 
Q5 7. Gravel ...... "........... . .......................................... . 
6. St. Peter sandstone ....... . ........ " ............................. . 
5. Shakopee, New Richmond, and Oneota . . ..................... . 
4. Jordan sandstone ......... . .......................... . 
3. St. Lawrence shale ................................................... . 
~. Dresbach (Franconia) sandslone ....................................... . 
1. Dresbach shale and sandsto:Je ........................................ . 
Total ............ . 
* After N. H. Winchell and Warren Upham. 
75 
Q~5 
100 
QOO 
100 
~5 
750 
er thickness was an interpretation he made later. as is shown by the log 
and report on the city waterworks well no. I at Faribault, in which Win-
chell and Upham assign 200 feet of beds illlmediately below the Jordan 
sandstone to the St. Lawrence formation."; This checks fairly well with the 
thickness assigned to the formation by Hall and others in the wells at Mer-
'3 Geology and Underground Waters of Southern Minnesota (U.S. Geological Survey, 
Water Supply Paper Q56, 1911), p. 340. 
G4 W. H. Norton, "Deep Wells of Iowa," Annual Report of the Iowa Geological Survey 
for 1927 (l9'28). Vol. 33, pp. 157, ~76. 396. and pas,s·;m. 
e.:; N. H. Winchell, Fourteenth Annual Report of the Geological and Natural History 
Survey of Minnesota (1886), p. 836. 
c,.j C. R. Stauffer, "Type Paleozoic Sections in the Minnesota Valley," Journal of Geology, 
4'2: ~41-42 (1984). 
PALEOZOIC: CAMBRIAN 
riam Junction,'" Chaska, and Minneapolis, although it obviously includes 
both the Bad Axe and the Hudson members, which have been transferred 
to the expanded Franconia formation. 
Nicollet Creek Member. - The St. Lawrence formation, as that name 
is now used, consists of two members, the lower being the Nicollet Creek 
member and the upper the Lodi shale. The Nicollet Creek member is 
nearly all dolomite and is especially well developed along the Minnesota 
River in the vicinity of Judson, where it was formerly quarried at several 
localities. It has a total thickness of about 35 feet. It is a gray to salmon 
pink or brown dolomite, much of which is richly sprinkled with grains 
of glauconite. Most of the beds range from over 2 to 5 or 6 inches in 
thickness, but some layers may be much thicker. Some beds carry 
rounded concretions. Others contain pebbles and are true conglomerates; 
at places the lower portion is intercalated with beds of glauconitic sancl. 
Occasionally a few fossils can be found in these beds, but they are com-
paratively rare and probably do not represent a very large assemblage 
of forms. 
The type section of the Nicollet Creek member is in Nicollet County, 
along a creek of the same name which enters the :Minnesota River from 
the north, nearly opposite the village of Judson. Nicollet Creek is the 
outlet for several lakes six miles or more to the north, of which Swan 
Lake is the largest. Near the river (EYl Sec. 33, T. 109 N., R. 28 W.) 
this creek flows through land owned by Mrs. Katharine Brown, cutting 
a fine section in the lower portion of the Nicollet Creek member. 
HEBRON, NICOLLET COUNTY 
Type Section of the Nicollet Creek Member, Nicollet Creek, Opposite Judson, 
Mrs. Katharine Brown's Farm 
11. Covered to terrace level, a dark, sandy loam 
ST. LA WRENeE FORMATION 
Nicollet Creek Member 
THICKNESS 
(in feet) 
2.0 
10. Dolomite, sandy, glaucollitic, thin-bedded, gray. . . . . . . . . . . . . . . . . . . . . . . 4.5 
9. Dolomite. even-bedded, glauconitic, gray to pink and brown. hard. with 
lenses of fine glauconitic sandstone .................................. 6.0 
8. Dolomite. hard, thin-bedded, gray, glauconitic, sandy, with lenses of 
glauconitic sandstone carrying concretions of dolomitic sandstone ... . . . . 'l.'; 
7. Conglomerate. hard, massive, gray, glauconitic. sandy, dolomitic. . . . . . . . 2.5 
6. Sandstone, glauconitic. gray to green, some worm borings . . . . . . . . . . . . . . 1.8 
5. Conglomerate, sandy, glauconitic. The pebbles are lighter in color than the 
matrix .......... ............... '. . . . . . . . . . . . . . . . . . . 0.3 
4. Sandstone, fairly thick-bedded, laminated. fine-grained. dolomitic, glau-
conitic ......... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 
3. Sandstone. thin-bedded, glauconitic, fine-grained. gray. slightly dolomitic 3.0 
-2. Covered to creek leveL but dolomite on opposite side of river. . . . . . . . . . . . 'l.5 
1. Covered. probabl~' much of it dolomite. to .Minnesota RiYel' level at 760 ft. 
A. T. ..................................................... 9.5 
67 C. W. Hall. O. E. :Meinzer. and M. L. Fuller. Geology and Underground Iraters of 
Southern Minnesota (U. S. Geological Survey, Water Supply Paper 256. 1911). pp. 150, 341, 
and PI. 10. 
46 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Lodi ]Hember. - The Lodi shale member of the St. Lawrence forma-
tion is the dolomitic, sandy, shaly phase occurring between the distinctly 
dolomitic beds represented by the type section at St. Lawrence and the 
overlying sandstone as found in the quarries at Jordan. This member 
includes a stratigraphically important siltstone traceable over all the 
southeastern part of Minnesota and bearing a remarkable trilobite and 
graptolite fauna. The siltstones were referred to by Owen as "ash-colored 
and yellowish argillo-calcareous and magnesio-calcareous beds containing 
Dikelacephalus minnesatensis." 58 They carry the fauna of his "fifth trilo-
bite bed" or the "Stillwater trilobite bed" and constitute one of the most 
satisfactory faunal zones of the whole St. Croixian series. 
The name Lodi shale was proposed by Ulrich 59 for these dolomitic 
shales and siltstones presumably occurring in the section at or near Lodi 
in southwestern Columbia County, Wisconsin. The fossil-bearing beds 
of the member are widely distributed and easily recognized over the 
Cambrian-covered portions of Minnesota, Wisconsin. and Iowa. At some 
places. as in the outcrops along Sand Creek in Jordan. or perhaps in the 
road cuts and old quarries at Judson, the beds of this member are dol-
omitic up to the contact with the overlying formation. Although both 
members of the St. Lawrence are readily recognized along the Minne-
sota River, better sections occur along the St. Croix and the Mississippi 
rivers. An excellent section of the Lodi member occurs in Fairy Glen, 
at Stillwater. Others of equal importance occur along the Mississippi 
River, among them the classic section at La Grange Mountain (Barn 
Bluff), Red Wing. 
JORDAN SANDSTONE 
The upper sandstone of the St. Croixian series crops out at numerous 
places along the Minnesota River and was formerly quarried at Jordan. 
Although generally a loose, friable sandstone, this rock has the property 
of hardening after removal from the quarry. Some layers long exposed 
are so case-hardened that they appear quite indurated even when the 
inside is still friable. This rock, therefore, was used in the early days of 
the Minnesota Geological Survey for heavy construction work. The im-
portance of the quarrying industry and the amount of rock exposed at 
the time undoubtedly led Winchell 60 to select Jordan as the type locality, 
although there are almost perfect outcrops (see Figure 11) showing the 
greater part of or the whole formation at many places along the Mississippi 
River, one of which would have been much more suitable as the type 
locality. 
f,' D. D. Owen, Report of n Geologicn/ Survey of Wisconsin, Iowa and Minnesotn (1852), 
p.52. 
59 "Notes on New Names in Table of Formations and on Physical E\'idence of Breaks 
bet\,-een Paleozoic Systems in Wisconsin," Transactions of the lViscoll.l'in Acndemy of Sci-
ences, Arts and Letters. 21: 86-87 (1924). 
00 Second Annunl Report of the Geologicnl and Nntum/ History Survey of Minnesotn 
(1874), p. 149. 
PALEOZOIC: CAMBRIAN 47 
FIGURE II. - The J ordan sandstone with basal Oneota (Ordovician) at the sand mine of the 
R ed Wing Filler Sand Company, Red Wing. 
The Jordan is a white or light gray to yellowish, iron-stained sand-
stone, medium- to fin e-grained in th e lower part, but sometimes coarse 
to very coarse in the upper part . Much of it is thick-bedded and cross-
bedding (see Figure 12) is common . At Jordan it is only the lower part 
of th e formation that is exposed in th e quarries and along Sand Creek. 
The upper beds are shown along Van Oser Creek, a tributary of Sand 
Creek about four and a half miles north of Jordan . There is a n inter-
vening thickness of many feet that does not actually crop out in the 
vicinity of either locality, but the nature of which is known from numer-
ous wells of the area . The coarse, massive sandstones a long Van Oser 
Creek constitute th e highes t part of th e forma tion a nd were included in 
the Jordan by Winchel1.61 This is the coarse portion of the formation, 
sometimes referred to a if typical of the whole deposit. Its sand grains 
are large and fairl y well rounded , but in many places, the original crystal 
faces hav ing been reconstructed , they are now sharp-edged quartz crystals. 
This coarse upper portion is often pink to brown in color, a lthough the 
colorle s to white sand is still predominant. Bedding varies from thin to 
thick , and cross-bedding is common throughout the formation. 
The Jordan sandstone crops out at various place along the Minne-
., Ibid ., p. 148. 
48 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNE OTA 
sota River, also along th e St. Croix and Missi sippi rivers, as well as 
along many of th e other important tributaries of the Mississippi. It is 
the conspicuous rock high up in the bluffs which shows differential weath-
ering in its upper part; usually it forms a vertical face ben eath th e capping 
of Oneota dolomite. 
FIGURE 12. - Cross-bedding ill the Jordan sand-
stone, Red Win g. 
Nonualk M ember. - The 
Jordan sandstone is made up 
of two members, th e Norwalk 
below and th e Van Oser above. 
The Norwalk member was 
named by Ulrich 62 from the 
fin e outcrops of sandstone at 
Norwalk, Wisconsin. It wa 
or iginally considered to lie be-
low th e Jordan sandstone of 
Minnesota, but was later 
proved to be the lower and 
more important part of that 
formation."3 The name orwalk, like several of the other Cambrian inno-
vations, had really been used and partly de cribed by Thwaites 64 prior to 
th e publication by Ulrich, but the discuss ion of the whole Cambrian ystem 
is admitted ly "as defined by Ulrich." 
The Norwalk member is a medium- to fine-grained yellow to white 
andstone which is often dolomitic . In the upper portion of the member 
these dolomitic lenses and layers stand out in relief against the differen-
tially weathered face of the sandstone cliff. At some places the Norwalk 
contains thin ll'eaks of blue clay shale, which preserve fragments of 
meristomes and linguloid brachiopods. Most of the member is unusually 
barren of any trace of fossils, probably because of poor conditions of 
preservation. However, along the St. Croix River from Stillwater north-
ward, fossils are common and often quite abundant even 50 to 60 feet 
above the base of th e member. Some of the better collecting localities 
are at Boom Hollow (S tillwater) , Marine, and near the west end of th e 
Osceola bridge. The fauna is characterized by such typical forms as 
Dikelocephalus norwalkensis, Osceolia osceola, T ellerina, Eurekia, Pro-
zacompsus, Sinuopea, Owen ella, and Finkelnburgia. Many of these and 
others are exceedingly abundant. 
Van Oser Member.-The upper member of the Jordan is the Van 
Oser, which was originally mentioned by Winchell Co :; and described by 
him as a part of the Jordan sandstone. Th e Van Oser member was men-
G' "Notes on ew Names in Table or Formations and on Physical Evidence or Breaks 
between Paleozoic Systems in Wisconsin," Transactions of the Wisconsin Academy of Sci-
ences, Arts and Letters, 21: 86-87 (1924). 
63 C. R. Stauffer, "The Jordan Sandstone," Journal of Geology, 33: 699-713 (1925). 
G< "The P aleozoic Rocks Found in Deep Wells in Wisconsin and Northern Illinois," 
Journal of Geology, 31:547 (1923). 
6(; Second Annual R eport of the Geological and Natural History Survey of Millnesota 
(1874) . p . 148. 
PALEOZOIC: CAMBRIAN 49 
tioned by Stauffer 1)6 and has lately been described by him and others 67 
as a distinct division of the Jordan, though not very definitely separated 
from the Norwalk. The Van Oser member has a thickness of 25 to 35 
feet and consists of coarse, friable, gray, white, pink, or brown sand 
grains, with the faces of the original crystals often partly or completely 
restored. On Van Oser Creek the rock is case-hardened, so that the great 
surface blocks formed by jointing appear like massive boulders. A few 
sharp blows of a sledge hammer, however, soon reduce them to a pile 
of sparkling crystals. 
This coarse upper sandstone at Van Oser has lately been found to 
carry a rather large number of fossils,oS designated the l'ellerina-Sauki-
ella fauna from the abundance of those two genera in it. Among other 
important genera are Calvinella, Prozacompsus, and Stenopilus; these 
occur sparingly through much of the member at Merriam Junction. It 
is not known how widely the fauna may be distributed, but it is sus-
pected it grades up from the Norwalk fauna without much interruption. 
JORDAN, SCOTT COUNTY 
Composite Type Section of the Jordan Sandstone 
THICKNESS 
JORDAN SANDSTONE (in feet) 
Y,m Oser Member 
12. Sandstone, coarse. gray to white. massive. with grains reconstructed to 
quartz crystals and partly case-hardened. This is the top of the Minnesota 
Quartz Company's pit near Van Oser Creek. .. . . .. .. . . .. . . . .. . .. . . . . .. 8 
11. Sandstone. medium to coarse. massive. friable. with grains mostly rounded. 
white to pink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 
10. Sandstone, medium- to fine-grained. massive, white, occurring along the 
Chicago and Northwestern Railroad tracks .......................... 10 
9. Sandstone. medium to coarse. massiYe, gray to white, well shown along 
Van Oser Creek . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 
Norwalk Member 
8. Sandstone. white to yellowish. covered to the top of the outcrop at Jordan. 
but known in various wells of the vicinity . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20± 
7. Sandstone, thin- to medinm-bedded. friable. yellow to red and brown, oc-
curring above the Jordan quarries but mostly covered ................ 5± 
6. Sandstone, thin. irregularly iron-stained. friable, white to yellow, in the 
upper part of the quarries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 
5. Sandstone, irregular. massive-bedded, white to buff. some of it obliquely 
banded and streaked with iron. This is the main part of the old quarries at 
Jordan .......................................................... 12 
4. Sandstone. medium-grained, friable. white to yellow or buff; part is cross-
bedded and often color-banded. This rock occurs in the lower part of the 
quarries at the dam. or the falls. of Sand Creek and in the old beer vaults. . 10 
3. Sandstone, gray to brown, partly coyered near the foot of the dam ...... 1 
2. Conglomerate. flat pebble; gray dolomitic pebbles imbedded in a pink. 
sandy dolomitic matrix along the bed of Sand Creek .................. 3 
ST. LA WRENeE FORMATION 
Lodi Member 
1. Dolomite, arenaceous. fine-grained, shaly, gray to pink and purple, now 
partly covered and disappearing in the bed of Sand Creek at the small 
bridge near the hatchery and opposite the lower brewery in Jordan. . . . . . . 2 
00 "The Jordan Sandstone." Journal of Geology. 33: 703 (192;». 
07 C. R. Stauffer. G. M. Schwartz. and G. A. Thiel. "The St. Croixian Classification of 
Minnesota." Bulletin of the Geological Society of America. 50: 1340 (1939). 
08 C. R. Stauffer, "Fauna of the Yan Oser Beds," Journal of Paleontology, 14: 54-56 and 
PI. 6 (1940). 
CHAPTER IV 
PALEOZOIC : ORDOVICIAN AND POST-ORDOVICIAN 
The St. Croixian series is overlain by rocks common ly referred to as th e 
Ordovician system. Along the Mississippi River the change is apparently 
so gradual that some geologists have regarded it as a transition without 
break from the sands of the Cambrian to th e dolomites of the Ordovician . 
Along the Minnesota River, however, the change is so abrupt and the 
contact so irregular that no other term than unconformity (disconformity) 
properly describes it. In fa ct , there appear to be remnants here and there 
of other formations, once more extensive, which separate the widespread 
do lomites from th e andstones of the St. Croixian series (see Figure 13) and 
which render doubtful the so-called transition from Jordan to Oneota. 
This contact a long the Minnesota River, moreover, shows the effect 
of solution in the younger beds, the development of caves, and the disturb-
ances produced by the collapse of the roofs of such caverns. Some of th e 
FIGURE 13. - The J ordan sandstone with the overlying Kasota sandstone and a remnant of 
the Blue Earth siltstone capped by the Oneota dolomite in the river bluff a t Kasota. 
50 
PALEOZOI ORDOVICIAN 51 
FIGURE 14. - An old sink in the Oneola dolomite (Ordovician ) partly filled from above, at 
Kasota. 
fin e silts that may have formed th e floor of th ese cavities apparently were 
squeezed into the crack or joints and other open space as th e slumping 
masses se ttled downward . That some of this silty shale must have been 
present wh en the caves were formed seems evident. Otherwi e, the water 
would have percolated down into the J ordan sandstone and would not 
have followed th e contact of the On eota and the underlying formation . 
Th e thickn ess of thi shale varies from a few inche to several feet, but 
th ere are very few or no cavern s, in fact, not even a uggestion of their 
former existence, except where the shale or silt is present. 
52 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN M I NNESOTA 
FIGURE 15.-The Blue Earth siltstone forced upward by collapse of caves in the basal part of the 
overl y ing Oneota dolomite. Along U. S. Highway No. 169 a t the southwes t edge or Mankato. 
Winch ell observed this silty shale, but part of it, at least , he regarded 
as Cretaceous silt that had descend ed through cracks from th e surface dur-
ing the invasion of a Cretaceous sea, filling old solution cavities.! (See Fig-
ure 14.) At some places, however. he seems to have considered the bed as 
pre-Oneota in age. Thus in discussing th e shale lying on top of th e Jordan 
at St. P eter, he says that "it may be a representative of the shale over-
ly ing the Jordan sandstone at the cement works at Mankato, though at 
no other point north of the cement works has such a shale been found 
immediately overlying the Jordan - not even in th e north ern confines of 
Mankato ." " In the many road cuts and th e more extensive quarries of the 
present time, thi s shale is more generally known . Much of it seems to be 
of pre-Oneota age. 
The region showing th e most marked break between the Jordan a nd 
the Oneota is from Ottawa to Gard en City (see Figure 15), a distance of 
more than twenty-five miles. H ere the basal contact of the Oneota is 
markedly irregular, and the beds above are greatly disturbed and dis-
placed. I solated blocks of On eota have well-stratified layers of silty shale 
beneath them, but the layers of shale are arched or squeezed upward into 
cavities between th e blocks of dolomite. Where the On eota is undisturbed 
1 N . H . Winchell, Second Annual R eport of the Geological and Natural History Survey 
of Minnesota (1874), p. 178. 
2 N . H . Winchell , Geology of Minnesota (Final Report of the Geological and Natural 
History Survey of Minnesota), Vol. 2 (1888), p. xix. 
PALEOZOIC: ORDOVICIAN 53 
and flat-lying, the shale beneath is likewise even-bedded and flat-lying. 
In other words, the shale shows every evidence of a deposit in place be-
tween the sandstone and the dolomite. 3 
A few brachiopods have been found in this shale. These are of the lingu-
loid type common in the St. Croixian and occasionally found in the Oneota, 
and seem to confirm the greater age for the shale. It is possible, however, 
that these fossils may have been derived from residual materials lying in 
caverns at the base of the Oneota, and thus be either Jordan or Oneota 
fossils incorporated in a cave-filling of the Cretaceous sea. Microscopic 
studies of this silt have so far shown no Cretaceous fossils. although the 
lithologically similar shales and clay beds lying beneath the drift and over 
the pre-Cambrian and Paleozoic land surface commonly show Cretaceous 
Foraminifera and in some places megascopic Cretaceous fossils. 
Other unconformities of major importance may occur within the 
beds here referred to as the Ordovician. The break between Oneota and 
Shakopee must be great because the faunas are so different. :Moreover, in 
tracing and correlating with beds to the south, it is found that important 
formations come in between the two. Another disconformity occurs at the 
base of the St. Peter sandstone, and less important breaks in sedimentation 
occur at several horizons in the middle and upper part of the system as 
developed in Minnesota. From these facts it is evident that the region lay 
near the margin of the Ordovician sea and that the strand line underwent 
frequent change. 
BEEKMANTOWNIAN SEHIES 
The lowest formations of the Ordovician system in Minnesota carry 
a fauna distinctly older than the usual basal formations of the Ordovician. 
or those commonly referred to as Canadian. These are said to be unusually 
well developed in the Appalachians and in the Southwest, particularly in 
the Ozark Mountain region, and Ulrich 4 has suggested that a new period, 
the Ozarkian, be introduced to include the beds carrying this older fauna. 
There is much to be said in favor of his contention, but there is some 
hesitancy about accepting the full change which the suggestion requires. 
Realizing the value of Ulrich's term as applied to the formational rem-
nants and the Oneota dolomite which are correlated with formations in 
Missouri presumed to be Ozarkian. Powell 5 has introduced the name into 
the Minnesota geological literature. Since the beds involved are closely 
related to the Beekmantown, which is still regarded as Ordovician, it has 
seemed wise to continue to refer to these formations as belonging to the 
well-established Beekmantownian, now used as a series name. 
"tV. A. P. Graham. "Petrology of the Cambrian-Ordovician Contact in :Millnesota," 
Journal of Geology. 41: 4G8-86 (1933); C. R. Stanifer and G. A. Thiel, ",Jordan-Oneota Con-
tact along the Minnesota River," Proceedings of the Geological Society of A merica for 1933 
(1934). p. 109. 
IE. O. Ulrich, "Revision of the Paleozoic Systems." Bulletin of the Geological Society 
of America, ':12:627 (1911), 
G A Study of the Ozarkian Faullas at Southeastern lUinnesota (Science Museum of the 
St. Paul Institute, Bulletin 1, 1935), pp. 1. 9-](), and PIs. 14-17. 
,H PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
KASOTA SANDSTONE 
The oldest of the remnants lying at the base of the Ordovician is the 
Kasota sandstone. Although discovered by Shumard, who first collected 
its fauna,s it was not recognized by him as separate from the Jordan sand-
stone or upper member of the St. Croixian series, and such fossils as he 
found have usually been referred to as the Jordan fauna. Recently the 
Kasota fauna has been collected and thoroughly studied by Powell,1 who 
illustrated and described its species. He also named and correlated the 
formation. 
The Kasota sandstone is known only at Kasota and at St. Peter along 
the Minnesota River, although some of its species have been reported from 
the river bluffs above Mankato. It varies from a few inches to 6.5 feet in 
thickness. It is a white sandstone with medium to coarse, well-rounded 
grains. The bedding is slightly irregular, and occasionally the contact with 
the Jordan is uneven, doubtless a disconformity. The materials of the 
Kasota were apparently derived from the underlying Jordan sandstone. 
In fact, they are so like it that these beds usually could not be separated 
except for the presence of the Kasota fauna, quite foreign to any belonging 
within the Cambrian. Powell correlates this sandstone with the Eminence 
of Missouri and regards it as part of Ulrich's Ozarkian.8 Some of the com-
mon fossil forms are Ophileta minnesotense, Dirhachopea rwnnalis, and 
Pelagiella staujJeri, as well as several species of pelecypods, probably be-
longing to the Ctenodontidae.9 
The presence of sandstone with thin beds of dolomite near the base 
of the Oneota at Red Wing and other points along the Mississippi Valley 
suggests a reworking of Jordan sandstone. The lower sandstone layer at 
Red Wing may be of the same age as the Kasota sandstone, but no fossils 
have been found to establish a definite correlation. Further south, in the 
region of Lake City and Wabasha, there is a conglomerate at this hori-
zon. 
BLUE EARTH SILTSTONE 
Immediately below the Oneota dolomite, and overlying the Kasota 
sandstone and spreading out beyond it in the Ottawa-St. Peter-Mankato 
region, there is a thin bed of white to greenish, very fine-grained, silty shale 
that is commonly referred to as a siltstone. At some places it rests on the 
Kasota sandston'e, but where that is lacking it is in direct contact with the 
Jordan sandstone. This is the siltstone often regarded as possibly Cretace-
ous. It seldom exceeds 'l feet in thickness and is usually thinner, except as 
a filling in cavities or nearly vertical fissures. Chemical analyses show that 
o B. F. Shumard in D. D. Owen, Repo<rt of a Geological Survey of Wisconsin, IOlOa and 
Minnesota (1882), p. 484. 
7 A Study of the Ozarkian Faunas of Southeastern Minnesota (Science Museum of the 
St. Paul Institute, Bulletin 1, 193.5). 
8 Ibid., pp. 7 and 10. 
9 Ibid., p. 11. 
PALEOZOIC: ORDOVICIAN 55 
it is high in potash, and X-ray analyses indicate that fine-grained authi-
genic feldspar is the predominant minerapo 
Powell 11 considers this siltstone as a sediment in place and directly 
succeeding the Kasota sandstone. Both of these remnants he regards as 
part of Ulrich's Ozarkian, probably immediately preceding the Oneota 
dolomite, although separated from it by a sharp break. There still may 
be some question as to the age of the siltstone, but Powell probably has 
the more forceful arguments. The fauna thus far known is so limited and 
of such uncertain origin that it may be neglected for the present. Only two 
species, belonging to linguloid genera, have been found in the siltstone, 
and they are not diagnostic forms. The following section shows both the 
Blue Earth and Kasota remnants at a place where the sandstone is typi-
cally developed. 
KASOTA, LE SUEUR COUNTY 
General Section through the Quarries to the Minnesota River 
11. Soil 
ONEOTA DOLOMITE 
THICKNESS 
(in feet) 
0.5 
10. Dolomite, gray, shaly, weathered. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0 
9. Dolomite, pink to buff, massive; the finest quarry beds. . . . . . . . . . . . . . . . . . . 14.0 
8. Shale, pink to purple, with some thick beds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 
7. Covered interval. including the quarryman's "hummocky layer" ........... 5.0 
6. Dolomite, gray to buff. mottled, thin-bedded; uneven base . . . . . . . . . . . . . . . . 3.0 
BLUE EARTH SILTSTONE 
5. Shale, green to white, silty, of variable thickness. Contains Lingulella ...... 0.5 
KASOTA SANDSTONE 
4. Sandstone, white, medium to coarse, fossiliferous; Ophileta minnesotense 
abundant ........................................................... 6.5 
JORDAN SANDSTONE 
3. Sandstone, white with streaks of green. medium to coarse. . . . . . . . . . . . . . . . . 6.0 
2. Sandstone, white with pink to yellow blotches, fine-grained to medium. cross-
bedded .............. ,.............................................. 20.0 
1. Covered to level of Minnesota River. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.0 
ONEOTA DOLOMITE 
The name Oneota dolomite originated in Iowa, Oneota being the former 
name of the Upper Iowa River. McGee 12 applied the term to the dolomitic 
rocks lying between the white Root Valley sandstone above and the "Pots-
dam sandstone" cropping out along the Upper Iowa River in Winneshiek 
and Allamakee counties. He described "Iowa Bluff" as "typical cliffs of 
Oneota limestone" and stated that "its thickness ranges from over 300 feet 
at the Minnesota line to something more than 200 feet at its southernmost 
exposure," but gave no type section. 
lO J. W. Gruner and G. A. Thiel, "The Occurrence of Fine-Grained Authigenic Feldspar 
in Shales and Silts," American Mineralogist, 22: 842--46 (1937). 
II A Study of the Oza-rkian Faunas of Southeastern Minnesota (Science Museum of the 
St. Paul Institute, Bulletin I, 1935), pp. 17-20. 
12 "Pleistocene History of Northeastern Iowa," Eleventh Annual Report of the U. S. Geo-
logical Survey (1891), Pt. I, pp. 331-33 and PI. 27. 
FIGURE 16. - The Oneola dolom ite a t Lanesboro. 
FIGURE 17. - The Jordan-Oneota contac t (a t level of man's head), Stockton Hill , Winona. 
56 
PALEOZOIC: ORDOVICIAN 57 
The Oncota dolomite, as thus defined, is a thick-bedded (see Figure 16) 
drab to buff and occasionally pink dolomite which may be sandy or shaly, 
often cherty, especially in the upper part, and frequently porous to cavern-
ous. Many of these holes are lined with quartz crystals, so that geodes, 
veins, and huge calcite-lined pockets are common. Some of the more 
massive beds in the lower portion of the formation are well suited to con-
struction work and are still finding a large market. l :; Along the Mississippi 
River and many of its tributaries in southeastern :Minnesota, the upper 
portion of the formation is fiinty; and in such beds the fauna is more faith-
fully preserved than in the dolomitic beds, where the process of dolomitiza-
tion may have destroyed any remains present at an earlier date. 
The thickness of the formation varies greatly. At Mankato it is about 
45 feet; at Minneapolis about 70 feet; at Stillwater 60 feet; at Faribault 
llO feet; at Winona 130 feet or more; and at Dresbach 150 feet. Even 
greater thicknesses occur in parts of southern JYIinnesota. In the Hormel 
Packing Company well at Austin there are 333 feet of dolomitic limestones 
and thin sandstones lying between the base of the St. Peter and the top of 
the Jordan sandstone. Of this more than 180 feet are believed to be Oneota. 
The base of the formation is irregular and shows a distinct unconform-
ity along thc St. Croix and Minnesota rivers. Along much of the JYIississippi 
River, however, the upper part of the Jordan sandstone may be so impreg-
nated with calcite and dolomite that it is difficult to distinguish it from the 
sandy dolomitic base of the Oneota. And yet Ulrich H is undoubtedly cor-
rect in considering this contact an important break in the sedimentary 
history of this region. The camoufiage of the contact (see Figure 17) does 
not minimize its magnitudc. The Oneota sea probably advanced oyer a 
relatively level surface of Jordan sand: the bottom beds of the Oneota were 
thus filled with redeposited sand and the top beds of Jordan cemented by 
the calcium-magnesium carbonate water percolating downward. This lat-
ter process may have gone on for a long time after the region was elevated 
above sea level. The evidences of solution throughout the Oneota suggest 
that this process was a lengthy one, and much of this highly charged water 
may have found its way into the porous sands below, there to deposit its 
solution load as a cementing material. Some layers from the upper part 
of the Jordan glisten with cleavage faces, like the famous "sand crystals" 
from western South Dakota. 
The following section of the Chicago and Northwestern Railroad Quar-
ry near Lewiston is characteristic of the Oneota formation in :Minnesota, 
except that it does not carry the cherty beds so common in the upper part 
along the Mississippi River bluffs. 
'" G. A. Thiel and C. E. Dutton, The Architectural, Structural. alld JIollumclltai Stolle, 
of Minnesota (Minnesota Geological Surwy. Bulletin 25,1935), pp. 112-34. 
H "Notes 011 New Names in Table of Formations and on Plwsical E"idence of Breaks 
between Paleozoic Systems in Wisconsin," Transactions of the ll'iscollsin Academy of Sci-
ences, Arts and Letters, 21:83, 105 (1924). 
58 PALEOZOIC A.ND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
LEWISTON, WINONA COUNTY 
Section at the Chicago and Northwestern Railroad Quarry 
THICKNESS 
ROOT V ALLEY SANDSTONE (in feet) 
II. Sandstone. loose blocks, brown to white. mingled with mantle rock .. . . . . . . . 3.0 
ONEOTA DOLOl\IITE 
10. Dolomite. rough, gray to drab. with calcite-filled cavities. Crypfozoon sp. 
m top.............................................................. 40.0 
9. Dolomite, gTay to buff, compact, even-bedded. . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 
8. Dolomite. hard, rough, gray to buff. with quartz-filled cavities and much cal-
cite ................................................................ 8.0 
7. Dolomite, massive-bedded, gnw to drab, with calcite-filled cavities. . . . . . . . . 36.0 
6. Dolomite, rough, cavernous, gray to buff, with cryptozoons ............... 10.7 
5. Dolomite. massive to thin-bedded, gray to buff. . . . . . . . . . . . . . . . . . . . . . . . . . 20.7 
4. Dolomite, massive, buff. "'eat hers rough and porous, part of it into thinner 
beds ............................................................... 25.0 
3. Dolomite. brown to buff in color. This is the floor of the old quarry. The top 
of the rock floor is covered with fucoids and occasional flat, coiled gastropods, 
probably poorly preserved Raphistoma 7ninnesotcllse .................... 5.0 
2. Covered interval from level of railroad tracks to outcrop below the bridge. . . 50.0 
JORDAN SANDSTONE 
1. Sandstone, white to yellow, medium-grained, to level of Rollingstone Creek 5.0 
Many of the shapeless cavities in the dolomites of this and other sec-
tions of the Oneota doubtless represent molds of fossils no longer recogniz-
able because of much solution. That this is true is easily established by 
occasional molds which may be traced through every stage of change, from 
easily recognized fossil molds to irregular holes or cavities. 
The Oneota fauna has been studied in detail by Powell,'5 who divided it 
into a lower and an upper fauna. Some species are found in both, but the 
upper carries by far the larger number of known species. The lower fauna 
appears to be largely a brachiopod-gastropod-trilobite fauna and the upper 
a cephalopod fauna. Althoughboth of these tentative divisions carry spe-
cies that led Powell to correlate the Oneota with the Gasconade dolomite 
of :lVIissouri, the lower fauna seems to show a definite relationship to the 
Mons fauna of Alberta.16 
Collecting fossils from this formation is seldom easy, as the rock does 
not split up readily and specimens are often rare. The upper or cherty lay-
ers have more faithfully preserved the fauna, and in them the specimens 
may be plentiful. Some of the better collecting places are Stillwater, Point 
Douglas, Hastings, Red Wing, Rollingstone, Bear Creek, Winona, Dres-
bach, Caledonia, Lanesboro, Mankato, and Ottawa. The fauna is only par-
tially known, and many undescribed fragments have been picked up. The 
complete fauna is evidently large. Some of the layers, particularly those 
that have been used so generally for flagstone in Winona, are made up 
largely of ramifying, branching algae that show up very distinctly on the 
worn surfaces. Even the steps of some of the older University of :lVIinnesota 
buildings show them. 
15 A Study of the Ozarlcian Fawws of Southeastern l11innesota (Science l\1useum of the 
St. Paul Institute, Bulletin I, 1935), pp. 31-78 and PIs. 1-13. 
'" Ibid., pp. 39-40. 
PALEOZOIC: ORDOVICIAN 59 
The Oneota dolomite is traceable along the Minnesota River from the 
vicinity of Mankato to Merriam Junction, where it disappears beneath 
younger formations or the drift and the river. It occurs in the deep wells 
of the Twin City region and crops out again along the St. Croix and Mis-
sissippi rivers from the region opposite Osceola, Wisconsin, southward to 
the Iowa state line. It caps the bluffs (see Figure 18) over much of this 
area, and many finc scctions are cut by the tributaries of the Mississippi 
River. 
ROOT VALLEY SANDSTONE 
Lying in the basal portion of the Shakopee dolomite, or between it and 
the Oneota, is a sandy horizon well recognized throughout the southeastern 
part of the state. In some regions, such as that around Shakopee, these 
sandy layers are interbedded with sandy dolomitic limestones or beds very 
similar to those at a slightly higher horizon. Wooster noticed these sandy 
beds along the Willow River at New Richmond, Wisconsin, where they 
consist of white sandstone, a foot or more thick, interbedded with dolo-
mites. For these Wooster 17 used the name New Richmond beds. When 
similar sandy layers were found deep in the thick magnesian limestones of 
Minnesota, Winchell 's adopted the Wisconsin term (New Richmond) that 
seemed to apply to the same horizon. At various places in Wisconsin, along 
the Willow River and elsewhere, Sardeson 19 found important parts of the 
Shakopee fauna in the dolomites interbedded with the sandstones of this 
horizon. It seems, therefore, that the New Richmond sandstone as a for-
mation ceased to exist and that, if designated at all, the horizon should be 
considered as a phase of the lower part of the Shakopee dolomite. 
There is, however, in the southeastern counties of lVlinnesota and in 
portions of Iowa 10 a definite sandstone, 35 to 40 feet in thickness, lying be-
tween the upper and often cherty beds of Oneota dolomite below and the 
dolomitic Shakopee above. This sandstone can be traced over large areas 
and shows persistent physical characteristics that make it easily traceable 
from outcrop to outcrop. As it occurs in Winona, Fillmore, and Houston 
counties, this sandstone is medium-to fine-grained, white to buff, yellow, 
or brown, and rather even-bedded, with hard quartzitic masses that have 
the appearance of an arenaceous chert. These may separate out as square, 
jointed blocks that resist weathering and persist when the outcrop is not 
shown. Many of the sand grains have reconstructed crystal faces that glis-
ten or sparkle in the sunshine, thus showing further results of percolating 
siliceous waters. Petrographically this sandstone is very similar to the up-
per part of the Jordan (see Table 5, page 75); the same is true of sandy 
17 Geology of the Lower St. Croix District," Tri...col1sil1 Geological Sun'ey, 4: 106, 127 
(1882). 
18 Geology of Minnesota (Final Report of the Geological and Natnral History Survey of 
Minnesota), Vol. 2 (1888), pp. xxi-xxii and 11-12. 
10 "Type Outcrops of the Minnesota River Valley," Pan-American Geologist, 41: ll5 
(1924); "The Shakopee formation," ibid., 62:29-34 (1934). 
20 Samuel Calvin, "Geology of Willlleshiek County," Annual Repo'rt of the Iowa Geologi-
cal Survey fOT 1905 (1906), Vol. 16, pp. 68-71. 
C) 
o 
J;'ICURE 18. - The J ordan sands tone capped by Oneo ta dolomite in the Mississippi Ri ' ·er bluffs near Winona. (Photograph by Cutler·s Stud io.) 
PALEOZOIC: ORDOVICIAN 61 
dolomitic layers in th e Shakopee. Although no fo il s have been found in 
the sandston e itself in this outhern region, there is seldom any difficulty 
in identifying it. In fac t, it prc ence can be detec ted readily, even where 
no visible outcrop occurs, throu gh th e characteristic hard , sq uared brown 
blocks, mentioned above, that strew th e lope or road ide cut . 
Front th e abundant fin e expo-
sures of this sand stone in th e valley 
of Root River , it is proposed to 
name it th e Root Vall y sa nd sto ne. 
It is t ypically expo ed along the 
highway abovc th e State Fish 
H a tchery we, t of La ne boro, a long 
th e river IJluff at Pre ton , in White-
wat er Stale Park (see Figure 19), 
where th e highway de cenel s from 
St. Charles, and at ma ny other 
places in that part of th e state. In 
this region th ere appear to be no in-
terbedded dolomite , and the sand-
st0ne takes on more of th e charac-
teristics of a true formation . Traced 
northward , however, or toward the 
margin of its development, interbed-
cling with overlying dolomites is 
often observable. Wh ether this 
dovetai ling of th e two types of sed i-
mcnt i to be considered a repre-
senting th e marginal gradation of 
two k inds of contemporaneous sedi-
mentation , or th e redeposition of 
parts of a n olel er sand y format ion in 
a limes tone-forming sea , is not at all 
clear. 
-
-~-
FrGURE 19 . - The Root Valley andstone 
and the o\'erlying Shakopee 'dolomite at 
Wh itewater State Park. The man stands at 
the con tact. 
Along th e highway fiv e and one-half miles west of Lake City, the Root 
Valley horizon consist of about 10 feet of sand and sand y shale with some 
do lomitic beels. Th e hales are mud-cracked and ripple-marked and con-
tain casts that uggest alt crysta ls. The sand beds are usually a little more 
than a foot thick, but resemble the Root Valley at other localitie to the 
south . The interbedded dolomites carry cryptozoo ns. In the .l\Iinn eapolis-
St. Paul area, where thin bed of sand occurring in well at about the con-
tact betwecn the On cota and th e Shakopee have been called Root Valley 
(New Richmond) sanel stone, Schwartz says that "it i questionable 
wheth er it is a continuous bed over the en tire area; probably there a re 
several interbeddcd sand stone at abou t th e horizon of the ew Richmond 
[Root Va ll eyl and that th e one so designated is not a lwa.vs the same 
62 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN 'MINNESOTA 
layer." ~l He further suggests that "in the eventual revision of nomencla-
ture the term be dropped for the Minneapolis-St. Paul area.""" At Still-
water conditions are still less satisfactory from the standpoint of the de-
velopment of a formation between the two dolomites under discussion. In 
fact, at that locality there is no intervening sandy horizon, according to 
Ulrich, and the Shakopee dolomite rests directly on an eroded surface of 
the Oneota dolomite, the two being separated by only a few inches of con-
glomerate."3 
The interval thus suggested for :lVIinnesota is said to be represented in 
Arkansas and lVlissouri by three distinct formations."4 Dake ",' correlated 
the New Richmond with the Roubidoux formation of Missouri, the upper 
part of which carries a fauna similar to the Tribes Hill limestone of New 
York, which is basal Canadian in age. The importance of the Root Valley 
horizon in stratigraphy cannot be ignored, even though the interpretation 
of the sandy beds commonly called New Richmond sandstone, or the Root 
Valley horizon, remains unsatisfactory. Indications are that this sandy 
phase is the basal portion of the Shakopee and probably a distinct member 
of that formation. 
As far as is known, the Root Valley sandstone does not exceed 40 or 50 
feet in thickness anywhere in lVlinnesota and is of importance only as an 
aquifer or water-bearing horizon. Even though one may be unwilling to 
regard it as separate from the Shakopee dolomite, there still seems to be 
need for a term to designate this horizon, and it has seemed wise to use a 
name from the region where it is fully developed and where its indepen-
dence of other divisions is best shown. The following section shows some 
of the characteristics of the Root Valley sandstone. 
WHITEWATER STATE PARK, WINONA COUNTY 
Section along State Highway No. 74 
THICKNESS 
(in feel) 
12. Mantle rock. Surface materials, chiefly loess. .. .. . . .. .. . . . . .. . .. . . .. .. . .. 15.0 
ST. PETER SANDSTONE 
11. Sandstone, yellow, medium to fine ............................... , . .. . . 8.0 
SHAKOPEE DOLO:r.IITE 
10. Dolomite, hard, gray to drab, oolitic. irregularly bedded, containing crypto-
zoons .............................................................. . 
ROOT V ALLEY SANDSTONE 
9. Sandstone. thick-bedded, cross-bedded, medium-grained. white to yellow. par-
tially consolidated .................................................. . 
8. Sandstone, hard, white; also sandy dolomile. gray to white .............. . 
7. Sandstone, white, with scattered dolomite pebbles ....................... . 
35.0 
32.0 
b.O 
l.O 
21 G. M. Schwartz. The Geology of the Minneapolis-St. Pall I Metropolitan Area (Minne-
sota Geological Survey, Bulletin 27, 1936), p. 42. 
" Ibid .. p. 4l. 
~3 E. O. Ulrich. "Notes on New Names in Table of Formations and on Physical Evidence 
of Breaks between Paleozoic Systems in Wisconsin," Tramactions of the lViscons;n Academy 
of Scie1l£·es. Arts and Letters, Q1: 101 (19Q4). 
'" Ibid .. p. 102. 
"" The Problem of the St. Peter Sandstone (Missouri School of Mines and Metallurgy, 
Bulletill 6. 1921). p. 8. 
PALEOZOIC: ORDOVICIA N 63 
FIGU RE 20. - The Shakopee dolomite along U . S. Highway No . 16, two miles sou thwest of 
Lanesboro. 
ONEOTA DOLOMITE (sha rp contact) 
6. Dolomite, massive, irregularl y bedded, very hard and compact. drab to gray. 
Cavity-fi llings of ca lci te common. Fossiliferous ...... . . .. ....... . ..... . .. 60.0 
5 . Dolomite, thick. even-bedded, often porous, highly foss ili fero us in lower part. 
M ost fossils occur as poorly p reserved molds. Com mon genera are Ophileta, 
Gasconadia. Sin1topea, Rlwchopea, Ellesmeroceras, and Cyrtoceras . . . . . . . . . 36 .0 
4. Dolomite, hard , gray, massive. porous .. . ... .. ... . . . . . ..... .... .... . ... 12.0 
J ORDAN SANDSTONE 
3. Sands tone, white to yellow, medium-grained, with in terbedded ha rd layers . . 32.3 
2. Sandstone, thin-bedded . white to yellow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 .7 
l. Covered in terva l to le\'el of Whitewater River a t the bridge by the park ing 
space and flag pole ..... . . . .... . ....... . ... . . . .. . .... . . . . . . . . . . . . . . . . . 32 .0 
S H AKOPEE DOLOMITE 
As indicated above, th e Shakopee dolomite overlies and its base is inter-
bedded with the R oot Valley sandstone. It was na med by Winche1l26 from 
the section exposed in the quarries at Shakopee. where quicklime and ome 
building stone formerly were produced. The Shakopee is much less dolo-
mitic than the Oneota . It i often referred to as a limestone a nd is still 
burned for lime in some localities .2 7 While the basal beds are often sandy 
or a true sandstone, as just indicat ed , and the succeeding layers are at 
places thin-bedded (see Figure 20). much of it is a mass ive, drab dolomitic 
,. Second Annual R eport of the Geological and N atural lIist ory Sttrvey of M inn esota 
(1874 ). pp. 138, 140. 
" C. R. Stauffer ancl G. A. Thiel, The Limestones and M arls of M innesota (Minneso ta 
Geological Survey, Bulletin 23, 1933), pp. 41-42 . 
64 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
limestone with cavities filled by white calcite, as are cavities in the great 
dolomitic formation at a lower horizon. In fact, locally the Shakopee some-
times resembles the Oneota dolomite so closely that the two have been 
confused,~8 and doubt has been expressed as to the existence of two dis-
tinct members of the dolomite that elsewhere has been called the Prairie 
du Chien group. 
Oolite may be found throughout the Shakopee and is by no means con-
fined to the upper part. Much of the flint, common in this formation, is also 
oolitic, and shaly beds may appear at various horizons. Large cryptozoons 
occur singly or in reeflike masses; or here and there parts of the formation 
bulge into great reeflike areas ~!J in which little algal structure is preserved. 
The Shakopee is nearly as widespread as the Oneota and crops out over 
much the same area, but its crumbling, sandy base may have caused its 
scarp to recede some distance, although never very far from the bluffs 
capped by the Oneota. 
Winchell's type section shows only about 20 feet, but the total thick-
ness of dolomitic limestone belonging to the Shakopee at the type locality 
probably exceeds 60 feet. Below is a section of the old J. B. ConteI' Quarry 
at Shakopee, which shows some of the variation in the lower part of the 
forma tion. 
SHAKOPEE, SCOTT COUNTY 
Section of the Shakopee Dolomite, J. B. Conter Quarry 
THICKNESS 
SHAKOPEE DOLOMITE (in feet) 
5. Dolomite, pink to brown. semicrystalline. alternating' with compact buff beds, 
all fairly thin-bedded and uneven. Fossiliferous ........................... 7 
4. Sandst~ne, irreg-ular. gray; sandy gray dolomite . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 
3. Dolomite, gray to pink. fairly massive but splitting into thinner beds. Extends 
to the bottom of the old quarry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 
2. Dolomite, thin-bedded, gray to pink or brown, occurring in the ditch and water 
hole below the quarry floor. Now partly covered. . . . . . . . . . . . . . .. . . . . . . . . . . .5 
1. Covered interval to level of Minnesota River (687 ft. A. T.). Outcrops and 
wells about the town show this portion to be a gray to brown dolomite. Springs 
along the river suggest sandstone below ................................. 14 
In the above section much of the upper part of the formation has been 
removed by erosion. The well on the J. A. Wilder property"O (now the 
Schessow home) on Shakopee Avenue, about two and one-half blocks east 
of the citv water tower, is at an elevation of 817.3 ft. A.T. and on somewhat 
higher gl:ound than the ConteI' q ua1'l'Y. It shows about 61 feet of Shakopee 
dolomite, and the various wells in Minneapolis and St. Paul penetrating 
the entire formation show an average thickness of 56 feet for the Shakopee. 
However, the thickness varies a great deal over wide areas, usually in-
,. A. C. Trowbridg-e and G. I. Atwater, "Stratigraphic Problems in the Upper Mississippi 
Vallev." Bulletin of the Geological Society of Am.erica, 45: 65-73 (1934). . 
'" F. W. Sardeson. "The Shakopee Formation," Pall-American Geologist, 62: 29 (1934). 
30 C. R. Stauffer, "Type Paleozoic Sections in the Minnesota Valley," Journal of Geology, 
42: 350 (1934). 
PALEOZOIC: OHDOVICIAN 6.5 
creasing to the south. Part of this variation is due to the disconformity at 
the top, where the thickness has been reduced by pre-St. Peter erosion. An 
excellent section is exposed in the hill along U. S. Highway No. 16 several 
miles to the west of Lanesboro, where the formation has a thickness of 38 
feet; if the basal sandstone (Root Valley) is included, the total thickness 
becomes 66 feet. The section at Lanesboro (see page 147) shows the three 
lower Ordovician formations just discussed and their relationship to the 
beds above and below. 
The Shakopee dolomite is not very fossiliferous, although diligent 
search of almost any outcrop will be rewarded by a few poorly preserved 
forms. At some places fossils have been found in abundance, but such lay-
ers are limited and often difficult to locate. Probably the best localities for 
prospective collecting are Shakopee, Stillwater. Cannon Falls, and North-
field, but a collector who expects great results from a few hours of even in-
tensive work is sure to be disappointed. The cherty masses are the most 
promising, but even they yield fossils only sparingly. The weathered cherts 
below the dam at Cannon Falls carry, in fair abundance, a diminutive mol-
luscan fauna of importance. Among the more common fossils of the forma-
tion is the great algal mass known as Cryptozoon minnesotense, but there 
are several other species that locally exceed it in importance. The Shakopee 
fauna is found in the Cotter of Missouri and to some extent in the Fort 
Cassin 31 of the Lake Champlain district. It is a typical Lower Ordovician 
association of species, but very distinct from the Oneota fauna. In fact, the 
latter carries many reminiscences of the Cambrian, and the beds which 
contain it are probably separated from the Shakopee by an important in-
terval,3" in part represented by the Root Valley sandstone and the con-
glomerate occasionally found at its base. 
In the East the succeeding beds belong to the Chazyan series, which in-
cludes limestones, shales, sandstones, and even conglomerates, but l\Iinne-
sota was probably emergent during most of that time, and the break at the 
top of the Shakopee may represent a large part of the interval. Eventually, 
however, the sea spread over this interior region, and the St. Peter sand-
stone was laid down. Throughout much of the region occupied by the St. 
Peter, the lower contact is a very irregular surface that \"as at one time 
interpreted as clue to folding and faulting.'!:' l\Iore recent field evidence 
indicates, however, that the relationship is an erosional disconformity. The 
normal type of sandstone is underlain in many places by beds composed of 
residual materials, representing the products of weathering and erosion of 
earlier formations. 
31 C. R. Stauffer. "A Diminutive Fauna from the Shakopee Dolomite (Ordovician) at 
Cannon Falls. Minnesota."' JOlll"llal of Pa.leolltology. 11: 55 (H)37). 
"' E. O. Ulrich. "Notes on New Names in Table of Formations anu on PllYsical Evidence 
of Breaks between ruleozoic S,vstems in 'Yisconsin," Transactions of the IT'iSC'OIlSill Academy 
of Science.s. Arts and Letters. Zl:100-4 (l9"l4). 
33 C. W. Hall and F. W. Sardeson. "Paleozoic Formations of Sonlheaslern Minnesota." 
Bulletin of the Geological Society of America. 3:331 (Isn'i). 
66 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
FI GU RE. 21. - The Pla tteville limestone overly in g the St. Peter sandstone a t the Soldiers 
H ome, Minneapolis. 
In Missouri and Arkansas, Dake 3 4 states that the contact is marked 
by cherty basal conglomerates and residual soils. In Wisconsin and nor-
thern Illinois, Thwa ites 35 reports tha t below the sandstone there are beds 
of purplish red and green hales. interstratified with layers of white disin-
tegra ted chert, and conglomerate with chert and limestone pebbles in a 
matrix of fin e to coarse sand. In I owa, Trowbridge 3 6 has observed tha t the 
basal St . P et er contains fragments of chert derived from the underlying 
dolomite. In the area of th e St. P eter outcrops in south eastern Minnesota 
a nd southwest ern Wi sconsin the basal conglomera tes are quite inconspicu-
ous. In the a rea of the Lancaster quadrangle (Wisconsin-Iowa-IlIinois), 
however, an outcrop of the contact shows sandy shales, green shale, a nd 
conglomerate representing th e basal beds of the St. P eter forma tion . 
CHAZYAN SERIES 
ST . P ETER S ANDSTONE 
The St. P et er andstone is one of the widely recognized formations of 
the Mississippi Valley. It crops out from Michigan, Wisconsin, and Minne-
sota southward to Arkansas and ha been reported in deep wells over a 
.. The Problem of t he St. Peter Sandstone (University of Missouri School of Mines and 
M etallurgy, Bulletin 6, 1921), p. 98. 
a:; "P aleozoic R ocks Found in Deep 'Wells of Wisconsin and orthern TIlinois," Journal of 
Geology, 31: 529 (1923) . 
3<J "The Pra irie du Chien-St. P eter Uncon formity," Proceedings of t he Iowa Academy of 
Sciences, 24: 180 (1917). 
PALEOZOIC: ORDOVICIAN 67 
much greater area .37 It is in general a clean white sandstone with frosted , 
medium-sized grains that usually are well rounded and well sorted . The 
yellow to brown stain common in some localities is due chi efly t o the oxi-
dation of pyrite concretions or to percola tion of iron-bearing wat er from 
the overlying formation s. P yrite concretion are common in the upper por-
tion of this sandstone, as shown in the sand mine a t the F ord Plant in 
St. Paul and in va rious sewer tunnels cut in thi sandstone a t Minneapolis. 
They show th e and gra ins in corpora ted in the iron sulphid e, and the whole 
mass takes on the odd shapes so commonly associated with these bodies, 
more rarely showing pyrite crystal forms. 
The St. Peter sandstone of Minnesota (see Figure 21) may show little 
evidence of stra tification , but wh ere it ca n be seen, there is every indica-
tion of a water-laid sand deposited under nearly uniform conditions. R arely 
does cross-bedding affect it, but where it does, the type of cross-bedding 
gives added evidence of water-laid sediment rather than eolian deposition . 
The heavy minerals character-
istic of the formation are ch iefl y zir-
con and tourmaline, with lesser 
amounts of rutil e, leucoxene, and 
garnet (see Table 5, page 75). The 
rutile increases among the smaller 
grains and garnet is more important 
in the upper beds of th e St. Paul 
area.3S These beds, however, repre-
sent the early phase of Glenwood 
deposition and have lately been 
added to that member of the Platte-
vill e. The St. Peter is an exceedingly 
high-grade quartz sand, consisting 
of nearly 99 per cent silicon diox-
ide,39 and in some states to the south 
this percentage is even higher .4° The 
iron content is low, making the St. 
P eter a good glass sand . Cementa-
tion is generally exceedingly poor . 
Although case-hardening may affect 
th e outer surface, in many localities 
it is so poorly consolidated a t the 
FIGURE 22. - C hi mney R ock , fo rm ed by 
wind eros ion. nor th of Cannon Falls; a St. 
Peter sandstone remnant capped by a t hin 
layer of t he Pla ttevi lle limes tone. 
outcrop that it may be cooped up like any unconsolidated material or 
blown away by the wind (see Figure 22). 
37 G. A. Thiel, "Sedimentary and P etrographic Analys i of the St. Peter Sandstone " 
Bulletin of the Geological Society of America, 46: 561, 562 (l935). ' 
38 Ibid., pp. 596, 598. 
3. Ibid., p. 60l. 
'" A. W. Giles, St. Peter and Older Ordavician Sandstones of Northern Arkansas (Arkan-
sas Geological Survey, Bulleti n 4, 1930), p . 73. 
6R PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
In Minnesota the average porosity is a little over 28 per ccnt,41 and it 
is one of the dependable water horizons of the southeastern part of the 
state. This water is probably responsible for the present low contcnt of 
solubles in the rock and has perhaps even removed the fossils which the 
formation originally contained. In Owen's description of the formation, he 
states that the sandstone "is remarkable for its whiteness. When examined 
by the magnifier, it is found to be made up of grains of limpid and colorless 
quartz." It is "designated on the sections as Formation 2c, and superim-
posed on the Lower Magnesian limestone .... It is the rock which forms 
the base of the bluffs at the St. Peter's. It constitutes also the lower nine-
teen feet of the chute of the Falls of St. Anthony." 42 
Discussing the St. Peter sandstone of Iowa, James Hall says: "Being 
also conspicuously developed at the mouth of the St. Peter's river, Dr. 
Owen has given it the name of St. Peter's sandstone." 43 The :Minnesota 
River was formerly called the St. Peter's; hence the outcrops just referred to 
are those at the junction of the Minnesota and Mississippi rivers. The type 
section is at Fort Snelling, where the upper part is well shown in the bluff. 
FORT SNELLING. HENNEPIN COUNTY 
Type Section of the St. Peter Sandstone 
PLATTEVILLE FORi\IATION 
McGregor Member 
8. Limestone, slightly dolomitic, blue to buff. fossiliferous 
Glenwood lYIember 
THICKNESS 
(in feet) 
.e5 
7. Shale. soft, argillaceous. arenaceous. gray to greenish ................... 3 
6. Sandstone, yellowish to brown. iron-stained. with some white day ....... 8 
ST. PETER SANDSTONE 
5. Sandstone, poorly cemented. medium- to fille-grained. massi,'e. white, partly 
covered at the base ................................................ 65 
4. Sandstone. white. friable. covered but partly shown in excavations for the 
Mendota Bridge piers adjacent to the cliff. . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 
3. Silt, siliceous. blue. reported as a shale in the Mendota well ............. 30 
2. Sandstone, white, shown in some of the excavations for piers and penetrated 
by the Mendota well. Elevation of the St. Peter-Shakopee contact in the 
excavations for bridge piers is 613.4 ft. A. T. (U. S. Army engineers) ...... 35 
SHAKOPEE DOLOMITE 
1. Dolomite, gray to brown. encountered in the bottom of an excavation for a 
pier ........................................ . 
The silt or siltstone (no. 3) referred to in the above section is persistent 
over the :Minneapolis-St. Paul area but is not well shown in outcrop. A 
similar bed is also reported in the St. Peter of Illinois ... This silt is suffi-
e. G. A. Thiel, "Sedimentary and Petrographic Analysis of the St. Peter Sandstone," 
Bulletin of the Geological Society of America, 46: .589 (193.5) . 
• 2 D. D. Owen, Report of the Geological Survey of Wisconsin. Iowa and JlIinnesota 
(1852), p. 69. 
43 Report of the Geological Survey of. the State of Iowa; Vol. 1. Pt., I (18~8l,; p. 54 .. 
H J. E. Lamar, "New Facts Concernmg the St. Peter Sandstone of Ilhnols. Bulletm of 
the Geological Society of America, 38: 461 (1927). 
PALEOZOIC: ORDOVICIAN 69 
ciently impervious to affect the flow of water in the formation. The total 
thickness of the St. Peter sandstone in the state varies from about 165 feet 
in Minneapolis to less than half that in the southeastern corner of the state. 
Few fossils occur in the St. Peter sandstone of Minnesota and even these 
few are rare. But in South St. Paul, at nearly the last outcrops along the 
streetcar line and again across the river at Highland Park, Sardeson found 
certain forms relatively abundant and in some layers even crowded. The 
fauna includes the following species: 
Ctenodonta novicia (Sardeson) Ilolopea obliqua Hall 
Cyrtodonta dignis (Sardeson) Ophileta fausta Sardeson 
,\lodiolopsis affinis Sardeson Platycera.~ vetulum Sardeson 
M odi%psis contigua Sardeson Pleurotomaria a;ens Sardeson 
Modiolo]Jsis litoralis Sardeson Orthoceras minnesotense Sardeson 
This is a typical marine molluscan fauna and precludes any reference 
of the formation as a whole to land or eolian origin. It is possible, of course, 
that parts of it might have had such an origin or that wind-blown sands 
may have been carried into the sea and there been laid down by water, 
but Minnesota seems to furnish little evidence of land deposition of this 
sandstone. 
To the southwest the sandstone increases in importance and has been 
correlated with several formations in Oklahoma!5 the upper of which is 
the Burgen sandstone. carrying a fauna very similar to that found in the 
St. Peter sandstone of the St. Paul region. This is a Chazy fauna and serves 
to separate the St. Peter from beds of :Middle Ordovician which followed 
rather closely!6 
.MOHA "'KlAN SERIES 
This is a typical marine molluscan fauna and precludes any reference 
sen ted by shales. limestones, and dolomites aggregating about 300 feet 
where fully developed. It carries several faunas which make general cor-
relation of these beds with the standard section 47 certain. yet it is prob-
able that no part of the formation as recognized in lVIinnesota can be 
exactly equated to the beds of the East. Figure 23. modified from Kay. 
attempts to show the relationship of the series in lVIinnesota to the equiva-
lent beds in Illinois and Iowa. A characteristic of the lVIohawkian in Min-
nesota is the abundance of pebbly corrosion zones 4S which seem to repre-
sent intervals of nonsedimentation or even wear and corrosion of those 
sediments that had been previously deposited. These diastems represent 
horizons at which rather definite faunal changes took place and were men-
<c, C. L. Dake, The Problem of the St. Peter Sandstone (Uni\'ersity of Missouri School of 
Mines and Metallurgy, Bulletin 6, 19~1), Pis. 1 and 2. 
"F. C. Edson, "Resume of St. Peter Stratigraphy." Bldletin of the American Association 
of Petroleum Geology, 19: 1116.1127 (1935). 
<7 G. Marshall Kay, "Stratigraphy of the Trenton Group," Bulletin of the Geological 
Society of A merica, 48: ~50 (1937) . 
.. F. 'V. Sardeson, "Intraformational Conglomerates in the Galena Series," American 
Geologist, 22: 315-~3 and PI. 9 (1898). . 
70 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
~..5Tevvorrv///e 
Prosser 
bc.~~ ~ 
5aechrs.-:-rerr 
fL-r--l-r-lA4 C Gregor 
1;---.c'-;-~..,.'?~C"'::Vf'go::c ~ 
.... .. .... 
M/NNESOTA 
s.c. 
GALENA 
PLATTEVILLE~ 
'>: .......... ··5T.AETER. 
IOWA /L.L/NO/S 
FIGURE 23. - Diagram showing relationship of the Ordovician section of Minnesota to those 
of Iowa and Illinois. (After G. Marshall Kay, "Stratigraphy of the Decorah Formation," 
Journal of Geology, 37:671 (1929). 
tioned by Sardeson as limiting certain of the faunal zones 40 which he 
worked out for the whole series.50 
Winchell and Ulrich 51 adopted Sardeson's faunal zones, with slight 
modifications, but did not use them very consistently in referring new 
species, described by them, to their proper faunal zones. This zonal study 
of the Mohawkian fauna by Sardeson constitutes some of the best work 
ever done on the Ordovician of this state, Some contacts have been slightly 
shifted to support varying views on correlation, but in general the work 
stands as originally presented. The corrosion zones, with their evidences 
of faunal changes, are probably represented to the southeast by beds of 
sediment in the thickening of the series and the fuller development of the 
fauna. In a study of a much wider area Kay 52 has recently returned to 
these faunal zones in the correlation of the Minnesota-Iowa-Wisconsin 
Middle Ordovician with beds of similar age farther to the east. It seems 
that both faunal and corrosion zones may, in certain cases, have wide 
significance. 
The Mohawkian series, or Middle Ordovician, of Minnesota consists of 
the Platteville and the Galena. Each is divided into several members, some 
of wl1ich have been recognized as distinct formations. 
PLATTEVILLE FORMATION 
The Platteville was named by Bain 53 from the outcrops at the town 
of Platteville, Grant County, Wisconsin. According to him, its base is a 
blue shale, which "rests directly on the St, Peter sandstone; in fact it rap-
idly grades downward into sandstone and at times is sandy throughout, 
., Ibid .. pp. 318-20. 
50 F. VV. Sardeson, "The Lower Silurian Formations of Wisconsin and Minnesota Com-
pared," Bulletin of the Minnesota Academy of Natural Sciences, 3: 319-26 (1891). 
01 Geology of Minnesota. (Final Report of the Geological and Natural History Survey 
of Minnesota), Vol. 3, Pt. 1 (1895), p.l; Pt. 2 (1897), pp. lxxxy-cxxiii. 
0' "Stratigraph~' of the Decorah Formation," Journal of Geology, 37: 642, 643 (1929). 
0.3 H. F. Bain, Zinc and Lead Deposits in Northwestern Illinois (U. S. Geological Survey, 
Bulletin 246, 1905), pp. 18-20. 
PALEOZOIC: ORDOVICIAN 71 
FIGURE 24. - The Platteville limesLone at the underpass on SLate Highway No. 44, we t of 
Spring Grove, Houston County. 
though most commonly there is a distinct bed of shale free from sand 
grains of noticeable size." 54 This is the Glenwood of other writers. 
The upper part of th e Platteville consists of limestone and shale, "com-
monly in thin alternating beds, but there is comparatively little uniformity 
in this member in different parts of the district. In general it can be stated 
that the shale layers are better developed toward the west, while the lime-
stone is the main part or the whole of the member in the east ern portion 
of the lead and zinc district." 55 This top member is the Stictoporella bed, 
which Sardeson said, on a faunal basis, "could be classed with the lime-
stone below as well as with the shales above." 56 The e are the beds which 
Kay named the Spechts F erry member and first placed in the D ecorah 
shale 5 7 but later included in the Platteville Iimestone.58 This inclusion of 
the shales at the top and bottom of the limestone r estores the term Platte-
ville to the full meaning as originally used by Bain . 
The Platteville formation then, as developed in Minnesota (see Figure 
24), is a shale member at the bottom, a thick limestone member in the 
middle, and a limestone and shale member at the top . The shales are more 
important in Minnesota but of less and less importance to the south and 
east, where they almost disappear in the region of the type locality. The 
shale at the base of the formation has commonly been considered a includ-
ing only the 1 to 5 or more feet of bluish green, argillaceous beds that make 
the St. Peter-Platteville contact zone so conspicuous; but as the basal 
contact of the formation is now understood, it includes also th e mixed sand 
•• Ibid ., p . 19. 
GO Ibid. , pp. 19-20 . 
•• F . W. Sardeson, "The Lower Silurian Formations of Wiscon in and MinnesoLa Com-
pared," B'1Illetin of the lIIinnesota Academy of Natural Sciences. 3: 3'11 (1891) . 
.. G. Marshall Kay, "Stratigraphy of the D ecorah Formation ," Jourllal of Geology, 
37: 64'1-58 (1929) . 
,. G. Marshall Kay, Guide B ook of the Ninth Annual Field Conferellce (Kansas Geological 
Society, 1935), pp . 286-87; Bulletin of the Geological Society of A lI~erica, 52: 294 (1937). 
7~ PALEOZOIC AND RELATED ROCKS OF SOUTHEASTEHN MINNESOTA 
and clay beneath the shale, which undoubtedly represent the early stages 
of Platteville sedimentation. The members thus assume such importance 
that they will be described separately and their limitations suggested. The 
following section shows the individual members. 
CHATFIELD. FILLMORE COUNTY 
Section along U. S. Highway No. 52, 6 lYfiles Nortlmest of Town in 
Olmsted County 
2(). Soil and drift 
GALEKA FORMATION 
Prosser Member 
THICKNESS 
(in feet) 
3.0 
~,;. Limestone. ,,'eatherco. gray; compact, hard. and blue-gray where fresh 8.0 
~-4. Limestone. thin-bedded, shaly, gray, with a few thick layers and occa-
sional streaks of soft gray shale alternating with thin layers of lime-
stone. The shaly layers are often fueoioa!' Among abundant fossils are 
Dalll7llTlclla rogata, Plectllmbonites sericeus, Rafillesquina sp., Dinorthis 
meedsi, and Receptaculites ol1'eni . . . .. . . . . . . . . .. . . .. .. . .. . ... ... . 19.8 
23. Shale. gray to oliYe, argillaceous, \"ith nodules of limestone. . . . . . . . . 1.0 
2~. Limestone, hard, gra~'; nodular. calcareous gray shale .............. ().O 
2l. Limestone, medium to thin beds, hard, blue. Contains Receptaculites 
011'e1l; ano other fogoils '. . . . . .. . . . . . . . . . . . . . . . .. . . . . . . .. . .. . . .. ... 4.8 
Decorah Shale Member 
Ion Submember 
20. Shale, nodular, gra~', \"ith numerous fossils . . . . . . . . . . . . . . . . 2.0 
19. Limestone, massi\'e, gra,\', containing an abundance of fossils. PrasopoTCl 
simulatrix abnndant in upper layers. numerous Bryozoa, also Recepta-
elllite.l· 01celli and Endoceras proteifonne .... . . . . . . . . . . . . . . . . 7.4 
18. Shale, gray, calcareous, nodular, with numerous poorly presen'ed fossils 2.0 
17. Limestone, massive, gray ....................................... 2.0 
l(). Shale, light gray to drab, calcareous, nodular, with abundant fossil 
fragments ............. ' ...................... ,. . . . . . . . . . . 1.2 
I;';. Limestone, gray, thick-bedded, weathering into thinner layers ...... 8.0 
14. Shale, gra~' to oli\'e, argillaceous, with layers of limestone. Contains 
an oiilitic laver-small, brass\" seedlike oolites and an abundant fauna 
of Bryozoa ~nd Brachiopoda: with an occasional Lophospira ........ 3.3 
Guttenberg Submember 
13. Shale, soft, gray-green ................. , . . . . . . . . . . . . . . . . . . . . . . . . 10.0 
I~. Covered interval .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.0 
PLATTEYILLE FORi\IATIOX 
Spechts Ferry :Member 
ll. Shale, blue, argillaceous. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0 
10. Shale, blue, with limestone lenses carrying abundant Pial/oelema Sllb-
aeqnata ................................ '..................... 5.0 
9. Shale, blue, soft ............................................... 0.5 
S. Limestone, gray .. , ................................... ,........ 0.8 
7. Shale, blue ................................................ 0.5 
6. Limestone, compact, hard, brown, with numerous specimens of [sotelus 
{/iyas and ZygOSpiTCl nicolleti ....... . . . . . . . . . . . . . . . . . 1.4 
,5. Shale. blue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5 
l\fcGreo'or Member 
4. Limestone, medium- to thick-bedded, gray to blue ancl buff. . . . . . . . . 21.0 
Glemyood Member 
3. Shale, green and yellow, sandy .................................. 5.0 
'2. Sandstone, \"hite to yellow or with yellow streaks. . . . . . . . . . . . . . . . .. 6.0 
ST. PETER SAXDSTONE 
1. Sandstone, friable, white, partly covered to level of creek . . . . . . . . . . . '20.0 
PALEOZOIC: ORDOVICIAN 73 
F, GU RE 25. - Pl atteville formation , the Glenwood member overla in by the :McG regor mem-
ber, at top of grade along U. S. Highway No. 16, three miles southwes t of Lanesboro. 
Glenwood M ember.-The blue to green shale lying on top of the St. 
P eter sandston e Calvin described as th e " basal shale ." 59 H e con idered 
this the initial stage of the "Trenton seri es," (now known as th e Plattevill e 
and Galena formation s) . But the presence of sand layer in the lower part 
of this shale led him to reconsider this assignment and to regard the shale 
as distinctly transitional between the St. P eter andstone and the lime-
stones above. Accordingly, he gave the member a distinct name, Glenwood 
shale, from th e outcrops in Glenwood Township, Winneshi ek County, 
Iowa.60 According to him, these shales occur over a wide area from the type 
locality to the Minneapolis region in Minnesota. 
In Winneshiek County the shales of the Glenwood have a thickness of 
about 15 feet , but th ere is great variation from place to place. In Illinoi 
the range appears to be from "a few inches to a few feet." 6 1 In 1Vlinnesota 
th e shaly beds occupying this horizon (see Figure 25) rarely exceed 3 or 4 
feet and are commonly rather barren of fossils. At a few places, however, 
megascopic fossils are fairly common and have long been refcrred to Platte-
ville species.G2 
More recent work on both the megascopic and th e microscopic forms 
has increased the known fauna, and it is safe to say that "the Glenwood sea 
" Samuel Calvin. "Geology of Allamakee County," Annual Report of the Iowa Geological 
Stt·rvey JOT 1894 (1895), Vol. 4, pp. 73-74. 
00 Samuel Calvin . A mwal R eport of the Iowa Geological Survey fo r 1905 (1906). Vol. 16, 
pp. 60, 61 , 74-76 . 
• , Arthur Bevan. Th e Glellwood Beds as a Horizon M arker at the Base of the Platte-
v ille Formation (Geologica l Survey of IIlinoi , Report of Investiga tions 9, 1926 ), p. 6 . 
• , F . W. Sardeson. Minn eapolis-St. Pattl Folio (U . S. Geologi('al Survey, Geological Atlas 
of the United States, Folio 201 , 1916), p. 6. 
74 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
was filled with Middle Ordovician life, and most of its fauna is of that age. 
Basal Glenwood sediments may be largely of St. Peter origin, and the bot-
tom of the formation too intimately mingled with the loose sands derived 
from older beds to allow a definite contact to be drawn between it and the 
St. Peter, but the fossil-bearing Glenwood beds belong in the Mohawkian 
series, and are not much older than the Platteville limestone." 03 
Beneath the shaly beds there is about 8 feet of a mixture of sand and 
clay that has usually been called the upper part of the St. Peter sandstone. 
These are the beds that have led to the idea of a transition from the St. 
Peter to the Platteville. An extensive series of samples has been collected 
from this unit at a number of important points in the region of the Glen-
wood outcrop and thoroughly analyzed by the usual methods of sedimen-
tary petrography. The final disposition of these beds may be summed up 
from the petrographic standpoint by the conclusion that "the upper 5 to 
10 feet of what is now called St. Peter sandstone in Minnesota and north-
eastern Iowa represents St. Peter sands that were reworked by the early 
lVIohawkian sea. The coarser texture of the sand and the presence of a 
small percentage of garnet in the heavy accessories suggest that other clas-
tic sediments were also being added from new source areas. (See Table 5.) 
This mixture is an early phase of the Glenwood beds and should not be 
termed upper St. Peter." 64 
The Glenwood beds, then, contain 8 to 10 feet of argillaceous sand-
stones, representing reworked St. Peter plus additional source material, 
and above that 18 inches to 3 or 4 feet of gray to greenish, argillaceous shale 
which carries scattered grains of sand. At some places, such as the highway 
cuts north of Fountain, cross-bedded sandstones occupy part of the shale 
horizon, with typical beds of the shale both above and below the sand-
stone. 
The quartz grains scattered through the shale vary in size from .1 to 1 
millimeter in diameter. They are frosted, somewhat pitted, and fairly well 
rounded. X-ray analyses show that most of the shaly material is very fine-
grained feldspar. 65 It carries very fine (.05 millimeter) crystals of pyrite, 
and the same mineral fills tubelike "burrows," thus producing cylinders 
or tortuous twiglike masses of pyrite which are common objects in the 
concentrates of heavy residuals. Most of these "burrow" fillings are about .5 
millimeter in diameter, but seem to possess no distinctive feature whereby 
their identity can be assured. Several that appear to retain a part of the 
wall surface of the burrow are longitudinally striated, although these stria-
tions are not uniform. Pyrite may be so abundant in the upper part of 
the Glenwood that it is aggregated into nodules or concretions. When 
03 c. R. Stauffer, "Conodonts of the Glenwood Beds," Bulletin of the Geological Soc'iety 
of A me1'ica, 46: 130, 131 (1935). 
U4 G. A. Thiel. "Petrographic Analysis of the Glenwood Beds of Southeastern Minne-
sota," Bulletin of the Geological Society of America, 48: 120 (1937). 
M J. W. Gruner and G. A. Thiel. "The Occurrence of Fine-Grained Authigenic Feldspar in 
Shales and Silts," American Jliinera/ogi.,t. 22:842--46 (1937). 
PALEOZOIC: ORDOVICIAN 75 
TABLE 5. - PERCENTAGE DISTRIBUTION OF HEAVY ACCESSORY MINERALS IN THE SANDSTONE 
FORMATIONS OF SOUTHEASTERN MINNESOTA 
Sedimentary 
Formations * 
Glenwood 39 
St. Peter . . . .. tr 
Root Valley .. 61 
Jordan ....... 61 
Franconia . . .. 21 
Galesville 13 
Mt. Simon. ... 2 
Hinckley ... .. tr 
Fond du Lac .. 5 
18 
3.5 
22 
16 
22 
52 
9 
13 
1.5 
Heavy Minerals (in Percentages) t 
40 tr 
48 8 
12 I 
18 2 
56 pr 
16 3 
17 tr 
35 I 
11 6 
3 
6 
2 
I 
pr 
8 
8 
17 
f 
1 
pr 
tr 
I 
3 
pr 
pr tr 
pr pr 
tr pr 
I I 
I I 
pr 
2 PI' 
pr pr 
pr 
tr 
pr 
pr tr 
pr 
8 35 
pr 
1 
tr 
pr 
pr 
3 
56 
32 
12 
'" 
'"' ~ 
..... 
o 
tremolite. tr 
chlorite. 2 
chlorite. 2 
tremolite. I 
chlorite, 3 
* Glenwood, composite sample from Minneapolis section; St. Peter. average of twenty-
four samples from southeastem Minnesota; Root Valley. composite of six samples from 
southeastern Minnesota; Jordan, composite of three series of samples from southeastern 
Minnesota; Franconia. composite of Taylors Falls section; Galesville, composite of type 
section; Mt. Simon. composite of type section; Hinckley. composite of section at Sandstone; 
Fond du Lac, composite of four sections along St. Lonis River. 
t tr = trace. less than .5 per cent. 
pr = present, less than 1.0 per cent, more than .5 per cent. 
f = flood, not included in count. 
samples of this shale are washed, small grains of "phosphatic" material 
appear in the concentrates with the microscopic fossils, which are chiefly 
conodonts. In the lower shale bed gypsum crystals, often twinned, are 
common. 
The Glenwood beds, especially the upper shaly part, persist over that 
part of the state covered by the St. Peter sandstone and extend into Iowa, 
Wisconsin, and Illinois.GG Sardeson 67 says that the outcrops in the gullies 
of northwestern Glenwood Township, Winneshiek County, Iowa, from 
which the beds were named, are exceedingly poor and that the type locality 
is of little importance. However, the name persists and has value as a 
means of reference to this horizon, even though the Glenwood is classified 
simply as a member of the formation above. 
At the base of the Glenwood "several thin irregular seams of limonite 
are very persistent over large areas and may represent corrosion surfaces 
formed at a time of negative deposition, when the sediments were built up 
to the profile of deposition in a shallow sea where an oxidizing environment 
prevailed." 68 Not only does this persistent horizon mark the bottom of the 
"" Arthur Bevan, The Glenwood Beds as a Horizon Marker at the Base of the Platteville 
FO'rmation (Geological Survey of Illinois, Report of Ilwestigations 9, 1926), pp. 1-13. 
67 "Stratigraphic Affiuities of Glenwood Shales," Pal1-A merican Geologwt, 60: 87-88 
(1933). 
68 G. A. Thiel. "Sedimentary and Petrographic Analysis of the St. Peter Sandstone," 
Hulletin of the Geological Society of A men'ca, 4(j: 606 (1935). 
76 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
FI GU RE 26. - Mississippi River blul\'. the Plattev ille ca ppin g the Sl. Peter. at the Washing-
ton Avenue Bridge, Unive rsity of Minnesota ca mpus. 
andy beds in which there is an admixture of clay, but a certain percen-
tage of the sand grains above that horizon are coarser and th ese beds carry 
a greater percentage of garnet than i present in the heavy residuals of the 
normal St. Peter sandstone. Including these sandy beds, the Glenwood in 
Minnesota has a maximum thickness of about 15 feet , although even this 
may be exceeded at a few places. 
Th e section at the Washington Avenue Bridge, on the edge of the Uni-
versity of Minnesota campu s, is probably t ypical. (See Figure 26.) 
MINNEAPOLIS, HENNEPIN COUNTY 
Ordovician Section Exposed a t the Washington Avenue Bridge 
THICKNESS 
PLATTEVILLE FORMATION (in fee t ) 
Spechts Ferry M ember 
10. Lime tone, ha rd , pyritiferous, blue to brown, with prominent ca lcite 
crystals . .......... . ..... . ...... . . .......... .. ............... . .... 1.7 
M cGregor M ember 
9. Limes tone, buff, even-bedded, containing a great many foss ils . ... . .. .. 10.7 
8. Limes tone, blue, nodu lar, weathering shaly. Lower 6 to 8 inches have 
black grains in streaks or burrows ... . .. . .. . .. . . ............... . . ... 17.0 
Glenwood Member 
7. Shale, hard , flaky, blue; or shaly blue limes tone conta inin g foss ils. ... . . 1.7 
6. Shale, soft, gray to brown ... ... ... ........ . ..... . ........... . ..... 0.3 
.5 . Shale, argillaceous, green, containing fros ted sand grains. . . . . . . . . . . . . . . 1.0 
4. Shale, sa ndy, yellow to white ... .... . .................. ..... ....... 0.7 
3. Sandstone, yellow to buff, intermin gled with clay .. . ...... . . ..... . ... 3.3 
!'l. Sandstone, white to yellow, with streaks of green, argill aceous sandstone 
and some clay ...... ... ..... .. ...... . .. .. . . . . . . ... . ... . ........... 5.5 
ST. P ETER SA NDSTONE 
1. Sandstone. white with yellow patches, partly covered a t the base near the 
water. to level of Mississippi River .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . !'l3 .0 
PALEOZOIC: ORDOVICIAN 77 
Thiel shifted Nos. 2 and S of this section from the St. Peter sand-
stone to the Glenwood beds. They certainly show evidence of change from 
their original condition as a part of the St. Peter, and have a clay content 
which has led some geologists to regard the whole deposit as transitional 
from the St. Peter sandstone to the Platteville limestone. 
That the Glenwood beds belong with the Platteville limestone 6D as a 
part of the Mohawkian series is certainly suggested by the fauna. Yet 
among the microscopic forms there is an element of conodonts which is 
decidedly older than Platteville, characteristic of strata lower than the 
Glenwood, and never found indigenous to the lVIohawkian. Possibly, as 
suggested by Branson and Mehl,71' the fossils constituting that element 
may be residual forms, weathered or washed out of an older bed and in-
corporated into the younger or Glenwood beds as they were being de-
posited. Among the common Glenwood fossils are a dozen or more genera 
of megascopic forms commonly found in the Platteville, together with a 
long list of conodonts and scolecodonts that are certainly Mohawkian 
forms; because of them we place these beds definitely in that series. It 
seems certain, therefore, that the Glenwood beds are to be regarded as the 
basal member of the Platteville formation in this state, and the same seems 
to be suggested elsewhere. 
~McGTegor Memuer.-The middle and major portion of the Platteville 
is the limestone so commonly quarried in and about .Minneapolis and 
St. Paul. For this member the name :McGregor limestone has been pro-
posed by Kay 71 from outcrops a mile and a half west of lVIcGregor, Iowa, 
where it "underlies the Spechts Ferry member. It includes the Blue Beds 
and Upper Buff Beds of the older vVisconsin classification .... In south-
ern Minnesota the McGregor lies on the Glenwood shale or on the St. Peter 
sandstone where that member is absent." ,C 
For lVIinnesota, then, there is recognized but one limestone member of 
the Platteville. In some of the adjacent states the old name, Pecatonica 
beds,,3 has been revived for the lower part of the central limestone member 
of the Platteville, and a new term, the :Magnolia member," has been pro-
posed for the upper part of the central limestone member in southwestern 
vVisconsin, northwestern Illinois, northeastern Iowa, and southeastern 
Minnesota. While it is quite true that remnants of both these proposed 
members occur throughout much of the Platteville-covered region of Min-
00 F. W. Sardesoll, Minneapolis-St. Paul Folio (U. S. Geological Survey, Geological Atlas 
of the United States. Folio 201, 1916). p. 6. 
7" In C. R. Stauffer. '"Conodonts of the Glenwood Beds,'" Bulletin of the Geological So-
ciety of America., -16: 130 (11)35). 
71 G1/ide Book of the Ni11th Annual Field Conference (Kansas Geological Society. 1935). 
pp. '186. '187. 
7" Ibid., p. 287. 
'" O. H. Hershey. '"The Elk Horn Creek Area of St. Peter Sandstone." American Geolo-
Uist, 14: 176 (lHH-t): A. C. Trmd)ridge. Guide Book of the Ninth Annual Field Conference 
(Kansas Geological Society, 1935). pp. 64, 70. 
71 C. A. Ba~'s and G. O. Raasch, GlIide Book of the Ninth Annnal Field Conference 
(Kansas Geological Society, 1935), pp. 297-300. 
78 PALEOZOIC AND RELATED ROCKS OF SOLTTHEASTEHN MINNESOTA 
nesota, their definitions are not sufficiently clear to separate them from the 
main part of the limestone, and it is quite certain that their overlap is tan-
tamount to eliminating much or all of the McGregor in this state. It is 
preferable, therefore. to use but one name for the limestone member of the 
formation; and the McGregor, as it has been defined by Kay. is quite 
satisfactory. 
The :McGregor limestone member of the Platteville varies somewhat, 
but in general is a rather thin-bedded limestone, often with shaly partings 
between beds. Much of it is pale blue or gray in color, often decidedly 
mottled, and where much weathered shows a buff color. (The mention of 
color as a distinctive feature of parts of the l'.'Iohawkian series has becn 
greatly overdone, and it is the present intention to ignore that property as 
much as possible.) 
It is the lower portion, about 1'2 feet of the McGregor, that is locally 
shaly. It is, in fact. a compact, hard blue limestone with numerous thin 
streaks of blue shale. The limestone layers are irregular and more or less 
nodular, yet continuous. and the thin, calcareous, shaly partings are an 
intimate part of the limestone. Where fresh, both calcareous shale and 
limestone separate into more or less thick beds at still more prominent 
partings. This is the building stone formerly used on a rather large scale 
in both Minneapolis and St. Paul. It contains a few fossils and many of 
them are broken; however, at certain places they are quite abundant. This 
portion of the formation has been changed but little from the original cal-
careous mud deposited on the bottom of the Ordovician sea; hence most 
of the fossils preserve the shell, occasionally with even the mother-of-pearl 
luster. At the bottom or 'within the bottom layer of this portion, or base, 
of the lVlcGregor member, there is a corrosion zone which usually shows 
numerous small black phosphatic pebbles.'" 
The middle portion of the McGregor consists of about 4 to 6 feet with 
a corrosion zone at its base. It is usually somewhat thicker bedded than 
the bottom layer. It may be a rather massive. argillaceous blue limestone 
or it may be chiefly shale. It is rarely fossiliferous, except in occasional 
pockets or nests where the shells must have drifted together as heaps on 
the sea bottom. Many of them are badly broken, and they are now pre-
served chiefly as molds. 
The upper part of the McGregor consists of about 8 to 10 feet of thin-
bedded, gray to bluish gray, brittle dolomitic limestone which breaks with 
a conchoidal fracture. These beds are often highly fossiliferous. and in 
places such remains are matted together like modern shells in a coquina. 
Except for the trilobites and the lingulas, which still retain their original 
shells, these fossils are preserved as molds still more or less open and not 
deformed. These molds were blackened by the deposition of finely divided 
pyrite and later covered by small crystals of calcite and quartz that sparkle 
" Frances Pettijohn. "Intrarormational Phosphate Pebbles of the Twin City Ordovician:' 
Journal of Geology,. 3.J.:361-73 (lD26). 
PALEOZOIC: ORDOVICIAN 79 
as their cavities are broken open. Pyrite is a common constituent of this 
part of the McGregor, and the corrosion zone marking the top of the 
member is an irregular blackened surface, the discoloration of which is due 
to this sulphide in a finely divided form.70 Some beautiful pyrite cubes. 
many of them twinned, are common, and occasional crystals of both sphal-
erite and galena are also found near the top. This upper or very fossiliferous 
portion of the McGregor member is the Vanuxemia bed of the Winchell 
survey. Its fauna is large and especially characterized by several Pelecy-
poda belonging to the genus Vanuxemia. 
The fauna of the McGregor member is that listed by Winchell and 
Ulrich 77 for the "Lower Buff" and Vanuxem,ia beds. In addition to num-
erous microscopic fossils, some of the more characteristic species are Rhyn-
chotrema 1ninnesotense val"., Rafinesqu·ina minnesotensis, HesperorthL~ 
tricena,ria, Clathrospira subconica, Trochonema beloitense, Lophospira 
comadana, L. serrulata, Vanuxemia dixonensis, V. obtusifrons, and Leper-
ditia fabulites. The chief distinction between the faunas of the lower and 
upper portions of the member is the abundance of preservation in the 
upper. 
Spechts Ferry Member.-The beds of alternating blue limestones and 
blue to green shales, designated the Stictoporella ,8 bed in Minnesota, 
were named the Spechts Ferry member by Kay'" and placed in the De-
corah shale. Winchell and Ulrich,so however, regarded them as the final 
stage of the "Lower Buff limestone" of Wisconsin, hence definitely a part 
of the Platteville. In his more recent work Kay has come to the same con-
clusion and designated the Spechts Ferry as the concluding member of 
that formation. S! 
The shales and fairly pure limestones of the Spechts Ferry member 
have a thickness of about 10 feet. (See Figure 27.) At Minneapolis it begins 
at the corrosion zone mentioned above, with 18 inches of brown limestone. 
This is succeeded by 4 inches of metabentonite 82 and then by 20 inches to 
2 feet of rather high-grade limestone, which at Faribault and southward 
has been referred to commonly as the "marble layer" or the "trilobite bed." 
Finally, this is succeeded above by a little more than 6 feet of blue to green 
shales, alternating with thin layers of bluish limestone and concluded by 
a corrosion zone with here and there a well-developed conglomerate or 
" C. R. Stauffer, "Mineralization of the Piatte\"ille-Decorah Contact Zone in the Twin 
City Region," Bulletin of the Geological Society of America, 36: 615-22 (19~5). 
77 N. H. Winchell and E. O. Ulrich, Geology of M innesoto (Final Report of the Geological 
and Natlll'al History Survey of Minnesota). Vol. 3. Pt. ~ (1897), pp. cxi--cxxiii. 7. F. W. Sardeson, "The Lower Silurian Formations of 'Visconsin and Minnesota Com-
pared." Bulletin of the Minnesota Academy of Natural Sciences, 3: 32~-25 (1891). 
" "Stratigraphy of the Decorah Formation," Journal of Geology, 37: 64~-49 (1929). 
'" Geology of Minnesota (Final Report of the Geological and Natural History Sur\"ey of 
Minnesota), Vol. 3, Pt. 2 (1897), pp. xcii-xcxiii. . . 
81 Guide Boole of the Ninth Annual Field Confe·rence (Kansas Geological Society 193,5). 
pp. 286-87: Bulletin of the Geological Society of A tlterica, 48: 294 and Fig. 13. ' , 
S!! V. T. Allen. "Altered Tuffs in the Ordovi('ian of Minnesota," Journal of Geology, 
37: 239-4R (19'29). 
80 PALEOZOIC AND R.ELATED R.OCKS OF SOUTHEASTERN MIN ESOTA 
pebble zone. A characteristic of the Spechts F erry member is its variability, 
but the basal bed retain th eir id entity over much of Minnesota and the 
brown limestone or Lingula bed can be identified with ease nearly every-
where. 
The Spechts F erry is distinctly a bryozoan member and fos il s belong-
ing to thi s phylum are very much in evidence, particu larly at certain lo-
calities where they co nstitute veritable reefs. From th e abundance of 
StictoIJm'ella this zone has received its faunal name. but other species are 
a lso charact eri stic. Some of the common forms are Rhynidictya mutabilis. 
Stictoporella frondifem, S. angula7'is, Climacogmptus typicalis, Pachy-
FIGURE ~7. - The Spechts Ferry member of the Platteville. along U. S. Highway No. 52 about 
five miles northwe t of Chatfield . 
dictya fimbriata, Pianodema subaequata, Lingula elclen', Zygospim nicol-
leti, and I sotelus gigas. 
The Specht Ferry member is often included in the D ecorah shale, sin ce 
it is lithologically more or less continuous with th e overlying shales that 
constitute that member. When this has been done, however, the D ecorah 
has been recognized as a convenient t erm to cover th e shale interval which 
is in part Platteville and in part Galena in age. The more recent usage, 
established by Kay, is much to be preferred, since it recognizes the contact 
between the Platteville and Galena as the base of the D ecorah shale mem-
ber and returns the Platteville to its original limits as established by Bain 
and, according to Winchell and Ulrich, as suggested by its fauna. 
The following section shows typical development of the Platteville 
formation in Minnesota (for furth er sections see pages 162-66) . 
PALEOZOIC: OHDOVICIAN 
ST. PAUL, HMISEY COUNTY 
Section at Dam No. I, Ford Motor Company Plant 
81 
26. Drift and ooil 
THICKNESS 
(in feet) 
5.0 
GALJlNA FORMATION 
Decorah Shale Member 
Ion Submember 
2.5. Shale. blue, with layers and thin lenses of limestone. Both shale and 
limestone beds are I'ucoidal, containing Hallopora pu1chella, H. ampra, 
llomotrypa minnesotensis, Hesperorthis tricenaria. Plectamoonites 
sericens. Zygospira recurvirostris, Lophospira bicincta, Isotelns gigas. . 5.5 
24. Shale, blue, with thin layers of limestone. Oolitic layer near the bottom. 
Fauna includes Halloporamu./titabulata, Batostonw winchelli, Hesper-
orthis tricenaria, Rafi.nesquina arternata, R. minnesotensis, Spyroceras 
oilineatum, CaUiops plattevillens;s ............................... 11.0 
Guttenberg Submember 
23. Shale. blue, alternating with layers of limestone. Contains A lilapora 
trentonen.lis. Stnptelasma profnndum, Caraoocrinus dicycl;cus, Vinella 
-repens, Pachydictya fi·moriata, Prasopora simulatrix, Bnnwstlls tren-
tanensis ............. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7 
22. Shale, blue, soft, containing RaujJella palmipes; also Pachydictya fim-
briata, Batostoma winchelli. Rhynchotrema minnesotense, Stropho-
17lena incllrt'ata. Cyrtodonta. ratll/ata. Ctenodonta soci<llis, C/<lfhro-
spira conica, Bumastu8 trentonelUri" ......... .................... 0.3 
21. Shale, blue, soft. with thin lavers of soft blue limestone. Contains 
Rhinidictya mntabilis, Ceram.o·porella inc.lu,m. Aulopora trentonen,~is, 
8tTOphomel1a incun,ata. Spyroceras bilineatum ................ 4.3 
:to. Shale, blue, soft, with a few limestone lenses. Contains Strepte/<lsma 
profnndllm. Rhinidictya mlltabilis. Strophomena incurvata. Rafi·nes-
quina minnesotensis, Phra.gmolites obliquus. Cameroceras? multicamera-
tum .......................................................... 3.8 
19. Shale. blue to green. with an occasional lens of limestone. Abundantly 
fossiliferous, containing Rhinidictya m"fabiUs. Homotrypa mil1neso-
tensis, StrophomenainCl1rt'ata, Lophospira bicincta, Clathrospira suo-
conica. CaUiops plattevillensis ................................... S.7 
IS. Shale. blue, argillaceous. with a few lenses and layers of limestone. 
The abundant fauna includes Rhinidictya mutabiT;',. R. fidelis, Berenicea 
minnesotensis, Rhynchotrellla minnesotense, H esperorthis tricenaria, 
Clathrospira conica, lsotelus gigas .............................. 5.7 
PLATTEVILLE FORlHATION 
Spechts Ferry Member 
17. Shale, white or light gray. argillaceous. The "putty layer" .......... 0.1 
16. Shale, argillaceous. with an occasional limestone layer. Contains Balo-
st01n<t minn&s·otense. HOlllotrypa mil1nesoten.\·I~'. Pachydictya foli<lta. 
Rhynchotrema ainsliei, Strophomel/a illcll,vata. lsotelus gigas 4.3 
16. Limestone. bluish. hard. Contains Stictoporella frondifera,. Pianodellla 
subaequata. Rafinesquina altemafa .............................. 0.7 
14. Shale, blue. argillaceous, soft .................................... 2.3 
13. Limestone, gray to brown. hard. partly cr~'stalline. with shaly partings 2.3 
12. Shale, pale blue to white. soft. A modified bentonite or metabentonite 0.3 
II. Limestone. brown. hard. Contains Linglll<l clderi. Pianodellw sub-
aeqllata, Endoceras proteiforme. and probably represents the trilobite 
bed of Iowa ................................................... 1.5 
:McGregor l'vIember 
10. Limestone. gray to bluish. highly fossiliferous. the fossils occurring in 
streaks or pockets. Fauna includes Va.lll/xell/ia oot.I/ .• ifrol/s, Clathro-
spira sltbconica. llesperorthis triccl/a ria , Ra.fi·llcsql/ina minnesotel/sis. 
Leperditia fabl/lites ...... , ......................... ,........... 8.7 
82 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
9. Limestone, argillaceous, somewhat shaly. Conchoidal fracture. Fauna 
includes Stre ptelasma profundu m, Rafinesquina rninnesoten.li.y. II esper-
orthis tricenaria, Strophomena. inCllrvata., Isotelus gigas . . . . . . . . . . . . . 5.3 
8. ~imestone, gray to bluish. mottled, composed of irregular thin layers 
mterbedded with films and thin layers of shale. Fauna includes lles-
perorthis tJicena'ria, Pianode71la su.baeqllata, Rafinesquina minnesoten-
sis, Climacogmptus typicalis, Rhynchotrema minnesotellse, Isotelus 
gigas ......................................................... 10.3 
7. Limestone, brown to gray. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 
6. Limestone, brown to gray. containing black pebbles, mostly near the 
top. Corrosion zone included .................................... 1.0 
Glenwood Member 
5. Shale, blue to green, argillaceous. occasional lenses of argillaceous lime-
stone ........................................................ 3.0 
4. Shale, green, argillaceous, soft ................................... 0.5 
3. Shale. green to yellow, sandy, passing downward into nodular. yellow to 
brown, sandy beds ............................................. 2.7 
2. Sandstone, somewhat argillaceous. white. cross-bf,dded. with a yellow 
streak and prominent break at the base . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 
ST. PETER SANDSTONE 
1. Sandstone, white, to level of the Mississippi River below the dam. . . .. 69.3 
GALENA FORMATION 
The Galena limestone, with its type locality at Galena, Illinois, was 
named by James Hall 83 in 1851, while working on the Lake Superior sur-
vey. In the type locality it is a gray to drab dolomitic limestone which 
weathers to a porous, yellow or buff, cliff-forming mass that caps the bluffs 
adjacent to the Mississippi River in Jo Daviess County, Illinois. It is the 
chief zinc and lead horizon of the region and attains a thickness of about 
250 to 300 feet. 8<1 
Kay S5 uses the Galena as a group name and correlates it with the Tren-
ton. Of course, the name Trenton has long been used in the upper Missis-
sippi Valley; in fact, it was chiefly James Hall's work that fastened it to the 
geology of this region. But he applied the term to rocks now known as the 
Platteville and regarded his Galena limestone as a younger formation rest-
ing on top of the Trenton. Now, however, the approximate Trenton age of 
the Galena and the Lowville-Black River age of the Platteville are well 
known, so that the use of the term Trenton, except for correlation pur-
poses, should be discouraged for the region along and near the Mississippi 
River. 
The Galena formation is composed of three members which are readily 
distinguishable in Iowa and Minnesota, but with more difficulty in Wis-
consin. The lower member is largely shale in Minnesota. The balance is 
limestone, part of which is of high calcium content. 
Decorah Shale Member.-The lower or shaly member of the Galena, 
83 In Foster and Whitney, Report on the Geology of the Lake Superior Land District 
(1851), Pt. 2, pp. 146-48. 
84 A. H. Worthen, "Geology of lllinois/' Geological Survey of Illinoi.y, Vol. I (1866), 
p. 141 and PI. 4. 
85 Guide Book of the Ninth Annual Field Conference (Kansas Geological Society, 1935), 
p.289. 
PALEOZOIC: ORDOVICIAN 83 
which carries a distinctly Trenton fauna, consists of about 60 feet of argil-
laceous blue to green shales with intercalated beds of limestone. (For 
analyscs see page 115.) From fine exposures of this member made by ex-
cavations at Decorah, Iowa, where it underlies much of the city, Calvin 80 
named it the Decorah shale. This name has long been applied, rather 
loosely, to all the shales and limestones lying between the quarry rock of 
the Platteville and the basal beds of the Prosser limestone. In so doing, it 
has been recognized that the formation crosses the boundary line between 
the Plattevillc and the Galena as those formations are defined in Illinois 
and Wisconsin. But the convenience of treating the shales of this general 
horizon as a unit has served as an inhibition against change. 
In 1929 Kay 87 made a study of the Decorah shale, dividing it into three 
sub members on a lithological basis, but correlating the beds with the 
earlier faunal work of Sardeson.88 At the time Kay recognized the hybrid 
nature of the Decorah as a formation and correlated its lower sub member 
with the upper part of the Platteville in Wisconsin.80 In his later work Kay 
reorganized his submembers and allocated the lower, corresponding to the 
Stictoporella beds, to the Platteville limestone of Iowa and Minnesota, re-
stricting the Decorah shale member to the basal or shaly portion of the 
Galena limestone.9o As thus restricted, the Decorah shale member is made 
up of the Guttenberg and Ion submembers, both of which are correlated, 
on a faunal basis, with beds cropping out in Minnesota. 
The Guttenberg submember lies at the base of the restricted Decorah 
shale member and begins with the pebbly corrosion zone at the top of the 
Stictoporella bed. In Minnesota this member is largely shale in the St. Paul 
area, but to the south the limestone layers increase in importance (see 
Figures 28 and 29), and at the type locality (Guttenberg, Clayton County, 
Iowa) it is chiefly limestone. The Guttenberg submember is the equivalent 
of the Rhynidictya and Ctenodonta faunal zones of :JVIinnesota. Its total 
thickness is about 30 feet, but occasionally slightly greater. Bryozoan reefs, 
with numerous brachiopod shells, are encountered at various places, and 
the fauna is relatively large. Some of the common forms are Rhinidictya 
mtdabilis, Homotrypa minnesoten,~is, Dalmanella rogata, Spyroceras bil-
ineatum, Ctenodonta compressa, and Calliops schmidti. 
The Ion submember completes the Decorah shale member. (See Figure 
30.) It is a calcareous shale which carries numerous layers or lenses of 
argillaceous limestone and includes the faunal zones of the Chas1natopora 
8<J "Geology of Winneshiek County," Annual Report of the Iowa Geological SUrt'cy for 
1905 (1906). Vol. 16, pp. 60-87. 
$7 "StratigTaphy of the Decorah Formation," Journal of Geology, 37: 639-71 09'19). 
88 "The Lower Silurian Formations of vVisconsin and Minnesota Compared," Bulletin of 
the Jllinnesota Academy of Natural Sciences, 3: 319-'26 (1891). 
8Q G. Marshall Kay, "Stratigraphy of the Decorah Formation," Journal of Geology, 
37: 657 and Fig. 8. 
JJQ G. Marshall Kay, G"ide Buuk of the Ninth Annnal Field Conference (Kansas Geologi-
cal Society, 1935), pp. !i/87-90; Bulletin of the Geological Society of A merica, 48: 294 and 
Fig. 13 (1937). 
FIGU RE 28. - The Guttenberg submember of the Decorah shale, along U. S. Highway No. 52 
about five miles northwest of Chatfield. 
FIGURE 29. - The Guttenberg submember of the Decorah shale, Gunderson clay pit, Zumbrota . 
84 
P ALEOZOI C: ORDOVI CIAN 85 
(Phylloporina) and the fu coid bed. It is limited a t the top by a corrosion 
zone and a n unu sual development of brassy ye llow ooli tes which occ ur at 
this hori zon in ma ny localities within th e sta te. The I on has a thickness 
of about 15 to 20 fee t in St. Pa ul , where th e e beds a re unusuall y well de-
ve loped . The fa una of th e I on subm ember, or of th e Phylloporina and 
fu coid beds, is large and welJ preser ved . In addition to the numerous fu -
coid , ome of the common foss il a re HallopoTa arnpla, Batosto'fIW httrnile, 
F IGURE 30 . - The Ion submember of the Decorah shale. along U. S. H ighway No. 52 about 
five miles northwest or Chatfield : 
B . rninnesotense, Dalrnanellarogata, R hynchotrema minnesotense. R . ain-
sliei, and Rafinesqttina alten wta. Th e fauna of t he D ecorah sha le member 
as a wh ole is distinctly a part of th e Galena. Thus it carries R eceptaculites 
oweni to its very ba e, and the same is true of R afinesqttina alte1'1ULta. 
One of the best sections of th e D ecorah shale is that given for the 
Twin City Brick Plant in St. Pa ul ( ee page 187). The following sections 
are also characteri stic: 
ZUMBROTA. GOODHUE COUNT Y 
Section in Clay Pi t, Lindel Brick and Tile Company, on R iver 1 l\Iile 
North of Town 
14. Drift 
GALENA FORMATION 
Decorah Shale Member 
I on Submember 
13. Shale, a.rgillaceous, blue to ~'ellow. with limestone lenses a.nd a few 
THfCKNESS 
(in feet ) 
1'2.0 
fossil s . . . ... ... .. ... ... ... ... . .......... . ... . ...... ...... .. . . . 4.0 
86 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
12. Limestone. yellow, with brassy oolites. .. .. . . .. . . . . . . . . . .. . . .. .. .. 0.5 
11. Shale, argillaceous, blue to yellow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 
10. Limestone, argillaceous, with numerous Bryozoa and some brassy oolites 0.8 
Guttenberg Submember 
9. Shale, argillaceous, blue to yellow. Abundant Bryozoa at base ..... , 2.4 
8. Shale, argillaceous, blue to yellow ............. ' ................ , . . 1.0 
7. Shale, argillaceous, blue to vellow, much weathered. Bryozoa scattered 
throughout .............. ' ...................... , . : ... , " .. , . . . . 4.6 
6. Shale, argillaceous, blue to yellow ....................... , , ..... , . 1.0 
5. Shale, argillaceous, blue, with abundant Bryozoa ........... , ..... , 3.4 
4. Shale, argillaceous, blue, soft ................... " ........... , .. , 1.0 
3. Shale, argillaceous, blue, soft ........ , ........... , .......... ,.,.. 3.4 
C) Shale, argillaceous, blue ........................................ 1.0 
1. Shale, argillaceous, blue, to level of water in bottom of pit. . . . . . . . . . 2.8 
ZUMBROTA, GOODHUE COUNTY 
Section in Clay Pit, Gunderson Brick and Tile Company, 2 Miles 
Northwest of Town 
8. Drift 
GALENA FORMATION 
Decorah Shale Member 
Ion Submember 
7. Shale, argillaceous, blue; also thin layers of fossiliferous limestone. Much 
THICKNESS 
(in feet) 
8.0 
of this portion is weathered yellow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.0 
6. Shale, blue, argillaceous ....................................... ,. 1.0 
5. Shale, blue, with lenses of fossiliferous blue limestone ............... 8.0 
4. Shale, blue; also fossiliferous blue limestone ................ . . . . . . . . 1.0 
3. Shale, blue, with lenses of fossiliferous blue limestone ............... 3.0 
2. Limestone, shaly, with numerous brassy oolites becoming abundant in 
lower part ..................................................... 2.0 
Guttenberg Snbmember 
1. Shale, blue, argillaceous, with little or no limestone. The main clay pit. 
To level of water in bottom of pit ............................. ,.. 16.8 
Prosser 1Vlember.-The lower part of the thick limestone belonging to 
the Galena is especially well developed and like the shale is well shown in 
Fillmore (see Figure 31) and Olmsted counties. Although part of it is shaly, 
much is a high-grade limestone with little impurity. (For chemical analy-
ses of it see page 115.) This hard, compact member, including its shaly 
limestones, has been named by U1rich 91 the Prosser limestone. No ade-
quate description of the member occurs with the first use of the term, nor 
is the type section properly located. However, Winchell and Ulrich 9" had 
previously given a section of "Prosser's ravine, near Wykoff, Fillmore 
County" 'which Ulrich undoubtedly intended as the type section. 
At that locality there crops out about 185 feet of rock of which 115 to 
120 feet may be assigned to the Prosser member. For the most part it is a 
hard, compact, drab limestone with a subordinate amount of shale. Some 
beds are fairly thick, particularly in the upper middle part, and several 
01 "Revision of the Paleozoic Systems," Bulletin of the Geological Society of America, 
22: 368.369,525, and PI. 27 (1911). 
02 Geology of iJIinnesota (Final Report of the Geological and Natural History Survey of 
Minnesota), Vol. 3, Pt. 2 (1897), pp. lxxxv-lxxxvii. 
PALEOZOIC: ORDOVICIAN 87 
horizons are cherty. The member has a total thickness of abo ut 185 feet 
at Wykoff, and probably does not greatly exceed that anywhere within 
the stat e. The Pros er limestone may be een to best advantage in Fill-
l1lore, Olmsted, and Dodge counties. Although it covers a omewhat larger 
area, much of the region is heavily drift-covered and the Prosser fails to 
crop ou t even along th e larger streams. 
FIGURE 31 . - The Prosser li mestone along Lost Creek, six miles we t of Cbalfield. 
This is one of th e very fossiliferous members of the Galena and the 
fauna i quite large, though in the hard, dense lime tone it i difficult to 
recover good specimens. Among the common and characteristic fossils are 
R eceptaculites oweni, I schadites iowensis, Climacograptus typicalis,Cata-
zyga upharni, Rafinesquina deltoidea, Plectarnbonites sericeus. PlectoT-
this 1Jlicatella b·entonensis. Vanuxernia abntpta, ConulaTia tTentonensis, 
BurnastJUs tTentonensis, I sotelus gigas, and Illaenus al1wricanus. 
The following section along Prosser Creek is probably to be considered 
the type of the Prosser limestone member. 
WYKOFF, FILLMORE COUNTY 
T ype Section of Prosser Limestone, Prosser Creek, 2% Mi le West of Town 
THICKNESS 
(in feet) 
19. Drift ...................................................... .. .... 15.0 
MAQUOKETA FORlVIATJON 
Dubuque Member 
18. Limes tone, shaly, gray to buff, fossi liferous. ... ... ......... .... .. .. . . . 20.0 
88 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
GALENA FORlIIATION 
Stewartville Member 
17. Dolomite. caveruous, yellow to buff, fossiliferous. Common fossils include 
Jlac/urina manitobensis and Horm,oto71UL major. . . . . . . . . . . . . . . . . . . . . . . 16.0 
16. Dolomite, very porous, yellow from weathering, in thin, knotty layers. 
Common fossils are Receptaculites owen;, ;UacillrirUl cuneata, JU. 11/(/ni-
tobensis, Hormotollla major, Endoceras sp., lliaenl~' all/ericanus........ 10.'; 
15. Dolomite, thick-bedded, gray to yellow. Common fossils are Receptaculites 
oweni, ;Uaclurina 1I/<l11itobellsis, Horll/otollla major, ll'estonoceras minne-
sote,we ............................... ,............. . . . . . 1'1.3 
14. Dolomite, gray to brown, weathering yellow. Common fossils are Recep-
taculites oll'eni, Rafinesquina altemata. Maclurina manitobensis, M. cras-
sus, Hurmotoma major, H. trentonensis, Iliaelllls americanus, lsoteills gigas 14.5 
13. Shale, argillaceous, yellow to gray. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 
Prosser Nlember 
12. Limestone, compact, drab, subcrystalline, with some thin, argillaceous layers 11.0 
11. Limestone, compact, hard, drab, thin-bedded, with numerous graptolites 1.0 
10. Limestone, compact, hard, drab, very fossiliferous. Common fossils include 
Rafi,nesqwna deltoirlea, ('atazyga uphami, PlectQ.1nbonites gibbosus, Byss-
onychia intermedia ........................................ " .. ,. R.O 
9, Limestone, bluish, compact, partly crystalline, thin-bedded to shaly. Com-
mon fossils include Streptela.Hna, corniculum. and Rafinesqllina. deltoidea, 1>,0 
8. Limestone, compact, drab, with some chert or flint, Fossiliferous ,....... 13.3 
7. Limestone, compact, drab with numerous fossils. Common forms are 
Ischadites iowensis, Hespero-rthis tricenaria, Plectambonites sericeu", Raf-
inesquina altemata, Vel/a rna diversa., Endoceras annulatum, lsotelus gigas 19.3 
6. Limestone, thick-bedded, compact, drab, with some chert. Common fossils 
include Hesperorthis tricenaria and Plectorthi., plicatella trentonensis ... , 10.3 
5. Limestone, compact, drab, with shaly beds at the base, fonning bottom of 
small caves and line of springs. Graptolites common ... , , , . . . . . . . .. . . . 9.::? 
4. Limestone, argillaceous, massive, but weathering into thin, knotty beds, 
blue to gray in color. Receptaczdites oweni common ....... , . , . , . . . . . . . 17.8 
3. Limestone, compact, drab, passing into arg-illaceous beds. Receptaculites 
oweni and Ple.ctarnbonites sericeus common ............... , . , ..... , . . 10.3 
::? Limestone, compact, Iig-ht drab in color. Abundant fauna includes Dinor-
this meedsi germana, HafinesCfuina alternata, Rhynchotrema illcrebescens 3.2 
1. Covered interval to lew] of Deer Creek at outlet of Prosser Creek, . . . .. 5,3 
StewQTtville "NI embeT.-Capping many of the bluffs in the counties over 
which the Galena is developed, there is a cavernous, gray to yellow or tan, 
mottled, thick-bedded dolomitic limestone, which Ulrich 93 named the 
Stewartville dolomite. (For chemical analyses see page 115.) As with the 
preceding member, the name was proposed without description or mention 
of type locality. However, the term is apparently used as a locality name 
for the lVlaclurea bed,"" which Sardeson made the top faunal zone of the 
Galena. Concerning the lVIaclurea bed, Winchell and Ulrich remark that 
"this entire bed is exposed in Prosser's ravine near Wykoff ... and the 
lower layers are quarried at Stewartville." 9" It is probable, therefore, that 
the name is taken from the town of Stewartville, Olmsted County, lVIinne-
"1 "Revision of the Paleozoic Systems," Bulletin of the Geological Society of A merica, 
Vol. 22, PI. 27 (1911) . 
• , F. 'V. Sardeson, "The Lower Silurian Formations of Wisconsin and Minnesota Com-
pared," Bldletin of the Minnesota Academ'y of Natural Sciences, 3:324-25 (1891) . 
• , N. H. Winchell and E. O. Ulrich, Geology of Minllesota (Final Report of the Geological 
and Natural History Survey of Minnesota), Vol. 3, Pt. 2 (1897), p. ci. 
PALEOZOIC: ORDOVICIAN 89 
ota, and that th e outcrop at that locality is to be considered the type ( ee 
Figure 32). 
The Stewartville dolomite is usually about 50 feet thick , but locally the 
thickness is slightly greater, as along Prosser Creek and at several other 
places in that vicinity, wh ere about 
55 feet have been measured. Some 
of the hard or resistant layer near 
the top are chiefly respon ible for 
the durability of the capping of 
many Galena bluffs in Fillmore 
County. 
The fauna i not large, nor are 
fossils abundant, though they are 
sufficiently common and well dis-
tributed for correlation purposes. 
The fauna i largely mollu can ; per-
haps the best guid e fossils are Hor-
motoma major, Macl~trina manito-
bensis, M . cuneata, Maclurites cras-
sus, and l-Vestonoceras 1'ninneso-
tense, although others may be found 
of much value in identifying th e 
member 
The preceding section for Prosser 
Creek shows the Stewartville dolo-
mite in some detail. The following 
section along the north side of Root 
River, on e-half mile west of Stew-
artville, may be considered typical , 
. although when the bridge was be-
ing built in town, a somewhat simi-
FIGURE 32. - The Stewarh' iUe dolomite at 
Stewartville, showing characteristic pitted 
surface due to weathering. 
lar section was exposed along th e highway at th e south bank of the river 
a.nd may still be seen at the Cusson Milling Company . 
STEWARTVILLE, OLMSTED COUNTY 
Section at the Old Quarry, North Bank of the River Vz Mile above the Dam 
THICKNESS 
(in feet ) 
7. Soil . .. ..................... . ............. . ....... . ........ . ..... . 2.0 
GALEN A FORMATION 
Stewartville Member 
6. Dolomite. wea thpred. sur race pitled . buff. Common ro sils include R ecep-
taculites o1Veni, IV estonoceras m innesotense, crinoid stems .......... . ... 8.0 
5. Dolomite, hard , gray to buff, lhick-bedded, crinoid ai , containing Calymene 
sp., Endoceras sp., and others . ...... . ................ . .............. 4.8 
4. Dolomite, massive, gray to blue, weathering buff, thin-bedded when 
weathered . Contains scattered crinoid stems, HOTllwtoma major, Endoceras 
cf. protei/onne, IV estonoceras m inn esotense, illacltlTina 7Ilanitobensis. . . . . . 7.5 
DO PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
3. Dolomite, buff, massive, weathering to thin beds. Scattered crinoid seg-
ments and j}lac1urina manitobensis abundant; also !;laclurites crassus, 
Hormatallla major, H. trentonensi". "Orthocems" d. bilineatum ........ 4.7 
2. Dolomite, weathered, buff. massi,·e. hard. Scattered crinoid stems; Recep-
taculites oweni and !;la.c/urina manitobensis common. ... .. . ... .. .... .. 3.3 
1. Partly covered to water level above the dam (1.212 ft. A. T.) ............ 2.0 
CINCINNATIAN SERIES 
l\1AQUOKETA FORMA'l'ION 
The Cincinnatian as developed in Minnesota is essentially the Maquo-
keta formation. which is often considered a group or series. It usually con-
sists of gray to bluish limestones interbedded with blue to brown shales. 
In Fillmore County it has a thickness which may exceed 100 feet. (For 
chemical analyses see page 115.) As in Iowa. much of the Maquoketa in 
l\1innesota is a limestone containing a modified but nevertheless recurrent 
fauna derived from the Mohawkian. The series may be subdivided into 
several memlwrs, in each of which a somewhat different assemblage of 
fossils is recognized. The subdivisions are therefore probably justified. 
The Nlaquoketa formation was named by White 9G from exposures along 
Little Maquoketa River. Dubuque County, Iowa, and regarded by him as 
the approximate equivalent of the Hudson River shales. as that term is 
used in New York State. The formation in Minnesota covers a relatively 
small area in several of the southern counties, from Fillmore County north-
ward and westward, passing under glacial drift. In the central portion of its 
development the formation is covered by Devonian and probably by small 
remnants or outliers of Cretaceous beds. 
Dubuque .Member.-The beds succeeding the Stewartville. but belong-
ing to the Nlaquoketa, in southeastern Minnesota and adjacent parts of 
Iowa, Sardeson 07 named the Dubuque formation from the outcrops at 
Dubuque, Iowa, where the type section may be seen in the upper quarry 
on Fourteenth Street hill, just below Columbia College. In Iowa the 
Dubuque is a soft, thin-bedded, light gray dolomitic limestone with gray 
shale partings, reported to rest conformably 98 on the Stewartville. In Min-
nesota it is mostly a gray shale with intercalated beds of gray to bluish 
limestone. The thickness of these beds in Minnesota seems to range from 
about qO to 30 feet or more, but they are not often exposed and the horizon 
cannot be thoroughly studied. 
Kay D0 shows that the Dubuque is the equivalent of the Oxoplecia 
(Tri7)lecia) ulrichi bed of Minnesota.' He thinks it is probably conform-
9n Report on the Geological Survey of the State of Iowa (1870), Vol. 1, pp. 180-82. 
""Galena Series," Bulletin of the Geological Society of America, 18: 193 and Fig. 2 
(1907). 
uS G. Marshall Kay, "Ordovician Stewartville-Dubuque Problems," Journal of Geology, 
43: .566-67 (193.5). 
"9 Ibid .. pp . .561-90. 
1 N. H. vVinchell and E. O. Ulrich. Geology of Minnesota (Final Report of the Geological 
and Natural History Survey of Minnesota), Vol. 3, Pt. 2 (1897), p. civ. 
PALEOZOIC: OHDOVICIAN 91 
able above the Stewartville, that it is to be correlated with the Colling-
wood, and that it is th e upper member of the Galena. On the basis of faunal 
content, Sardeson placed this bed in the Maquoketa series, but states that 
"between the TrilJlecia bed and the Diplogmptus bed there i a weIl-
marked stratigraphic change," 2 thus sugge ting the occurrence of the 
break above the Dubuque pointed out by Kay. The writers regard the 
Dubuque in Minnesota as part of the Maquoketa formation . If it correla-
tion with the Collingwood of Ontario is correct, the age is still somewhat 
in question, for that formation is periodically shifted from the top of the 
Trenton to basal Utica. 
FIGURE 33. - The Stewartville dolomite and the Dubuque or basal member of the 
Maquoketa formation in the Lime City Quarry, north of Sprin g Valley. 
The Dubuque fauna in Minnesota includes uch forms a Dalmallellc£ 
corytdenta, D. ftdilis, Oxoplecia td1'ichi, Plecrombonites precosis, and 
others not definitely limited to the zone. It seems to lack most of the 
diagnostic Galena fossils that one would expect to find in beds properly 
referred to the Galena. 
The following section of the Lime City Quarry, two and one-half miles 
north of Spring Valley, Minnesota, shows th e Dubuque member near the 
top. (See Figure 33.) 
2 F . W . Sardeson, "The Galena and l\1aquoketa Series," A Inerican Geologist. 19: 30-31 
(1897). 
1J'Z PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
9. Glacial drift 
LIME CITY QUARRY, FILLMORE COUNTY 
Section '2% 'Miles North of Spring' Valley 
l\IAQUOKETA FORl'IIATlON 
Dubuque Member 
THICKNESS 
(in feet) 
10.0 
8. Limestone, thin-bedded, hard, compact, gray to blue, with some blue to 
brown shale partings. Fossiliferous ................................... 20.0 
7. Limestone, thin-bedded, dolomitic. gray, with shaly partillgs ............ 6.0 
6. Limestone, gray, arenaceons, dolomitic, with some shale partings. .. . . . . .. 5.0 
5. Shale, arenaceous, gray ............................................. 0.1 
GALENA LIMESTONE 
Stewartville Member 
4. Dolomite, rough, weathered surface pitted, gray, carrying Receptaculites 
oweni, Jl1ac/urilla, and others. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.0 
3. Dolomite, compact, gray to ashen, with Rece.pta.clliites M(Jeni, lIlaclnrina 
IIwnito/Jells;". lI'estollo('eras minne"ote"se. anfl others. ... 20.0 
'? Dolomitic limestone. gray, hard. with JlIuc/llr;na manitobensis, Norm%ma 
major, .M acltlriies crass-us, and others ................................ 15.0 
Prosser :Member 
I. Limestone. compact. gray, very fossilirerous, to level of Deer Creek. 4.0 
Wykoff lI1ernber.-The name Wykoff member, proposed by Hall and 
Sardeson 3 for the highly fossiliferous beds occuring around Wykoff, Min-
nesota, and in the railroad cuts between Wykoff and Spring Valley, is 
yery satisfactory and should be retained in the :Minnesota classification. 
The Wykoff member consists of about 30 to 45 feet of argillaceous gray 
limestone and weathered shale that form the UppEr part of the Ordovician 
in southern Minnesota. ]\i1any of its fossils are silicified and weather out 
of the soft rock, so that they cover the surface in great numbers; even 
where the beds are not remarkably full of them, they may be concentrated 
by the weathering process. Over the region where this member forms the 
surface or near surface, every rock cut along the road or railroad forms an 
excellent collecting ground for those interested in its fauna. This is espe-
cially trne of the region between Spring Valley and Wykoff. These beds are 
characterized by such forms as Streptelasma rnsticum, Dinorthis sub qua-
(/rata, Dalmanellameeki, Leptaena unicostata, Rafinesquina killgi, Stro-
phomcna fiuctuosa, and S. sp. 
One of the better sections is that east of Spring Valley, where the fol-
lowing strata occur along U. S. Highway No. 16: 
SPRING VALLEY, FILLMORE COUNTY 
Section 1 Mile East of Spring Valley 
THICKNESS 
DEVONIAN (in feet) 
Cedar Valley Limestone 
4. Limestone, weathered, yellow to buff, thick-bedded. Atrypa reticularis 
common ......................................... ·............. 4 
3 "Paleozoic Formations or Southeastern 'Minnesota," Bulletin of the Geological Society 
of A merica, 3: 349, 359, 366 (1892). 
ORDOVICIAN 
Maquoketa Formation 
Wykoff Member 
PALEOZOIC: ORDOVICIAN 
3. Limestone, shaly, weathered, gray to ashen. Dalmanella meeki abundant 
2. Limestone, gray to ashen, weathered, thick-bedded. Dinorthis subqua-
drata abundant ................................................ . 
1. Limestone and shale, weathered. Fossils are few but include a variety 
of forms, such as Ischadites, Plectambonites, Lingula .............. . 
POST-ORDOVICIAN INTERVAL 
4 
6 
5 
93 
The weathered surface and depth of weathering of the Wykoff beds are 
evidence of the long interval that elapsed between the Ordovician and the 
younger beds that lie on top of it. Whether any part of the Silurian sea 
ever covered southern Minnesota is a question that cannot be answered, 
but no remnants of Silurian deposits are known within the state. Not only 
that, but all of the Lower and perhaps all of the Middle Devonian is also 
missing, and limestones of late Middle or early Upper Devonian lie on the 
deeply weathered surface of the Wykoff beds. Moreover, the contact, al-
though an overlap, is so nearly a true disconformity that the erosion taking 
place during the long interval must have been essentially to base level and 
with no intervening deformation. Even though the interval between the 
Ol'dovician Wykoff beds and the Devonian Cedar Valley limestone is a 
long one, it is only a portion of the interval between the late Ordovician 
and the Cretaceous, or the pre-Cambrian and the Cretaceous, which will 
be discussed below. The depth of weathering of the pre-Devonian surface 
in southeastern Minnesota suggests that erosion was unable to keep pace 
with the weathering, and therefore that the region must have stood near 
base level for a very long period prior to deposition of the overlying rocks. 
CHAPTER V 
PALEOZOIC: DEVONIAN AND POST-DEVONIAN 
As jnst indicated, the Devonian system succeeds the Ordovician in 
Minnesota, the whole Silurian and early Devonian being absent. The sea 
covering this region at that time was evidently cut off from the east by 
land or other eqnally effective barrier, as the eastern Devonian fauna was 
quite completely excluded from this embayment except for a few widely 
distributed species. Even in the case of these few species there is some varia-
tion; hence it is probable that the communication between this and the 
New York area was indirect. In other words, the remnant of Devonian in 
this state is western Devonian, with its main faunal affinities to the south 
and west, and probably contributing to the later :\few York faunas rather 
than forming a part of them. 
SENECAN SERIES 
CEDAR V ALLEY LIMESTONE 
The Devonian of Minnesota is probably represented by a single forma-
tion, the Cedar Valley limestone, which was named by McGee 1 for the 
outcrops in the valley of Cedar River, Iowa. McGee says this designation 
was originally proposed by Owen, but was never used except in a very 
general way, such as "the limestones of Cedar Valley," which Owen said 
were "of the age of the Hamilton of New York."" The name is therefore 
credited to McGee. 
The Cedar Valley limestone covers the southwestern corner of Fillmore 
County, about three-quarters of :lVIower County, and a small corner of 
southeastern Freeborn County in :lVIinnesota. It is an exceedingly variable 
formation, as to both lithology and fossil content. The lower portion be-
gins with a gray to buff or yellow, heavy-bedded, tough, porous magne-
sian limestone (see Figure 34), which is succeeded by coarse gray lime-
stones and dolomites, with one or two brecciated layers in the upper part. 
About the middle of the formation is a fine-textured, compact, gray to 
nearly ""hite (weathers to white) limestone of high calcium content (see 
Figure 35) associateu with brown magnesian layers, the whole forming 
the unit one time exploited as a "lithographic limestone" in Iowa. (For 
ehemical analyses see page 115.) Still higher in the formation there is a 
heavy-bedded, soft magnesian rock, followed by the earthy beds of the 
upper part, common around Austin. At no one place is more than a small 
fraction of the formation exposed, but from a comparison of the various 
1 Eleventh An"nal Report of the United States Geological Snrvey, Pt. 1 (1891), p. SH. 
'D. D. Owen. Report of the Geological Survey of Wisconsin, Iowa and Minnesota (185£), 
pp. 77-81 and .586. 
94 
PALEOZOIC: DEVONIAN 9,5 
quarry and natural sections with those immediatcly to the south in How-
ard and Mitchell eo unties, Iowa, it is evident that the complete section in 
Minnesota has a thickness of about 130 feet. 
The lowest beds are exposed at Spring Valley and the highest along 
Cedar River south of Austin. At Austin and to the west in Freeborn 
County, the Cedar Valley limestone is overlain by a soft gray to nearly 
white shale or clay with some limestone or dolomite, which suggests 
remnants of higher Devonian beds. Microscopic study of these beds at 
Austin has shown a mixture of Ordovician and Devonian conodonts, 
both of which may be residual and washed into a much later deposit. 
On Rose Creek, a' few miles to the south of Austin, silicified Devonian 
corals occur as residual fossils in similar clays. The early survey by Win-
chell B reported Cretaceous leaves from the same deposits at Austin, 
and recently Foraminifera have been washed out of similar clays from 
a deep well (Hormel's) at Austin. These facts seem to fix the age as 
much more recent than that suggested by the conodonts. Since these 
beds are known chiefly from well logs, and neither the meager outcrops 
nor the well-log descriptions seem to suggest the beds immediately over-
lying the Cedar Valley limestone across the state line in Iowa, they are 
still tentatively classified as Cretaceous. 
Calvin partially divided the Cedar Valley limestone into faunal 
zones, based on work immediately to the south of the Iowa-JVIinnesota 
state line, and Stainbrook" has suggested member names for these dif-
fering zones, though they have not been used in JVIinnesota. Calvin's' 
general section for Howard County, Iowa, is essentially that of the adja-
cent region in Minnesota, although in this state the rock is less favor-
ably exposed, and the total thickness may be somewhat less. With slight 
modifications, the generalized section for .Minnesota " may be made quite 
similar to Calvin's for Howard County, Iowa. The numbers in paren-
theses in the following section indicate the divisions of Calvin's section. 
(5) 
CEDAR VALLEY LIMESTONE 
Condensed General Section for l\linnesota 
9. Limestone, buff to brown, massi,·e. coarse. Common fossils include Stropheo-
donta, Cranaena, Atrypa. Exposed along Cedar Ri"er just west of Lyle ..... . 
8. Limestone, blue to buff and brown, argillaceous. in thin to massive beds, with 
some chert. Fossils not COIllmon; those found include Ath!Jri~', Spirijer, FavositlY!. 
Shown in the old quarry along Rose Creek at Varco ..................... . 
THICKNESS 
(in feet) 
20 
30 
"Geology of jlIinnesota (Final Report of the Geological and Natural Historv SUr\'ev of 
Minnesota), Vol. I (l884), p. 3,54. • . 
1 Guide Book of the Ninth Annual Field Conference (Kansas Geological Society. 1935), 
pp, 254-55. ' i ! 
G "Geology of Howard County," Annual Report of the Iowa Ge.ological Sun'ey for 190.2 
(l903). Vol. 13, p. 62. 
6 C. R. Stauffer, "The :Minnesota Devonian and Its Relationship to the General Devoll-
ian Problem of North America," American Journal of Science, 4:405 (1922). 
FIGURE 34. - The lower or Productella beds of the Cedar Valley limestone at Spring Valley. 
FIGURE 35 . -- The hard, compact, high calcium beds (StrollUttoporelia beds) of the Cedar 
Valley limestone at Le Roy. 
96 
PALEOZOIC: DEVONIAN 
(4) 
7. Limestone, gray to yellow or brown. Known only from well logs. . . . . . . . . . . . . 10± 
(3) 
6. Limestone, gray to nearly white, compact, fine-grained, with partings of gray 
shale and often alternating with beds of coarse brown dolomite. Fossils rare, 
but Stromatoporella, Spirifer, Cyrtina, Pleurotoma'ria, and others have been 
found. Shown in quarries at LeRoy. The Stromatoporella beds of Iowa. . . . .. 12 
(2) 
5. Limestone, gray to buff and brown. Exposed along the state line seven miles 
west of Granger. Common fossils are brachiopods, among which Stropheodonta 
and Atrypa are conspicuous. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . 12 
4. Limestone, brown and gray, brecciated, with no I'ossils. Shown along the state 
line at Charles Grimm's farm, five miles west of Granger . . . . . . . . . . . . . . . . . . 4 
3. Limestone, gray to buff, massive. Common I'ossilg are corals, brachiopo:ls, and 
mollusks, chiefly gastropods. Shown along the state line at Charles Grimm's 
farm, five miles west of Granger. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 
2. Limestone, gray to brown, in massive beds, full of corals and stromatoporoids. 
Shown along the state line at Charles Grimm's farm, five miles west of Granger. 
The Acervularia beds of Iowa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 
(I) 
1. Limestone, gray to buff and brown, in massive beds. Common fossils include 
Productella, At-rypa, Cyrtina, Spirifer, Stropheodonta, Bellerophon. Shown in 
the quarries at Spring Valley and at Hamilton. The Productella beds of Iowa 30 
POST-DEVONIAN INTERVAL 
97 
Following the Devonian, prolonged erosion reduced the northern 
Mississippi basin region to a near base-leveled condition, removing any 
later formations that may have been laid down in l\tlinnesota. Some of 
the old granitic monadnocks of this peneplain still stand in Yellow Medi-
cine County and even pierce the thick glacial drift covel'. Beneath the 
drift much of the area is still covered by a deep blanket of regolith or 
weathered rock which at many places has never been moved from its 
position as part of the pre-Cambrian schists and gneisses of the old land 
area. In the vicinity of Redwood Falls the weathered mantle, part of 
which was formed long before the Cretaceous, is 75 to 100 feet thick and 
shows gneissic and schistose structures that still bear large quartz veins 
carrying through to the very base of the drift. Exposures of this old 
weathered surface are widespread along the deeper valleys of Redwood 
County, and its weathered materials were adequately discussed by the 
Winchell survey.' Associated with the kaolinized feldspars are quantities 
of iron derived from the ferromagnesian minerals. This has been con-
centrated at places, staining the residuals red to brown and even forming 
thin beds of impure manganiferous iron ore. 
In Blue Earth, Nicollet, and Le Sueur counties, where the Oneota 
dolomite overlies the Blue Earth siltstone, a great system of sinks and 
caves was developed, with the fairly impervious siltstone acting as the 
7 Second Annual Report of the Geological and Natural lliHtory SurNlI of Minnesota 
(1874), pp. 167-69; Geologll of Millncwta (Final Report of the Geological and Natural His-
tory Survey of Minnesota), Vol. 1 (1884), pp. 57()-7~. 
98 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
cavern floor. The ,'leathered surfaces of the dolomite. the widened joints. 
and the walls of the caves are coated with a limonite crust. At places 
where the water broke through the siltstone. iron was carried to lower 
levels and deposited along some impervious layer in the Jordan sand-
stone. In the vicinity of Mankato and St. Peter, where the cave develop-
ment was especially extensive and the support insufficient, the roofs 
gave way and great masses of the dolomite were plunged into the water-
soaked siltstone. causing it to be squeezed up into the caverns, at places 
completely filling them. When later the Cretaceous clays were laid down 
over this same area. most of the remnants of the solution cavities were 
filled by the clays of that age. The sequence of events which produced 
this unusual history is evident in the cliffs along the Minnesota River 
and in the highway cuts north from the vicinity of Minneopa Falls 
throughout a distance of nearly twenty miles. In fact, suggestions of the 
same condition are present in the outcrops at Garden City. where the 
dolomites have caved in to produce what appears to be a small syncline.s 
The siltstone carries a few linguloid brachiopods. but the clays above. 
which are regarded as Cretaceous,') seem to be without fossils in the 
:Mankato region. Farther west and north, however. similar shales do 
carry a definite Cretaceous fauna. 
In other regions. such as Fillmore County and southeastward into 
Iowa, Paleozoic limestones suffered leaching. and the upper portion was 
gradually transformed into residual iron oxides through deposition from 
iron-bearing solutions. Occasionally 4 to 6 feet or more of the surface are 
thus affected, and the region has been prospected with the hope of 
developing some favorably located deposit on a commercial basis. The 
best prospects seem to be those associated with the Devonian south of 
Spring Valley and southeast of Etna, where some attempt is now being 
made to utilize it for commercial purposes. Numerous silicified fossils were 
weathered out of these limestones. lVIany of them were water-worn or 
rounded to cobbles and pebbles, which then took part in the formation 
of other deposits of much later deposition. 
S N. H. Winchell. Second Annual Report of the Geological and NCLtural History Survey 
of JIillllesofa (1874). p. 147. . . . 
U Ibid .. pp. 176-8'1; Geology of Mmnesofa (FlIlal Report 01 the Geological and Natural 
Hislory Surveyor Minnesota). Vol. I (1 H84). pp. 423-39. 
CHAPTER VI 
MESOZOIC: CRETACEOUS 
DAKOTA SERIES 
Just when weathering and erosion ceased to be the dominant factor 
on the old Paleozoic land surface, and when sedimentation set in, is not 
very clearly demonstrated for Minnesota. But by the beginning of the 
Cretaceous period, the streams attempted to move more sediment than 
they could carry and some of it accumulated in catchment basins. These 
were apparently fresh-water sediments and consist of clays, silts, sand-
stones, and conglomerates that spread out over a wide area of the south-
ern part of the state. Here and there swampy conditions prevailed, and 
thin beds of impure lignite were formed. In some localities the shales 
and sandstones carry numerous leaves and occasional molluscan shells, 
but they are not very fossiliferous. A study of the fossil plants from the 
shales at Springfield and from the sandstones along the Big Cottonwood 
River south of New Ulm has led to their correlation with the Dakota 
sandstone.' Farther to the north these deposits seem to continue as 
sands and clays beneath the drift and have been penetrated by numerous 
water wells. On the :Mesabi Range, however, the iron formation is over-
lain by conglomerates and gray to greenish argillaceous shales carrying 
an abundant marine molluscan fauna, which is correlated with the Ben-
ton formation of the Cretaceous." This is the shale that is so well exposed 
in the open-cut mines at Coleraine and Calumet and which has been 
called the Coleraine formation. 
DAKOTA FORMATION 
The most orthodox portion of the 'Minnesota Cretaceous thus belongs 
definitely in the Dakota and the lower portion of the Coloradan series. 
Southeastward from the margin of the Dakota formation in the :Mankato 
region there is a wide area of scattered gravel. sand. and clay deposits, 
extending from Blue Earth to Goodhue and Houston counties. These 
overlie the old post-Devonian erosion surface and are in turn overlain bv 
the glacial drift. ' 
These gravels (see Figure 36) are largely composed of clear quartz 
pebbles, but contain an important admixture of pink quartz and chert 
pebbles as well. The sands are poorly assorted and vary from coarse to 
fine. Cross-bedding is common. and both sands and pebbles may be ce-
mented by iron oxides into hard. resistant sandstones and conglomerates. 
1 Leo Lesquereux, Geology of Jl1illnesota (Final Report of the Geolog;ical and Natural 
History Survey of Minnesota). Vol. 3. Pt. I (1895), pp. 1-:14 and Pis. A and B. 
2 Harlan Bergquist, unpublished Ph. D. thesis on file in the Department of Geology, Uni-
versity of Minnesota. 
99 
100 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
FIGURE 36. - Gravel pit in the Ostrander member one mile east of Ostrander. 
One bed, 3 to 6 or more inches thick, near the top of the gravel beds, 
is thoroughly cemented by iron at many places, and its hard masses are 
strewn over the fields of Fillmore County, where it immediately under-
lies the thin drift. Parts of the sandstone may also be thus cemented by 
iron and form float blocks similar to those of the conglomerate. A general 
characteristic of both the sand and the gravel is the yellow color due to 
the limonite that clings to pebbles and sand grains, making them readily 
distinguishable from drift sands and gravels. This characteristic has led 
to the name "orange gravels" often being applied to them. This, how-
ever, is a poor name, as the sands may be nearly white, and both sand 
and clay are a definite part of the formation. The gravels make excellent 
road material and are widely used for smfacing secondary roads. It is 
for this reason that so many of these deposits have been opened and 
worked as gravel pits in parts of Mower and Fillmore counties. 
Although many of the pebbles are fairly well rounded and somewhat 
polished, in among th em in certain localities are a few larger ones of 
highly polished flint and quartz. These are usually subangular but thcir 
corners and edges are rounded . They at once suggest ga troliths; indeed, 
when placed among such relics from T exas or Wyoming, the Minnesota 
specimens cannot be distinguished. No reptilian remains have been found 
in these sands and gravels of southeastern Minnesota, but such highly 
polished pebbles suggest the presence of dinosam s. Undoubtedly the 
Minnesota region was favorable t erritory for the reptilian hordes during 
Cretaceous time, and their presence here is suspected even though there 
are no remains to prove it. One pelecypod specimen, a Unio, found in 
the sandstone, is definitely a fossil of the age of the sand and gravel de-
MESOZOIC: CRETACEOUS 101 
posit. But the unios have such general characteristics that it is hardly 
justifiable to place much dependence on a single specimen. 
In the sandy shales associated ~with lignitic beds in southern lVIorri-
son County several other species of Unio and one or two related genera 
have been found. These beds probably underlie the marine Cretaceous a 
little farther to the west and south, where shark teeth and various gen-
era of Cephalopoda and Pelecypoda have been collected in shales taken 
from a well 3 and from the bank of the Sauk River. It seems, therefore, 
that other fresh-water forms should be found as fossils in these lower 
beds, and that they might be expected in the sandstones associated with 
the yellow gravels. As indicated earlier in this discussion, residual fossils 
are common among the pebbles. These are characteristic Ordovician and 
Devonian forms, such as corals, brachiopods, bryozoans, gastropods, and 
pelecypods, together with rather large pieces of StTOmatoporella, all well 
silicified. The clays, such as those at Austin. carry both Ordovician and 
Devonian conodonts of a similar residual origin. 
There are other yellow gravels in this portion of the state that must 
be distinguished from those under discussion. Thus the pebble con-
tent differs and the hard cemented layers when present are seldom iron 
cemented. The drift gravels south of Spring Valley," for example, suggest 
but do not belong to this formation. In other places gravel deposits, also 
of glacial origin, are partly derived from the old gravel formation. 
These old gravels in lVlinnesota were first reported by the Owen sur-
vey, but the men engaged in that survey were chiefly impressed by the 
iron content of the formation, as is readily understandable from the 
economic nature of the investigation. Thus Dr. Shumard remarks, "The 
nodules of iron ore have mostly a concentric stru~cture. and appear to be 
of good quality. The superficial indications render it probable that this 
bed of iron ore may be both extensiYe and easily accessible." 5 'Vinchell 
discussed both the iron and the gravel. as well as the sands and clays, 
referring them all to the Cretaceous,5 with the probability that they be-
long to the Dakota series. 
Much of the iron encountered beneath the drift oYer a large part of 
several counties in southeastern lVIinnesota is older than the gravel, sand, 
and clay here under discussion. It is an impure limonite, from zero to 
twenty feet in thickness, that lies on rocks ranging in age from Jordan 
to Cedar Valley. Doubtless a good deal of this iron may have been moved 
from the place where it weathered from the bed rock, and some of it may 
3 Warren Upham, Geology of Minnesota (Final Report of the Geological and Natural 
History Survey of Minnesota), Vol. 2 (1888). p. 461. 
'N. H. Winchell, Geology of Minnesota (Final Report of the Geological and Natural 
History Survey of Minnesota). Vol. 1 (1884). p. 309. 
o B. F. Shumard in D. D. Owen, Geological Su/'t'ey of Wisconsin. [ou'a and Jiirwe-
sofa (1852). p. 487. 
oN. H. Winchell. Geology of Jliinnesota (Final Report of the Geological and Natural 
History Survey of Minnesota), Vol. I (I884), pp. 307-11. 
IO'? PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
be a bog ore as suggested by Winchell and others; but in the test pits near 
Etna, Fillmore County, this iron deposit grades downward into the Cedar 
Valley limestone and many specimens of ore containing Cedar Valley 
fossils may be collected. It is, in fact, a residual formation that accumu-
lated over a very long period (Ordovician to Upper Cretaceous) of lime-
stone weathering. 
About the end of the Lower Cretaceous or Comanchean period it ap-
pears that the attitude of the land surface of southeastern Minnesota 
changed and streams bearing gravel and sand spread over the region 
where weathering had long been the dominant geological process. Here 
and there shallow ponds or lakes developed and acted as catchment basins 
for the fine products of rock decomposition; the coarser sediments spread 
over the adjacent land or may have been deposited in the approaching 
stream channels themselves. These beds are poorly sorted and may change 
abruptly from gravel to sand or even to clay. Near Goodhuc the gravels 
overlie the clay but are in part interbedded with it. The clay commonly 
giyes way to sand. These changes suggest the inconstant conditions under 
which the sediments were laid down. 
Similar gravels and arenaceous sands have long been known in adja-
cent states. In Iowa 7 they have been designated the Rockville conglom-
erate. However, the Rockville conglomerate contains granitoid S boulders 
and other evidence that makes their equivalence to the Minnesota beds 
seem uncertain. In Illinois ferruginous conglomerates 0 at the base of the 
drift were thought to be Tertiary. In Wisconsin various authors have dis-
cussed the gravels of the Driftless Area. On Windrow Bluff, Wisconsin, a 
small amount of the gravel with its quartz and chert pebbles in a highly 
ferruginous sandstone appears to rest directly on about eight feet of resi-
dual iron ore like that so widely distributed in southeastern Minnesota. 
Thwaites and Twenhofel 1o used this as the type section and named both 
iron ore and gravel the Windrow formation. Although this deposit in-
cludes gravel that is similar to the sandstones and conglomerates that 
spread over part of Minnesota, it is not at all typical of the formation as 
it occurs in Fillmore and :iVIower counties. 1\10reover, the authors appear 
to have included the iron ore 11 in the Windrow formation, whereas in 
lVlinnesota the iron bears evidence of being much older than the gravels, 
sands, and clays that overlie it. These latter sediments carry evidence, 
particularly in the flora, that they are the landward fringe of the Dakota 
formation, but the residual iron ore may vary in age from Ordovician to 
Cretaceous and some of it even overlies the Cretaceous itself. 
'W. J .. McGee, The Pleistocene IIistory of Northeastern Iowa (U. S. Geological Survey, 
1891). pp. 304-8. 
, Ibid., p. 307. 
c· A. H. Worlhen, Geological Survey of Illinois, Vol. 1 (1866), p. 330. 
'" "Windrow Formation," Bulletin of the Geological Society of America. 3'l: 'lfJ3-·3H 
(19'21 i. 
11 Ibid .. pp. c?94 .. 297, 299. 
MESOZOIC: CHETACEOUS 103 
In view of the uncertain age of the Windrow it has seemed better to 
give a local member name to these lVIinnesota sediments and the name 
Ostrander member of the Dakota formation is here used. Ostrander is a 
small town in the southwestern part of Bloomfield Township, Fillmore 
County. Two more or less active gravel pits occur in this immediate 
vicinity. In them the sand, gravel. and iron conglomerate are typically 
developed but the clay is poorly shown. However, the clay is much less 
typical of the member, except in the clay pits of Goodhue County. The 
gravel pit at the south edge of town on land now owned by Mr. Carthog 
(SE 1/4 Sec. 29, T. 102 N., R IS W.) is fairly typical and may be regarded 
as the type section, although it should be supplemented by the large pit 
a mile northeast on the SE 1/4 Sec. 20 (see page 148), where part of a clay 
bed in the bottom is also shown. 
OSTHANDEH, FILLMOHE COUr\TY 
Section at the Carthog Gravel Pit, South End of the Village 
8. Loess and soil ............................... . 
7. Drift, with a few boulders .......................................... . 
DAKOTA FORMATION 
Ostrander Member 
THICKNESS 
(in feet) 
2.0 
2.0 
6. Sandstone, brown, coarse, pebbly. iron-stained and iron-cemented. \'ery hard 2 .. 5 
5. Sand, coarse, and sandy yellow gravel. The pebbles are smooth. rounded to 
ellipsoidal, pink and white quartz, together with subangular flint and chert 
pebbles about Ij~ to VOl inch thick . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.0 
4. Sandstone. brown, pebbly, hard. and in part a real conglomerate. . . . . . . . 1.5 
3. Gravel, yellow, medium to fine. pebbles of flint and quartz as throughout 
the formation ..................... . . . . . . . . . . . . . . . . . . . . 1.5 
2. Sandstone, brown, coarse. pebbly. poorl~· cemented. . . . . . . . . . . . . 1.0 
1. Gravel, yellow-stained. poorly sorted, medium to coarse. some pebbles an 
inch or more in diameter. The pebbles are quartz and flint as elsewhere, and 
some residual siliceous fossils even of large size may be found in these beds. 
In the Farnhill pit a mile northeast, this bed is underlain b~' clay. To the 
level of water in bottom of pit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0 
It has been stated that these gravel deposits may be traced as far west 
as Blue Earth County and they are still prevalent in Brown County, where 
they occur in the thick Cretaceous sandstones along the Big Cottonwood 
River. It is not possible, however, to state definitely that all these gravel 
beds are of exactly the same age as the Ostrander member, though they 
probably fall in the Dakota formation. The section given below crops out 
at the highway bridge on Nick lV[etzen's farm two and one-half miles 
southeast of New Dim. It shows a conglomerate near the middle that may 
be a representative of those farther to the east. 
At Springfield the Cretaceous is represented chiefly by an argillaceous 
shale which is being used in the manufacture of brick. Within the clayey 
shale are layers of hard, calcareous sandstone, carrying an abundance of 
fossil leaves, some of which are the same as the leaves in the sandstones 
near New Dim. Somc attempt has been made to piece together the Creta-
104 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
ceous section from the scattered and rather unsatisfactory outcrops. It 
seems probable at least that the basal portion, consisting of conglomer-
ates, sandstones, and shales, varies much from place to place, and that 
these are nonmarine beds representing various environments of the same 
period of sedimentation. 
NEW ULM, BROWN COUNTY 
Section on Nick lVletzen's Farm, Southeast End of Bridge over Cottonwood River, 
State Highway No. 15 
10. Drift to top of adjacent hills ........................................ . 
9. Drift, bouldery ..................................................... . 
DAKOTA FORMATION 
8. Sandstone, white, medium to fine, massive, poorly cemented. Some coarse 
grains and clay pebbles occur in layers in the sandstone ................. . 
7. Sandstone, yellow, medium-grained with some coarse grains, cross-bedded. 
Plant remains occur in the thin, brown, shaly layers at the top ............ . 
6. Sandstone, white to yellow; thin layers of silt interbedded with thin layers of 
gray shale. Plant remains in the silty layers ............................ . 
5. Conglomerate, consisting of quarter-inch quartz pebbles in cross-bedded white 
to yellow sand with included chnnks and pebbles ,A charcoal .............. . 
4. Sandstone, \"hite to yellow, medium-grained, with some coarse grains. Cross-
bedded, with occasional streaks of gray shale .......................... . 
3. Sandstone, coarse. pebbly, gray to white and yellow .................... . 
2. Shale, blue, with nodules of sandstone. Not very well exposed ............ . 
1. Covered inten'al to level of Big Cotton\\'ood River (approximately 780 ft. 
A. T.) ............................................................. . 
COLORADO SERIES 
COLERAINE FORMATION 
THICKNESS 
(in feet) 
30.0± 
10.7 
16.0 
4.0 
14.0 
5.0 
15.0 
1.0 
6.0 
12.0 
In Stearns and Morrison counties the same type of deposition as that 
in the Dakota series continued but with less coarse sediment. These land 
deposits are probably overlain by the marine shales, which occur near 
Richmond in south-central Stearns County, where shales of apparent 
Benton (Coleraine) age crop out along the Sauk River. Similar beds are 
penetrated by the wells in that vicinity. Upham 1:2 supplies a section, of 
which the one below is a modification, for H. Sieverding's well in Munson 
Township, Stearns County. In addition to the fossils mentioned in this 
section, which were identified by F. B. Meek, several others were also sent 
to him, and he reported them as InocemlnUS problematicus, Ammonites 
percarinatus, 8caphites larvifoT1nis, fish scales, and shark teeth, probably 
Com:r and Galeus. These identifications have not been checked, as no ad-
ditional material has been obtained from that region. It is clear, however, 
that the fauna is Cretaceous and may be Coleraine. 
On the i\Iesabi Range the Cretaceous beds have been known for 
many years. They are mostly iron-bearing shales, but include conglom-
erates and sandstones. Around Virginia and Hibbing there are unfossil-
iferous beds referred to the same formation. At the western end of the 
"Geology of Minnesota (Final Report of the Geological and Natural History Suryey of 
Minnesota), Vol. 2 (1888), p. 461. 
MESOZOIC: CRETACEOUS 
RICHMOND, STEARNS COUNTY 
Section of H. Sieverding's Well (SW1.4, Sec. 35, Munson Twp.). 
105 
THICKNESS 
(in feet) 
6. Drift, gravel and sand .............................................. 8 
CRETACEOUS (Colorado series) 
Coleraine Formation 
5. Shale, dark blue, laminated clay with gypsum crystals and fragments of 
Inoceramus problematicus .......................................... 30 
4. Shale, argillaceous and hard. sandy, light blue. with pyrite. mica, and fish 
scales. Also Inoceramus sp. A thin seam of lignite near the base . . . . . . . . . . 8 
3. Shale, argillaceous; also 3- to 4-inch layers of hard, sandy shale. Inoceramus 
sp. and Scaphites, showing original color and pearly luster. A thin seam of 
lignite near the base .............................................. 10 
~. Shale, argillaceous, dark blue to nearly black, very hard at the base. . . . . . 15 
1. Shale, argillaceous, with thin layers and seams of pyrite ................ 10 
Mesabi Range the most conspicuous pebbles of the conglomerate are 
hematite and iron-bearing taconite. Some of these are well polished, and 
many are covered with a coating resembling desert varnish. The follow-
ing is a section of the south side of the Hill-Annex mine at Calumet, 
where such pebbles are common in the Cretaceous. 
CALUMET, ITASCA COUNTY 
Section at the Hill-Annex Mine 
1~. Drift, sands, grayels, and boulder beds 
CRETACEOUS (Colorado series) 
Coleraine Formation 
11. Iron ore, redeposited, red and gray. soft. massive. with fine pebbles. Fossils 
THICKNESS 
(in feet) 
Ift5.0 
common......................................................... 9.0 
10. Conglomerate, red pebbles in a gray matrix .......................... 6.3 
9. Iron ore, redeposited, red to gray. gritty. with fragments of wood at some 
places. At other places this same horizon carries an abundant molluscan 
fauna ........................................................... 3.0 
8. Conglomerate, coarse, pebbly, un assorted ............................ 0.5 
7. !ron ore, re~eposited, green, gritty, with occasional pebbles of chert and 
Iron formatIOn ................................................... 4.0 
6. Conglomerate, gray. coarse pebbles cemented by a green iron sand. . . . . . 0.7 
5. Conglomerate, very coarse, with polished black pebbles. chert. taconite, 
paint rock. hematite, slate. quartz. and other pebbles and cobbles up to 8 
inches in diameter ................................................ s.ft 
PRE-CAMBRIAN 
Biwabik Formation 
4. Paint rock and slaty red taconite with white bands ................... 8.0 
3. Iron ore. deep red, cherty. gritty, with altered taconite . . . . . . . . . . . . . . . . . 16.0 
ft. Iron ore. laminated, blue, cherty, with sandy beds and unaltered taconite 20.0 
1. Iron ore. blue. hard, massiye. cherty. laminated to bottom. . . . . . . . . . . . . . 28.0 
The Cretaceous of this section is abundantly fossiliferous. It varies 
greatly. both lithologically and structurally. from place to place, espe-
cially in its middle and upper portion. Good fossil specimens may be 
found even among the pebbles and cobbles of the coarse basal conglo-
merate. In some localities on the Range the Cretaceous is distinctly shaly, 
106 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
and oyster beds developed in which the shells are packed together by the 
thousands. Although it is chiefly a molluscan fauna, there are several spe-
cies of arthropods and numerous shark's teeth belonging to a half dozen 
or more species. Parts of the skeletons of several reptiles have been col-
lected at the Hill-Annex mine. One vvas an ichthyosaur and the other 
probably a plesiosaur. The cones and needles of conifers occur frequently, 
and the conglomerate beds even contain logs thoroughly infested with an 
ancient shipworm, Teredolites. It is the molluscan fauna of this locality 
that has led to the correlation of the Coleraine formation with the Benton 
shale of the Great Plains region. 
The heavy drift cover over much of the state makes it impossible to 
observe in detail the underlying stratigraphy, but many remnants of the 
Cretaceous are known and it is suspected that the Cretaceous is present 
over a large area in the state. Some of the material called Cretaceous, 
however, is merely the weathered residue on the old pre-Cretaceous erosion 
surface, the deposits of which are difficult to assign to anyone period of 
geologic history. 
CHAPTER VII 
CENOZOIC 
PUE-PLEISTOCENE EROSION 
Following the Coloradan series, another prolonged period of erosion 
set in. Over part of the state the surface which then developed merges 
with that of the post-Devonian and the old pre-Cambrian, without any 
means of distinguishing them. It is probable, however, that the later sur-
face was much elevated and that erosion was producing a very rugged 
topography when the cycle was interrupted by glaciation. This left the 
Cretaceous over much of the state as scattered remnants separated by the 
deep and relatively wide late Tertiary valleys. Some of these could not be 
filled by the rock debris bl'Ought in by the glacier, but remain today as 
disconnected basins now occupied by chains of lakes of glacial origin. 
THE PLEISTOCENE 
GLACIAL DRIFT 
The term Pleistocene as originally defined by Forbes of England in-
cluded all glacial deposits younger than the Pliocene and older than the 
Recent. For many years the recognized classification embraced five gla-
cial epochs and four interglacial ages, each of which had been mapped, 
described, and named. This classification had the following subdivisions: 
Pleistocene 
Wisconsin 
Peorian 
Iowan 
Sangamon 
Illinoian 
Yarmouth 
Kansan 
Aftonian 
Pre-Kansan 
Since the above classification was adopted, much new work has been 
done in the field and in the laboratory. Glacial and interglacial sediments 
have been studied in detail on several continents. Hundreds of profiles of 
weathering in various types of drift have been thoroughly investigated. 
Correlations and comparisons have been attempted between the glacial 
deposits of America and those of other countries, so that at present there 
exists an extensive literature on the classification and history of the 
Pleistocene. 
107 
108 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
:Much of the earlier work was done by Chamberlin,' Leverett," Sarde-
'Son,3 Calvin! and their associates. The more recent work in the upper 
Mississippi Valley has been and is being done by Kay," Leighton,6 
Thwaites! and others interested in more local problems. These more re-
cent workers have recommended the classification given in Table (5 below. 
TABLE 6. - CLASSIFICATION OF PLEISTOCENE HISTORY IN THE UPPER lYlISSISSIPPI VALLEY * 
Period (System) 
Pleistocene 
or 
Glacial I 
Epoch (Series) 
Eldoran { 
Centralian 
Ottumwan 
Grandian 
Ages (Stages) 
Recent 
Wisconsin 
Sangalnon 
Illinoian 
Yarmouth 
Kansan 
Aftonian 
Nebraskan 
Substages 
{
Mankato 
Cary 
Taz'ewell 
Iowan 
" From G. F. Ka~'. "Pleistocene Histor"' and Early Man in America." Bulletin of the 
Geological Society of America, 50: 4;j3-64 (1939). 
When the findings of the two groups of workers are compared, no very 
distinct differences are noted. Both groups agree that from the beginning 
of the advance of the pre-Kansan ice sheet to the present time, there has 
1 "Discussion of Geikies 'Great Ice Age,''' Journal of Geology, 4: 875l-76 (1896). 
'''Outline of the Pleistocene History of the Mississippi Valley," Journal of Geology, 
5l9: 615-~6 (195lI); Quaternary Geology of Minnesota and Parts of Adjacent States (U. S. 
Geological SurYey, Professional Paper 161, 1932); Moraine and Shore Lines of the Lake 
Superior Basin (U. S. Geological Survey. Professional Paper 154A. 1929); with F. W. Sarde-
son, Surface Formations and Agricultural Conditions of the South Half of j"Iinnesota (Min-
nesota Geological Survey, Bulletin 14. 1919). 
:l "Glacial Drift Sheets of Minnesota." Pan-American Geologist, 38: 383--402 (195l5l). 
4 "Iowan Drift," Bulletin of the Geological Society of America. 10: 107-~0 (1899); 
"Present Phase of the Pleistocene Problem in Iowa." Bulletin of the Geological Society of 
America. 20: 341-56 (1909). 
o "The Relative Ages of the Iowan and Wisconsin Drift-Sheets," American Journal of 
Science, 5l1: 1.58-75l (1931); "Pleistocene History and Early Man in America," Bulletin of the 
Geological Society of America, 50:453-64 (1939); with J. H. Pearce. "The Origin of Gum-
botil," Journal of Ge.ology, 5l8: 89-15l5 (195l0); "History of Investigations and Classifications 
of the Pleistocene Deposits of Iowa," Annual Report of the Iowa Geological Survey for 19:28 
(195l9), Vol. 34, pp. 70-133. 
6 With Paul MacClintock, "Weathered Zones of the Drirt-Sheets of Illinois," Journal of 
Geology, 38: 5l8-50 (1930). 
7 Olltline of Glacial Geology (1937). 
CENOZOIC 109 
been a succession of cycles with a recurrence of similar geological events 
that produced similar geological results. 
N early all of Minnesota was covered by a mantle of glacial deposits, 
but subsequent stream erosion has removed or modified the deposits 
along many of the major valleys. The oldest known glacial deposits of 
this region are referred to as Nebraskan. The ice sheet responsible for 
their deposition moved from the Keewatin center of glaciation and ex-
tended as far south as the lower course of the :Missouri River. The geo-
graphic extent of the Nebraskan drift in :Minnesota is as yet unknown, 
because many of the deposits have been subsequently obliterated or 
concealed. However. in Fillmore and 'Winona counties isolated patches 
of deeply weathered drift and sca ttered erratic boulders occur beyond 
the eastern margin of the Kansan drift sheet, and similar relations are 
found in Rock and Pipestone counties in the southwest. Such drift de-
posits may be Nebraskan. i.e .. pre-Kansan, in age. The Aftonian inter-
glacial materials and associated Nebraskan gumbotils S are for the most 
part unrecognized in :Minnesota. 
The second Pleistocene glacial invasion also moved from the Kee-
watin center and left the Kansan drift sheet. which occupies about the 
same area as the Nebraskan. The Kansan drift is exposed not only in the 
valley walls but also over extensive uplands in the region from Red Wing 
southeast to Rochester. Chatfield. and the Iowa-lHinnesota state line. 
The Kansan drift is commonly referred to as the "old gray drift." Its 
gray color is due to the presence of a high percentage of gray Cretaceous 
shales and limestone. which became incorporated in the glacial debris 
as the glacier moved over the unconsolidated Cretaceous sediments of 
:Manitoba and northwestern Minnesota. 
The Kansan old gray drift is deeply leached and weathered. Many 
of its pebbles and boulders are partially decomposed and disintegrated. 
Over poorly drained. ground. moraine deposits the leaching has extended 
to a depth of 10 to 1'2 feeP Such leaching is found also where the Kan-
san drift sheet is covered by younger drifts. thus indicating that the Yar-
mouth was an exceedingly long interglacial period. 
The third ice sheet. the Illinoian. moved from the Labrador center of 
glaciation and extended southward into southern Illinois. Indiana. and 
Ohio. One lobe moved southwestward to the west of the driftless area 
and covered east-central Minnesota. The glacial debris it deposited is the 
"old red drift" of earlier reports. The constituent rocks seem to be 
chiefly representative of the pre-Cambrian formations common in the 
Lake Superior region. Its exposed area in Minnesota is mainly in Da-
kota and 'Washington counties. It extends southwestward into north-
western Goodhue County and northeastern Rice County. 
3 G. F. Kay and J. H. Pearce, "The Origin o[ Gumbotil." Jonrnal of Geology, 28: 89-1'25 
(1920). 
OM. M. Leighton and Paul MacClintock, "Weathered Zones of the Drift-Sheets of 
Illinois," Journal of Geology, 38: S'8-.50 (1930). 
110 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Where the Illinoian drift is found in the area between the St. Croix 
and "Mississippi rivers, it occurs as a thin blanket averaging scarcely 10 
feet thick. Several miles southwest of the junction of these two rivers 
an apparent terminal moraine of the Illinoian can be traced. This is the 
so-called Hampton moraine, which forms a prominent range of hills in 
the vicinity of Hampton and southwestward in Dakota County. The 
upper surface of the old red drift is also deeply leached, indicating a 
long period (Sangamon) of weathering before the advance of the next 
glacier. 
The fourth stage of glaciation began with the Iowan. The earlier 
workers (Chamberlin, Leverett, and others) recognized the close rela-
tionship in age between the Iowan and Wisconsin drifts, but neverthe-
less gave each of them a distinct stage rank. :More recent work in Illinois 
and Iowa has led to the conclusion that glaciation was continuous from 
the beginning of the Iowan to the end of the Wisconsin stage. Therefore, 
the Iowan is now included in the Wisconsin, and is referred to as the first 
substage of "Wisconsin glaciation.10 
The Wisconsin drift sheets show distinctly ~'outhful topographic fea-
tures and slight \Yeathering. which is in marked contrast to the charac-
teristics of the older glacial deposits. The history of this stage of glacia-
tion is very complex. Detailed studies show that in many localities the 
ice advanced, retreated, advanced again, halted, receded, and so on. At 
some places. it is evident that after the advance and retreat of one lobe, 
a neighboring lobe overrode or pushed aside deposits left by the earlier 
one. 
The Iowan ice lobe covered most of :Minnesota and northeastern Iowa. 
n advanced southward from the Keewatin center west of Hudson Bay 
and consequently left a mantle of gray drift. The Iowan drift as ex-
posed in southeastern :Minnesota (see Figure 37) has an average thickness 
of less than '20 feet, forming a veneer of comparatively fresh till that 
rests on deeply weathered Kansan gumbotil or on post-Kansan loess. 
During and following the retreat of the Iowan ice, extensive deposition 
of loess took place. The name Peorian loess is used for the widespread 
deposit of wind-blown material that lies on the Iowan drift and around 
its borders and beneath the Late Wisconsin (Mankato) drift sheet. Mixed 
with humus, this loess forms the soil of large areas in southeastern Min-
nesota. Undoubtedly, not all of the loess is contemporaneous, nor are its 
sources uniform. lYlost of it in "Minnesota, however, appears to be related 
to the Iowan substage. 
The Tazewell Lobe of the Wisconsin glacier did not extend west as 
far as :Minnesota. (See Figure 37.) Tazewell drift covers large areas in 
Illinois, Indiana, and Ohio. If it was deposited to the northwest of the 
10 G. F. Kay, "The Relative Ages of the Iowan and Wisconsin Drift-Sheets." American 
Journal of Science, e1: 1.58-7e (1931). 
CENOZOIC III 
FIGURE 37. - Map of the north-central United Stales, showing the distribution of glacial 
drift of the successive Pleistocene stages. (Modified from R. C. Moore.) 
driftless area in Wisconsin and Minnesota, it has been entirely obliter-
a ted by the more recent advance from the Patrician center . 
During Middle Wisconsin or Cary time a tongue of ic , now referred 
to a the Minneapolis Lobe of the Patrician ice sheet ," invaded Minne-
sota from the north , leaving th e Patri cian or "young red drift." The 
material is mainly a matrix of dull reddish sand and gravel, bearing an 
abundance of pebbles, cobbles, and boulders. It contain little clay, and 
limestone pebbles a re practically absent. A conspicuous curving t erminal 
moraine, with its apex south of Minn eapoli in D akota County, marks 
its south ern limit. Thi t erminal moraine, named the St. Croix M orainic 
System by Berkey,12 is a striking phy iographic feature, forming a broad 
belt of typical knob and kettle topography from Dakota County north-
wes tward across Wright, Stearns, and Todd counties. West of iinneapo-
li s th e St. Croix Moraine wa overridden by the Late Wi con in (Man-
ka to) ice sheet . 
The last incursion of a Pleistocene glacier into Minne ota was in Late 
Wisconsin or Mankato time, after th e Minneapolis Lobe of the Patricia n 
ice heet had receded . The ice advanced from areas of accumulation 
both eas t and we t of the Patrician center, producing two new lobe, 
11 C. P . Berkey, "Geology of the St. Croix Dalles," A merican Geologist, ~O: 345-83; 
~ l : 139-55, 270-94 (1897). 
10 Ibid . 
ll~ PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
which converged upon central ]\t[innesota. The one from the northeast, 
or Labrador center. formed the Superior Lobe, which traversed the basin 
of Lake Superior, transgressing its northwestern and southern bound-
aries, and continued southwestward to a point approximately sixty 
miles south,vest of Duluth. (See Figure 37.) The second and by far the 
greater of the two lobes of this period advanced from the Keewatin cen-
ter. The axis of this lobe lay along the valley of the Red River of the 
North, along the valleys of the Minnesota River and the Blue Earth 
River, and still farther southward along the valley of the Des Moines 
River. The southern limit of the ice sheet was near the city of Des 
:Moines, Iowa. It covered all of northwestern, western, and south-central 
Minnesota. To the north of the Twin Cities a sublobe advanced from the 
southwest as a minor northeastward-moving offshoot of the main lobe. 
This lobe, oYE'rriding the Patrician drift. extended as far as Grantsburg, 
Wisconsin. Thus it is called the Grantsburg Lobe. 
The Keewatin drift deposited by the Late Wisconsin or Mankato gla-
cier is characterized by the presence of a relatively large number of lime-
stone and shale fragments in a clayey matrix and by its comparative 
freshness. The exposures are commonly gray to tan in color, with the 
unoxidized portions darker gray. Because of its color and freshness it is 
commonly referred to as "young gray drift." 
PLEISTOCENE DRAINAGE CHANGES 
In view of the fact that Cretaceous marine sediments are widespread 
in Minnesota, it appears probable that the drainage systems that existed 
at the beginning of the Pleistocene developed during the Tertiary, and 
that the first ice sheet moved over a maturely eroded surface of moder-
a te relief. Undoubtedly, the major drainage systems of Minnesota were 
well established by late Tertiary. The first Pleistocene glacier covered 
the Mississippi Valley as far south as Winona, and the St. Croix drain-
age area was entirely covered during this glacial stage. It is thus evident 
tha t unequal deposition of glacial drift had a profound effect upon the 
preglacial topography of the areas that were glaciated. Numerous val-
leys were completely filled with glacial till, and as the ice receded, many 
old channels were so obstructed that new surface drainage courses were 
established. Even such major streams as the St. Lawrence, the Missouri, 
and the JVlississippi, each of which receives surface waters from Minne-
sota, were locally turned from their late Tertiary channels by the Pleis-
tocene glaciers. Detailed evidence regarding drainage changes in Minne-
sota is presented in a number of papers pertaining to the Pleistocene his-
tory of the state.13 
"William S. Cooper, The History at the Upper Mississi/}])i Riller in Late Wisconsin and 
Postglacial Time (Minnesota Geological Survey, Bulletin 26. 1935): G. M. Schwartz, Geology 
of the 1tIinneapolis-St. Paul Metropolitan Area (Minnesota Geological Survey, Bulletin 27. 
1936); F. W. Sardeson. Minneapolis-Sf. Paul Folio (U. S. Geological Surl'ey, Geological Atlas 
or the United States, Folio 201). 
PART TWO 
COMPOSITION OF MINNESOTA LIMESTONES 

COMPOSITION OF MINNESOTA LIMESTONES * 
Insolubles 
Stratigraphic Sample Silica, Oxides Total CaO CaCOa MgO MgCOa Horizon etc. (Iron, etc.) 
DEVONIAN 
Cedar Valley 22 .... ndt nd 2.02 nd 54.48 nd 43.58 
23 .... nd nd 2.6 nd 60.69 nd 38.56 
24 .... nd nd 0.66 nd 98.1.5 nd 1.25 
2.5 .... nd nd 1.01 nd 97.76 nd 1.38 
41. ... .76 .28 1.04 55.35 98.65 .48 1.0 
ORDOVICIAN 
Maquoketa 21 .... nd nd 18.62 nd 80.3 nd 1.63 
.54 .... ILl l.2 12.3 34.9 62.3 12.1 25.3 
55 .... 9.4 0 .. 5 9.9 46.5 83.0 3.4 7.1 
6.5 .... 16.0 0.8 16.8 4.5.5 81.2 0.9 1.9 
66 .... 5.3 0.3 5.6 .52.0 92.8 0.6 1.3 
Galena 
Stewartville 62 .... 2.3 0.3 2.6 41.7 74.4 11.0 23.0 
63 .... 2.4 0.3 2.7 4.5.7 81.5 7.5 15.7 
64 .... 1.7 0.4 2.1 47.8 8.5.2 6.1 12.7 
92 .... 5.1 0.5 5.6 37.0 66.0 13.6 28.4 
1l0 .... 5.2 0.5 5.7 4.5.4 81.0 6.7 14.0 
120 .... 6.6 1.9 8.5 41.0 73.1 8.6 18.0 
a1. ... 6.3 0.7 7.0 46.3 82.6 5.0 10.4 
129 .... 4.9 0.3 5.2 46.1 82.3 6.3 13.2 
Prosser 26 .... 2.5 .42 2.92 53.85 96.1 .51 1.07 
27 .... 17.19 .58 18.48 44.7 79.8 .81 1.69 
28 .... 2.87 .12 2.99 .53.4 95.3 .85 1.78 
29 .... 2.78 .23 3.01 53.4 9,5.3 .86 1.8 
30 .... 6.15 .20 6.3.5 49.4 88.1 2.9 6.07 
31. ... 4.16 .37 4.53 52.35 93.4 l.2 2.51 
37 .... 2.13 1.09 3.22 54.4 93.5 1.35 2.82 
38 .... 1.96 .49 2.45 54.25 96.75 .59 1.23 
39 .... 4.47 .87 5.34 52 .. 55 93.75 .46 .96 
40 .... 4.75 .54 5.29 .52.1 92.95 .51 1.07 
95 .... 4.1 0.2 4.3 .52.4 95 .. 5 1.0 2.1 
114 .... 7.2 0.5 7.7 49.3 88.0 2.1 4.4 
123 .... 10.9 0.7 11.6 48.1 85.9 1.1 2.3 
a4 .... 6.4 0.4 6.8 50.2 89.6 1.9 4.0 
125 .... 6.4 0.4 6.8 50.6 90.3 1.5 3.1 
126 .... 2.8 0.3 3.2 52.5 93.7 1.7 3.5 
127 .... 7.3 0.5 7.8 48.8 87.0 2.8 5.8 
128 .... 6.5 0.4 6.9 48.4 86.4 3.6 7.5 
133 .... 11.5 1.0 a.5 45.9 81.9 2.7 5.6 
Decorah 13 .... nd nd 4.96 nd 92.77 nd 2.22 
14 .... nd nd 6.34 nd 92.59 nd 1.19 
15 .... nd nd 3.78 nd 93.56 nd 2.13 
33 .... 3.75 .88 4.63 52.5 93.7 .77 1.61 
34 .... 4.17 .71 4.88 52.3 93.3 .70 1.46 
35 .... 5.61 .59 6.2 51.6 92.0 .43 .9 
132 .... 4.6 1.60 6.2 45.3 80.9 6.1 12.8 
* For a more nearly complete tabulation see C. R. Stauffer and G. A. Thiel, The Lime-
stones and Marls of JJiinnesota (Minnesota Geological Survey, Bulletin 23. 1933), pp. 72-74. 
t nd = not determined. 
115 
116 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Insolubles 
Stratigraphic S I Silica, Oxides Total CaO CaC03 MgO MgC03 Horizon ampe etc. (Iron, etc.) 
Platteville 
McGregor 7 .... nd nd 16.44 nd 70.9 nd 10.54 
8 .... nd nd 39.43 nd 33.65 nd 22.16 
9 .... nd nd 13.42 nd 47.88 nd 35.78 
10 .... nd nd 18.75 ud 69 .. 58 nd 7.46 
11 .... nd nd 21.22 nd 4.5.6 nd 30.23 
12 .... nd nd 41.01 nd 37.74 nd 21.01 
69 .... 11.7 2.7 14.4 29.7 53.0 1.5.4 32.2 
70 .... 8.7 1.5 10.2 39.3 70.1 9.4 19.7 
71 .... 13.0 1.9 14.9 30.3 .54.1 14.6 30.6 
13.5 .... nd nd 12.79 nd 77.44 ud 6.39 
136 .... nd nd 23.8 nd 4.5.76 nd 26.44 
137 .. , . nd nd 1.5.89 rid 46.15 nd 29.98 
Shakopee 6 .... nd nd 8.48 nd 46.74 nd 41.11 
57 .... 7.7 0 . .5 8.2 32.1 .57.3 16.8 35.2 
04 .... 1.2 0.4 1.60 32.4 57.8 19 . .5 40.8 
97 .... 2.8 0.4 3.2 32.2 57.5 18.7 39.1 
98 .... 4.0 0.5 4 . .5 33.8 60.3 17.0 3.5.5 
Oneota 2 .... nd nd 11.5.5 nd 48.49 nd 39.83 
3 .... nd nd 8.99 nd 51.02 nd 40.06 
4 .... nd nd 11.23 nd 49.95 nd 39.01 
48 .... 3.7 2.30 6.0 29.7 .53.0 19.3 40.4 
49 .... 3.7 2.70 6.4 29.9 .53.4 19.0 38.8 
.50 .... 6.6 1.40 8.0 28.9 .51.6 19.1 40.0 
.51. ... 3.4 2.60 6.0 30.4 .54.2 18.8 39.4 
.52 .... 4.3 1.30 .5.6 29.9 53.4 19.1 40.0 
.53 .... 1.7 0.30 2.0 30.2 53.9 20.9 43.7 
73 .... 1.3 1.00 2.3 30.5 54 .. 5 20.8 43.5 
74 .... 8.8 1.30 10.1 28.8 .51.4 18.8 39.3 
7.5 .... l.l 0.50 1.6 30.3 54.1 21.3 44.5 
76 .... 3.7 0.50 4.2 \!9.5 .5'2.6 20.8 43.5 
142 .... nd nd 16.0 nd 48.7 nd 33.95 
143 .... nd nd 1l.67 nd 50.97 nd 33.01 
144 .... nd nd 13.18 nd 49.54 nd 32.34 
145 .... nd nd 8.94 nd 54 .. 58 nd 30.99 
146 .... nd nd 3.26 nd .56.82 nd 40.0\! 
147 .... nd nd 11.4 nd 54.04 nd 28.76 
148 .... nd nd 8.34 nd 52.79 nd 28.\! 
CAMBRIAN 
St. Lawrence 102 .... 73.1 1.4 74 .. 5 13.\! 23.6 l.l 2.3 
103 .... 26.2 2.1 \!8.3 22.2 39.6 15.4 32.2 
104 .... 24.9 2.6 27 .. 5 23.2 41.4 14.8 31.0 
119 .... 23.0 3.4 26.4 2'2.2 39.6 16.0 33.4 
1.57 .... nd nd 52.93 nd 25.68 nd 19.83 
1.58 .... nd nd 54.43 nd 20.01 nd 17.32 
159 .... nd nd 53.67 nd 20.32 nd 17.02 
160 .... nd nd 52.2 nd 21.42 nd 16.88 
LOCALITIES FROM WHICH SAMPLES WERE TAKEN 
DEVONIAN 
Cedar Valley Limestone 
22. Cedar Valley limestone, Larsen's Quarry, Spring Valley, Fillmore County. Buff-
colored, massive limestone with abundant fossils. 
23. Cedar Valley limestone, Le Roy, Mower County. Sample from the brown magnesian 
layers at the Fowler and Pay Quarry, 1 mile east of Le Roy. 
24. Cedar Valley limestone, same location as no. 23. Gray to brown limestone contain-
ing indistinct masses resembling stromatoporoids. 
25. Cedar Valley limestone, same location as no. 23. Gray to white, compact limestone 
apparently containing no fossils. 
41. Cedar Valley limestone, same location as no. 23. Gray to brown limestone contain-
ing indistinct masses resembling stl"Omatoporoids. 
ORDOVICIAN 
Maquoketa Formation 
21. Maquoketa formation, 1 mile northwest of Granger. Fillmore County. Sample from 
shaly outcrop in road . 
. 54. Maquoketa limestone. Clinton Falls, Steele COUllty. Sample from lower part near 
stream level. 
55. Maquoketa limestone. same location as no. 54. Sample from middle part aboye 
stream. 
65. Maquoketa shale. Lime City (Spring Valley), Fillmore County. Thin-bedded lime-
stone, rarely shaly. 
66. Maquoketa shale. same location as no. 65. Thin-bedded limestone, rarely shaly. 
Galena: Stewartville Member 
62. Galena limestone (Stewartville dolomite), same location as no. 65. Fairly hard lime-
stone. 
63. Galena limestone (Stewartville dolomite), same location as no. 65. Fairly compact 
dolomite, ashen in color. 
64. Galena limestone (Stewartyille dolomite), 2.8 miles north of Spring Valley, Lime 
City, Fillmore County. Rough, POI"OUS dolomite. 
92. Galena limestone (Stewartville dolomite), Sec. 12. Bristol Twp .. Fillmore County. 
no. Galena limestone (Stewartville dolomite). along State Aid Road No. 10. about 8 
miles south of Preston, Sec. 3, Bristol Twp .. Fillmore County. 
120. Galena limestone (Stewartville dolomite). from the western part of Sec. 18, Roches-
ter Twp., Olmsted County. 
I'll. Galena limestone (Stewartville dolomite), I mile south of Byron. Olmsted County. 
129. Galena limestone (Stewartville dolomite), on county road to Rochester. I mile west 
and I mile north of Pleasant Grove, Olmsted County. Composite of four samples 
taken throughout the Stewartville outcrop. 
Galena: Prosser Member 
26. Galena limestone, 2% miles sonthwest of Preston. Fillmore County. 
27. Galena limestone. Prosser Creek, Wykoff. Fillmore County. Sample from basal 
Prosser limestone. 
28. Galena limestone, same location as no. 27. Sample from lower middle Prosser lime-
stone. 
29. Galena limestone. same location as no. 27. Sanlple from middle Prosser limestone. 
30. Galena limestone. same location as no. 27. Sample from npper middle Prosser lime-
stone. 
31. Galena limestone. same location as no. 27. Sample from npper Prosser limestone. 
37. Galena limestone. Troy Road (Waterworks Hill). Chatfield, Olmsted Connty. Com-
pact gray limestone. 
38. Galena lime$tone. same location as no. 37. Hard. compact gray limestone. often thin-
bedded. 
39. Galena limestone. same location as no. 37. Hard. compact gray limestone, often thin-
bedded. 
117 
IlS PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
40. Galena limestone, same location as no. 37. Hard, compact gray limestone, often thill-
bedded. 
95. Galena limestone, Sec. ll. Bristol Twp., Fillmore County. Sample from upper part 
of Prosser limestone on John Hahn property. 
I H. Galena limestone. lYlasonic Park, Fillmore County. General sample of the Prosser 
limestone taken throllghout the Masonic Park section. 
I '23. Galena limestone, near the quarry on the V. P. Chase land, on county road, I mile 
west ,md I mile north of Pleasant Grove. Olmsted County. Sample taken 4 feet. 
'* inches ahm'e the north branch of Root Hiver. Thin-bedded, knotty limestone, 
buff in color. 
I '2.J.. Galena limestone, same location as no. 1'23. Fossiliferous. mottled. coarse-grained 
limestone, brownish gray in color. Sample taken 3 feet. 3 inches above no. 1'23. 
1'25. Galena limestone. same location as no. 1'23. Sample taken 9 feet. '2 inches above no. 
1'24. 
1'26. Galena limestone, same location as no. 1'23. Sample taken 5 feet, 4 inches above no. 
1'25. 
1 '27. Galena limestone. same location as no. 1'23. Fine-grained brownish gray limestone, 
taken 10 feet above no. 1'26. 
1'28. Galena limestone. same location as no. 1'23. Sample taken S feet above no. 1'27. 
133. Galena limestone. on county road, I mile west of Genoa. Olmsted County. Composite 
from three samples. 
Galena: Decorah Shale Member 
13. Decorah shale, near District School 34. along U. S. Highway No. 5'2. north of Chat-
field, Olmsted County. Sample from the "marble layer," which is composed of com-
pact bluish gray limestone containing abundant fauna. 
H. Decorah shale. along U. S. Highway No. H. 3% miles east of Rochester, Olmsted 
County. Sample from fossiliferous blue to gray limestone. 
15. Decorah shale. Hallet's Quarry, Faribault, Rice County. Sample from "marble 
layer," which is made up of hard gray limestone and is full of fossils. 
33. Decorah shale. Troy Road (Waterworks Hill). Chatfield, Olmsted County. Sample 
from basal position; composed of hard gray limestone. 
3.J.. Decorah shale. same location as no. 33. Sample from a bed composed of compact 
blue to gray limestone. 
35. Decorah shale. same location as no. 33. Sample from the "marble layer" or trilobite 
bed, composed of hard blue-gray limestone. 
13'2. Decorah shale. on U. S. Highway No . .5'1, 3 miles south of Cannon Falls. Sec. 31, 
Cannon Falls Twp .• Goodhue County, at the creek tributary to the Little Cannon 
Ri,'er. on the property of R. M. Poe. Composite of three samples (from bottom, 
middle. and top of exposure). 
Platteville: McGregor lVlember 
7. Platteville limestone. High Dam. Minneapolis, Hennepin County. Sample from the 
ll-foot bed. which is mostly compact brown to gray limestone. weathering bluish. 
Composed of thin. irregular, often nodular layers separated by thinner shaly layers. 
Fossils broken aud segregated in thin layers. 
S. Platteville limestone. Ford Plant. St. Paul. Ramsey County. Sample from bed 5 feet. 
3 inches thick, which is composed of argillaceous. thin-bedded limestone showing 
conchoidal fracture and containing few fossils. 
9. Platteville limestone. ,a me location as no. S. Sample from bed S feet. 8 inches thick, 
which is composed of highly fossiliferous gray to bluish dolomite, the fossils being 
more abundant in streaks or pockets. 
10. Platteville limestone. High Dam. Minneapolis. Hennepin County. These beds are 
an arg·illaceous. compact brown limestone, often mottled and weathering to a bluish 
color. - , : I i I I 
11. Platteville limestone. same location as no. 10. Sample from compact bluish to brown 
limestone with few fossils. 
1'2. Platteville limestone. same location as no. 10. Sample of a bed which is a shaly. 
argillaceous blue limestone. breaking conchoidally. 
G9. Platteville limestone. Stale Quarry (State Hospital). Rochester. Olmsted County. 
SampJe from the top beds. 
70. Platteville limes Lone. same location as no. 69. Sample from the middle beds. 
71. Platteville limestone. same location as liO. 69. Sample from the bottom beds. 
COlVIPOSITION OF MINNESOTA LHvIESTONES IH) 
135. Platteville limestone. quarry of the Minnesota Crushed Stone Company, .Johnson 
Street, Minlleapolis, Hennepin County. Sample from the lowest beds. 
136. Platteville limestone, same location as no. 135. Sample from bed 5 feet above no. 135. 
137. Platteville limestolle. same location as no. 135. Sample from bed 7 feet above no. 136. 
Shakopee Dolomite 
(j. Shakopee dolomite, Cannon Falls, Goodhue County. Sample from the oijlitic beds 
below the dam at Cannon Falls. 
57. Shakopee dolomite. along U. S. Highway No. 16. 1 % miles southwest of Lanesboro, 
Fillmore COUllty. Sample taken just above the Root Valley sandstone. 
94. Shakopee dolomite, 1 J,~ miles south of Tawney, E% Sec. 3, Newberg Twp., Fillmore 
County. 
97. Shakopee dolomite, along U. S. Highway No. 16 out of Lanesboro, Fillmore County. 
Sample from upper part of Shakopee dolomite, which is thin-bedded. often oiililic, 
with Jarge nlasses of calcite crystals in cavities. 
9R. Shakopee dolomite, same location as no. 97. Sample from lower part of formation, 
which is a thick-bedded dolomitic limestone with calcite cf),stals filling the cavities. 
Oneota Dolomite 
2. Oneota dolomite (Kasota stone), Kasota, Le Sueur County. Sample of the pink 
layer sawed and polished by the Breen Stone and .Marble Company. This is a 
building-stone horizon, consisting of pink to buff beds of fine dolomite 14 reet thick. 
3. Oneota dolomite, White Cliff or White Rock Bluff. Ottawa, Le Sueur Counly, on 
Charles Schwartz's farm along the Minnesota River. Sample from the 6-foot bed of 
brown to reddish brown or pink magnesian limestone with a little chert. Fossils 
common but poorly preseryed. 
4. Oneota dolomite from cliff opposite Sibley Park, Mankato, Nicollet County. 
4R. Oneota dolomite, Merriam .Junction, Scott County. Rather massiw, hard, rough 
gray to brownish dolomite, often with pink streaks and cayities containing pink 
crystals. 
49. Oneota dolomite, same location as no. 48. Rough gray to pink dolomite, "ith a com-
pact, thin buff bed at the top. 
50. Oneot" dolomite, same location as no. 48. Compact buff dolomite, fairly thin-bedded. 
51. Oneota dolomite, same location as no . .J.8 .. Massiye, porous pink dolomite. weather-
mg gray. 
52. Oneota dolomite. same location as no . .J.8. Sample from the railroad cut Ileal' the 
quarry but somewhat lower than the quarry floor. 
53. Oneota dolomite, same location as no . .J,8. Compact, hard gray to buff dolomite. 
streaked with pink. 
73. Oneota dolomite. Old Frontenac Quarr)', Frontenac, Goodhue County. Sample from 
bed which is a coarse, mHssil'e dolomitic limestone. hard and compact but full of 
holes with some chert- and quartz-filled cavities. 
74. Oneota dolomite, same location as no. 73. Sample from bed which is thin-bedded, 
compact, drab to pink dolomite. 
75. Oneota dolomite, same location as no. 73. Sample from bed which is composed of 
several beds of hard, gray, drab to pale pink dolomite with some chert. 
76. Oneota dolomite, same location as no. 73. Sample from bed which is the basalla,'er 
and is composed of massi"e, porous dolomite of a g-ray to ashen color, often with a 
pinkish tinge; the pores glisten with crystals. 
14'? Oneota dolomite, Coughlin QuarQ'. Mankalo. Blue Earth County. Sample from 
the upper 15 feet of lhe formation. 
143. Oneota dolomite, same location as no. U'2. Sample from the 10 feet immediately 
below no. 142. . 
14.J.. Oneola dolomite, quarQ' of the Breen Stone Company (B:1b('O(·k and Wilcox). 
Kasola, Le Sueur County. Sample fro III the 7 feet. 't inches of pink lo cream-colored 
"polish ledges." 
146. Oneota dolomite, same local ion as no. I'H. Sample from the 10 feet below the 
"polish ledges." 
146. Oneola dolomite, quarry of the Hastings Crushed Stone Company, Hastings, Dakota 
County. 
147. Oneota dolomite, qUmT), of the Biesanz Stone COlllpan"' near ,,'inona, Winona 
County. Sample from the lower 3 feet, 8 inches of the quarry. 
120 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
148. Oneota dolomite, same location as no. 147. Sample from the upper 11 feet, 6 inches 
exposed in the quarry. 
CAMBRIAN 
St. Lawrence Formation 
102. St. Lawrence formation, west edge of Rushford, Fillmore County, on State Highway 
No. 30. Sample from upper part of the formation. 
103. St. Lawrence formation, along U. S. Highway No. 16, 2 miles west of Hokah, Houston 
County. Sample of the trilobite bed, which is about 12 to 16 inches thick. 
104. St. Lawrence {ormation, same location as no. 103. Sample from the dolomitic beds, 
which are just below the trilobite beds. 
119. St. Lawrence formation. Jordan, Scott County. Sample of the lowest outcropping 
rock in the bed of Sand Creek about 150 feet above the bridge at the lower brewery. 
157. St. Lawrence formation, Dikelacephalus minnesatensis horizon, Stillwater, Washing-
ton County. 
158. St. Lawrence formation, Dikelacephalus minnesatensis horizon, Fairy Glen, Still-
water, Washington County. 
159. St. Lawrence formation, Dikelacephal-us minnesatensis horizon, Mt. Tom, Hokah, 
Houston County. 
160. St. Lawrence formation, Dikelacephalus minnesotensis horizon, Barn Bluff, Red 
Wing, Goodhue County. 
PART THREE 
SECTIONS AND WELL RECORDS 
(Listed by Counties in Alphabetical Order) 

COLUMBIA HEIGI-!TS, ANOKA COUNTY 
Section at the Sand Pit, North Minneapolis 
PLATTEVILLE FORMATION 
McGregor Member 
THICKNESS 
(in feet) 
8. Limestone. gray to blue. mottled, massive to thin-bedded .............. 8.5 
Glenwood Member 
7. Shale. yellow. argillaceous. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 
6. Shale. blue. argillaceons; fossils common .............................. 1.0 
5. Shale. blue to yellow; also sand mingled with clay. . . . . . . . . . . . . . . . . . . . . . 1.3 
4. Sandstone. yellow. hard. with some clay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 
3. Sandstone. white. poorly cemented ................................... 4.0 
2. Sandstone. green. with some clay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5 
ST. PETER SANDSTONE 
1. Sandstone, white, friable, showing some cross-bedding to bottom of quarry 15.0± 
JUDSON, BLUE EARTH COUNTY 
Section from Minnesota River Level along Road South from the Depot 
THICKNESS 
9. Soil covering to terrace level. ...................................... . 
ST. LAWRENCE FORMATION 
Lodi Member 
8. Dolomite. arenaceous. thin-bedded, gray to buff, with buff siltstone carrying 
Lingule1la; some vermicular beds ................................... . 
7. Dolomite, hard. gray to bufl', glauconitic, arenaceous, irregularly bedded .. 
6. Dolomite. thin-bedded, gray to buff or brown, hard, somewhat sandy .... 
Nicollet Creek Member 
5. Dolomite. massive to thin-bedded, gray to buff, glauconitic, somewhat aren-
aceous ........................................... ' ................ . 
4. Dolomite, gray to brown, glauconitic, thin-bedded. containing trilobite and 
brachiopod fragments ............................................. . 
3. Covered interval, perhaps partly shown at some places ................. . 
2. Dolomite. massive, gray to brown. with much glauconite. often in streaks 
along bedding planes. Cystoid fragments and Billingsella common in upper 
part ...... , ........ , ............................................. . 
1. Covered to level of Minnesota River (760 ft. A. T.) ................... . 
JUDSON, BLUE EARTH COUNTY 
(in feet) 
1.5 
11.7 
6.5 
14.1 
11.1 
8.0 
4.0 
9.0 
5.0 
Section Starting at Bridge in Town and Extending Eastward 3 Miles 
THICKNESS 
(in feet) 
8. Drift ............................................................. 150.0 
JORDAN SANDSTONE 
7. Sandstone, white. medium, with hard lenses and layers. .. . .. . . .. . .. . . . . . 20.0 
6. Sandstone. white, massive, showing some cross-bedding. not well cemented. 
lower part thin-bedded ............................................. 34.0 
ST. LAWRENCE FORMATION 
Lodi Member 
5. Covered interval ...... , ........... , . . . ... ... .. . .. . ...... .. .. .... .. . 11.0 
123 
124 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
FIGURE 38. - Outline map of Blue Earth County, showing locations of measured 
stratigraphic section (solid trian gles). 
4. Dolomite, pink to buff, weatherin g brown , medium- to thin-bedded . .... 
Nicollet Creek Member * 
3. Dolomite. thick- to thin-bedded, glauconitic, gray to buff. Shown along 
roadside ditch. Cystoid plates and rragments common .... .. ........ . ... . 
2. Dolomite, mass ive. glauconitic, gray to pink or brown , fossiliferous ..... . 
1. Dolomite. partly covered , to level of Minnesota Rive,' at bridge in town 
(760ft. A.T .) ......... .. .......................... . ..... .. ... ... .. 
MANKATO, BLUE EARTH COUNTY 
THICKNESS 
(in feet ) 
8.0 
13.5 
16.0 
16.0 
Bunker Hill Well (Drilled in 1874-75; Approximately 975 Ft. A.T .) 
THICKNESS 
(in feet) 
41. Drift, boulder clay with a few layers of sand . . . . . . . . . . . . . . . . . . .. 290 
DEPTH 
(in feel) 
290 
* In this section no allowance has been made for the westward dip , so that the meas-
urements for the Nicollet Creek member are probably too large. However. it is said thal 
in drillin g artesian wells in the village the dolomite was found to ex tend downward for 
50 feet and to be alternately hard and soft. The con/{Iomerates occurring in the section 
on Mrs. Brown 's farm along Nicollet Creek (see above, page 45) suggest the lower part 
of the member, but south of the river pebbles occur in the dolomite about 7 feet below 
the Lodi and far above the base of the Nicollet Creek member. 
BLUE EARTH COUNTY 
THICKNESS 
(in feet) 
ST. LAWRENCE ForUVIATION 
40. Limestone, hard, gray, dolomitic ............................. . 
39. Shale, greenish, calcareous .................................. . 
3H. Limestone, reddish gray, siliceous, dolomitic, glauconitic ........ . 
FRANCONIA FORMATION 
37. Sandstone, greenish to reddish gray, dolomitic, containing grains of 
glauconite and a green cement .............................. . 
36. Sandstone, calcareous, containing mnch greensand .............. . 
3.5. Dolomite, somewhat siliceous, pinkish ...... . ........... . 
:34. Sandstone, hard, fine-grained, dull red, with fine grains of greensand 
or glauconite ......................... , ............ , ....... . 
DRESBACH FORMATION 
33, Sandstone, friable, white ... , ............................ , ... . 
32. Shale, fine, dull pink, with some sandstone ..................... . 
31, Shale, fine, dull pink, with some sandstone ................... . 
30, Sandstone, yellowish, iron-stained ........................ . 
29. Sandstone, fine-grained ................................. . 
'Z8. Sandstone, yellowish with red and greenish streaks, some of which 
are shale ................................................. . 
27. Sandstone, coarse-grained, gray .......................... . 
26. Sandstone, medium-grained, gray .............. . .......... . 
2.5. Shale, slightly gritty, dark, dull red ............... . 
24. Sandstone, white to dull red. . . . . . . . . . . . . . . . . . . . .. . ......... . 
HINCKLEY SANDSTONE 
23. Sandstone, iron-stained, pinkish, shaly ....................... . 
22. Sandstone, light red, medium-grained, with some shale .. . 
21. Sandstone, coarse, gray, with angular grains .................... . 
'ZO. Sandstone, medium-grained, light pink ... , .................... . 
19. Sandstone, fine-grained, light pink .................... . 
FOND DU LAC BEDS 
18. Sandstone, coarse, reddish gray .............................. . 
17. Sandstone and red shale ................................... . 
16. Sandstone, reddish, shaly ................... . 
15. Sandstone, very fine-grained, soft, pinkish gray ........... , . 
14. Sandstone, coarse, angular-grained, gray ....................... . 
13. Sandstone, reddish gray to yellowish, fine-grained ... . 
1 Q. Sandstone, very coarse. iron-stained. poorly assorted. some grains 
more than 'I,; inch in diameter .......... . 
11. Sandstone, medium-grained, reddish, with some shale ......... . 
10. Sandstone, fine-grained, whitish, with some red shale ......... . 
9. Shale, dull red, arenaceous .............. , ................. . 
8, Shale, red, arg-illaceons .................................... . 
7. Sandstone, light gray to dusky brown, fine-grained ............. . 
6. Sandstone, reddish, medium-grained, friable ................ . 
5. Sandstone, reddish gray, fine-grained .................... . 
4. Shale, very fine-grained, siliceous, dull red ,.. . ...... , .... . 
3. Shale, sort, red, ,,·ith an occasional sand grain ........ , ......... . 
'Z. Shale, slightly arenaceous, red ...... ,... . ....... . 
1. Shale, rec\, with fine grains of white quartz * .. , ................ . 
20 
20 
50 
10 
60 
~3 
42 
G5 
40 
40 
10 
10 
140 
50 
6.5 
% 
,50 
40 
50 
90 
25 
;j 
10 
40 
7 
5 
8 
110 
150 
50 
50 
20 
90 
17 
33 
1'Z 
1'28 
1.50 
50 
4 
DEP'I'H 
(in feet) 
310 
330 
380 
390 
450 
453 
495 
560 
600 
640 
650 
660 
800 
850 
915 
1,010 
1,060 
1,100 
1,150 
1,'240 
1,265 
1,'270 
1,280 
1.320 
1,327 
1,33'2 
1,3 .. 0 
1,450 
I,GOO 
1,(150 
1.700 
1.nO 
1.810 
1,827 
1,860 
1,87'2 
2.000 
U50 
2,200 
'-2,~O-l 
* The correlation here shown is merely approximate. The St. Lawrence is given by Hall 
and Meinzer in Geology (Ind Underground Waters of Southern Jiil1ncsota (U. S. Geological 
Survey, Water Supply Paper 256), p. HI. Twenty-nine samples from this ,,·e11 are in the 
Museum of Geology, University of :Minnesota. See "Tarren Upham, Geology of Jiinnesota 
(Geological and Natural History Survey of :Minnesota), Vol. 1 (lH84), pp. 423-24. 
126 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
MANKATO, BLUE EARTH COUNTY 
Section at the Carney Company Quarry, Pilgrim Rest Cemetery 
THICKNESS 
10. Drift 
..... , .. , ..... , ....................... , ........ , .............. . 
ONEOTA DOLOMITE 
(in feet) 
2.0 
9. Dolomite. weathered buff, thin-bedded ................................. 3.5 
8. Dolomite, buff to brown or pink, thick-bedded, cavernous, usually mottled. . . 4.0 
7. Dolomite, pink weathering to buff. thick-bedded. porous. . . . . . . . . . . . . . . . . . 4.2 
6. Dolomite. buff with splotches of pink. thick-bedded. separating into two layers 7.5 
5. Dolomite, purple to ashen gray, shaly .................................. 2.5 
4. Dolomite, gray, massive, with several poorly developed bedding planes. .. .. . 4.2 
3. Dolomite. gray, massive to shaly ...................................... 4.0 
JORDAN SANDSTONE 
2. Sandstone. white sand with hard masses. massive. " .......... , .. .. .... .. 10.0 
1. Covered interval to level of creek in abandoned channel of Minnesota River 
(750 ft. A.T.) ................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.0± 
MANKATO. BLUE EARTH COUNTY 
Section at the T. R. Coughlin Company Quarry 
17. Soil covering ..................................... , .................. . 
SHAKOPEE DOLOMITE 
16. Dolomite. oolitic. with occasional development of gray to brown conglomerate. 
These beds contain some oolitic chert. and weathered surfaces may show sand 
grail1s ............................................................. . 
15. Covered interval .................................................... . 
14. Dolomite. sandy, brown. with some flat pebbles and indefinite contact with 
beds below ......................................................... . 
ROOT V ALLEY SANDSTONE 
13. Sandstone, white to yellowish, with hard masses like quartzite. Some layers are 
ripple-marked ...................................................... . 
12. Shale. sandy, green, uneven at base. Contains a few fossils, chiefly Raphistoma 
sp ................................................................. . 
ONEOTA DOLOMITE 
II. Dolomite. porous. occasionally oolitic, gray to drab in color. often with a pink 
tinge. Calcite geodes common ........................................ . 
10. Dolomite, massive. gray to yellowish. with occasional cherty masses ....... . 
9. Dolomite, massive, gray to brown and pink or reddish brown, usually mottled. 
Contains small cavities and calcite geodes. Some sand penetrates the cracks to 
this depth, filling cavities ............................................ . 
8. Dolomite, in a single layer. fine, gray to buff, almost without cavities ....... . 
7. Dolomite, massive, buff, slightly mottled. fine-grained. The best building stone 
in the quarry. In two layers with barely perceptible parting ............... . 
6. Shale. hard. dense. buff with purple blotches, grading to purple. When un-
weathered this bed may appear massive ................................ . 
5. Dolomite, massive, buff. continuing to the quarry floor and to water ....... . 
4. Dolomite. massive, buff to brown (covered) ........................... . 
3. Shale, gray (covered) ............................................... . 
2. Dolomite, massive, unevenly bedded, gray to buff ....................... . 
JORDAN SANDSTONE 
1. Sandstone, white. covered to level of Minnesota River (750 ft. A. T.) ..... . 
THICKNESS 
(in feet) 
0.5 
7.3 
1.0± 
2.5 
5.0 
0.5 
.5.5 
9.8 
13.0 
4.0 
7.5 
2.5 
3 .. 5 
9 .. 5 
3.0 
7.5 
40.0± 
BLUE EAHTH COUNTY 
MANKATO, BLUE EARTH COUNTY 
Section at the Fowler and Pay Quarry 
127 
13. Soil covering 
THICKNESS 
(in feet) 
0.5 
SHAKOPEE DOL01\IITE 
12. DolomiLe, gray Lo broll'n, ofililic; some development of conglomerate, occasion-
ally sandy; some ofililic chert ......................................... . 
II. Covered interval .................................................... . 
10. Dolomite. brown. sandy. A lean conglomerate with some flat pebbles ....... . 
ROOT VALLEY SANDSTONE 
9. Saudstone. white to ydlow. the upper layers grading into dolomite. Hard quart-
zite masses. which the quarry workers call flint. occur in the sandstone. Some 
layers arc ripple-marked ............................................. . 
8. Shale. green, sandy ................................................. . 
ONEOTA DOLOllIITE 
7'. Dolomite. gray Lo drab, of Len with a pink cast, hard. weathered surface pitted. 
sometimes o(ililic. Cryptozoons and calcite geodes common ................ . 
6. Dolomite. gray to yellow, massive, with occasional cherty masses ....... . 
5. Dolomite. gray to brown. pink or reddish brown. usually mottled. massive. 
Small cavities and calcite geodes common. Some sand penetrates cracks and 
fills cavities to this depth. . . . . . . . ..................... . 
4. Dolomite, in a single layer. gra,' to buff. fine-grained. almost without ca\·ities. 
3. Dolomite, buff to mottled. Occurs in several laJ'ers but bedding is indistinct. 
The finest quarry stone .............................................. . 
2. Dolonlite, buff with purple blotches, shaly .. . .................. . 
1. Dolomite. buff, massi\'C, to bottom of quarry at the old lime kiln .......... . 
l\lANKATO. BLUE EARTH COUNTY 
7.3 
l.0:±: 
2.5 
5.0 
0.6 
5 . .5 
9.8 
10.'1 
4.6 
6.0 
2.5 
2.2 
Section along the New Highway Cut Opposite Sibley Park, 1I1 Nicollet County 
THICK~ESS 
10. Drift. Two or three drift sheets shown. a very old one at base .......... . 
DAKOTA FORIIIATION 
Ostrander Member (() 
(in feet) 
150.0:±: 
9. Shale. blue, argiJlaceous. alternating' with white sandstone. In addition to 
conring the surface, it fills some of the old solution cavities in beds below 5.0 
ONEOTA DOLOMITE 
8. Dolomite. buff, lhick-bedded. with a crust of secondar~' iron at the top. . 5.0 
7'. Dolomite. gray to buff. thick-bedded. Upper part much \yeathered. . . . . . . '15.0 
6. Dolomite, gray to buff and brown. Upper 3--.f inches infiltrated with iron 1.4 
5. Dolomite. thin-bedded to shal~'. purple leaching to buff. Contains Lin-
gula sp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7 
4. Dolomite. gray to buff. thick-bedded. Solution cavities common. Trails 
common on bedding planes. Base irregular. . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.0 
BLUE EARTH SILTSTOKE 
3. Shale or siltstone. fine-grained. poorl~' cemented. pale green. localiy hrown. 
with much iron at the base. Thickness variahle ....................... 7.0 
JORDAN SANDSTONE 
2. Sandstone. white. medium-grained. poorly cemented. . . . . . . . . . . . . . . .. . . 16.0 
I. Sandstone. white to yelio\\', partly cOI'ered to level of l\linnesota Hiver 
(750 ft. A.T.) ..................................................... 37.0 
1'28 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
RAPIDAN, BLUE EARTH COUNTY 
Section along the Le Sueur River, J1/z Miles East of Town 
THICKNESS 
(in feet) 
6. Drift, variable !'rom place \0 place but usually Kansan at base. . . . . . . . . . .50± 
DAKOTA FOR:\IATION 
Ostrander Member 
.5. Gravels. largel~' quartz and flint. cross-bedded. partly cemented at the top 8 
4. Gravel. like that above. with streaks or sand. At places these streaks are ce-
mented into beds of sandstone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 
3. Grayel. like that above. with some thin. iron-cemented beds of pebbles. 
White. rose. and clear quartz pebbles predominate but flint, quartzite, and 
limestone pebbles also abound ...................................... 1 '2 
'1. Covered. but apparentl~' shale, like that at the base or the Oneota. . . . . . . . .5 
.]ORDAX SANDSTONE 
1. Sandstone. vello,,' to "'hite, coarse to medium. Some lavers are cemented in-
to hard, re;istant beds. To level of Le Sueur River .:.................. 27 
NEW ULJ\T, BROWN COUNTY 
Section along State Highway No. 15, at Southeast End of Bridge over the 
Cottoll\vood River. on the Nick Metzen Farm (see page 104) 
NE\Y ULM, BROWN COUNTY 
Section of Rock Outcrops in Gully vVest of the Heimann Quarry and 
Lime Kiln (Abandoned). in Nicollet County 
1 'I. Soil. black 
DAKOTA FOR:\JATIOi\' 
THICK~E~S 
(in feet) 
'2.0 
II. Shale. green and red. argillaceous . . . . . . . . . . . . . . . . . . . . . . . . 3.8 
10. Sandstone. pink. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 
9. Shale. so!'t. green .................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 
R. Lin1estone. gray to green. cavernous. . . . . . . . . . . . . . . . . . . . . 2.0 
7. Shale. red. argillaceous ............................................... 3.3 
6. Limestone. gTay to bull ca,'ernous. shaly ...................... 1.3 
;5. Shale. green and red. argillaceous. . . . . . . . . . . . . . . . . . . . . . . . 1.3 
4. Limestone. greenish gray. argillaceous. shaly ... , , ' . , . , , ' , , 1.0 
3, Shale, green and red, argillaceous "." .. ".,.""",."", .. " .. "" 0,9 
2. Limestone, greenish gray, argillaceous ................................ 'l.3 
1. Concealed. probably red shale. to lewl or stream. ' ' , . ' , , ' , , 1),5 
l\'E\y ULM. BROWN COUNTY 
Section in Gully at the Heimann Lime Kiln (Abandoned), in Nicollet County 
THICKNE8S 
5, Drift, gra)'. \"ith pebbly glacial clay, , , , , .. , .. , , . ' , , , .. , , . ' , , . , .. 
4, Sand. with brown-stained glacial gravel, ' , ' , , . , , .. , , , , ... ' , , , , ' , , , .. , ' , . ' 
DAKOTA FOR:\fATIO:\ 
3, Shale. red and green. nll'iable; and argillaceous shale interbedded \I·ith buff 
limestone .. , . . ' , , , . , , . ' , . , , . , , .. , . ' , ' , , . , . , ' , , , . ' . , , , 
~, Shale. greenish gray, argillaceous ""."""" .. "",.",.",.""""" 
1. Shale. red. ca'careous. ,,·ith hard, light-colored lime, tone nodules to level of 
creek .,.".,"',.,',.,., .. ,"", ... "."., .. """ .. ,.""' .. "."'., 
(in feet) 
40,0 
8.0 
30.0 
4,0 
2.5 
BROW. COUNTY 129 
T 
I~O I===~;==?i~ 
R3!>W 
FIGURE 39 . - Outlin e map of Brown County, showing loca tions of meas ured tratigraphic 
section s (so lid triangles). 
'VISCONSI N DRIFT 
NEW ULM. BROWN COUNTY 
Section along Kalb Creek 
11. Drift, sandy, gravell y, gray .................... .... ..... .. ... . .... . 
KA NSAN DRIFT 
10. Drift. hard , pebbly. dMk bluish gray. of Len shaly in appearance .... 
DAKOTA FOlUIIATION 
9. Shale. dark gray Lo brown . with thin beds of sand ............ .. . . ... . ... . 
8. Sandstone. white , medium· to coarse-grained. cross-bedded .. . .. .. ........ . 
7. Sandstone, yellow. coarse. pebbly, very iron-stained ...... . ...... . . . 
6. Sha le, gray to dark bluish , argi ll aceous, with fin e crysta ls of pyrite and abun-
dant gypsum ........................... . ................. . ......... . 
:i. Shale. gray. sandy. gypsum-bearing. iron-s tained . . . ... .. ............ . ... . 
4. Shale. gray. sandy . ...... . ............. . ....................... . 
3 . Sandstone. light gray, slightly calca reous ............................. . . 
2. Limestone. a thin layer of ifl'egular ca lcareous nodules ................... . 
1. Shale. gray, argi ll aceous, with calca reous nodules. T o level of Big CoLton-
wood R iver at mouth of K a lb Creek .. . .... ... .. . .... .. ...... .. .. . ..... . 
NEW ULM, BROWN CO NTY 
THI CK NESS 
(in feet ) 
1.5 .0 
20.0 
16.0 
2l..5 
0 . .5 
l..5 
1.2 
1.3 
U 
0.3 
1.5 .0 
Section along County Road , 2 Mi les Southwest of Towll, E% Sec. 31 
THICK N ESS 
6. Drift. sandy ... .. ... ........... ....... . .....•....... . ... .... . ... ...... 
DAKOTA FOHlI l ATION 
(in feet ) 
6.0 
5. Sandstone. yellow to brown , so ft ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 
130 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
4. Shale. gray. argillaceous. with occasional sandstone layers. Contains abundant 
THICKNESS 
(in feet) 
leaf fragments. Uncomformable on beds below. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.8 
3. S~ndsto~e: white to yellow. fine-grained. friable. Contains leaf fragments and 
pIeces 01 hglllte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.0 
'2. Talus of sand and limonite concretions. . . . . . . . . . . . . . . . . . . . . . . . . . . .5.0 
1. Covered interval to level of Cottonwood River. . . . . . . . . . . . . . . . . . . . . . . . . . . . '25.0 
NEW ULM. BROWN COUNTY 
Section at the Old 'Yinkelmann Quarry. South Bank of the 1\iinnesota River. 
Sec. 2. Cottonwood Twp. 
THICKNESS 
(in feet) 
8. Soil. mixed with weathered shale and limestone. . . . . . . . . . . . . . . . . . . . . . . . . Z.O 
DAKOTA FORMATION 
7. Limestone. gray-green. shaly. cavernous. with much secondary calcite........ 12.5 
6. Shale. gray. argillaceous ............................................... 8.5 
5. Shale. red. marly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 
4. Shale. gr'eenish gray. marly ............................................ 3.0 
3. Shale. red. marly ..................................................... 2.0 
!'!. Limestone. gray. shaly, weathered, cavernous. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7 
1. Covered interval to level of Minnesota River (775 ft. A.T.) . . . . . . . . . . . . . . . . 6.3 
'VISCONSIN DRIFT 
SPRINGFIELD. BROWN COUNTY 
Section at the Ochs Clay Pit 
10. Drift. gray. gravelly. with a few boulders .............................. . 
KANSAN DRIFT 
THICKNESS 
(in feet) 
1;5.0 
9. Drift. blue. argillaceous, with fine pebbles and small cobbles. much-compacted 5.0 
DAKOTA FORMATION 
8. Shale, blue, argillaceous. with iron pyrite concretions and ironstone concretions 
containing fossil plants; also some lignite lenses. . . . . . . . . . . . . . . . . . . . . . . . . . . 15.0 
7. Sandstone, hard. containing fossil leaves. . . . . . . . . . .. . . . . .. . . . . . .. .. . . . . . 0.8 
6. Shale. argillaceous, blue. some parts mottled a lighter blue-gray. . . . . . . . . . . . 11'.0 
S. Lignite. impure ...................................................... 1.0 
4. Sandstone. hard. white ..................................... ......... 3 . .1 
3. Shale. blue. argillaceous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 
'2. Sandstone. hard. white ............................................... 3.0 
1. Rock. rather soft. but resembling concrete. Lowest level excavated (about 946 
ft. A.T.) ............................................................ 1..5 
FOND DU LAC. CARLTON COUNTY 
Section along the St. Louis River below Powerhouse (see page 14) 
FRANCONIA. CHISAGO COUNTY 
Type Section of the Franconia Sandstone (see page 39) 
FRANCONIA, CHISAGO COUNTY 
Section along East Side of Lawrence Creek, in Daggett's Gulch 
THICKNESS 
(in feet) 
14. Conred to top of hill. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.0 
T 
37 
N 
T 
36 
N 
CHISAGO COUNTY 
R21W R20W RI9W 
FIGURE 40. - Outline map of Chisago County. showin g locations of 
measured stratigraphic sec tions (so lid triangles). 
131 
THICK NESS 
(in feet ) 
FHA NCONIA FOHl\JATION 
Taylor Falls M ember 
13. Sandstone, tan to brown, fin e-grained. mass ive. Lower 3 feet abundantly 
fossiliferous. Upper part tends to split along beddin g pl anes " 'here weath-
ered . Abundant foss il s collected from the lowel' 3 fee t of this d ivision. . . . . 7.0 
12. Sandstone, slightly massive to thin-bedded. tan to brown, fin e-grained , 
somewhat cross-bedded. pa rts very porous owin g to leaching and oxida-
tion , friable. Fragments of brachiopod shells and trilobites abundant in 
some parts .... .. . ................... . ... ..... .................... 3.7 
11. Sandstone. massive, white, with fin e grains of glauconite; upper 8 inches 
tan to brown . . .... . ... . ..... . .... . ................ . .......... 4.5 
10. Sandstone. thin-bedded. fine-grained. buff to brown. glauconitic. bearin g 
shell fragments; mud cracks at tops of some beds. .. . . .. . . . .. . . . . . .. . . . 2.5 
9. Sandstone, massive, buff to bl'Own . fine-grained. partly ross-bedded and 
laminated . A few grains of glauconite in the lower part. Some scattered 
brachiopod shell fragments ....... . ....... . .... . . . . . .... . ... . ...... 8.3 
8. Sandstone and shale, partly covered ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.0 
7. Glauconite. shaly , sandy. Lower foot very sha ly and thinly lamina ted. up-
per part partially oxidi zed red ........ . .... . .... . ................... !L5 
13'2 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
(i. Covered interval to base of shaly glauconite ......................... . 
;5. Glauconite. sandy. with a little laminated gra~'-green shale. partially cov-
ered ............................................................ . 
4. Covered interval to base of sandy glauconite ............... . 
3. Sandstone. medium-grained. gray to tan. massive. bearing Dieellomlls sp. 
shell fragn1ents and glauconite; some cross-bedding ................... . 
Ironton lVlember 
'2. Partly covered interval .......................................... . 
1. Sllale. gray to buff. hardened. with iron oxide and green stains and lenses 
or brown to gray sand. To lewl of creek at bridg'e in village ........... . 
FRANCONIA, CHISAGO COUNTY 
THICKNESS 
(in feet) 
4.0 
5.7 
17.'2 
3.5 
21.5 
2.8 
Section from Boat Landing to Top of Quarry Hill near Site of Old Nlill 
THICKNESS 
1 '2. Drift to top of hill 
FRANCONIA FOKMATIOJi 
Taylors Falls Member 
II.' Sandstone. thin-bedded. white to yellow and brown. fine-gTained. slightly 
(in feet) 
14.7 
glauconitic. Contains brachiopod and trilobite fragments. poorly preserved 7.3 
10. Sandstone, massive. fine-gTained. white grading upward into buff. Some fine 
glauconite scattered throughout. Brachiopod and trilobite fraglnents com-
mon ............................................................ 2.7 
9. Sandstone. thin-bedded. yellow to brown. fine-grained. with some cross-
bedding. Brachiopods and trilobites throughout. also some tracks and trails 3.8 
8. Sandstone. massive. fine-grained. white to tan and buff. Brachiopods and 
trilobites throughout .............................................. 12.0 
7. Sandstone, fine-grained. massive. white. with scattered fine grains of glau-
conite ........................................................... 2.0 
6. Sandstone. fine-grained. cross-bedded. thin-bedded to shaly, dolomitic. tan 
to brown. with irregular streaks of iron stain. The shales show mud cracks 1..5 
5. Sandstone. thinly laminated. fine-grained. tan to buff. with scattered ii;rains 
of glauconite ..................................................... 9.3 
Ironton lVlember 
4. Covered interval. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.7 
3. Shale. gTay to bluish gray. sandy. with sandstone lenses. 1.8 
2. Glauconite, sandy ................................................ 1..5 
KEEWEENAWAN 
1. Conred interval to level of St. Croix River (686 ft. A.T.). 43.2 
OSCEOLA BRIDGE. CHISAGO COUNTY 
Section along Highway at West End of Bridge 
22. Drift .............................. . 
JORDAN SANDSTONE 
Van Oser Member (1) 
THICKNESS 
(in feet) 
2.5.0 
21. Sandstone. thin-bedded. yellow to brown. ferruginous. weathered. . . . . . . 18.0 
20. Sandstone. massive, white to yellow. fine- to medinm-grained. thin-bedded 
at top ........................................................... 32.0 
19. Sandstone. brown. heavily impregnated with iron ......... " . . . . .. . . . . 0.5 
CHISAGO COUNTY 
Norwalk Member 
THICKNESS 
(in feet) 
IS. Sandstone, thick-bedded. yellow to brown, with scattered fossils. . . . . . . . . 10.5 
17. Sandstone, thin-bedded, vermicular, brown, containing a few fossils. 2.5 
16. Sandstone, {Toss-bedded, laminated, brown. not well separated I"rom that 
above but containing two thin. edgewise conglomerates . . . . . . . . . . . . . . . . 1.5 
15. Sandstone, massive, laminated, (Toss-bedded. brown. full of characteristic 
Norwalk fossils ................................................... 5.3 
14. Covered inten'al ... " . . . . . . . . . . . . . . .. . . . .. . . . .. . . . . . . . . . 16.0 
13. Sandstone. thin-bedded, medium-grained, brown, with Norwalk fossils 2.5 
12. CO\'ered interval. .. . . . . . . . . . . . . . . .. . . . . . . . .. . .. . . . . . .. . . . . . . . . . . 3.0 
ST. LAWRE:-':Ci': FOI{j\IATIO:-': 
Locli Member 
II. Sandstone. thin-bedded. fine-grained. glauconitic; with some gray-green 
shales. Ripple-marked and mud-cracked; worm trails common. . . . . 4.0 
10. Shale, gray to greenish; with streaks 01" fine sand. . . . . . . . . . . . . . . . . . . . . . 0.7 
9. Dolomite, sandy, gray, glauconitic, with pebbles at the base. . . . . . . . . . . . . !';5 
H. Shale, green, in layers, alternating with fine-grained, laminated glauconitic 
sandstone; some layers are very glauconitic. The Dikelocephalus minneso-
te"sis fauna ..... ,............................................ 4.0 
7. Shale, gra>' to green, with sandy glauconitic lenses. Some layers are a fine 
siltstone, Ripple marks, mud cracks, and worm trails common ... , . . . . . . 8.0 
Nicollet Creek Mernber 
(i. Conglomerate, flat pebble ..... , ..... , , .. , ....... , ... , .... , . 0 . .5 
5. Shale, blue clay, soft, sticky ..... , ...... " ...... ,., ... ,.,... 0.3 
FRANCONIA FOR:\[ATJON 
Bad Axe Member 
4. Sandstone, fine-grained, poorly cemented, glauconitic ............ , . . .. . . 10.7 
3. Shale or shaly sandstone, fine-grained, glauconitic, yermicular , . , , , . . . . . 5.0 
2. Sandstone, massi,'e. white, medium-grained, poorly cemented ... , , . , , . . . 8.0 
1. COYered interval to level of St. Croix River (684 ft. A.T.) . . . . . . . . . . . . . . 10.7 
TA YLORS FALLS, CHISAGO COUNTY 
Section along Curtain Falls Trail 
14. Drift to top of hill 
FRANCONIA FOR~I.ATJON 
Taylors Falls Member 
13. Sandstone, thin-bedded, fine-grained, buff to brown, much-weathered. 
THICKNESS 
(in feet) 
60,0± 
Fossils mainly trilobites and fragmentary ..... , .... , ...... , .. ,...... (i.,; 
12, Sandstone, massiYe, buff, fine-grained. , , ... , .. , , , .. , ... , , ....... , , ,. . 5.0 
Ironton Member 
II. Sandstone, thin-bedded, buff to brown, fine- to medium-grained, with some 
cross-bedding, Scattered fragments of trilobites ........... , . . . . . . . . . . . . 7.;'; 
10, Sandstone, fine-grained, buff to brown, cross-bedded, with iron-stained 
streaks. All more or less fossiliferous ........ , . , ...... , .. , , , ..... , . . . . 4.0 
9. Sandstone, white, fine-grained. Gastropods common ............. , , . . . . 1.0 
8. Sandstone, buff to brown, fine-grained, containing trilobites and striated 
brachiopods ........ , ... " .... ,., ........ " ... , .. , .... , .......... , 2,0 
7. Sandstone, thin, irregularly bedded, hard, fine-grained, gray to brown, glau-
conitic, with thin shale partings .... , .............. , , , . , ..... , ..... , 6.8 
134 PALEOZOIC A D RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Roc-c L . 
C> 
MINNE.50 A 
cotbY£,~ 
IN 
TJ4N 
TJ.3N 
P opLar L-. 
I 
" 
FICURE 41. - Outline map of tbe St. Croix River in the 
Taylors Falls region, showin g locations of measured strati-
graphic sections (solid triangle ). 
DRESBACH FORMATION 
THICKNESS 
(in reet) 
6. Sandstone, gray, shaly , very glauconitic, somewhat iron-stain ed . . . . . . . . . 10.3 
5. Sandstone, thin-bedded, fin e-grained, gray, glauconitic, cross-bedded, iron-
streaked; bedding somewhat lenticular . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 
4. Shale, sandy, glauconiti c, mud-cracked, gray ,,·ith much iron stain . . . . . . 4.7 
3. Sandstone, medium-grained , mass ive, buff to brown. . . . . . . . . . . . . . . . . . . . 4.7 
2. Covered interval , stream wash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63.3 
K E\VEENA \ VAN 
1. Trap showin g at many places from highway through tourist park to St. 
Croix River level (688.1 ft. A. T .) . . .... . .. . .. ........ . . .......... . . 57.0 
CHISAGO COUNTY 
TA YLORS FALLS, CHISAGO COUNTY 
Section along Highway Cut I Mile South of Town 
135 
12. Drift ........................................................... . 
THICKNESS 
(in feet) 
55.0 
FRANCONIA FOR~JATION 
Taylors Falls Member 
11. Sandstone. massiw- to medium-bedded. friable. white with yellow streaks, 
medium-grained. with fragmentary fossils ............... ~ . . . . . . . . . . . . 25.0 
10. Sandstone. white Lo yellow, partly covered .......................... 6.8 
9. Sandstone, thin-bedded. yellow. with a few grains of glauconite. Contains 
fragments of fossils, chiefly trilobites, among which are Conaspis sp.. . . . . . 12.4 
8. Sands Lone. massive. medium-grained. white with yello\\" streaks, finely 
glauconitic. Fossils common . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.0 
7. Sandstone. white to yellow. massi,·e. fine-grained; some layers ('1'OSS-
bedded. Contains scattered fine grains of glauconite and some fossils..... 15.0 
6. Sandstone. massive. medium- to fine-grained, white to ~·ellow. . . 15.0 
Ironton Member 
5. Sandstone. massiYe- to thin-bedded. medium- to fine-grained, gray to 
brown. glauconitic. cross-bedded. with streaks of gTeen shale along bedding 
planes. Some layers are rnuch indurated. Contains Dicellomus and vari-
ous trilobites. among them Call1(lmspis COllveXIlS and C. hemisphericus. . 21.4 
DRESBACH FORMATION (top at 747.9 ft. A. T.) 
Galesville Member 
4. Absent ......................................................... . 0.0 
Eau Claire Member 
3. Shale. with streaks of sandy glauconite, fossiliferous . . . . .. ....... 1.6 
2. Sandstone, fine-grained. very glauconitic. Contains Dicellolllus sp.. . . 13.8 
KE'VEENA"~ AN 
1. Partly covered lava flows to river level (688.1 ft. A. T.) .............. . 
TA YLORS FALLS. CHISAGO COUNTY 
Section along Pine Point Trail 
13. Drift ........................................................... . 
FRANco~rrA FORMATION 
Taylors Falls Member 
44.3 
THICKNESS 
(in feet) 
65 . .5 
12. Sandstone, massi,·e. vello\\' to white. friable. Trilobites and small brachio-
pods common. esperially in the lower part. . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.8 
Ironton NIember 
11. Sandstone. thin-bedded to massive. fine-gTained. white to brown. hard, con-
taining some streaks of glauconitic sandstone. .. . . . . . . . .. . 5.9 
10. Sandstone, brmm. dolomitic and glauconitic, banded and laminated. fine-
grained. hard ..................................................... 10.6 
DRESBACH FORlIIATION 
9. Shale. in gray to buff argillaceous beds ,vith sand lenses. . .. . . . .. . .. . .. . 16.0 
8. Covered inlerval ............. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,2..5 
7. Greensand or sandy glauconite. partly covered. . . . . . . . . . . . . . . . . . . . . . . . 3.0 
6. Sandstone. soft. fine-grained. glauconitic........... . . . . . . . . . . . . . . . . . . 10.0 
5. Greensand or sandy glanconite, partly coyered. . . . . . . . . . . . . . . . . . . . . . . . . 5.0 
4. Covered interval ................................................. 1.5..5 
3. Sandstone, fine-grained. gray, slightly glauconitic. . . . . . . . . . . . . . . . . . . . . 2.0 
2. Shale. gray to bnff. Some layers arenaceous. Fossiliferous. . . . . . . . . . . . . . . 34.0 
KE"rEEN A ,\-VAN 
1. Partly cOYered intenaL with diabase flo\\'s showing at numerous places 
to th~ St. Croix River (688.1 ft. A. T.). ........................... 44.0 
136 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERl M I NNESOTA 
FIGURE 42. - Outline map of Dakota County, howing loca tions of measured 
stratigraphic sec tions (solid triangles). 
HAMPTON, DAKOTA COU TY 
Section a long U. S. Highway No. 52, 3 Miles Southeast of Town 
T HICK NESS 
9. Soi l and drift ..................................... . ............... . 
(in feet ) 
0.5 
PLATTEVILLE F ORMATION 
McGregor M ember 
8. Limestone, gray to bluish. mass ive to thin-bedded . .. . . ... .. . . . ..... . . . . 6.0 
7. Limestone, gray, sha ly, grading to shale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0 
Glenwood :Member 
6. Shale. gray to blue. often weathered yellow, argill aceous. . . . . . . . . . . . . . . . . .5.0 
5. Shale, blue-gray, argi ll aceous. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 
4. Shale, gray to yellow. sanely, alternating with argill aceous gray shale. . . . . 1.8 
3. Sha le, light gray. argillaceous ... .... ..... ... .. .............. . ....... 0.5 
2. hale. yel low to brown , san dy, with thin layers of while sand . . . . . . . . . . . . 2.5 
ST. P ETER SANDSTONE (Lop a t 973.2 ft. A.T. ) 
1. Sandstone, white, beco ming yellow a t Lop, massive ......... . ... , .. . . . . . 18.0 
DAKOTA COUNTY 
HASTINGS, DAKOTA COUNTY 
137 
Section 100 Yaros above the Hastings Dam, in Washington County 
THICKNESS 
7. Covered interval to top of hill .................................. . 
ONEOTA DOLOMITE 
(in feet) 
60,0 
6. Dolomite, gray to drab. massive. rough, irregular. . . . . . . . . . . . . . . . . . . . . . . . . . 58.4 
5. Dolomite, gray to tan or buff. arenaceous. Lower beds thick, upper thin to shaly 8.1 
.JORDAN SANDSTONE 
4. Sandstone, yellow to white. massive, medium- to fille-grained with some hard 
layers ............................................................... 11.6 
3. Sandstone, yellow to brown, massive. cross-bedded. medium to coarse. . . . . . . . 21.9 
2. Sandstone, white to yellow, massive, cross-bedded. . . . . . . . . . . . . . . . . . . . . . . . . 46.1 
1. Covered interval to Mississippi River level above the dam (687.'1 ft. A.T.) . . . . 6.9 
HASTINGS, DAKOTA COUNTY 
Section at the Hastings Stone Company Quarry 
5. Soil and drift ...................................... . 
SHAKOPEE DOLOMITE 
4. Dolomite, massive, gray to drab. in part oolitic and with some oiilitic chert. The 
THICKNESS 
(in feet) 
10 
rock is cavernous and has few fossils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 
ROOT V ALLEY SANDSTONE 
3. Sandstone and sandy layers of dolomite ................................. . 
ONEOTA DOLOMITE 
2. Dolomite, massive. brown. at places pink. rarely of a gTeen cast. Contains 
numerous cavities. many partly filled with crystals of quartz: some retain traces 
of cryptozoon structure .. . . . . . . . . . . . . . .................... . 
1. Dolomite or thin-bedded dolomitic limestone, hard. dense. interbedded with 
sandy layers. These beds lie below the floor of the quarry but are shown along 
the bluff ............... . 
HASTINGS. DAKOTA COUNTY 
4 
40 
15 
Well at the Milwaukee Railroad Depot (Drilled in 1885; 710 Ft. A.T.) 
ONEOTA DOLOMITE 
25. Limestone. dolomitic 
.JORDAN SANDSTONE 
THICKNESS 
(in feet) 
80 
24. Sandstone ................................................. . 15 
12 
l15 
23. Grit. dolomitic ..... . .................................... . 
22. Sandstone ................ . 
ST. LAWRENCE FORMATION 
'21. Sandstone, white, with sandy shale .................... . 
20. Shale. gray. sandy. with son;e dolomite 43 
FRANCONIA FORMATION 
DEPTH 
(in feet) 
80 
9;) 
107 
20t 
227 
'270 
19. Sandstone and greensand .............................. '20 '290 
18. Sandstone and greensand, with some sandy green shale. . . . . . . . . .. 110 400 
17. Sandstone. sandy shale. and greensand ........................ 15 415 
138 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
THICKNESS 
(in feet) 
DRESBACH FORMATION 
16. Sandstone with some pyrite ................................. . 
15. Shale, sandy. gray ......................................... . 
14. Shale, blue to gray ......................................... . 
13. Sandstone and greensand ................................... . 
12. Shale, gray, with sandy dolomite and sandstone ................ . 
11. Sandstone. with p~'rite lumps and dolomitic grit .............. . 
10. Sandstone. medium to fine, white ............................ . 
HINCKLEY SAl\'llSTONE 
60 
20 
70 
20 
5 
5 
100 
DEPTH 
(in feet) 
475 
495 
565 
.585 
590 
595 
695 
9. Sandstone, coarse and fine ................................... 8{j 780 
8. Sandstone. coarse and fine. with traces of red shale. . . . . . . . . . . . . . 40 820 
7. Sandstone. pink and red to white. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 850 
FOND DU LAC BEDS 
6. Shale. red. with some white sandstone ........................ 20 870 
5. Sandstone. red and white .................................... 15 885 
4. Shale. red .................................................. 40 925 
3. Sandstone. white, with some red shale. . . . . . . . . . . . . . . . . . . . . . . . . . 75 1,000 
2. Sandstone and red shale ..................................... 50 1,050 
1. Sandstone and red shale .................................... llO 1,160 
HASTINGS, DAKOTA COUNTY 
Section in the Vermillion River Gorge 
SHAKOPEE DOLOMITE (top of outcrop at the railroad bridge below King Midas 
Flour Mills at 781.5 f1. A. T.) 
THICKNESS 
(in feet) 
6. Dolomite, gray to drab, massive, cavernous. with some thin beds . . . . . . . . . . . 36.5 
ii. Dolomite, rough, massive and thin-bedded, mud-cracked and cavernous . . . . . . 10.0 
4. Dolomite. gray to ashen, thin-bedded to massive. both plain and oOlitic. Con-
tains some oolitic gray chert. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.0 
ROOT V ALLEY SANDSTONE 
3. Sandstone, in thin lenses, with sandy yellow dolomite ..... ............... 1.0 
ONEOTA DOLOMITE 
2. Dolomite, gray to drab, massive. rough, with some cavernous beds having holes 
partly filled with quartz crystals ....................................... 22.~; 
1. Dolomite. partly covered but showing in Hastings down to Mississippi River 
le"el (67~; ft. A. T.) ................................................... 24.5 
MENDOTA, DAKOTA COUNTY 
Well Drilled by W. E. Swan in 1885 (Approximately 750 Ft. A.T.) * 
THICKNESS 
(in feet) 
1,5. Surface deposits. loose blocks of limestone. . . . . . . . . . . . . . . . . . . . . . 22 
ST. PETER SANDSTONE 
DEPTH 
(in feet) 
22 
14. Sandstone. brown ........................................... 60 82 
13. Shale. blue ................................................. 30 112 
12. Sandstone ................................................. 35 147 
SHAKOPEE AND ONEOT A DOLOMITES 
11. Dolomite .................................................. 14.5 292 
JORDAN SANDSTONE 
10. Sandstone.. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 95 387 
* Slightly modified from a description by N. H. Winchell. Fourteenth Annual Report oj 
the Geological and Natural History Survey of Minnesota (1885), pp. ,;5-56. 
DAKOTA COUNTY 139 
THICKNESS 
(in feet) 
DEPTH 
(in feet) 
ST. LAWRENCE FOHMATION 
9. Shale. gray ....... . 50 437 
FHANCONIA FORMATION 
8. Shale. green ................................................ 110 .547 
7. Sandstone, eakareous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 557 
6. Shale. blue ................................................. 30 587 
DRESBACH FOHl\IATIO).! 
5. Sandstone .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 637 
4. Shale. gray .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 677 
3. Shale. green........... ................................... 35 712 
2. Sandstone. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 812 
HINCKLEY SANDSTONE 
1. Sandstone, very hard, reddish. with beds of red shale. . . . . . . . . . . . . 45 857 
ROSEMOUNT, DAKOTA COUNTY 
Lund-Gunberg Well No. I (Drilled in 19:35) 
THICKNESS 
(in feet) 
DRIFT 
42. Sand. gravel. and boulders 
4l. Sand and gravel ......... . 
40. Clay. sticky, with hardpan 
ST PETER SANDSTONE 
39. Sandstone, coarse, white . 
SHAKOPEE AND ONEOTA DOLOMITES 
38. 
37. 
36. 
35. 
34. 
33. 
32. 
3l. 
30. 
Limestone. hard. gray ...................................... . 
Limestone. hard. gray to light buff .......... . 
Limestone, hard ...................... . 
Limestone. blue, with pyrite showing ......................... . 
Limestone. buff. sand v . . ................ . 
Limestone. sandy .. ' ~ . . . . . . . ...................... . 
Limestone, buff. sandy ..................... . 
Limestone, blue, sandy ........... . ........ . 
Limestone. blue' .......... . 
JORDAN SANDSTONE 
29. Sandstone. gray .......... ...................... . 
28. Sandstone, bro~\,llish yellow ... . 
27. Sandstone. blue .... 
'lG. Limestone. blue. saudy 
ST. LAWHENCE FOHl\·lATION 
'2.5. Shale. sand\'. calcareous ..................... . 
24. Limestone. ~haly. with some shale 
23. Shale. blue. witi1 some limestone 
FHANCONIA FORl\IATION 
31 
64 
15 
16 
50 
25 
15 
/5 
12 
18 
28 
22 
15 
41 
9 
10 
DEPTH 
(in feet) 
31 
9.5 
110 
134 
1;')0 
200 
'22.5 
240 
245 
257 
275 
303 
325 
340 
381 
390 
400 
428 
450 
472 
'1'2. Shale. green. with some white sandstone. . . . . . . . . . . . . . . . . . . . .. 126 598 
2l. Limestone, gray ................. . . . . . . . . . . . . . . . . . . . . . . . . . . 8 606 
'W. Sandstone. gray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 620 
19. Sandstone, blue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G 626 
DRESBACH FORMATION 
18. Sandstone. gray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 643 
17. Sandstone. gray and blue .......................... '17 670 
16. Sandstone with some limestone and pyrite ......... 3 67'3 
15. Shale. sandy. with some limestone ................. 32 705 
14. Shale andli'mestone, gray-green, with pyrite ............. , . . . . . . 10 715 
13. Shale. blue .................................. , ......... ,... 5 720 
l-J,O PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
THICKNESS 
(in feet) 
1 '2. 
11. 
10. 
Shale. dark blue ............................................ 8 
Shale. green ............................................... . 
Shale. gray ................................................ . 
9. Sandstone. hard. gray ........................... . 
R. Sandstone. hard. gray. with some shale ............ . 
7. Sandstone. hard. gray .......................... . 
6. Sandstone. hard. gray ...................... . 
5. Sandstone, pinkish .................. . 
HINCKLEY SANDSTONE 
48 
10 
23 
11 
57 
'20 
35 
DEPTH 
(in feet) 
7'28 
776 
786 
R09 
R20 
877 
897 
93'2 
4. Sandstone, pink to reu and salmon-colored. . . . . . . . . . . . . . . . . . . . .!l'2 1.0'24 
3. Limestone. hard. gray, siliceons ............................. '2 1.0'26 
'2. Sandstone. . . . . . . . . . . . . . . .. . . . . .. . . . . . . . . . . . . .. . . .. . . . . . . 17 1.043 
FOND DU LAC BEDS 
l. Shales, red. with red to gray sandstones .......... 757 1.800 
SOUTH SAINT PAUL, DAKOTA COUNTY 
Armour and Company Well No. e (690 Ft. A.T.) 
THICKNESS 
1'2. River deposit ........................................ . 
JORDAN SANDSTONE 
11. Sandstone. medium. white. coarse 
ST. LAWRENCE FORMATION 
10. Limestone. sandy, magnesian ............................... . 
FRA:<CONIA FORMATION 
(in feet) 
170 
110 
40 
DEPTH 
(in feet) 
170 
'280 
3'20 
9. Greensand. fine. greenish gray ............................... 30 350 
8. Greensand. lime)' ........................................... 30 380 
7. Greensand, lime.v, very fine . . . . . . . . . . . . . . . . . . . . '20 400 
6. Greensand, fine ............................................. '20 4'20 
DRESBACH FOR.'\IATION 
5. Sandstone, coarse and medium. light gray. . . . . . . . . . . . . . . . . . . . . . 50 470 
4. Siltstone. blue and greenish gray with some shale ......... 1 '20 590 
3. Sandstone. fine. clean. white ................................ 100 690 
HINCKLEY SANDSTONE 
'2. Sandstone 
FOND DU LAC BEDS 
80 770 
1. Shale. coarse to fine, red, sandy, limey . . . . . . . . . . . . . . . . . . . . . . . . . 1'27 897 
SHAKOPEE DOLOMITE 
WATERFORD. DAKOTA COUNTY 
Section along the Cannon River 
1 '2. Dolomite. gray, thin-bedded to massive. with some oolitic and some fossilifer-
THICKNESS 
(in feel) 
ous layers. Several thin layers of sandy green shale near the top. . . . . . . . . . . . 10.0 
11. Dolomite. gray to drab. hard. with oolitic layers ........................ 6.0 
10. Dolomite, gray. pebbly. containing Hormotoma . . . . . . . . . . .. . . .. . . . . . . . . 3.0 
9. Dolomite, sandy aad pebbly .......................................... 1.5 
8. Dolomite, gray to drab. hard. fossiliferous .............................. 0.6 
7. Dolomite. gray. hard, sandy .................... , .. . . . . . . . . . . . . . . . . .. . 4.1 
6. Covered interyul .................................................... 3.0 
DODGE COUNTY 
5. Dolomite, gray, sandy, t hin-bedded .... .. ....... . . . . . .. .............. . . 
4 . Dolomite, gray, pilled , conta ining a few lIorTIw toma . . . .. . . ..... . ..... . . . 
3. Dolomite, in grilly, pebbly beds altern ating with fin e-gra ined , sandy beds, 
a ll gray , thin , irregular . ..... . .. . . . . . .. . ..... . .. . . . .. . ..... . . . .. . . . . . 
2. Dolomite, gray , fu ll of cryptozoons .. . . ..... . . .. . . .. . .......... .. . . .. . . 
1. D olomite. gmy, irregula rly bedded to level of Cannon Ri ve r by the old mi ll 
(about 900 flo A. T .) ........ . ............ . . .. ... . . . ..... . . . .... . . . . .. . 
T 
10 
N 
lew 
FIGU RE 43. - Outline map or D odge County, 
showing loca tions of measured stratigraphic 
sec tions (sol id triangles). 
MANTORVILLE. DODGE COUNTY 
Section a t the McDonough Quarry, 1 Mile West of the Village, 
a long the Great Western Rai lroad 
5. Dri ft, cl ay, gravel, and boulders . . ........ . . .. ......•..... .. .. . ... .. 
G ALE NA F OHMATION 
Stewartvi lle Member 
4. Dolomite. soft . porous, gray, wea thering to buff. fossiliferous, with thin , 
shaly partings .... . . .... ..... . .. . ... . .. . ... . .. . . .. . ..... .. . ... . ... . 
3. Dolomite. very fossili ferous. porous. breaking between beddin g planes with 
a subconchoida l fracture . . . .. . ....... . . . ... .. . . . . . . . . ... . .. . . ...... . 
2. Dolonlite. compact, blue to buff. to the quarry floor . . . ......... . .. . ... . 
1. Covered inten 'al to level of Zumbro River (1.110 flo A. T .) ....... . .. . . 
141 
TH I CK NESS 
(in feet ) 
3.6 
2.0 
.5.(; 
2.0 
3.6 
THI CK KESS 
(in reet) 
8.0 
25.0 
11.0 
9.6 
5.0 
142 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
MANTORVILLE, DODGE COUNTY 
Section at the Pierson Stone Company Quarry in the Village 
THICKNESS 
(ill feet) 
6. Drift ............................................................. 1.5.0 
GALENA FORMATION 
Stewartville Member 
5. Dolomite. massive, gray to buff, containing a few fossils ................ 20.0 
4. Dolomite, thin- to medium-bedded, gray to buff. Fossils common ........ 7.7 
3. Dolomite, thin-bedded. shaly, gray to brown. . . . . . . . . . . . . . . . . . . . . . . . . . 6.5 
2. Dolomite. gray. 6- to 14-inch beds .................................. 5.5 
1. Covered interval to level of Zumbro Ri"er (1,100 ft. A. T.) .............. 20.0 
WASIOJA. DODGE COUNTY 
Section at the Bielengberg Quarry, 112 Mile West of the Village 
THICKNESS 
(in feet) 
6. Drift and soil. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0 
:MAQUOKETA FOR;\IATION 
Dubuque Member 
5. Limestone. thin-bedded, gray, with partings of gray shale. . . . . . . . . . . . . . . . 12.0 
GALENA FORMATION 
Stewartville Member 
4. Dolomite, massi"e, gray to buff, separating into thinner beds on weathering 18.2 
3. Dolomite, massive, fossiliferous, gray to buff .......................... 6.7 
2. Dolomite. thin-bedded, porous, gray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 
1. Covered to le"el of Zumbro River (about 1,150 ft. A. T.) . . . . . . . . . . . . . . . . 5.0 
BLUE EARTH, FARIBAULT COUNTY 
City Well (Drilled in 1930; 1,005 Ft. A.T.) 
8. Drift 
THICKNESS 
(in feet) 
1.52 
GALENA FORMATION 
Decorah Shale Member 
7. Shale, blue, sticky, with limestone streaks ................... . 
PLATTEVILLE FORMATION 
Spechts Ferry Member 
6. Shale, blue, with layers of limestone ....................... . 
McGregor Member 
5. Limestone, gray ......................................... . 
Glenwood Member 
4. Shale, soft, with some sandstone 
ST. PETER SANDSTONE 
3. Sandstone. white 
2. Sandstone. shaly 
SHAKOPEE DOLO;\IITE 
1. Limestone, gray ......................................... . 
53 
5 
10 
5 
70 
28 
61 
DEPTH 
(in feet) 
152 
20.5 
210 
220 
22.5 
295 
323 
384 
FILLMORE COUNTY 143 
RI3W RI2W RIIW RIOW R9W R8W 
FI GURE 44 . - Outline map of Fillmore County. showing locations of measured trati-
graphic sections (solid triangles). 
FILLMORE COUNTY 
Condensed General Sec tion of the Cedar Valley Limestone m ~1illnesota 
(see page 95) 
ClIA TFIELD, FILLMORE CO N TY 
Section along U. S. Hig-hway No. 52, 6 Iiles )l'orthwe t of T own, 
in Olmsted County ( ee page 72) 
ClIA Tf'IELD, FILLMORE CO NTY 
Section along Sta te Highway No. 74. SW% Sec. 9, J ordan Twp. 
THICKNESS 
(in ree t) 
4. Covered ...... .. ... . .... .. .. .............. . ......... .... ......... . lO± 
G A LENA F O IlMATION 
Stewartville Member 
3. Dolomite, gray to drab. compact to porous. . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 
Prosser Member 
2. Limes tone, gray to drab, massive. compac t. Beds are 5 to 6 feet thick but 
weather in to much th inne r layers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 
1. Covered interval to lel'el of Los t Creek . ...... . .. . ........... . ...... 11 
144 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
CHATFIELD, FILLMORE COUNTY 
Section along Troy Road (Waterworks Hill) at the Northern Limits of Town, 
in Olmsted County 
16. Drift, gravel and clay 
GALENA FORMATION 
Prosser :Member 
THICKNESS 
(in feet) 
6.0 
15. Limestone, gray. compact. hard. often thin-bedded . . . . . . . . . . . . . . . . . . . . 32.0 
14. Limestone, gray, compact. partly covered. . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.3 
Decorah Shale Member 
13. Covered interval ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.0 
12. Shale, blue, partly weathered. poorly exposed. .. . .. . . . . . .. .. .. .. . . .. . 5.0 
PLATTEVILLE FORMATION 
Spechts Ferry Member 
II. Shale, blue, alternating with layers of limestone ...................... 5.7 
10. Limestone, blue to gray, hard ...................................... 1.0 
9. Limestone, blue to gray. compact ................................... 2.2 
8. Shale, white to light gray. The "putty layer" or metabentonite. . . . . . . . . 0.2 
7. Limestone, gray, hard ............................................ 0.6 
McGregor Member 
6. Limestone. gray to buff ........................................... 5.7 
5. Limestone, blue-gray, hard, compact, iron-stained at the top. Contains 
numerous fossils .................................................. 16.0 
4. Limestone, gray, poorly exposed ......... " . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 
Glenwood Member 
3. Shale, gTeenish to yellow, sandy, poorly exposed. . . . . . . . . . . . . . . . . . . . . . 5.0 
ST. PETER SANDSTONE 
2. Sandstone, white, soft, friable, iron-stained at the top ................ 36.7 
I. Co\"ered interval to cross street at town limits . . . . . . . . . . . . . . . . . . . . . . . . 30.0 
FOUNTAIN, FILLMORE COUNTY 
Section along U. S. Highway No. 52, 1 Mile South of Town 
17. Co\'ered to top of hill 
GALENA FOHlHATION 
Prosser Member 
THICKNESS 
(in feet) 
1.5.0 
16. Limestone, gray to drab, compact, hard ............... . . . . . . . . . . . 5.0 
1.5. Limestone, blue to drab, compact. hard, weathering into thin beds. 
highly fossiliferous ............................................ 24.0 
Decorah Shale Member 
Ion Submember 
14. Shale, blue-green, alternating with beds of argillaceous, fossiliferous 
limestone ..................................................... 10.3 
Guttenberg Sub member 
13. Covered interval .............................................. 1R.3 
12. Shale, blue, argillaceous .... ,.................................. 5.0 
PLATTEVILLE FORNIATION 
Spechts Ferry Member 
II. Shale, blue, argillaceous, alternating with limestone lenses. Fossiliferous; 
Pianodema subaequata abundant ................................ 5.3 
FILLMORE COUNTY 
10. Limestone. in two layers, gray, hard, compact: Lingula elderi common 
9. Shale, light gray to olive gwen, argillaceous ....................... . 
8. Limestone, gray, massive, compact ......... . ............... . 
7. Shale. light gray to white. Altered bentonite .............. . 
6. Limestone, gray. compact, in two beds . . . . . . . .. . .............. . 
1\1cGregor .Memher 
.5. Limestone, gray to blue, thin-bedded to shaly ... 
4. Limestone, blue to gray, thin-bedded, in irregular, knotty layers, with 
thin, shaly partings ............... . 
Glenwood .Member 
3. Shale. gray to olive, argillaceous, with yellowish sands. . ........ . 
'2. Sandstone, yellow, poorly cemented ................... . 
51'. PETER SANDSTONE 
1. Covered interval to level of creek. Upper part is Glenwood 
FOUNTAIN, FILLMORE COUNTY 
Seetion along U. S. Highway No . .52, 2 ~!files North of Town 
'2'2. Soil and drift 
GALENA FORi\IATION 
Decorah Shale Member 
Guttenberg Submember 
21. Shale, argillaceous, oli"e to gray. aitemating with layers of gray lime-
stone ... . .................................... . 
20. Shale, gray, iron-stained, with layers of limestone and oolite ....... . 
19. Shale, argillaceous, olive to gray ... . ..................... . 
lR. Shale, argillaceous, olive, with an occasional layer of limestone 
17. Shale, argillaceous, olive ....................................... . 
PLATTEVILLE FORi\lATION 
Specht,; Ferry Member 
16. Shale, argillaceous, olive gray, with a fell' layers of limestone 
1.5. Shale, argillaceous, olive, with interbedded thin layers of limestone. 
14. Limestone, gray, containing Zygospira nicolleti .......... . 
13. Shale, brown to gray, with a suggestion of bentonite 
1 '2. Limestone, brown, containing abundant Pianodema 
11. Limestone, brown to blue, containing Lingula elderi 
1\1cGreo'or :Membel' 
10. Limestone, massive to thin-bedded, gray to blue .......... . 
Glenwood lVlember 
9. Sandstone, cross-bedded, well-cemented, yellow to white, with cakite-
filled cavities .............. ' ....................... . 
R. Sandstone, thin-bedded, flat-lying, yellow to white .. 
7. Shale, argillaceous, gray to gTeen ............................ . 
6. Sandstone, yellow to brown ...... . 
S. Shale, argillaceous, blue to green, with a few sand gTains .. 
4. Shale, ver~' sandy, argillaceous, gray ................... . 
3. Sandstone, hard, yellow to brown .................... . 
'2. Sandstone, rather well cemented, yellow ........ . 
ST. PETER SANDSTONE 
1. Sandstone, yeUOI\' to white, to bottom of ditch along highway 
14;'; 
THICKNESS 
(in feet) 
1.3 
0.6 
'2.1 
0.3 
0.8 
:).8 
9.':; 
3.3 
1.0 
18.3 
THICKXESS 
(in feet) 
'W.O± 
10.0 
2 .. 5 
0.7 
16.0 
3.7 
7.0 
0.7 
1.2 
0.3 
0.3 
0 .. 5 
18.0 
4.7 
0.8 
2.0 
0.3 
0.4 
0.3 
0.7 
4.5 
30.0± 
146 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
GRANGEH, FILLMOHE COUNTY 
Section along Road at the Aberg Farm near District Schoolhouse No. 130 
THICKNESS 
6. Soil covering to top of hill 
CEDAR V ALLEY LIMESTONE 
5. Dolomite, buff to yellow. massive, porous. Common fossils include A trYFa 
(in feet) 
8.0 
reticn/aris, Spirifer sp., crinoid stems, Stromatoporel/a erratica .......... 15.3 
4. Covered interval, with "concrete" float... .. . . . . . . . . . . . . . 5.7 
'MAQUOKETA FORMATION 
Wykoff Member 
3. Dolomite, weathered, gray to buff, with weathered gray to buff shale. 
Fossils not especially abundant but include Da/mane/la corpulenta and 
others ............................................................ 12.0 
2. Limestone. weathered. gray to light tan and bluish white, siliceous, with 
flint nodules. Abundant fossils; common forms include Streptela.s-ma rnsti-
Cllm, Coll1rnnaria vac"a, Rafinesq1lina a/temata, Dalmal/ella corpu.lenfa, 
Plectambonites saxeus, Ctenodol1ta similis ........................... 8.7 
1. COYered interval to intersection of road with driveway to schoolhouse. . . . 11.5 
GRANGER. FILLMOHE COUNTY 
Section 5 Miles vVest of Town on the Charles Grimm Farm 
4. Soil 
CEDAR VALLEY LIMESTONE 
THICKNf<~SS 
(in feet) 
0.5 
3. Limestone, rough, brecciated. brown . . . . . . . . . . . . . . . . . . . . . . . . 3.0 
2. Limestone, fairly massive. rough, gray to brown, containing masses of chert 
and cavities filled with calcite crystals. Abundant fossils; corHis especially 
common . . . . . . . . . . . . . . . . . . . 10.0 
1. Limestone, gray to brown, rough, with abundant corals and stromatoporoids. 3.0 
GRANGER, FILLMORE COUNTY 
Section along Road Northwest of the Village 
CEDAR V ALLEY LIl\IESTONE 
THICKNESS 
(in feet) 
8. Limestone, buff to brown, massiYe, porous. fossiliferous ....... 30.0 
7. Coyered inter"al ............................................. 35.0 
J\;IAQUOKETA FORMATION 
Wvkoff Member 
6. 'Limestone, light gray, hard. siliceous. Some la~'ers are full of fossils; com-
mon forms include Plectambo1lites saxcus, Dalmanella corpulenta, and Iso-
felus gigas ........................................................ 29.0 
5. Limestone. hard, gray, with some flint. Fossils not abundant but /sote/us 
and a few Dip/ograptl1s may be found. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.3 
4. Limestone, gray to cream, with nodular flint layers. Contains 1soteTus gigas 
and Comdaria sp.; Diplograptt"~ especially abundant ................. 11.3 
Dubuque Member 
3. Covered inter"al, probably a shaly buff limestone . . . . . . . . . . . . . . . . . . . 22.0 
2. Limestone, hard, gray. alternating with gray shales. Fossils common, e. g., 
Plecfambonites sericeus, Rafinesquina "ltemata, Dalmanel/a corlm/enta .. 20.0 
1. Limestone, thick-bedded. hard, gray, dolomitic, with few fossils. To level of 
Upper Iowa River in Granger ...................................... 8.8 
FILLMORE COUNTY 
HAMILTON, FILLMORE COUNTY 
Seetion along Bear Creek in the Village 
147 
7. Drift .............. . 
THICKNESS 
(in feet) 
6.0 
CEDAR VALLEY LIMESTONE 
6. Limestone, gray to bull', dolomitic; fossils common .................... 15.3 
5. Limestone, gray to buff or brown, thick-bedded. Very fossiliferous, common 
forms being Productella .I"balata, Schizophoria stTiahda, Atrypa histryx, 
Spirifer bimesiali.l, and Chonetes sp. . . . . . . . . . . . . . . . . . . . . . . . . . . 16.0 
4. Limestone. gTay to buff, rather thick-bedded, partly co\'ered 10.7 
3. Covererl in terval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 
J\1AQUOKETA FORMATION 
Wykoff Member 
'2. Limestone, buff to brown. containing such typical fossils as Strophomena 
f/uctuosa and Plectambonites sp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.0 
1. Shale. buff to brown. thick-bedded, containing Dalmanella ignota, Plectam-
bonites sericeus. and Lingula sp .. and extending to the level of Bear Creek 10.7 
9. Alluvium ... 
OXEOTA DOLO:\IITE 
S. Dolomite, buff 
.JORDAN SANDSTONE 
LA~ESBORO, FILLMORE C01JNTY 
City 'Veil (Drilled in 1939; 860 Ft. A.T.) 
7. Sandstone, medium-grained, white .. 
ST. LAWRENCE FORl\IATION 
Lodi Member 
6. Siltstone, calcareous. sandy 
Nicollet Creek Member 
5. Dolomite. hard, buff, sandy 
FRANCONIA FORlVIATION 
THICK:s'ESS 
(in feet) 
10 
70 
70 
20 
SO 
4. Sandstone, calcareous, glauconitic. fine. with some siltstone ... . 180 
3. Sandstone, brownish. nledium-grained ..................... . 30 
DRESBACH FORJ\JATION 
2. Sandstone, coarse- and medium-grained, gray. poorly sorted 30 
1. Sandstone, fine, glauconitic, with silt and shale ............... . 110 
LANESBORO. FILLMORE COUNTY 
Section along U. S. Highway No. 16, Running through Town 
26. Soil .................................................... . 
PLATTEVILLE FORr-rATION 
McGregor Member 
DEPTH 
(in feet) 
10 
SO 
1.50 
170 
2.50 
430 
460 
490 
600 
THICKNESS 
(in feet) 
2.0 
2.5. Limestone, gray to blue. weathered (top at 1.137.2 It. A. T.) .......... 1.3 
24. Limestone, gray to buff ............................ . . . . . . . . . .5.0 
23. Limestone. gray to blue, compact. fossiliferous, thin-bedded. ,,·itl! shaly 
partings ......................................................... 4.8 
22. Li1nestone. sandy. gray. with calcareous gray sandstone. . . . . . . . . . . . . . . . 1.2 
21. Sandstone, yellow to brown. with iron crust at top. . . . . . . . . . . . . . . . . . . . 0.3 
148 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Glenwood .i'l1ember 
20. Shale, argillaceous. blue to green, with a '2-inch sand parting in the middle. 
Polychaeta and conodonts common ................................ . 
19. Sand, yellow to brown, very friable, upper part shaly ............... . 
18. Shale, gray to gTeen, argillaceous ................................... . 
17. Shale, olive lo darker green, argillaceous ............................ . 
16. Shale, gray, argillaceolls, mingled with white sand ................... . 
15. Shale, bluish green, argillaceous, soft, plastic, with yellow clay at the base 
14. Sandstone, yellow, somewhat cemented by limonite ................... . 
1:3. Sandstone, yellow to brown, orten with red streaks ................... . 
ST. PETER SANDSTONE 
1 '2. Sandstone, white, massive. friable, somewhat cross-bedded in the upper 
THICKNESS 
(in feet) 
0.7 
1.'2 
1.3 
1.0 
0.5 
1.6 
0.5 
1.5 
part, medium- to fine-grained; grains well-frosted. . . . . . . . . . . . . . . :25.0 
11. Covered interval. Some evidence of sandstone on top of dolomite below . . 75.0 
SHAKOPEE DOLOj\IITE 
10. Dolomite, calcareous, thin-bedded, often oolitic, with large calcite-filled 
Cl::L\rities .,.................................... . .............. . 
9. Dolomite. calcareous, massive, with numerous cr~·stals of calcite glistening 
from the walls and in cavities ..................................... . 
HOOT VALLEY SANDSTONE 
8. Sandstone, yellow to white, eH'n-bedded, partly cemented. Much of the 
fresh rock is buff in color .............................. . 
ONEOTA DOLO~lITE 
7. Dolomite. rough, arenaceous, InassiYe ............ . 
6. Dolomite, gray to buff or drab, massive, with crystal-lined cavities 
5. Dolomite, gray to drab, massive and thin-bedded, with some light gra~· 
chert ........................................................... . 
4. Dolomite, thin, even-bedded, gray ............. . ............... . 
3. Dolomite, gray to buff, somewhat arenaceous, in thin and thick beds 
,JORDAN SANDSTONE (top at 782.9 ft. A. '1'.) 
2. Sandstone, white to yellow, friable, massive, with hard layers ......... . 
1. Sandstone, typical Jordan showing at several places along the hig'hway 
down to Whalen bridge. At one place 33 feet shows, at another about 30 feet 
OSTHANDER FILLMORE COUNTY 
20.7 
17.8 
'28.0 
10.0 
75.0 
31.9 
22.4 
028.0 
3.0 
63.0± 
Section at the Carthog Gravel Pit, South End of the Village (see page lOS) 
OSTRANDER FILLMOHE COUNTY 
Section on the Frank Farnhill Farm, SE% Sec. 20, Bloomfield Twp, 
THICKNESS 
4. Soil, carrying float of the iron conglomerate ......................... . 
DAKOTA FORMATION 
Ostrander Nlember 
3. Gravel. fine, yellow, cross-bedded, with streaks of coarse sand. All poorly 
(in feet) 
1.0 
assorted .......................................................... 3.0 
2. Gravel, ('oarse, mixed with argillaceous sand, poorly assorted. The size of 
pebbles varies. Most are 1!~ to % inch; howeyer, some are % to 1 inch in 
diameter. The bottom portion has much larger pebbles and cobbles, :2 to 6 
inches or more in diameter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.0 
1. Clay streak in east side of pit. This may not be the bottom of the forma-
lion. To boltom of pit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5 
FILLMORE COUNTY 
PRESTON, FILLMORE COUNTY 
149 
Section along U, S. Highway No. 16, Starting at the Fair Grounds 
THICKNESS 
21. Soil .................. . 
PLATTEVILLE FOHMATION 
McGregor Member 
(in feet) 
3.0 
20. Limestone. gray to buff. fossiliferous. . . . . . . . . . . . . . . . . . . .. . . . . . 10.0 
Glenwood Member 
19. Shale. gray to greenish. soft. argillaceous, sandy at the top b,O 
18. Shale, olive green, argillaceous ..... , . , ............. , . . . . .. ..,.,.... '!.7 
17. Shale. greell to brown, argillaceous .. , ........ , ........ , . . . . . . 0.7 
16. Shale, gray, argillaceous. sandy, with yellow sand .. , .......... , ... ' . . . '!.O 
ST. PETEH SANDSTONE 
lb. Sandstone, white, massive, poorly cemented; several yellowish beds '!O.O 
14. Covered interval .. ' .................... " . . . . . . . . . . . . Q6.7 
13. Sandstone, coarse, porous .. , , ..... , . . . ......... , .... , . 6,0 
SHAKOPEE DOLOMITE 
I'!. Dolomite, g'fay to buff, weathered, ....... , ...... ,. ,. , . ' ........ , . . . 5.7 
11. Partly covered. An occasional slab of hard gray dolomite exposed in the 
gutter suggests the type of material coyered .... " , ....... , ...... ' '!6.7 
10. Dolomite, gray, massive; crystals of white calcite common ............. 10.4 
9. Dolomite, massive, often arenaceous; some fossils, such as Ophileta, in the 
upper part ... " .... , .......... ' .. " ........... , ....... , ... ,...... 3.5.0 
ROOT V ALLEY SANDSTONE 
8. Sandstone, yellow to white. ripple-marked; some bedding planes show mud 
cracks .... , ..... "., ....... ,.,', ............. ,. . ........ , . . . 1 8.3 
7. Sandstone, an indurated, prominent bed, \I·hite to yellowish. almost a 
quartzite .. , ............ ,.,' ..... ,., ........... , ..... ,., ...... , .. , 1.3 
6. Sandstone, yellow to white, poorly cemented, eyellly stratified, with little 
cross-bedding ............ ".,", ...... ,., ... , .... ,.. 1 '!.7 
ONEOTA DOLOMITE 
5, Dolomite, gray to ashen, compact, with occasional crystalline masses '2,7 
4, Sandstone, rough, hard, dolomitic, with a parting of '2 to 6 inches of green-
ish gray, argillaceous shale . , , . . . . . . 2.,! 
3. Dolomite, gray, with grains of glauconite and oiilites, occasional pebbles 
and cryptozoons ."....... . ... , . , ... , , , ..... , . , . ' ·1.0 
2. Dolomite, gray to buff, with arenaceous streaks, Oolites and pebbles also 
common " .. , ........ , ... ,., ............ ,..... 3,;5 
1. Covered inten'al below the highway, near the rair g-l'onnds. to the leyel 
of Root RiYer aboye the bridge (900 ft. A. T.) .. . .. , , , .. ' 1'2.;5 
PRESTON, FILLMORE COUNTY 
Section on the R. C. Thatcher Farm. West Side of Sec. '2, Bristol Twp, 
THIf'K::\'ESS 
(in feet! 
GALENA FORMATION 
Stewartville Member 
.5. Dolomite, gray, weathered ...... ,.,.' 
4. Dolomite, gray to buff, thin-bedded .,.,' 
Prosser Member 
{j.5 
31,0 
3. Limestone, gray, with occasional chert nodules, mostly along a single layer 7.8 
2. Limestone, blue-gra~" compact, thin-bedded ., .. ".,.,....... 24.7 
1. Coyered interval La leyel of Willow Creek , .... ",., .. "., ........ ' 15.3 
1.'50 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
RUSHFORD. FILLMORE COUNTY 
Section along State Highway No. 43, Starting 2.~3 Miles North of Town 
THICKNESS 
23. Loess. fine. gray to buff ......................................... . 
2'2. Hesidual weathered material and loose blocks of Root Valley sandstone 
mingled ,,·ith hard sandstone masses and weathered dolomite. None in place 
O:-lEOTA DOLO?dITE 
21. Dolomite. massive. arenaceous, gray, partly oolitic, with calcite··filled cavi-
ties .. Much residual red clay and weathered material in solution cavities .. 
'20. Dolomite, m'Lssive, gray, ·flinty. with much red day and many cavity-
fillings. The Hint carries the usual upper fauna of the Oneota 
H). Dolomite, massive, weathered gray, with some chert streaks and layers 
of nodules . , . . . . . . . . . ,', , : ................... , ............ , , . 
18. Dolomite, massive to even-bedded, gray, ........ , , , .. 
]7, Dolomite, massive, gray to buff. with occasional thin-bedded zones toward 
the top. Calcite-filled cavities common ." ....... . 
16, Dolomite. even-bedded, in ]- to 3-foot beds, gray to buff 
16. Shale, blue-green: a dolomitic siltstone ......... . 
14. Dolomite, hard, sandy with pebble streaks. gray with green streaks that 
may be glauconitic, Irregular base . , .. , , , ... , . . . , .. , ..... 
13. Sandstone, soft. white to yellow, with hard lumps; basal layer quartzitic .. 
I'!. Dolomite, gray to buff, with many cryptozoons forming a layer near the 
bottom ., .... , .............. , ....... , ........ , .. ,',.,., ... ,. 
II. Dolomite, oolitic. gray, slightly arenaceous. with sandstone and occasional 
quartz pebbles. Calcite fillings in ca\·ities ........................ . 
JORDAN SANDSTONE 
10. Sandstone, hard, gray to yellow, with mud-cracked, shaly partings .. 
9. Sandstone, white to yellow, soft, with thin beds or lenses of very hard 
quartzitic material ., ....... , .............. , ................... . 
8. Sandstone, "erO' hard, cross-bedded, gray, with thin partings of soft yellow 
sand and sandy shale showing worm trails; these are especially abundant in 
the lower part . . ................ , .......... , ........ . 
7, Sandstone, massive, cross-bedded, soft, yellow, rather coarse. These la,'ers 
are frequently streaked with brown ............ , ........ , ........... . 
6. Sandstone. soft, ,,·hite to "ellmy. Brown Scalithus tubes weather out .... , . 
,5. Sandstone, massive, hard. gray, full of Scalitlms ..................... , 
ST. LAWRENCE FORMATIO:-I 
Lodi Member 
4. Dolomite, sandy, gray. "ery hard .................................. . 
3. Siltstone, fine, dolomitic, buff, with a few of the com mall brachiopods and 
trilobites , ..... , ......... , ........ , . . . . . . .. . .................... . 
Nicollet Creek Member 
'1. Dolomite, sandy, gray. alternating with beds of bluish shale and siltstone .. 
1. Covered inten-al, in part covered by great slumped blocks carrying the 
conglomerate zone of the Nicollet Creek member with a small portion of 
the Bad Axe below, To creek lenl at bridge, near middle of Sec. '2, T. 104 
N., R. 8 W .. , also llear the Tellborg- School (about 800 ft. A. T.) ....... , 
SPRING VALLEY. FILLMORE COUNTY 
Section at the Lime City Quarry. 21j2 Miles North of Town 
(see page 92) 
SPRING VALLEY, FILLMORE COUNTY 
Section on U. S. Highway No. 16, 1 Mile East of Town 
(see page 92) 
(in feet) 
6.0 
5.0 
10.7 
16.0 
]6.0 
32.0 
37.5 
3'1.0 
0.9 
10.5 
'2.3 
2,0 
4.0 
7.7 
2.5 
8.5 
55,0 
1.5.0 
'16.7 
.5,0 
5.0 
23,0 
56.0 
FILLMORE COUNTY 
SPRING VALLEY, FILLMORE COUNTY 
Section at the August Koball Pit, Sec. 13, Bloomfield Twp. 
4. Loess ..................... ' ................................. , .. , .. 
3. Drift, with a few boulders ......................................... . 
DAKOTA FORMATION 
Ostrander Member 
2. Gravel, poorly assorted. White and rose quartz pebbles abundant; some 
sand and some clay with pebbles .................................... . 
I. Sandstone, white to buff, soft, micaceous, medium- to fine-grained ...... . 
SPRING VALLEY, FILLMORE COUNTY 
Section at the Larson Quarry, Southwest Part of Town 
I.E 
THICKNESS 
(in feet) 
3.0 
1.5 
10.0 
2.0 
THICKc'1ESS 
(in feet) 
4. Soil and drift ........................................................ 1.0 
CEDAR V ALLEY LIMESTONE 
3. Limestone, massive but badly weathered, gray to buff or brown, fossiliferous. . 5.0 
2. Limestone, massive. buff. abundantly fossiliferous ........................ 3.0 
I. Limestone, brown to buff, very fossiliferous to floor of quarry. . . . . . . . . . . . . . . 3.3 
SPRING VALLEY, FILLMORE COUNTY 
Section at Masonic Park 
12. Covered to top of hill. Part is doubtless drift ......................... . 
GALENA FORMATION 
Stewartville Member 
II. Limestone, gTay, dolomitic. rough, weathered surface pitted. llJaclllrina 
cuneata and Horm-otoma m.ajor common ........................... . 
10. Limestone, gray, dolomitic, hard, rough ............................ . 
Prosser Member 
9. Limestone, gray. compact. hard. thin-bedded, with few fossils ......... . 
8. Limestone. gray to ash-colored. thin-bedded; possibly dolomitic, although 
some layers are partly crystalline. resembling high-grade limestone ..... . 
7. Limestone, gray to bluish, hard. often thin-bedded ................... . 
6. Limestone, gTay to bluish gray, with shaly partings near the top. Abundant 
fossils .......................................................... . 
5. Limestone, gray to blnish gray. massive, compact to partly crystalline, with 
an abundant fauna and occasional graptolites ....................... . 
4. Limestone, gray, massiYe; a hard. compact layer. with a shaly parting at 
the top. Fossil fragments common ................................. . 
3. Limestone, gray to light gray. dense. with an abundant fauna ......... . 
2. Limestone, bluish gray. impure. with a few crinoid siems and graptolites 
I. Limestone, bluish gray, shaly, with few fossils. To lewl of Deer Creek ... 
SPRING VALLEY. FILLMORE COUNTY 
THICKNESS 
(in feet) 
43.0 
20.0 
12.0 
16.8 
5.6 
27.9 
11.2 
11.9 
1.3 
1.3 
4.8 
3.0 
Section 1 Mile Northeast of Town, SE Cor. Sec. !t!t, T. 103 N., R. 13 W. 
THICKNESS 
(in feet) 
8. Covered to top of hill .............................................. 5.6 
152 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
THICKNESS 
(in feet) 
"MAQUOKETA FORMATION 
Wykoff Member 
7. 'Limestone, gray to nearly white, shaly. Abundant fossils, such as P/ectam-
bonites recedens. Dinorthis subquadrata, Rafinesquina a/temata, Dalmall-
ella ignota, Plectambonites sericeus, Lophospira quadrisulcata, Hindia sp., 
and crinoid sterns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.3 
6. Limestone, gray, crinoidal, with abundant gastropods. Common fossils in-
clude Hormatoma gracilis, Lophospira acuminata, L. bicincill. Dalnwnella 
igl1ota, Dinorthis sllbqlladrata, Plectambonites recedens, and Rhynchotrema 
capax .......................................... "...... Z.5 
5. Limestone, gray to bluish. Fossils abundant, including Dalmanel/(L ignota, 
D. corpulenia, Pleclambonites recedens, Rafinesquina a/femata, Leptaella 
llnicostata, and crinoid sterns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.6 
4. Limestone, gray to bluish gray, poorly exposed. Common fossils include 
Dalmanella ignota, Plectambonites recedens, Hormotoma. gracilis. and Iso-
tdus gigas ........................................................ 3.5 
3. Limestone, gray to nearly white. Fossils rather scarce, though Dalmallella 
ignota, Plectambonites recedens. and others do occur. . . . . . . . . . . . . . . . . . . 2.0 
2. Limestone, gray to ashen. fucoidal. Common fossils include Dalmanella 
corpulenta, D. Ignota, P/ectmnbonitesrecedells, Leptaena unicostata, and 
Strophomena sp. ........................................... 3.6 
l. Limestone, gray to yellow, crinoidal, with such forms as Plectambonites 
recedens and P. sericeus common. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 
WYKOFF, FILLMORE COUNTY 
Section along Prosser Creek, 21/2 Miles West of Town (see page 87) 
WYKOFF, FILLMORE COUNTY 
Section in the Highway Quarry, East Side of Sec. 19, Forestville Twp. 
6. Loess, covered to top of hill 
:MAQUOKETA FORl\IATION 
Wykoff Member 
5. Dolomite, weathered, thin-bedded, argillaceous, buff to yellow 
Dubuque Member 
4. Limestone, hard, gray to blue, pyritiferous, 
and brown shales. Fossiliferous; common 
Rafinesquina altemata, Plectambonites sp., 
GALENA FORl\IATION 
Stewartville Member 
with interhedded blue to gray 
forms include crinoid sterns, 
and Dalmanella corpulenta .. 
3. Dolomite, massive, gray, mottled. Quarry bench at base. Contact with 
beds above is wavy or uneven ..................................... . 
2. Dolomite, massive: ill 3- to 8-foot beds. hard, blue to gray, mottled. The 
darker spots weather yellow then become much-pitted. Common fossils 
include Receptaculites oweni, Isotel1ls giga..'. Jl1aclllrina manitobensis, Ilor-
motoma major, and ll'estonoceras r"innesotense ...................... . 
l. Covered from floor of quarry to le,'el of Root River above the iron bridge 
(approximately 1,180 ft. A. T.) ..................................... . 
THICKNESS 
(in feet) 
35.0± 
3.0 
46.3 
9.0 
5l.0 
6.0 
FILLMORE COUNTY 
WYKOFF, FILLMORE COUNTY 
Section 1 Mile West of Prosser's Corner 
153 
6. Drift and soil 
THICKNESS 
(in feet) 
6.0± 
MAQUOKETA FORMATION 
Wykoff Member 
5. Limestone, gray, fairly massive ...................................... 16.0 
Dubuque Member 
4. Limestone, thin-bedded to shaly, alternating with gray shale .,. . . . . . . . . . 22.0 
3. Limestone, drab, alternating with gray to ashen shales, compact, massive 10.0 
GALENA FORMATION 
Stewartville Member 
2. Dolomite, gray, massive, cavernous, hard, compact .................... 16.0 
1. Dolomite, gray to buff, massive, fossiliferous. To level of creek in gully. . . . 21.3 
WYKOFF, FILLMORE COUNTY 
Section along Highway at South Branch Root River, 
Sees. 15, Q2, and 27, Forestville Twp. 
18. Soil and loess covering 
Jl.iAQUOKETA FORMATION 
Wykoff Member 
THICKNESE 
(in feet) 
20.0 
17. Dolomite, weathered buff. No fossils found. . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 
16. Float-covered interval; no rock in place. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.0 
15. Dolomite, shaly, buff. with thin. fossiliferous layers and nodules carrying 
graptolites and trilobites .......................................... 2.0 
14. Dolomite, buff, mostly covered .................................... 4.0 
13. Dolomite. shaly, gray to buff. with flinty nodules. Graptolites abundant. 
Common genera of fossils include Diplograptus, Plectambonite .. , Conularia, 
BUrruJ.stus, and /sote/us ..................... . . . . . . . . . . . . . . . . . . . . . . . 8.5 
Dubuque Member 
12. Dolomite, shaly. buff, with abundant fossils. among which are Plectam-
bonites precosis .. Dalmanella corpzdenta, Strophomena f/llctllosa, and 
Rafonesqll.ina king; ................................................ 6.0 
11. Dolomite, shaly, buff, in even beds, cut into rhombic blocks. Common fossils 
include Plectambonites precosis, Dalmanella meeki, and Dillorthis sub-
quadrata ........................................................ 11.0 
10. Dolomite, gray to buff, shaly, with irregular bedding. Calcite geodes com-
mon; crinoid stems scattered throughout. Common fossils include Plect-
ambonites serice1lS, Dalma.ndla. corpulenta .. Dinorthis sllbquadrata, and 
Rafinesqllina kingi ................................................ 7.0 
9. Limestone. dolomitic. gray to buff, with numerous crinoid segments. . . . . . 0.7 
8. Covered interval. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.0 
7. Limestone, ('om pact. hard. gray. alternating with beds of gray to brown 
shale. Common fossils include lsotelus gigas, Plectambonites precosi,., and 
Dalmanella ...................................................... 10.5 
6. Limestone, gray to blue, in 8- to 10-inch layers. Few fossils ............ 10.0 
GALENA FORMATION 
Stewartville Member 
5. Dolomite, massive, guy to buff, cliff-forming. Few fossils............ 30.0 
4. Dolomite, gray to brown. medium- to thick-bedded. with numerous 
Receptaculites oweni, Horm·otoma major, and l11aclurina manitobensis .. 23.5 
154 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Prosser :Member 
3. Limestone, compact. hard. thin-bedded, gray, full of fossils, including 
THICKNESS 
(in feet) 
Rafine.~quina altemata, Plectambonites sericeu.'!, and !sotelus gigas ...... 24.5 
2. Limestone. compact, light gray to drab, with flint nodules. Relatively few 
fossils; those found are Stuptelasma corniculnm, Climacograptus typicalis, 
Clathrospim sp., Plectambonites sericeus, Rafinesqnilla alternata, Rhyn-
chotrema sp. ..................................................... 6.0 
1. Limestone. thin-bedded. hard. light gray. full of fossils. Common forms 
include Receptaclilites oweni, Ischadites iowensis. St-reptelasma corniculum, 
Plectambonites sericeus, Plectorthis plicatella, Rafinesqu.ina. alternata, 
Endoceras sp .. and [sotelll.'! gigas. To level of South Branch Root River at 
the stone arches (1,107 ft. A. T.) ....................... ... . . . . .. .... 16.0 
WYKOFF, FILLMORE COUNTY 
Section along Highway at North Edge of Town 
16. Soil and drift 
GALENA FORMATION 
Prosser Member 
THICKNESS 
(in feet) 
75.0 
15 Limestone, gray, compact, with some flint in the upper part . . . . . . . . . . . . 30.0 
14. Limestone, gray. with some gray shale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7 
13. Shale, gray, argillaceous. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 
12. Limestone, gray, with shaly beds .................................. 21.3 
11. Limestone, gray to bluish, thin-bedded to massive .................... 26.7 
Decorah Shale Member 
10. Shale, gray, argillaceous, badly slumped and largely covered. . . . . . . . . . . . 21.3 
9. Shale. gray to green, argillaceous. with thin layers of limestone ......... 2.0 
8. Shale, gray, argillaceous .......................................... 0.5 
7. Shale. gray to green, argillaceous ................................... 5.0 
6. Shale. gray to green, argillaceous .................................. 0.5 
PLATTEVILLE FORMATION 
Spechts Ferry Member 
5. Shale, gray, argillaceous. with highly fossiliferous layers of limestone 2.0 
4. Covered interval. Surface strewn with shale . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 
McGregor Member 
3. Covered interval. Numerous blocks of limestone ...................... 13.0 
2. Limestone. gray. thin-bedded. prominently jointed. . . . . . . . . . . . . . . . . . . . 16.0 
Glenwood Member 
1. Shale, gray to green, with sandy layers to creek level . . . . . . . . . . . . . . . . . . 1.0 
ALBERT LEA, FREEBORN COUNTY 
Well of the Interstate Power Company (1,22.5 Ft. A.T.) 
11. Drift 
CEDAR VALLEY LIMESTONE 
10. Limestone, light brown 
MAQUOKETA FORMATION 
THICKNESS 
(in feet) 
89 
95 
DEPTH 
(in feet) 
89 
184 
9. Limestone, buff. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 126 310 
GOODHUE COUNTY 1.55 
THICKNESS 
(in feet) 
DEPTH 
(in feet) 
GALENA FORMATION 
Stewartville and Prosser Members 
8. Limestone, gray ........ . 
Decorah Shale Member 
7. Shale, gray and green 
PLATTEVILLE FORMATION 
Spechts Ferry Member 
6. Shale, with layers of limestone ........................... . 
McGregor Member 
5. Linlestone, gray ....... , ................................ . 
Glenwood Member 
4. Sandstone, light green, with some shale .............. . 
ST. PETER SANDSTONE 
3. Sandstone, white 
ONEOTA AND SHAKOPEE DOLOMITES 
'iI. Dolomite, gray and buff, sandy ............ . 
JORDAN SANDSTONE 
1. Sandstone, white, medium to fine 
BELLECHESTER GOODHUE COUNTY 
HO 
60 
5 
30 
10 
110 
275 
100 
Section V2 Mile East of Town, Sec. 33, T. III N., R. 14 'V. 
450 
;)10 
515 
545 
555 
665 
940 
1,040 
THICKNESS 
(in feet) 
9. Soil, loess, loam, and surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.'2 
DAKOTA FORMATION 
8. Iron layer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.'iI 
7. Shale, white, argillaceous. Potter's day ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 
6. Iron layer, very hard ............................................ , . . . . . 0.2 
5. Shale, gray to white. Polter's clay ...................................... 2.5 
4. Iron layer, red to brown, yery hard .............. , . . . . . . . . . . . . . . . . . . . . . . 0.'2 
3. Sand, reddish brown, loose, coarse ...................................... 0.5 
'2. Shale, gray. A fine, unctuous potter's clay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.7 
1. Covered to lenl of pond in pit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9 
GALENA FORnlATION 
Prosser .Member 
CANNON FALLS, GOODHUE COUNTY 
Section'l Miles Southeast of Town ,. 
8. Limestone, blue-gray. with blue shales. The Nematopora bed. carr~·i.tlg' 
such species as Dinorthis meedsi germana, Vellamo diversa, H orl/.otrypa 
"i·milis, Pachydictya pumila, Rhinidictya minima, Nematopora oralis, 
THICKNESS 
(in feet) 
and N. granosa ................................................ 3 
7. Shales, gray to yellowish. with irregular or nodular la~·ers of limestone 
in the lower part. The Vellamo (Clitambonites) bed. carrying' Vellamo 
diversa, Dinorthis m.eed.~i, Plectambonites sericc1ls, Hallopora ampla, 
H. goodh1l.ensis, El'idotrypa aedilis. Prasopora ins1llaris, and others. . . . 2'2 
* Compare with sections in N. H. Winchell and E. O. Ulrich. Geology of Minnesota 
(Final Report of the Geological and Natural History Survey of Minnesota), Vol. 3, Pt. 't 
(1897), pp. Ixxxv-Ixxxvi. 
156 PALEOZOIC AND HELATED HOCKS OF SOUTHEASTEHN MINNESOTA 
FrCUR.E 45. - Outline map of Goodhue County. showin g locations of measured strati-
graphic sections (so lid triangles). 
Decorah Shale M ember 
Ion Submember 
6. Shales, soft, blue to greenish, with several layers of rusty gray limes tone 
THICKNESS 
(in reet) 
at the top. The fu coid bed; other foss ils scarce and poor. . . . . . . . . . . . . . 5 
5. Shales, soft, greenish, with rough limestone layers composed la rgely of 
fossils . The Chasmatopora (Phylloporina) bed, carryin g an abundance of 
Bryozoa, among which are Batostoma 7nontuosum, Homotrypa tubercu-
lata, Chasmatopora corticosa, Prasopora conoidea, and Trigonodictya 
conciliatrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 
Guttenberg Submember 
4. Shales, gray to bluish , with irregular layers of limestone in the upper 
part. The Ctenodonta bed, carrying Ctenodonta several species, Cyrto-
donta affinis. C. tenella. Plethocardia umbonata, Matheria rngosa, lVhit-
ella scofield •. Carabocrinus sp.; also numerous Gastropoda and Cephalo-
poda . . . . .. . ..... . . .... . .............. ........ . ........... ..... 12 
3. Shales, soft . blue to green ish. witb numerous irregular layers of highly 
foss iliferous limestone in the upper part. The Rhin·idictya bed, with an 
abundance of Bryozoa, chiefly Rhinidictya mutabilis .. .............. 24 
GOODHUE COUNTY 157 
THICKNESS 
(in feet) 
PLATTEVILLE FORMATION 
Spechts Ferry Member 
2. Shales, soft, gray, with several layers of bluish limestone, C'omposed 
largely of fossils. The Stictoporeila bed, with such species as Stictoporella 
frondifera, Pachydictya foliata, Ii on/otrypa min nesotensis, A nolotichia 
-ilnpolita, and Rhynchotrema 11linnesotense ........................ 6 
I. Limestone, gray Lo buff. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I 
CANNON FALLS, GOODHUE COUNTY 
Section from Cannon River to Old Quarry on the Hill, Southeast Edge of Town 
THICKNESS 
29. Soil ...... , .............................................. ···.···· 
PLATTEVILLE FORMATION 
Spechts Ferry Member 
(in feet) 
2.8 
28. Limestone, blue, compact, hard. Pianodema abundant ................ 1.3 
27. Shale, gray, soft, containing Pianodema . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5 
26. Limestone, blue to gray, hard, containing Lingula elden' . . . . . . . . . . . . . . . . 1.0 
25. Shale, gray, with lenses of gray limestone . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.2 
24. Limestone, gray to blue. hard, in two layers . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 
23. Shale, gray, soft .................................................. 0.2 
McGregor Member 
22. Limestone, gray to blue, hard, weathering to buff . . . . . . . . . . . . . . . . . . . . 8.0 
21. Limestone, gray, shaly, mostly covered .................. , .. . . . . . . . . . 15.0 
Glenwood lVlember 
20. Shale, argillaceous, becoming sandy. Poorly exposed .................. 3.0 
ST. PETER SANDSTONE 
19. Sandstone, yellow to white, partly cemented. . . . . . . . . . . . . . . . . . . . . . . . . . 30.0 
18. Covered interval, doubtless mostly sandstone, but including the Shakopee-
St. Peter contact ................................................. 102.5 
SHAKOPEE DOLOMITE 
17. Dolomite, gray to drab, oolitic, fossiliferous, with some thin beds of sand H.O 
16. Covered interval ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 
15. Dolomite, gray, thin-bedded, in part oolitic. . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 
14. Dolomite, gray, made up of large cryptozoons . . . . . . . . . . . . . . . . . . . . . . . . 1.2 
13. Dolomite, gray. rough, containing numerous Raphistoma sp. .......... 1.4 
12. Dolomite, ashen-colored to light tan. thin-bedded to shaly. Thin streaks 
of sand grains occur in the dolomite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 
II. Sandstone, yellow, medium-grained, banded ................... 3.3 
10. Dolomite, gray. rough, sandy ,................................... 1.0 
9. Dolomite, gray to drab, massiYe, rough, irregularly bedded. . . . . . . . . . . . . 14.3 
8. Sandstone, dolomitic, gray to buff, cross-bedded, shaly ................ 1.5 
7. Dolomite, gray, massive, with Raphistoma sp. filling streaks or pockets .. Z.7 
6. Dolomite, gray, oolitic. with flat pebbles of compact dolomite scattered 
through the bed .................................................. 1.1 
5. Dolomite, gray to greenish gray, oolitic, mixed with sand and weathered 
white chert ...................................................... 1.0 
4. Dolomite, gray, made up almost entirely of yery large cryptozoons . . . . . . 2.5 
3. Dolomite, gray, irregular, fossiliferous, with gTeat masses of oolitic white 
chert, much of which is disintegrated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 
Z. Dolomite, gray, thin-bedded, compact .............................. 1.1 
1. Dolomite, gray, massive, containing Raphistoma. To the le\'eI of Cannon 
River (774.2 ft. A. T.) ..................................... 8.6 
158 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
CANNON FALLS, GOODHUE COUNTY 
Section along U. S. Highway No. 5£, about 5 Miles Northwest of Town, 
in Dakota County 
10. Soil 
PLATTEVILLE FORMATION 
McGregor Member 
THICKNESS 
(in feet) 
1.0 
9. Limestone, weathered, brown to buff, much-leached .................. 6.0 
8. Shale, yellow, argillaceous ......................................... 2.5 
7. Limestone, gray to buff, impure. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 2.0 
Glenwood Member 
6. Shale, brown ..................................................... 6.8 
.S. Shale. green, argillaceous .......................................... 1.5 
4. Sandstone, brown, with occasional streaks of green shale .............. 1.0 
3. Shale, sandy, gray to greenish. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 
2. Sandstone, yellowish, iron-stained .................................. 'l.0 
ST. PETER SANDSTONE 
I. Sandstone, white, poorly cemented, to bottom of hill . . . . . . . . . . . . . . . . . . 'l0.0 
CANNON FALLS, GOODHUE COUNTY 
Section along U. S. Highway No. 5.£, 4.9 Miles South of Town 
THICKNESS 
(in feet) 
16. Drift ......................................................... 10.0 
GALENA FORMATION 
Prosser Member 
15. Limestone, gray, thin-bedded. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.0 
14. Limestone, gray, fossiliferous ................................... 4.0 
13. Limestone, gray to bluish, fossiliferous . . . . . . . . . . . . . . . . . . . . . . . . . . . . 'l.0 
1'l. Limestone, buff to bluish, fossiliferous, impure .................... 5.3 
II. Limestone, buff to bluish. impure, dolomitic .. , . . .. . . . . . .. . . .. ..... . 10.7 
10. Limestone, buff, thin-bedded, partly covered ...................... 5.3 
Decorah Shale Member 
Ion Submember 
9. Shale, gray to olive green, argillaceous, fossiliferous. .. .. .. .. .. . ... .. 14.0 
8. Shale, gray, oolitic, with limestone layers. ......... .. .. ... .. . .. . .. 'l.0 
Guttenberg Submember 
7. Shale, gray to olive green, argillaceous. . . . .. . . . . . . . . . . . . . . . . . . . . . . 10.7 
6. Shale. gray to olive green. argillaceous, with thin layers of limestone. . 6.0 
5. Shale, gray to olive green and yellow, argillaceous. with thin layers 
of limestone ................................................. , . 9.0 
4. Shale, olive green, argillaceous. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . 10.7 
3. Shale, olive green, argillaceous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 
PLATTEVILLE FORMATION 
Spechts Ferry Member 
'l. Shale, blue-green to olive green. yellowish at base, argillaceous 6.5 
I. Limestone. gray to bluish, compact, fossiliferous. . . . . . . . . . . . . . . . . . . 0.7 
EGGLESTON. GOODHUE COUNTY 
Section at the Taber Sand Mine 
THICKNESS 
(in feet) 
8. Covered to top of hill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40.0 
GOODHUE COUNTY 
ONEOTA DOLOMITE 
7. Dolomite, massive, gray to drab, pitted ill upper part ..................... . 
JORDAN SANDSTONE 
6. Sandstone, yellow to white, mostly covered .............................. . 
5. Sandstone, in massive and thin-bedded layers, medium- to fine-grained, with 
numerous hard lenses and layers ....................................... . 
4. Sandstone, massive, white to yellow, medium- to coarse-grained, cross-bedded, 
with hard lumps and lenses of well-cemented sand ....................... . 
3. Sandstone, covered interval ........................................... . 
ST. LAWRENCE FORMATION 
2. Dolomite, gray to buff, slightly sandy, to level of Milwaukee Railroad tracks. 
1. Covered interval to le\'el of Vermillion River (670 ft. A.T.) ............... . 
EGGLESTON, GOODHUE COUNTY 
159 
THICKNESS 
(in feet) 
95.4 
29.2 
8.0 
41.6 
57.14 
.5.0 
21.0 
Section along Goodhue County Highway No. 18 from Eggleston 
to the Top of the Grade 
14. Covered interval to top of hill ........................................ . 
SHAKOPEE DOLOMITE 
J 3. Dolomite, yellow to brown, weathered ................................. . 
12. Dolomite, gray to brown, composed mostly of cryptozoons, some of them re-
placed by flint ............................................ , ......... . 
11. Dolomite, gray, shaly .... " ........................................ , .. 
10. Dolomite, hard, sandy ............................................... . 
9. Sandstone, white to yellow, medium-grained, laminated, with some hard, flinty 
masses ............. , ............................................... . 
ONEOTA DOLOMITE * 
8. Dolomite. gray, massive .............................................. . 
7. Dolomite. gray, massive, rough, occurring in great cliffs along the adjacent 
creek ...................................................... , ....... . 
6. Dolomite, gray, thin-bedded, arenaceous, weathered surface pitted ......... . 
JORDAN SANDSTONE 
5. Sandstone, yellow to white. medium to fine, with hard streaks and layers .... 
4. Sandstone, white to yellow, cross-bedded, medium to coarse, with a few hard 
streaks ............................................................ . 
3. Sandstone, white to yellow, mostly covered ............................. . 
ST. LAWRENCE FORMATION 
2. Dolomite, gray, arenaceous. thin-bedded to shaly ....................... . 
1. Covered to level of Mississippi River (675 ft. A.T.) ........ , ............. . 
9. Drift to top of hill 
ONEOTA DOWMITE 
FRONTENAC. GOODHUE COUNTY 
Section at the Old Frontenac Quarry 
THICKNESS 
(in feet) 
75.0 
3.0 
1.5 
1.0 
0.8 
4.7 
35.0 
135.5 
10.0 
8.0 
33.4 
57.1 
5.0 
13.0 
THICKNESS 
(in feet) 
10.0 
8. Dolomite. gray, massive, hard, compact, but with holes. some chert, and quartz-
filled cavities ......................................................... 28 .. 5 
* The nllusual thickness of Oneota in Welch and Burnside townships was discO\'ered and 
discussed by Winchell in Geology of Minne~ota (Final Report of the Geological and Natural 
History Survey of Minnesota), Vol. 2 (1888), pp. 36 and 37. 
160 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
7. Dolomite, drab to pink, thin-bedded. compact ........................... . 
6. Dolomite, in several beds, gray or drab to pale pink, with some chert. ....... . 
5. Dolomite, gray to ashen, with a pink tinge when fresh, massive, fossiliferous, por-
ous, the pores glistening with crystals. Bottom of quarry at 937.8 ft. A. T .... . 
4. Covered interval, probably sandy dolomite, to base of formation ........... . 
JORDAN SANDSTONE (contact covered) 
3. Sandstone, yellow to white, massive, with hard streaks or layers. Mostly co,'-
ered, but 80 feet show in adjacent hills above the schoolhouse to the southwest. 
Bottom covered, amount approximate .................................. . 
ST. LAWRENCE FORMATION 
2. Dolomite, gray to buff, thin-bedded, with shales showing below the schoolhouse 
but covered at the quarry ............................................ . 
1. Covered interval to level of Lake Pepin (667.0 ft. A. T.) ................... . 
4. Drift 
GALENA FORMATION 
Prosser Member 
KENYON, GOODHUE COUNTY 
Section in the Town of Kenyon 
3. Limestone. hard, gray, interbedded with gray to blue, argillaceous shales. 
THICKNESS 
(in feet) 
3.5 
4.9 
7.0 
20.0 
120.0 
30.0 
100.8 
THICKNESS 
(in feet) 
25 
Receptaculites oweni common ...................................... 10 
2. Limestone, hard, gray, with blue shale. Zygospira 'recurviTostris common.. 2 
Decorah Shale Member 
1. Shale, argillaceous, blue. with interbedded layer5 of limestone. To the level 
of North Branch Zumbro River. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 
RED vYING. GOODHUE COUNTY 
Section on La Grange :Mountain 
18. CO\'ered to top of hill (U. S. B. M. 1,001 ft. A.T.) .................... . 
O"'EOTA DOLOfiUTE 
17. Dolomite, massive, gray to drab, ca"ernous, with quartz-lined cavities and 
some gray chert .................................................. . 
16. Dolomite, massive. gray, fucoidal .................................. . 
15. Dolomite. shaly. light gray ....................................... . 
14. Dolomite, massive, rough. weathered surface pitted, gray to drab ....... . 
13. Dolomite, sandy. gray ............................................ . 
12. Sandstone, coarse, yellow to white, cross-bedded. slightly dolomitic .... . 
11. Sandstone, fine-grained, vermicular, while to yellow, slightly dolomitic .. . 
JORDAN SANDSTONE (top at 861.7 ft. A. T.) 
10. Sandstone, massive, cross-bedded, yellow to white, with hard streaks ..... . 
9. Sandstone, medium-grained to coarse, cross-bedded. yellow to white. fri-
able, but with a few hard layers ................................... . 
8. Sandstone, massive, fine-grained, yellow, vermicular ................. . 
ST. LAWRENCE FOR:\[ATION (top at 746.3 ft. A.T.) 
Lodi Member 
7. Dolomite. sandy, yellow to buff. with dolomitic buff shales ............ . 
6. Siltstone. fine-grained, dolomitic, blue-gray to buff. fossiliferous. The Dikel-
ocephalus minnesotensis zone ...................................... . 
5. Shale, blue-gray to buff, arenaceous, alternating with arenaceous dolomite 
THICKNESS 
(in feet) 
63.2 
36.2 
20.0 
2.3 
3.3 
8 .. S 
1.8 
4.0 
40.7 
50.3 
24.4 
21.8 
4.0 
5.0 
GOODHUE COUNTY 161 
THICKNESS 
(in feet) 
Nicollet Creek Member 
4. Dolomite, gray to buff, glauconitic. with some fine-grained dolomitic sand-
slone and gray shale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.5 
3. Conglomerate. brown to buff dolomitic pebbles in a matrix of arenaceous 
glauconitic dolomite. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 
FRANCONIA FORMATION (top at 699 .. 5 ft. A.T.) 
Bad Axe Member 
2. Sandstone. fine-grained, shaly. glauconitic. with fragments of trilobites and 
vermicnlar glauconitic sandstone at the bottom ....................... 8.0 
1. Covered interval over the Milwaukee Railroad to Mississippi Hi,'er level 
below the dam ((j()7.0 ft. A.T.) ,....... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.:'; 
9. Alluvium 
DRESBACH FORMATION 
HED WING. GOODHUE COUNTY 
City Well, Colvill Park (678 Ft. A.T.) 
THICKKESS 
(in feet) 
120 
DEPTH 
(in feet) 
120 
8. Shale, gray ......... ,.,...................................... 80 200 
7. Shale, gray-gTeen ............................................. 40 240 
6. Sandstone, fine. gray ........... , . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 100 340 
.5. Sandstone, fine, red ....... , ... , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 385 
4. Sandstone, medium to coarse. gray ............................. 11.5 500 
3. Sandstone, coarse, white. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 100 600 
HINCKLEY SANDSTONE 
2. Sandstone, coarse. pink 
1. Sandstone, medium-grained. pink 
RED WING. GOODHUE COUNTY 
,,0 
68 
Section at the Sand ~fines. Southwest Part of Town 
11. Covered interval to top of hill . , ................................... . 
.JORDAN SANDSTONE 
10. Sandstone, vellow. massiYe. in hard lavers with thin. friable lavers bet,,·een. 
Some fucoidal beds .. , .......... , . : .................... : ........ , .. 
9. Sandstone, yellow, massive. with hard lenses and lumps ............... . 
8. Sandstone. white, massive. medium-grained. cross-bedded. Scattered 
pebbles the size of peas occur in the sand. also thin seams and lenses of 
argillaceous green shale, with a few hard lenses near the top ........... . 
7. Sandstone, white. medium-grained. with thin lense3 and seams of argillace-
ous green shale. Fossils occur in the shale ........................ . 
6. Sandstone. white to yellow. fine-grained ............................ . 
ST. LAWRENCE FOHMATION 
Lodi Member 
5. Dolomite, yellow. soft. badly weathered and poorly exposed .......... . 
4. Dolomite. gray Lo buff. sandy. shaly ............................... . 
3. Dolomite, gra." to buff. fine-grained. Contains trilobites; Saukiella fypicalis 
collected ........................................................ . 
Nicollet Creek Member 
2. Dolomite, gray. sandy. shaly. glauconitic. thin-bedded to massiye. 
FRANCONIA FORMATION 
1. Covered interval to level of Mississippi River (667.0 ft. A.T.) ......... . 
650 
718 
THICK KESS 
(in feet) 
15.0 
3'1.6 
7.0 
17.0 
33.0 
18.7 
lQ.6 
8.4 
4.0 
-1.9.3 
170.8 
162 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
ZUMBROTA, GOODHUE COUNTY 
Section in Clay Pit of the Gunderson Brick and Tile Company, 
2 Miles Northwest of Town (see page 86) 
ZUMBROTA, GOODHUE COUNTY 
Section III Clay Pit of the Lindel Brick and Tile Company, on River 
1 Mile North of Town (see page 85) 
FORT SNELLING. HENNEPIN COUNTY 
Type Section of the St. Peter Sandstone (see page 68) 
MINNEAPOLIS. HENNEPIN COUNTY 
Formations beneath the City of Minneapolis 
(see page 25) 
MINNEAPOLIS. HENNEPIN COUNTY 
Ordovician Section Exposed at the Washington Avenue Bridge 
(see page 76) 
MINNEAPOLIS. HENNEPIN COUNTY 
Section at Dam No.1, Ford :Motor Company Plant 
!21. Soil and drift ...... . 
PLATTEVILLE FORMATION 
Spechts Ferry Member 
THICKNESS 
(in feet) 
12.0± 
!'IO. Limestone. bluish gray, in a single layer. . . . . . . . . . . . . . . . . . . . . . . . . . . O.S 
19. Shale. argillaceous. blue ........................................ !'I.'l 
IS. Limestone, hard, blue, with thin. shaly partings. Pianodema common. :2.3 
17. Shale, gray to bluish: an altered bentonite. . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 
16. Limestone. hard, compact, pyritiferous, brown. Lingula elder; common. . 1.5 
McGregor Member 
1.5. Limestone. gray to brown or buff. dolomitic. Top irregular and impreg-
nated with iron. Fossils abundant . . . . . . . . . . . . . . . . . . . . . . . . . . . . S.'l 
14. Limestone, compact. bluish to brown. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 
13. Limestone, shaly, argillaceous. blue, breaking with conchoidal fracture. . . 1.3 
1!2. Limestone. massive. bluish to buff. A black pebble zone and evidences of 
corrosion at the base. A few fossils in streaks or "nests" . . . . . . . . . . . . . . . . . !2.0 
II. Limestone, compact, brown to gray, weathering bluish. Layers thin, irregu-
lar, often nodular and separated by thinner layers of shale. Fossils usually 
broken . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.0 
10. Limestone. hard. bluish gray ....................................... 0.7 
9. Limestone, hard. bluish gray, with small black pebbles. . . . . . . . . . . . . . . . 1.0 
Glenwood Member 
S. Shale. argillaceous, gray to greenish ................................. 2.0 
7. Limestone. arenaceous, gray. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.2 
6. Shale. argillaceous. gray to greenish ................................ 0.5 
.5. Shale. arenaceous, green ........................................... 1.,5 
4. Sandstone. argillaceous. nodular, yellow to brown .................... 'l.S 
3. Sandstone, whiLe, often iron-stained to yellow or hrown ............... '. .5.8 
T 
118 
N 
T 
117 
N 
HE NEPI COUNTY 
FIGU RE 46. - Outline map of H ennepin County, showing locations of mea ured 
stratigraphic sec tions ( olid triangles). 
163 
T 
ST. PETER SANDSTO NE 
THICK NESS 
(in fee t) 
2. Sandston e. whi le, cross-bedded ... . ...... . ..................... . .... 2.5 
1. Sandstone. mass ive, white. poorl y cemented, with occasional hard lumps 
which a re more or less spherical. Disintegratin g pyrite or ma rcasite has left 
brown st reaks or patches over the outcrop. To level of Miss iss ippi Ri ver be-
low the dam (700 f t. A.T.) .............. .. .. . ...... . .............. 65.0 
MINNEAPOLIS, HENNEPIN COUNTY 
Lakewood Cemetery Well (Drilled in 1895; Approximately 900 Ft. A.T. ) * 
DRIFT 
THICK NESS 
(in feet 
135 36 . Gravel and sand . .. . ........... . ...... . ... . ....... . . ....... . 
DEPTH 
(in feet ) 
135 
* T he well star ts at about 900 feet above sea level and ends a t 1.260 ree t below sea 
level. Slightly modi fied from descriptions by N . H . Wi nchell in Thirt eent h A nmlal R eport of 
t he Geological and Naturctl History Survey of lIlinn esota (1885). pp .. 50-54. 
16-1, PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
THICKNESS 
(in feet) 
3,3. Boulder clay, weathered. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 
3-1,. Till, blue. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 
33. Gravel, sand, and blue till . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 
32. Boulder sand and till . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 
ST. PETER SANDSTONE 
31. Sandstone, friable, ill rounded grains 
30. Sandstone, friable. in rounded grains 
'19. Sandstone, friable. in rounded grains 
SHAKOPEE DOLOMITE 
'18. Dolomite, compact, yellowish gray ........................... . 
':17. Dolomite ................................................. . 
26. Sandstone, white, ferruginous, with some dolomite ............. . 
ONEOTA DOLOMITE 
25. Dolomite, homogeneous, slightly red ......................... . 
JORDAN SANDSTONE 
2-1,. Dolomite and sandstone .................................... . 
23. Sandstone, in rounded, translucent grains ..................... . 
22. Sandstone, in rounded grains ................................ . 
':11. Sandstone, white, in rounded grains .......................... . 
'10. Sandstone, white, with some pyrite and traces of light green shale .. 
ST. LAWRENCE FORMATION 
19. Sandstone, white, with greensand and green shale 
FRANCONIA FORMATION 
20 
20 
2'1 
43 
13 
8 
10 
47 
23 
18. Sandstone, white, with greensand ............................. 49 
17. Sandstone, medium to coarse, white . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 
16. Sandstone, white. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 
DRESBACH FORMATION 
15. Sandstone, fine, gray to white or pink . . . . . . . . . . . . . . . . . . . . . . . . . 17 
H. Shale, argillaceous, green. with fine sand . . . . . . . . . . . . . . . . . . . . . . . 155 
13. Sandstone, gray to white with a yellow tint ................. . . . 70 
HrNCKLEY SANDSTONE 
12. Sruldstone, pink, medium to fine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 
11. Sandstone, coarse, pink to red and yellow ..................... 50 
10. Sandstone, coarse, light pink. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 
9. Sandstone, coarse, pink, with some reddish shale. . . . . . . . . . . . . . . . 18 
FOND DU LAC BEDS 
8. Shale, compact, red partly mottled with green. Contains some mica 
flakes, also some sandstone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 
7. Shale. red to gray or brown, with fine red sandstone. . . . . . . . . . . . . . 6H 
6. Shale, sandy. reddish brown. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5 
,5. Shale. reddish brown, with some sand . . . . . . . . . . . . . . . . . . . . . . . . . . 34 
4. Shale, argillaceous. reddish brown ... . . . . . . . . . . . . . . . . . . . . . . . . . . 20 
3. Shale, red to brown. with some layers of white sand . . . . . . . . . . . .. 460 
2. Shale, red, with sandstone (no definite information) ............. 341 
ARCHEOZOIC 
1. Hornblende granite. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 
MIl\TNEAPOLIS, HENNEPIN COUNTY 
DEI>TH 
(in feet) 
138 
212 
248 
266 
286 
306 
328 
330 
335 
370 
413 
426 
434 
444 
491 
5H 
568 
617 
704 
773 
790 
945 
1,015 
1,0~W 
1,070 
1,115 
1,133 
1,177 
1.245 
U90 
1,3'14 
1,344 
1,804 
2,H,o 
2,160 
Section on the University of Minnesota Campus, Starting at the Washington 
Avenue Bridge and Continuing through the Tunnels 
and Vertical Shafts 
14. Drift and ri"er fill. sands, graveL and large boulders 
THICKNESS 
(in feet) 
20.0 
HENNEPIN COUNTY 165 
THICKNESS 
(in feet) 
GALENA FORMATION 
Decorah Shale Member 
Guttenberg Submember 
13. Shale, argillaceous, blue, with thin lenses and layers of blue to gray 
limestone, all very fossiliferous ........ ,......................... 15.0 
PLATTEVILLE FORMATION 
Spechts Ferry Member 
12. Shale, blue, argillaceous, alternating with beds of hard gray limestone. 7.4 
11. Limestone, hard, gray to brown, pyritiferous, including the metabento-
nite layer and thin beds of blue shale. Base is a prominent corrosion 
zone ......................................................... 3.9 
McGregor Member 
10. Limestone, gray to buff, even-bedded, very fossiliferous .. . . . . . . . . . . . 10.7 
9. Limestone, blue, nodular, weathering shaly. Fossils commonly in 
pockets or irregularly distributed ................................ 16.0 
8. Limestone, gray to brown, with streaks or burrows partly filled by black 
grains. A prominent corrosion zone. Conodonts common. .. . . . . . . . . . 1.0 
Glenwood Member (top at 757 ft. A.T.) 
7. Shale, hard, flaky, blue (or a shaly blue to brown limestone), contain-
ing a few fossils including Rhynchotrema minnesotense and Stropho-
mena incurvata .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. 7 
6. Shale, soft, gray to brown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 
5. Shale, argillaceous, green or blue-green. Contains frosted grains of 
quartz. Conodonts ('ommon ..................................... 1.0 
4. Shale, argillaceous, sandy. yellow to white. . . . . . . . . . . . . . . . . . . . . . . . 0.7 
3. Sandstone, yellow to bnff, argillaceous ........................... 3.2 
2. Sandstone, white to yellow, with streaks of argillaceous green sandstone 5.5 
ST. PETER SANDSTONE 
1. Sandstone, white, medium- to fine-grained, with marcasite concretions. 
Occasional fossils. To level of Mississippi River ,.... . . . . . . . . . . . . . . . 23.0 
MINNEAPOLIS, HEN:t\TEPIN COUNTY 
Section at Quarry of the Landers-Norblom-Christenson Company, 
1501 Johnson Street N.E. 
12. Soil and river gravel 
'VISCONSIN DRIFT 
THICKNESS 
(in feet) 
4.0 
11. Drift, red ....................... ".,.......... ........ .. ......... 8.0 
PLATTEVILLE FORMATION 
Spechts Ferry Member 
10. Limestone, hard, semicrystalline, gray to brown, with calcite and pyrite 
cavity-fillings. The Lingula elderi zone .............................. 1.3 
McGregor Member 
9. Limestone, buff to gray, dolomitic, with numerous fossils in lenticular lay-
ers or pockets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4 
8. Limestone, blue to gray, thin-bedded to shaly ... . . . . . . . . . . . . . . . . . . . . . 1.0 
7. Limestone, blue to slaty gray, massive, argillaceous. Breaks with conchoi-
dal fracture ...................................................... 3.0 
6. Limestone. shaly, blue to gray. Weathers rapidly into clay ............. 1.5 
5. Limestone, gray, dense, shaly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . 2.0 
4. Limestone, gray, mottled, dense, thin-bedded, with streaks of shale. Upper 
part very fossiliferous ............................................. 8.5 
3. Limestone, gray to bluish, forming the floor of the quarry . . . . . . . . . . . . . . 2.0 
166 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Glenwood :Member 
~. Shale, argillaceous, greenish to gray, soft and plastic when wet ....... , , 
1. Sandstone, white, friable, fine-grained, somewhat iron-stained (approxi-
mately SOO It. A.T.) ............................................. . 
:MINNEAPOLIS, HENNEPIN COUNTY 
THICKNESS 
(in feet) 
4.0 
1.0± 
Section at Northern Pacific Railway and North County Line, 
Thirty-Seventh Street N.E. 
n. Drift 
PLATTEVILLE FOIBIATIO)I 
McGregor Member 
THICKNES5 
(in feet) 
10± 
S. Limestone, massi"e to thin-bedded, mottled, gray to blue .............. 8.5 
Glenwood 'Member 
7. Shale, argillaceous, blue to yellow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 
6. Shale, argillaceous, blue, containing brachiopods and trilobites ........... 1.0 
5. Shale, argillaceous, sandy, blue to yellow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 
4. Sandstone, hard, yellow, with some argillaceous shale .......... , ..... , . , !2,0 
3. Sandstone, white, poorly cemented ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.0 
'2. Sandstone, green to gray, with argillaceous shale ................... , , . , 0.5 
ST. PETER SANDSTONE 
1. Sandstone, white, cross-bedded, poorly cemented, to bottom of quarry 15.0 
CALEDONIA, HOUSTON COUNTY 
Section at the Gengler and Henry Quarries, 3% Miles East of Town 
THICKNESS 
S. Mantle rock 
OXEOTA DOLO:\IITE 
(in feet) 
!2.0 
7, Dolomite, gray to buff, badly weathered, with abundant flint nodules .. , ... , , 6.0 
6. Dolomite, gray to buff, thin-bedded, weathered ....... , , ..... , . , .. , . . . . . . . !2.0 
5. Dolomite. gray to buff. thick-bedded ......................... , . . . . . . . . . . !2.0 
4. Dolomite, gray, fine. even-textured. thick-bedded. A good building stone. . . . . 5.5 
3. Dolomite, gTay, e"en-textured, fine-grained. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . !2.0 
2. Dolomite, gray. shaly, forming the bottom of the quarry. . . . . . . . . . . . . . . . . . . 1.0 
1. Dolomite, gray, unexposed; probably 40 to 60 feet down to the Cambrian .... 60.0 
CALEDONIA. HOUSTON COUNTY 
Section at Quarry on State Highway No. 44, 6% Miles Southwest of Town 
THICKNESS 
7. Soil and weathered shale 
PLATTEVILLE FOR]VIATION 
Spec-hts Ferry Member 
(in feet) 
~.O 
6. Shale. bluish green, argillaceous. weathered, with layers of limestone ~.5 
5. Limestone. blue, compact, highly fossiliferous ........................ !2.5 
4. Shale, light gray, argillaceous ....................................... 0.1 
T 
103 
N 
T 
101 
N 
HOUSTON COUNTY 
R7W R6W R!)W R4W 
FIGURE 47. - Outline map of Houston County, showing location of measured strati-
grapbic sections (solid triangles). 
167 
THICKNESS 
(in feet) 
McGregor Member 
3. Limestone, blue, thin-bedded, prominently jointed, fossiliferous 31.3 
Glenwood Member 
2. Shale, green to blu ish. much-weathered to yellow and brown. . . . . .. . . . . . 3.0 
1. Sandstone, while, showing in gully by side of road . . . . . . . . . . . . . . . . . . . . . . 2.0 
FREEBURG, HOUSTON COUNTY 
Section of Bluff 1 Mile West of Village 
J ORDA N SA NDSTONE 
THICKNESS 
(in fee t ) 
7. Sandstone. mass ive, white lo yellow. with projec ting ha rd layers ....... . . 
6. Sandstone, mass ive, cross-bedded, while to yellow, partly covered 
S T . LAWRENC E F ORMATION 
20.0 
80.0 
5. Shale, sandy. dolomitic, mostly co\·ered. but strewn with floa t . .. . . . . . . . . 40 .0 
Nicollet Creek M ember (lower part) 
4. Dolomite, gray lo pink, glauconitic. Contains tri lobites and brachiopods. . 4.0 
3. Conglomerate, dolomitic and glauconitic. .. . . . . . . . . . . . . . . . . . . . .. . . . . . . 0.3 
Hi8 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
FRANCONIA FORMATION (top at 700.0 rt. A.T.) 
Bad Axe Member 
2. Sandstone. fine-grained, glauconitic, gray to buff, with glauconitic, gray, 
sandy shale ...................................................... . 
1. Covered interval to level of railway at depot (656.0 ft. A.T.) ........... . 
HOKAH. HOUSTON COUNTY 
Section on :Mollnt Tom 
22. Covered inten'al to top of Mount Tom ............................. . 
ONEOTA DOLO:\HTE 
THICKNESS 
(in feet) 
40.0 
4.0 
THICKNESS 
(in feet) 
35.3 
21. Dolomite, gTay to drab. massive. shown in old quarry on Mount Tom. .. . 50.3 
20. Dolomite. in massi"e and thin-bedded layers, gray, sandy, partly covered 24.2 
JORDAN SANDSTONE 
19. Sandstone, white to yellow, massive. with hard, calcareous beds and lenses 46.5 
18. Sandstone, white to yellow, coarse, with hard. calcareous layers. . . . . . . . . 27.9 
17. Coycred interval. . . .. .. . . . . . . .. . . . . . . . . . . . . . . .. . . . .... . . .. .. . . . . .. 7.5 
16. Sandstone. in occasional white to yellow outcrops. coarse. massive. cross-
bedded .......................................................... 30.0 
ST. LA"rRENCE FORl\IATIO;\T 
15. Covered interval, but slopes show float with Lodi fossils 
FRANCONIA FORMATION 
Bad Axe Member 
52.3 
14. Covered interval; limits of member uncertain . . . . . . . . . . . . . . . . . . . . . . . . . 33.5 
Hudson :l\1ember 
13. Sandstone. thin-bedded. laminated, fossiliferous. with shaly gTeensand. . . . 44.7 
12. Sandstone, gTay. thin-bedded. shaly, dolomitic. with beds of sandy glauco-
nite. Trilobite fragments common ................................... 31.0 
Tavlors Falls Member 11: Sandstone. shaly, dolomitic. gray. laminated, with much shale and glau-
conite ........................................................... 22.3 
10. Sandstone, dolomitic. laminated, gray. massive, alternating with beds of 
gray shale and layers of glauconite. Common fauna includes Dicellomus, 
Billingsella, Agnosfus. Taenicephalus bipllnetatus, Conasp;'" perseus, and 
Wilburnia cf. halli ............................... 16.8 
Ironton ~Iember 
9. Sandstone, white to yellow and greenish yellow, medium- to coarse-grained, 
cross-bedded. poorly cemented. Dieel/omus sp. common.. . . . . . . .. . . . . 3.8 
8. Sandstone. white to yellow. coarse- to fine-grained, cross-bedded. Dicello-
mus abundant ................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6 
DRESBACH FORMATION 
GalesYille Member 
7. Sandstone. ,,·hite. coarse. massive 
Eau Claire Member 
22.5 
6. Sandstone, medium-grained. "ray to brown. locally red-brown. thin-bedded .S.l 
.S. Sandstone. coarse. hard. gray to yellow or brown. locally purple. . . . . . . . 2.0 
4. Sandstone. white to yellow and brown. medium- to coarse-grained... . .. 3.0 
3. Sandstone. white to ~·ellow. medium to coarse. massive, partly cross-bedded 
and poorly cemented .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.8 
2. Sandstone, white to yellow. rnassiye . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.3 
1. Covered to level of Root River at the highway bridge (638.3 ft. A.T.) . . . 10.0 
HOUSTON COUNTY 
RENO, HOUSTON COUNTY 
Section at Hell Hollow 
169 
THICKNESS 
(in feet) 
ONEOTA DOLOMITE 
16. Dolomite, rough, massive, gray, with pockets of calcite crystals 50.0 
JORDAN SANDSTONE 
15. Sandstone. white to yellow. medium- to coarse-grained. massive, with 
some cross-bedding and hard streaks or lenses . . . . . . . . . . . . . . . . . . . . . . . . . 60.0 
14. Sandstone, yellow to white, medium-grained, much of it poorly cemented. 45.0 
ST. LAWRENCE FORMATION 
Lodi Member 
13. Sandstone, dolomitic, laminated, thin-bedded to shaly, blue to buff, com-
pact ............................................................ 8.0 
12. Dolomite, gray, arenaceous, shaly, interbedded with siltstone carrying 
Dikelocephalus minnesotensis, Saukiella typicali-s, and others. . . . . .. . . . . 11.1 
II. Dolomite. gray to drab. hard. A porous bed at the top. Glauconite abun-
dant in the lower part. . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . 16.8 
Nicollet Creek Member 
10. Shale, sandy, blue to gray, thin-bedded, dolomitic. Some beds contain 
much glauconite .................................................. 20.5 
9. Dolomite, sandy, gray to blue, conglomerate, massive, with glauconite.... 16.2 
FRANCONIA FORMATION 
Bad Axe Member 
8. Sandstone, gray to buff, laminated, glauconitic, thin-bedded, containing 
beds of both glauconite and shale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37.0 
7. Shale, gray, sandy, glauconitic. with beds of laminated gray sandstone. Oc-
casional hard layers cause falls and rapids. . . . . . . . . . . . . . . . . . . . . . . . . . . . 43.0 
Hudson Member 
6. Gray shales and soft glauconitic sandstone, partly covered. The Idahoia 
zone ........................................ '... .. ...... ...... ... 10.0 
5. Shale. arenaceous, glauconitic ...................................... 15.0 
4. Covered interval ................................................. 9.7 
Taylors Falls Member (?) 
3. Dolomite, gray to brown. arenaceous. glauconitic, shaly . . . . . . . . . . . . . . . . 14.7 
Ironton Member 
'to Sandstone. yellow. coarse. massive, cross-bedded, glauconitic. . . . . . .. . . . 4.4 
I. Covered interval to level of Mississippi River (63l.0 ft. A.T.)............ 3~.4 
ONEOTA DOW:MITE 
RENO. HOUSTON COUNTY 
Section of Well, Road Cut, and Cliff 
18. Dolomite, massive, rough, gray to buff. Extends northward to crest of bluff 
JORDAN SANDSTONE (top at 964.0 ft. A.T.) 
17. Sandstone, coarse, massive, hard. yellow to white .................... . 
16. Sandstone. white to yellow, medium-grained ........................ . 
1.5. Sandstone, mostly covered ..•...................................... 
ST. LAWRENCE FORlIIATION 
Lodi Member 
14. Covered interval ................................................. . 
Nicollet Creek Member 
13. Covered interval .. , ................................... , .......... . 
THICKNESS 
(in feet) 
150 
20 
40 
50 
35 
30 
170 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
THICKNESS 
(in feet) 
FRANCONIA FORMATION 
Bad Axe Member 
12. Covered interval ................................................. 5 
11. Sandstone, fine-grained, glauconitic ................................. 56 
Hudson Member 
10. Sandstone, thin-bedded, glauconitic, red at top. Lower beds at least w'e fos-
siliferous. ldahoia ham-uiu8 in loose blocks of talus slide ......... . . . . . . 46 
9. Sandstone, fine-grained, pink to gray, glauconitic. The Ptychaspis granu-
losa zone ........................... _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 
8. Covered interval ..................... _ . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 
Taylors Falls Member 
7. Covered interval. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .. . . . . . . . . . . 1.') 
Ironton Member 
6. Covered to level of river pool above Genoa Dam (631.0 ft. A.T.). . . . . . . . 5 
5. Covered below pool by river fill (in Milwaukee Railroad well; top of well 
is 636.0 ft. A.T.) .................................................. 5 
DRESBACH FORMATION 
Galesville Member 
4. Covered by river fill .............................................. 30 
Eau Claire Member 
3. Covered by river fill .................. _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 
2. Sandstones and shales .. _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 220 
Mt. Simon Member 
1. Sandstone. gray to white, to bottom of well (25.0 ft. A.T.) . . . . . . . . . . . . .. 34.5 
SPRING GROVE. HOUSTON COUNTY 
Section at Railroad Underpass West of Town 
THICKNESS 
(in feet) 
17. Overburden, chiefly loess. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.0 
GALENA FORMATION 
Decorah Shale Member 
16. Shale. green to bluish. with thin layers of bluish limestone. Pi4nodema 
abundant ........................................................ 9.0 
1.5. Metabentonite ............... _ ....... _ . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.2 
PLATTEVILLE FORMATION 
Spechts Ferry Member 
14. Shale. gray to blue, with flat limestone concretions showing fucoids on un-
der side . _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 
13. Limestone, hard, brown. pyritiferous. Some layers show fucoids on under 
side ............................................................. 2.8 
12. Shale. soft, argillaceous, blue ....................................... 0.2 
McGregor Member 
11. Limestone, blue to gray, massive to rather thin-bedded. Contains the usual 
f ossiIs ........................................................... 25.3 
Glenwood Member 
10. Shale, gray to green. . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . . . . 3.0 
9. Sandstone, fine, yellow to white, with some clay ...................... 4.0 
ST. PETER SANDSTONE 
8. Sandstone, massive, cross-bedded, well-cemented; reconstructed crystals of 
quartz sparkle in sun ............................................. 5.0 
7. Sandstone, massive, cross-bedded. still showing sparkling crystal grains .. 5.0 
HOUSTON COUNTY 171 
TIDCKNESS 
6. Covered interval ...... . ..................................... . 
. 5. Sandstone, friable. medium-grained, white with irregular yellow bands .. . 
4. Covered interval ... . ........................................ . 
SHAKOPEE DOLOMITE 
3. Dolomite, tbin-bedded. gray with a pink cast ....................... . 
2. Dolomite, gray; upper parl thin-bedded, lower two-thirds massive ..... . 
1. Dolomite, massive, gray. but mostly covered with a few rough ledges show-
ing through sod. Base al level of Riceford Creek at Houston-Fillmore 
county line (1,075 ft. AT.) ......... . ..................... . 
HOUSTON COUNTY 
(in feet) 
10.0 
15.0 
40.0 
15.0 
20.0 
45.0 
Section along State Highway No. 26, Sec. II, T. 101 N .. H. ~ W. 
ONEOTA DOLOMITE 
28. Dolomite, massive. hard. gray 
.JORDAN SANDSTONE 
27. Sandstone, massive, cross-bedded, white to yellow. with hard lenses and 
THICKNESS 
(in feet) 
30.0 
layers ........................................................... 15.0 
26. Sandstone, massive, white, medium-grained. cliff-forming .............. 65.0 
2fi. Sandstone, white to buff, fine-grained, thin-bedded ................... 10.7 
ST. LAWRENCE FORMATION 
LodiMember 
24. Dolomite. hard, sandy, gray to buff, with vermicular layers . . . . . . . . . . . . 5.0 
9.3. Siltstone, sandy. Some layers show burrows. . . . . .. .. . . . . .. .. . . . . . . . . . 11.0 
22. Conglomerate, sandy, dolomitic ..................................... 0.4 
21. Dolomite, hard, gray ............................................... 1.0 
20. Covered interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9..0 
19. Siltstone. fine-grained, gray to buff, containing Dike/acephalus millneso-
tensis. Saukiella typicalis, and others ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 
IS. Sandstone, fine-gTained, gray to buff, with thin streaks of gray shale. . . . 2.0 
17. Conglomerate, hard. dolomitic, gray to buff ......................... 0.7 
16. Dolomite, fine-grained, arenaceous. gray to buff, resembling siltstone. . . . 4.5 
II). Dolomite, fine-grained, gray to buff. arenaceous. with scattered pebbles .. 0.8 
14. Sandstone. fine-grained, laminated. glauconitic. gray .................. 5.0 
13. Conglomerate, hard. gray, glauconitic, dolomitic ...................... 1.0 
Nicollet Creek Member 
12. Dolomite, shaly, sanely, glauconitic, gray, irregularly bedded. Partly cov-
ered in lower part . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.0 
II. Dolomite, sandy, glauconitic. gray. .. .. .. . . . . . . . . . . . . . .. . . .. .. . . .. .. 3.0 
lO. Conglomerate, dolomitic, very hard. Contains scattered pebbles but lower 
part is a true conglomerate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0 
9. Dolomite, fine, sandy ............................................. 0.6 
R. Conglomerate, harel, dolomitic, pink to brown. with flat pebbles of fine-
grained glauconitic sandstone ...................................... 1.5 
FRANCONIA FORMATION 
Bad Axe Member 
7. Sandstone, fine-grained. glauconitic. gray to buff, laminated ........... 6.0 
6. Covered interval ................................................. 53.4 
Hudson :Member 
5. Sandstone, thin-bedded. fine-grained, gray to pink. glauconitic. Ptychaspis 
granulosa fauna .................................................. 36.0 
4. Sandstone, thin-bedded, laminated, glauconitic. gray to buff, fine-grained. 
with some vermicular layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.0 
172 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
3. Sandstone, gray to buff ........................................... . 
2. Covered interval ................................................. . 
Taylors Falls and Ironton Members 
1. Covered to level of river pool (620.0 ft. A.T.) ........................ . 
CAMBRIDGE, ISANTI COUNTY 
THICKNESS 
(in feet) 
6.3 
4.0 
20.3 
Well at the Colony for Epileptics (Drilled in 1933; 1,000 Ft. A.T.) 
THICKNESS 
(in feet) 
11. Sand, fine ............ 00 ............ 00 .... 00.............. . 31 
10. Clay. .... .. .... .. . . .. . . . . .. .. .. .. .. .. .. .. .. ... ... .. .. .. ... 4 
9. Sand, fine ................................................. 16 
8. Sand and gTavel ........................................... 37 
FRANCONIA FORMATION 
DEPTH 
(in feet) 
31 
35 
.51 
88 
7. Sand rock, soft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 119 
6. Sand rock, hard. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 162 
DRESBACH FORMATION 
5. Shale, sandy ............................................... 73 235 
4. Shale, blue ................................................ 5 240 
3. Sandstone, fine, hard, white . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 247 
2. Sandstone, white. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 287 
1. Sandstone, soft, yellow ...................................... 3 290 
CALUMET, ITASCA COUNTY 
Section on the South Face of the Hill-Annex Mine 
13. Drift 
COLERAINE FORMATION 
THICKNESS 
(in feet) 
125.0 
12. Iron ore, red and gray. soft, massive. with fine pebbles. .. ...... . .. .. .. ... . 9.0 
11. Conglomerate, red pebbles in a gray matrix. .. .... .. ...... ......... ..... 6.3 
10. Iron ore, guy to red, gritty, with fragments of wood ..................... 3.0 
9. Conglomerate, coarse, pebbly, un assorted .............................. 0.5 
8. Ore, green. gritty, with scattered pebbles of chert and iron formation. . . . . . . . 4.0 
7. Conglomerate, gray. coarse pebbles cemented by green iron sand. . . . . . . . . . . 0.7 
G. Conglomerate. very coarse, with polished black pebbles, chert, paint rock, 
hematite, green stone, and other pebbles up to 8 inches in diameter . . . . . . . . . 8.2 
BIWABIK FORMATION 
5. Paint rock .......................................................... 8.0 
4. Taconite, slaty ...................................................... 8.0 
3. Iron ore, deep red, cherty. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.0 
2. Iron ore, laminated, blue. cherty, with some taconite .. . . . . . . . . . . . . . . . . . . . 20.0 
l. Iron ore, hard, massive, cherty, to bottom of mine ....................... 28.0 
COLERAINE, ITASCA COUNTY 
Section at the Canisto Mine 
11. Drift, gray; boulders mostly dark schist, some granite 
COLERAINE FORMATION 
THICKNESS 
(in feet) 
90.0 
10. Shale, red to green, soft, with small, rounded iron pebbles. . . . . . . . . . . . . . . . . 7.0 
9. Conglomerate, shaly, hard, green to red ................................ 2.3 
8. Shale, greenish red, soft, massive, gritty, with very few pebbles . . . . . . . . . . . . 3.1 
7. Conglomerate, coarse, with pebbles of taconite, hematite, and green stone. .. l.2 
ITASCA COUNTY 
R26W R25W R24W R23W 
173 
T 
56 
N 
T 
~5 
N 
COO~LAND T 
R22W 
54 
N 
FIGU RE 48. - Outline map of southeast Itasca County, showin g loca tions of measured 
stratigraphic sections (solid tri angles). 
BIWABIK F ORl\IATION 
T HICK NESS 
(in feet) 
6. Limon.ite, cher~y , in thick beds, with intercalated chert bands. Some hematite 16.5 
5. Tacolllte, mass Ive. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.9 
4. Limonite, earthy; thin layers separated by hard , cherty bands ... . . . . . . . . . . 4.9 
3. Taconite, banded, dark, mass ive ....... . . .......... . ,.............. . . . . 4.7 
2. H ematite, cherty; thin red a nd blue layers separated by porous, dark, sandy 
taconite ................... . ........................................ 18.1 
1. Covered to flood level of pit . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 7.7 
KEEWATIN, ITASCA COUNTY 
Section at the Bennett Open-Pit Mine 
THICK N ESS 
(in fee t ) 
15. Drift, gray, hardpan, bouldery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35.0 
COLERAIN E FORl\IATION (?) 
14. Conglomerate, coarse. brown , with pebble of iron formation, taconite, and 
others ............................ ... ..... .. . . . . ............ . ....... 7.0 
174 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
13. Shale, dark greenish red .............................................. . 
12. Shale, a fine-grained, gritty iron ore ................................... . 
II. Shale, a fine, granular, lean, gritty ore, with streaks of red and ,vellow ('Ia~· .. 
10. Conglomerate, fine pebbles of iron formation in a green matrix ........... . 
9. Iron ore, lean, greenish red, gritty, with many tiny pebbles ............... , 
8. Limonite concretions, a layer ........................................ . 
7. Iron ore. fine-grained, earthy, with few pebbles . ......................... . 
6. Conglomerate, very coarse, with pebbles of iron formation, taconite, quartz, 
and others ......................................... , ............... . 
BIWABIK FORMATION 
S. Hematite, slaty, yellow, with some bands of earthy limonite .............. . 
4. Hematite, red, slaty, with occasional beds of earthy limonite and some hard, 
cherty blue hematite ................................................ . 
3. Hematite, blue to red, cherty, massive; also some botryoidal limonite ...... . 
2. Coyered interval. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... , ... . 
1. Hematite, slaty, to leYeI of water in middle of mine ..................... . 
TACONITE, ITASCA COUNTY 
Section at the Arcturus Mine 
9. Drift, graveL boulders, and till .......................... . ....... . 
8. Drift, hardpan, red, with boulders of taconite, slate, and igneous rock. 
COI"ERAI;-{E FORMATIOK (?) 
7. Conglomerate, gray to brown, argillaceous, with pebbles of hematite ....... . 
6. Shale, fossiliferous, gray, mostly covered ............................... . 
.J. Shale. gra,v; a lean iron ore with oyster shells .......... . 
4. Conglomerate, a yellow limonitic matrix with small, well-polished pebbles of 
hard hematite ....................................................... . 
3. Conglomerate, a coarse basal bed of iron formation and taconite pebbles 
BIWABIK FORMATION 
2. Iron ore, blue, cherty, interbedded with sandy taconite ................... . 
1. Iron o:e, dark blue to. black, massive, cherty, with some taconite. To level of 
water III lowest part of pit ............................................. . 
KASOTA, LE SUEUR COUNTY 
General Section through Quarries to the Minnesota River 
(see page 55) 
OTTAWA, LE SUEUR COUNTY 
Section of River Bluff on the Charles Sch"'artz Farm 
7. Soil ...... . 
O;-{EOTA DOLOMITE 
THICKNESS 
(in feet) 
7.5 
10.0 
(U 
0.5 
6.0 
0 . .5 
2.0 
2.3 
19.2 
25.0 
29.2 
11.5 
4.0 
THICKNESS 
(in feet) 
40.0 
10.0 
5.3 
5.0 
7.2 
0.7 
1.2 
30.5 
37.7 
THICKNESS 
(in feet) 
1.0 
6. Dolomite, brown to yellowish brown, weathered .......................... 4.5 
5. Dolomite, brown to reddish brown or pink, with a lillIe chert. Fossiliferous 6.0 
.JORDA;-{ SANDSTONE 
4. Sandstone, white, poorly cemented, with occasional green shale partings. . . . . 8.3 
3. Sandstone, ",hite, parLly coyered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.7 
2. Sandstone, ",hite to yellowish, poorly cemented, medium-grained, cross-bedded, 
",ith fragments of fossils in streaks of green shale ........................ , 16.0 
1. Covered interyal to leye! of Minnesota Ri\'er (730 ft. A.T.) . . . . . . . . . . . . . . . . 3.0 
MOWER COU TY 
FIGURE 49 . - Outline map of Le Sueur County, showing loca-
tions of measured stratigraphic sec tions (solid triangles). 
TWO RIVERS, MORRISO COUNTY 
T 
T 
Section at Rapids in Two River , 500 Feet Northwest of Mill, 
SW14 Sec. 8, T . 127 ., R. 29 W. 
175 
THICKNESS 
(in fee t ) 
5. Drift, gray, with many large boulders. . . . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . 4 .7 
DAKOTA FORMATION 
4. Shale, blue-b lack, highly p lastic ....... . ....... . ........................ 1.9 
3. Sandstone, brown, coarse, pebbly, with iron-sta ined concretions ............ 1.7 
2. Shale, gray, hard , stiff, with iron stains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 
1. Covered by reworked gray clay and boulder clay, showing fragments of ligni te. 
To level of Two Rivers (1,050 ft. A .T .) ................................. 2 .1 
AUSTIN, MOWER COUNTY 
Well of the HOrInel Packing Company (1,190 Ft. A.T .) 
THICKNESS 
(in fee l ) 
1.5 . Drift .......................••.......................... 10 
CEDAR VALLEY LIMESTONE 
DEPTH 
(in ree t ) 
10 
14. Limes tone, soft. yellow (possibly C relaceous) .......... . . . .. 20 30 
13. L imes tone, buff, with shale . . . . . . . . . . . . . . . . . . . . . . . .. ...... 150 180 
MAQUOKETA AND GALENA FORMATIONS 
12. Limes lone, massive, tan to white .................. .. . " . . .. 214 39-1, 
176 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
T 
133 
N 
T 
128 
N 
R31W R W 
FIGU RE 50 . - Outline map of western Morrison County, showing 
loca tions of measured stratigra phic sect ions (solid tria ngles). 
THICKNESS DEPTH 
GALENA FORMATION 
Decorah Shale M ember 
(in feet ) (in fee t) 
11 . Shale, greenish, calcareous .. . . . ... .. . .... . ....... .. ... ... . 43 437 
PLATTEV ILLE FORMATION 
Spechts F erry M ember 
10. Shale, blue, with layers of limestone ..... . ..... . . . .. .. ... . . . 5 442 
McGregor Member 
9. Limestone, gray . . . .. ... .... .. . . . . .. . ... . ....... . . . ... . . . 15 457 
MOWER COUNTY 177 
THICKNESS 
(in feet) 
DICPTH 
(in feet) 
Glenwood Member 
8. Shale, pale green 
ST. PETER SANDSTONE 
7. Sandstone, white 
ONEOTA AND SHAKOPEE DOLOMITES 
6. Dolomite, sandy ........................................ . 
JORDAN SANDSTONE 
5. Sandstone, white 
ST. LAWRENCE FORMATION 
4. Limestone and shale 
FRANCONIA FORMATION 
3. Sandstone and green shale ............................... . 
DRESBACH FORl\IATION 
2. Sandstone and sandy shale .............................. . 
1. Shale, reddish .......................................... . 
LE ROY, MOWER COUNTY 
8 
88 
333 
120 
111 
119 
100 
17 
Section at the Fowler and Pay Quarry, 1 .i'liile East of TO\yn 
II. Drift .............................................................. . 
CEDAR VALLEY LIMESTONE 
465 
553 
886 
1,006 
1,117 
1,236 
1,336 
1,353 
THICKNESS 
(in feet) 
3.5 
10. Limestone, gray to brown, thin-bedded, probably some\"hat disturbed. . . 4.0 
9. Limestone, gray to white, surface usually weathering to brown. fairly thick-
bedded, sparingly fossiliferous ......................................... 2.0 
8. Limestone, gray to brown; fossils rare .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.'2 
7. Limestone, gray to gray-white. with thin. shal~' partings. Fairly fo<;siliferow: 
some common forms are crinoid stems, Athyris fulto-nensis, Cyrfi.na hamil-
tonensis. and Spirifer orestes .................... O.~ 
6. Limestone. gray to brown, containing Stromatoporoidea. . . . . . . . . . . . . . . . . . 0.7 
5. Limestone, gray to white. compact, hard, nearly barren of fossils .......... 2.4 
4. Shale, green to gray. calcareous. irregnlar in thickness . . . . . . . . . . . . . . . . . . . . 0.5 
3. Limestone. gray to white, compact, thick-bedded. with a few fragmentary 
fossils .............................................................. '2.3 
2. Covered interval. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 
1. Limestone, gray to brown, to lowest level in quarry ...................... 7.0 
LYLE. MOWER COUNTY 
Section along Cedar R.iver, 3 Miles West of Town 
4. Soil and allnvium .................................................... . 
CEDAR V ALLEY LrMESToNE 
3. Limestone. gray to bnff, massive to thin-bedded. containing an abundance of 
THICKNESS 
(in feet) 
5.0 
Athyris fultollensis and a few other fossils ............................... 4.0 
2. Limestone, gray to buff or brown. hard, rough. massive. A tl'ypa reticuiaTis very 
abundant in some layers ....... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.5 
1. Limestone, gray to brown, partly covered to level of Cedar River. . . . . . . . . . . 6.0 
178 P ALE OZOIC AND RELATED ROC KS OF SOUTHEASTER J MI NESOTA 
T 
104 
N 
T 
103 
N 
T 
102 
N 
T 
101 
N 
FIGURE 51. - Outline map of M ower County, showin g loca tions of mea ured 
stra tigra phic sec tions (solid tri angles). 
RACI NE , MOWER COUNTY 
Section along South Side of Bear Creek, 1% Miles South of Town 
THICKNESS 
(in fee t) 
8. Drift , showing a few sca ttered graniti c boulders. . . . . . . . . . . . . . . . . . • .. . . . 1.0 
D AKOTA F ORMATION 
Ostra nder M ember 
7. Conglomera te. ha rd, brown, iron-stained , with cemented qua rtz a nd chert 
pebble . . ... .. . ... ... . . . . . . . . . ............ . . . . . ............... . ... 0.5 
6. Sandstone, coarse. rough, brown, with cross-beddin g and ripple marks . . . . 2.0 
5. G ravel. loose, orange to yellow; made up la rgely of qua rtz, Aint. chert. jas per. 
a nd rose quartz pebbles, wi th some sand . .. . ... . . . ............. . ...... 5.0 
4. Sand, yellow to white, menium- to fi ne-grained . . . . . . . . . . . . . . . . . . . . . . . . 3.0 
3. Covered in terval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.0 
CEDAR VALLEY LIMESTONE 
2 . Limestone, yellow to brown , conta ining a few fossils. . . . . . . . . . . . . . . . . . . . 12.0 
M AQUOKETA F ORMATION 
Wy koff M ember 
1. Limestone, ha rd , gray to buA'. T o level of Bear C reek . . . . . . . . . . . . . . . . . . 10.0 
VAR CO, MOWE R COUNTY 
Section along Rose Creek and Old Quarry, NW% Sec. 26, Austin Twp. 
4. Soil and drift gravels 
THICKNESS 
(in feet ) 
2 
NICOLLET COUNTY 179 
THICK NESS 
(in feet) 
DAKOTA (?) F ORMAT ION 
3. Clay, blue to red, in pockels over une\'en surface of limeslone 5 
CEDAR V ALLEY LIMESTON E 
2. Limeslone, blue lo gray , weatherin g lo buff. A few fo ils ...... . ... .. ..... . 10 
1. Limestone, massive, gray to buff, containin g some chert and limestone pebbles 
in the lower part . T o the level of Rose Creek (about 1,150 ft . A.T .) .. . . . ..... 15 
FIGURE 52. - Outline map of N icollet County. showing locations of measured stra tigraphic 
sec tions (solid triangles). 
FORT RIDGELY. ICOLLE T CO NTY 
Section along Ea t Bank of Fort Creek, on the George Floerup Farm 
T HICK NESS 
(in feet ) 
8. Drift .. . ...... . .... . . . ......... . .... . ...... .. .... . . . ................. 25.0 
D AKOTA F ORM ATIO N 
7. Shale, gray, fin e-grained , a rgill aceou .... . ... ... ... . .... .. .. . .. . . .. . ..... 3.0 
6. Sandstone, li monitic, argillaceous ... . .... . ..... . . .... . ....... . . . ... . . . .. 0.3 
5. Shale, black, lignitic . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 
4. Sandstone, brownish yellow, coarse . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 0.3 
3. Shale, lignitic . . ....... ... . .. .......... .. . . .. . .. .. .. .. . .. . ...... . .. . .. 0 .6 
o Clay, white. with angu lar quartz pebbles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7 
1. Covered to level of Fort Creek . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 .0 
HEBRON, NI COLLET COU TY 
Sect ibn along Nicollet Creek. Opposite Judson, on Mrs. I~a tharine Brown's 
Fa rm ( ee page 45) 
180 PALEOZOIC AND RELATED ROCKS OF OUTHEASTERN MINNESOTA 
FIGURE 53. - Outline map of Olmsted County, showing locations of measured 
stratigraphic sections (solid trian gles). 
DOVER, OLMSTED COUNTY 
Section along U. S. Highway No. 14, 1 Mi le West of Town 
GALENA FORMATION 
Decorah Shale Member 
THICKNESS 
(in fee t) 
8. Limestone and gray shale, in oolitic beds ........................ . .. . 1.0 
7. Shale, argillaceous, olive, with layers of limes tone. . . . . . . . . . . . . . . . . . . . . . 13.0 
6. Shale, argillaceous, olive ........ .... . ... . ... ........... . .. . ... . ..... 2.5 
5. Shale, argillaceous. gray to olive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 1.0 
4. Shale, argi llaceous, olive, with thin layers of limestone. . . . . . . . . . . . . . . . . . 1.5 
3. Shale, a rgillaceous, olive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.0 
PLATTEVILLE FORMATION 
Spechts Ferry M ember 
2. Shale, gray to olive, with limestone lenses. Pianodema subaeq"ata common 8.0 
1. Limestone, gray. Trilobites and Zygospira near the bridge. .. . . .. . . . . . . . 2.0 
DOVER. OLMSTED COUNTY 
Section along U. S. Highway No. 14, 1 Mile East of Town 
PLATTEVILLE FORMATION 
McGregor Member 
9. Limestone, gray to bluish. with prominen t jointing 
TH ICK NESS 
(in feet ) 
12.0 
OLMSTED COUNTY 181 
THICKNESS 
(in feet) 
Glenwood Member 
8. Shale. argillaceous, gray to mottled, containing fossils ................. . 
7. Shale, thin. papery, brown ......................................... . 
6. Shale, sandy, gray, with occasional chert pebbles ..................... . 
5. Shale. argillaceous, gray to green ................................... . 
4. Sandstone and sandy shale. with several streaks of blue-green shale ..... . 
3. Shale, argillaceous, olive to brown ................................... . 
2. Sandstone, red to brown and yellow ................................. . 
ST. PETER SANDSTONE 
1. Sandstone, white with occasional yellow streaks. To bottom of outcrop .... 
DOVER, OLMSTED COUNTY 
1.3 
0.2 
0.2 
0.6 
3.0 
0.6 
2.5 
20.0± 
Section at the Dennis Oredson Pit, NE Cor. SW% Sec. 32, Dover Twp. 
THICKNESS 
(in feet) 
3. Loess. . . . . . . .. .. . . . . . . . . . . . . . . . . .. .. . . . . . . . . . . .. . . . .. . . . . . . . . . . . . 2 
2. Drift. with a few boulders, mostly weathered but a few still showing 
striations ........................................................ . 
DAKOTA FORMATION 
Ostrander l\1ember 
1. Gravel. sandy, showing little sign of stratification and very poorly assorted. 
Contains quartz pebbles and an unusual amount of chalky ,,,hite chert. To 
water level in bottom of pit ........................................ 12 
MARION, OLMSTED COUNTY 
Section 2¥2 Miles Northwest of the Cemetery 
PLATTEVILLE FORMATION 
McGregor Member 
10. Limestone. thin-bedded. gray .............................. . 
9. Limestone, very sandy. gray ................................ . 
Glenwood :Member 
THICKNESS 
(in feet) 
15.0 
0.6 
8. Shale. argillaceous, gray. fossiliferous . . . . . . . . . . . . . . . . . . . . . . . 0.5 
7. Sandstone. brown to yellow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.2 
6. Shale. argillaceous. gray to olive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 
5. Sandstone. brown ................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.4 
4. Shale. argillaceous, gray ........................................... 0.3 
3. Shale. sandy, gray to brown. fucoidal ............................... 0.5 
2. Shale. argillaceous. gray to green, partly sandy ......... 1.5 
1. Sandstone. brown, in bottom of highway gutter . . . . . . . . . . . . . . . . . . . . . . 0.5 
PLEASANT GROVE. OLMSTED COUNTY 
Section at the John Engel Pit. 5 Miles Southeast of Town 
Sec. 1. Sumner Twp., Fillmore County * 
9. Loess ........................................................... . 
8. Drift. with boulders of granite . . . . . . . . . . . . . . . . . . . ........ . 
THICKNESS 
(in feet) 
3.0 
~.O 
* Although about 30 feet is exposed here, this is not the entire thickness of the 
Ostrander member at this locality. l\'lr. Engel says that the gTavel continues below the 
water hole as far as explored. 
182 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
DAKOTA FORMATION 
Ostrander Member 
THICKNESS 
(in feet) 
7. Quartz pebbles and pebbly brown sandstone .......................... 1.0 
6. Sand. ioose, yellow, coarse. poorly assorted, with a few scattered pebbles. . 12.0 
5, Clay, silty, gray to yellow or buff - a lenticular bed .................. 3.0 
4. Conglomerate, a hard, brown, irregular bed with iron cement. Contains 
quartz pebbles, many of them fairly well polished ........ , .... ,',., .. , 0,5 
!> 'ongiornerate, varying from poorly cemented to a loose gravel ......... :3.0 
2. Sand, yellow, pebbly ................................ ,.............. 2.0 
1. Gravel bed, largely of loose quartz pebbles, % to % inch in diameter, 
some larger; also some chert pebbles. Cross-bedded, poorly assorted, yellow 
to orange. Down to water level in bottom of pit .... . . . . . . . . . . . . . . . . . . . 8.0 
PLEASANT GROVE, OLMSTED COUNTY 
Section at the J. P. Chase Quarry, NW%. Sec. 20, T. 10.5 N., R. 13 W. 
GALENA FORMATION 
Stewartville Member 
THICKNESS 
(in feet) 
7. Dolomite, buff to yellow, with secondary calcite. Weathers porous 't8.0 
6. Covered interval .................................................. 12.0 
5. Dolomite, buff to tan .............................................. 16.5 
Prosser :Member 
4. Limestone. fine-grained, compact, gray to brown. 'Veil exposed in the quarry 16.0 
3. Limestone, compact, gray to brown .................................. 27.3 
2. Limestone, coarse, massive, gray to mottled .......................... 1.0 
1. Limestone, thin-bedded, knotty, gray to buff. To level of North Branch 
Root River ....................................................... 7.0 
PLEASANT GROVE, OLMSTED COUNTY 
Section along Root River, 2 1VIiles Northwest of Town 
GALENA FORMATION 
Stewartville Member 
THICKNESS 
(in feet) 
7. Dolomite, massive, porous, with secondary calcite. . . . . . . . . . . . . . . . . . . . . . 28.0 
6. Covered interval. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.0 
5. Dolomite, gray, weathering tan, massive ............................. 16.4 
Prosser Member 
4. Limestone, gray, massive, well exposed in old quarry on ,J. P. Chase farm. . 16.0 
3. Limestone, gray to brown, fine-grained, with occasional coarse, massive beds 27.3 
'to Limestone. gray, mottled, coarse-grained . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 
1. Limestone, buff. thin-bedded. knotty. weathering shaly. To level of North 
Branch Root River ................................................ 7.0 
ROCHESTER, OLMSTED COUNTY 
Deep Well on Bigelow Hill, 2 Miles East of Town (Drilled in 1923-24; 
l,130 Ft. A.T.) 
37. Drift, yellow clay 
PLATTEVILLE FORMATION 
THICKNESS 
(in feet) 
9 
36. Limestone, dolomitic, gray to blnish ......................... . 21 
DEPTH 
(in feet) 
9 
30 
OLMSTED COUNTY 
ST. PETER SANDSTONE 
35. Sandstone, soft, white 
SHAKOPEE AND ONEOTA DOLO!lUTES 
THICKNESS 
(in feet) 
92 
34. Dolomite, buff to brown ..................................... 304 
.JORDAN SANDSTONE 
33. Sandstone, gray to white .................................... 79 
ST. LAWRENCE FORMATION 
32. Dolomite .................................................. 127 
FRANCONIA FORMATION 
31. Shale, sandy, green. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 142 
DRESBACH FORMATION 
30. Shale and sandstone ........................................ 76 
29. Shale, gray. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ll8 
28. Sandstone and shale ........................................ 18 
27. Sandstone. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 100 
HINCKLEY SANDSTONE 
26. Sandstone. very hard ....................................... 106 
FOND DU LAC BEDS 
25. Shale, red. with sandstone ................................... 96 
24. Shale, red, hard, heavy with iron; some quartz sand ............ 33 
23. Sandstone, coarse, clear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 
22. Shale, red, alternating with sandstone . . . . . . . . . . . . . . . . . . . . . . . .. IIO 
21. Sandstone, nearly clear ..................................... 3 
20. Shale, red, alternating with sandstone ......................... 91 
19. Sandstone, with streaks of conglomerates as coarse as wheat. . . . . . 4 
18. Shale, red, alternating with sandstone. . . . . . . . . . . . . . . . . . . . . . . . .. 184 
17. Shale. red, mixed with coarse sand ............................ 6 
16. Shale, hard, red, with some sand ... . . . . . . . . . . . . . . . . . . . . . . . . . .. 389 
15. Sandstone, clear ............................................ 3 
14. Shale, red, alternating with sandstone ......................... 167 
13. Sandstone, bearing salt water .................... ... . . . . . . . . . . 23 
12. Shale. red. alternating with sandstone. . . . . . . . . . . . . . . . . . . . . . . . .. 598 
II. Shale, red. with streaks of limestone . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 
10. Shale, red. alternating with sandstone ......................... 9 
9. Shale, hard, red ............................................ 1.52 
8. Shale, light red. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 
7. Shale. hard, red ............................................ 35 
6. Shale, red .................................................. 9 
5. Shale, red, alternating' with sharp-grained sandstone ............. 21 
4. Shale. red, very tough . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 
3. Shale, light green ........................................... 35 
ARCHEOZOIC 
2. Granite. red 
I. Biotite schist 
ROCHESTER. OLMSTED COUNTY 
4 
36 
Section along Old Highway No.7. 3lj2 Miles East of Town 
GALENA FORMATION 
Prosser Member 
10. Limestone, irregularly bedded. compact, gray, often crinoidal ......... . 
Decorah Shale Member 
9. Shale, bluish to greenish. argilla('eolls, soft. with a few limestone layers ... 
183 
DEPTH 
(in feet) 
122 
426 
50.5 
632 
774 
850 
968 
986 
1,086 
1,192 
1,288 
1,321 
1.344 
1.454 
1,4.57 
1,548 
1.552 
1.736 
1,742 
2,131 
2,134 
2.301 
2,324 
2.922 
2.928 
2.937 
3.089 
3.101 
3.136 
3,145 
3,166 
3,190 
3,22.5 
3.229 
3.265 
THICKNESS 
(in feet) 
39.0 
27.9 
184 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTEHN MINNESOTA 
PLATTEVILLE FORMATION 
Spechts Ferry Member 
THICKNESS 
(in feet) 
8. Limestone, blue to gray. highly fossiliferous .......................... 3.0 
7. Shale, blue. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . .5 
McGregor Member 
6. Limestone, blue to gray ........................................... 7.7 
5. Limestone, blue to gray, partly crystalline. . . . . . . . . . . . . . . . . . . . . . . . . . . l.0 
4. Limestone, blue to buff . . . . . ........ , . . . . . . . . . . . . . . . . . 3.6 
3. Limestone, buff to brown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.8 
Glenwood Member 
'to Shale, sandy, blue to green ............................ " ..... , .. " . 12.7 
ST. PETER SANDSTONE 
1. Sandstone, white to yellowish, to bottom of ontcrop. Upper part may be 
Glenwood ...................... . . . . . . . . . . . . . . . . . . . . . . . . . . 10.7 
ROCHESTER, OLMSTED COUNTY 
Section at the State Hospital Quarry 
8. Soil and drift ..... 
PLATTEVILLE FORMATION 
Spechts Ferry Member 
7. Shale, blue to brown, argillaceous, with beds of gray to brown limestone. 
THICKNESS 
(in feet) 
5.0± 
One layer is full of Zygospira nicolleti . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 
6. Limestone, hard, gray to blue, with thin, shaly partings. Very fossiliferous 2.2 
5. Shale, yellow to brown ........... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 
McGregor Member 
4. Limestone, compact, hard, blue to gray, weathering to buff or yellowish. 
To bottom of quarry .............................................. 14.0 
3. Limestone, buff to brown. Covered .................................. 10.8 
Glenwood Member 
2. Shale, blue to green, argillaceous, sandy below. Covered ............... 10.0± 
ST. PETER SANDSTONE 
1. Sandstone, white to yellowish, partly exposed along road up the quarry hill 10.0± 
7. Soil 
STEWARTVILLE, OLMSTED COUNTY 
Section at the Old Quarry on North Bank of the River, 
ifz Mile above the Dam, (see page 89) 
STEWARTVILLE, OLMSTED COUNTY 
Section at the Cusson Milling Company, below the Dam 
GALENA FORMATION 
Stewartville Member 
6. Dolomite, thin-bedded, weathered buff 
.5. Dolomite, massive, pitted, gray to buff 
THICKNESS 
(in feet) 
l.0 
6.0 
8.0 
T 
38 
PINE COUNTY 
4. Dolomite, massive, buff, full of Maclurina manitobensis .. ............. . 
3. Dolomite, gray to but{, partly covered . .......... . .... . .............. . 
2. Dolomite, massive, buff. Commonly found are R eceptaculites oweni, Hor-
motoma major, ltlaclurina manitobensis, Maclurites crassu,y, Lophospira sp. , 
Sinuites sp., Endoceras cr. proteiforme, Orthoceras sp., lllaenus d. a1neri-
canus, and others ................................................. . 
1. Covered interval to ri ve r level (1,208 flo A.T .) .. . ............. . ...... . . 
185 
TH ICK NI::SS 
(in feet) 
.5 .3 
10.5 
16.0 
1.0 
N 1====4"-
FIGU RE 54. - Outline map of Pine County, showin g loca tions of measured stratigraphic 
sections (solid triangles), 
186 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTEHN MINNESOTA 
PINE CITY, PINE COUNTY 
Well of the Northern Pacific Railroad (Drilled III 1900; 945 Ft. A.T.) 
DRIFT 
THICKNESS 
(in feet) 
14. Sand, fine .............................................. . 
13. Sand, clean ............................................... . 
12. Sand and gravel ........................................... . 
11. Clay, red ................................................. . 
HIXCKLEY SANDSTONE 
10. Salldstone ... 
FOND DU LAC BEDS 
9. Rock. red ............................................ . 
8. Shale. red ................................................. . 
7. Sandstone. white .................................... , ..... . 
6. Sandstone, red ....................................... . 
5. Sandstone~ white . . . . . . . . . . . . . . . . . . . . ................ . 
4. Rock. red ....................... . 
3. Shale, hard, red, with sandstone ............ . 
2. Sandstone, white, with red rock ......... . 
1. Sandstone, red and white, interbedded with shale. Quartzite and 
pyrite at the bottom ....................................... . 
RIVERDALE FERRY, PINE COUNTY 
50 
100 
20 
60 
20 
10 
22 
13 
12.5 
!W 
20 
20 
32 
188 
Section along Snake River, % :lVIile above Outlet at Riverdale 
11. Drift, a dark red boulder clay, with boulders of all kinds but trap pre-
DEPTH 
(in feel) 
50 
150 
170 
230 
250 
260 
282 
295 
420 
440 
460 
480 
512 
700 
THICKNESS 
(in feet) 
dominating ...................................................... 20.0 
DRESBACH FORMATION 
Mt. Simon Member 
10. Sandstone, white, almost a loose salld. with layers of light gray clay shale 8.0 
9. Conglomerate, quartz pebbles with some mingled white sand. . 2.0 
8. Sandstone, white, medium to coarse, with an occasional pebble ......... 1.0 
7. Conglomerate, quartz pebbles ..................................... 0.5 
6. Sandstone. white, cross-bedded. poorly assorted, coarse to fine . . . . . . . . . . 11.0 
5. Sandstone, white to pink. with an occasional pebble. . . . . . . . . . . . . . . . . . . 0.3 
4. Sandstone, white, medium to coarse, with quartz pebbles '" . . . . . . . . . . 0.3 
3. Conglomerate, quartz pebbles of various sizes, mixed with some sand . . . . 0.7 
2. Sandstone, gray to white .......................................... 1.0 
1. Covered interval to level of Snake River (800 ft. A. '1'.) ............... 2.0 
SANDSTONE, PINE COUNTY 
Section of Quarries and Gorge, West Bank of the Kettle River 
(see page 23) 
SANDSTONE, PINE COUNTY 
Well at the Federal Prison (Drilled in 1938; 1,050 Ft. A.T.) 
THICKNESS 
(in feet) 
7. Drift, sand, grawl, and boulders. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 
HINCKLEY SANDSTONE 
DEPTH 
(in feet) 
25 
6. Sandstone, .vellow and pink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 110 
5. Sandstone, dark red .......................................... 60 170 
4. Sandstone, pink .............................................. 130 300 
RAMSEY COUNTY 
THICK NESS 
(in Ceet) 
3. Sandston e, red, soft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 
2. Sandstone, pink and yellow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 
1. Sand tone, brigh t red . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 
R 2 3 W R.22W 
FIGU RE 55. - Outline map oC Ramsey County, showing loca-
tions of measured stratigraphic sec tions (solid triangles). 
ST . PAUL, RAMSEY COUNTY 
Section at Dam No . 1, Ford Motor Company Plant 
(see page 81) 
ST. PAUL, RAMSEY COUNTY 
T 
30 
N 
T 
29 
N 
T 
2.8 
N 
187 
DEPTH 
(in Ceet) 
345 
420 
465 
Section at the Twin City Brick and Tile Plant, Cherokee H eights 
THICK NESS 
(in Ceet) 
38. Drift and soil . .................... . ....... . .... . ........ . ..... 125.0 
188 PALEOZOIC AND BELATED BOCKS OF SOUTHEASTEBN MINNESOTA 
GALENA FORMATION 
Prosser J\;Iember 
37'. Limestone. blue. with interbedded argillaceous bluish shales ........ . 
36. Shale. bluish. with interbedded bluish limestones .................. . 
35. Limestone. blue ............................................... . 
34. Shale. blue. with thin layers of bluish limestone; one 4-inch layer of 
limestone is very persistent ..................................... . 
33. Shale. blue. with many thin layers of blue limestone. the latter making 
up about a third of the rock. Zygospira -rec1trvirostTu very common .. 
32. Limestone. hard. brown. iron-stained. with brown, oolitic grains and 
pebbles at the base ......................................... . 
Decorah Shale Member 
Fucoid Bed 
31. Shale, blue. with fucoid~l. shaly limestone at the top .............. . 
30. Shale, blue, comparatively free from limestone but full of fucoids ... . 
29. Shale. blue. with manv thin layers of limestone. Very fossiliferous; 
among others Endoeerds and large crinoid stems commo;, .......... . 
Chasmatoporn (Phylloporina) Bed 
28. Shale. blue. with lenticular beds of blue limestone .. 
27'. Shale, blue. with lenticular layers of blue limestone. Contains DinoTt.his 
pect.inella. RhynchotTema minnesotense. Endoceras proteifo,.,,,e. Piano-
dema slloaequata, St.TophomenainCl1r1'ata, and numerous Bryozoa ... 
26. Shale. blue, with a band of brown oolites more or less throughout the 
full thickness ................................................. . 
Ctenodonta Bed 
25. Limestone, blue. ripple-marked ................................. . 
'24. Shale. blue. with limestone lavers ................................ . 
23. Limestone. blue ........................................ . 
22. Shale, soft, blue, comparatively free from limestone ......... . 
Rhinidictya Bed 
21. Shale, soft, blue, alternating with lenses and layers of blue limestone. 
'20. Limestone. blue. . . . . . . . . . . . . . ............................ . 
19. Shale, blue, with lenses of blue limestone ........................ . 
18. Shale. soft. blue. containing some fossils, such as Elldoceras prot.eiforme, 
Strophomena inC1lTvata. Pianodema sllbaequata. Sinuites pen'olutus, 
lsotelus gigas, also numerous Bryozoa ........................ . 
PLATTEVILLE FORMATION 
Spechts Ferry Member 
Stictop0l'el/a Bed 
17'. Limestone. hard, hIlle, fossiliferous ....................... . 
16. Shale, soft. light gray; an altered bentonite .................. . 
}.'i. Limestone, hard, blue ............................... . 
14. Shale. blue, fossiliferous. with some pyrite .................. . 
13. Shale, hard, blue ............................................. . 
12. Shale, hard, blue to bottom of active clay pit ................. . 
11. Limestone, gray to blue ...................................... . 
10. Shale. blue, with no limestone .................................. . 
9. Limestone, hard. blue, crystalline ............................... . 
8. Shale, soft, blue to greenish white. of variable thickness. Metabentonite 
7'. Limestone, blue to brown. hard. pyritiferous ..................... . 
McGregor Member 
G. Limestone, gray to buff, ,'ery fossiliferous ........................ . 
5. Limestone, argillaceous, shaly, blue. with conchoidal fracture ....... . 
4. Limestone, mottled, blue, thin-bedded ........................... . 
Glenwood J\;Iember 
3. Shale. blue to green, sandy ............................... . 
2. Sandstone, whit-e, mingled with gray-green clay and yellow streaks .... 
THICKNESS 
(in feet) 
8.8 
8.3 
1.3 
5.5 
2.8 
1.8 
5.3 
5.0 
6.0 
8.0 
G.O 
1.0 
0.2 
3.4 
0.3 
6.1 
8.2 
0.2 
4.0 
9.1 
0.3 
0.1 
0.3 
2.1 
0.4 
1.6 
0.7' 
1.9 
1.8 
0.3 
1.2 
8.0 
.5.0 
11.7' 
,5.0 
8.0 
RENVILLE COUNTY 189 
THICKNESS 
(in feet) 
ST. PETER SANDSTONE 
1. Sandstone, while, friable, medium- to fine-grained. To level of Missis-
sippi Ri"er «(jR7.\! ft. A.T.) ..................................... 71.0 
ST. PAUL, RAMSEY COUNTY 
Section at the St. Paul Crushed Stone Company Quarry, 
Stewart and Victoria Avenues 
R. River gravels, sand, and clay 
PLATTEVILLE FORMATION 
McGregor Member 
THICKNESS 
(in feet! 
3+ 
7. Limestone, thin-bedded, while mottled with gray streaks. . . . . . . . . . . . . . . . 3 
6. Limestone, light gray mottled with white, compact, abundantly fossilifer-
ous ............................................................... 4 
5. Limestone, gray often mottled with a lighter color, fossiliferous, with small 
grains of pyrite or marcasite . . . . . . . . . . . . . . 3 
Glenwood .Member 
4. Shale, blue to green, often sandy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 
3. Sandstone, yellow to white, with some shaly material ............... 8 
ST. PETER SANDSTONE 
\!. Sandstone, white, exposed in city excavations adjacent to the quarry. . . . . 7 
1. Covered interval to level of the Mississippi River (687.\! ft. A.T.) ........ 65 
MORTON, RENVILLE COUNTY 
Section at Pit of the Minnesota Clay 'Works, on South Bank of the 
Minnesota River, in Redwood County 
18. Drift ............................................................ . 
DAKOTA FORMATION 
17. Shale, gray to drab, weathering nearly white ........................... . 
16. Lignite, with well-preserved plant stems at top ......... . 
15. Shale, dark gray, argillaceous, with some plant remains ................. . 
14. Lignite, impure ..................................................... . 
13. Shale, gray to drab, argillaceous ....................................... . 
HZ. Shale, green, argillaceous ............................................ . 
11. Shale, white, resembling fire clay ..................................... . 
10. Shale, gray to drab, argilla.ceous, often carbonaceous, and with 3- to a-inch 
beds of impure lignite .......................................... . 
9. Shale, white, sandy. with streaks of impure lignite. This may give place to a 
layer of bauxite .................................................... . 
8. Shale, gray to drab, a.rgillaceous, with plant fragments . . . ........ . 
7. Shale, blocky, white, argillaceous, grading into bauxite .................. . 
6. Shale, gray to white, argillaceous, often sandy. Grades into beds below 
5. Sandstone, cross-bedded, arkosic, with streaks of fine quartz pebbles ... 
4. Sandstone, coarse, arkosic, with numerous streaks of quartz pebbles. The 
pebbles range up to 5 or 6 inches in diameter and pass laterally into a true 
conglomerate. The thickness of this bed is variable ...................... . 
PRE-CAMBRIAN 
3. Gneiss, probably originally a biotite granite gneiss, much-weathered, cut by 
veins of quartz. A marked unconformity at the top ...................... . 
2. Covered interval .................................................... . 
1. Gneiss, partly cO\'ered to level of 'Minnesota River (825 ft. A.T.) ......... . 
THICKNESS 
(in feet) 
100.0± 
5.0 
Ui 
14.0 
0.5 
1.0 
0.8 
O.\! 
1.0 
1.1; 
5.0 
~20.:> 
4.:5 
8.0± 
22.0 
2\!.0 
'20.0 
190 P ALEOZOIC AN D RELATED ROCK S OF SOUTHEASTERN MINNESOTA 
T 
112 
N 
• WRBSTER 
T F===;I,... 
III 
N 
FrGURE 56. - Outline map of Rice County, showing locations 
of measured st ra tigraphic sec tions (solid triangles). 
FARIBAULT, RICE COUNTY 
City Well TO. 1 (see page 44) 
FARIBAULT, RICE COUNTY 
City Well No.3 (Drilled about 1919; 973.4 Ft. A.T. ) 
T HICKNESS 
(in feet ) 
32. Drift, gra vel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 
S T . P ET ER SANDSTONE 
31. Sandstone, in medium, well-rounded yellowish grain s, with very lit-
DEPTH 
(in fee t) 
24 
tle cement ..... . .... .. ....... . ..................... . .. ... . . 19 43 
30. Sandstone, gray, well cemented . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 44 
S HA K OPEE D OLOMITE 
29. Limes tone, dolomitic, gray, partly crys talline, with some pyrite. 0 
fossil s ev ident . . .................... . .... . .............. . ... 33 77 
28. Limes tone, dolomitic, gray, fin e-gra ined . . . . . . . . . . . . . . . . . . . . . . . . 9 86 
27. Limes tone, foss iliferous, buff, with much white quartz sand ; grains 
rounded . . ........ . . . ..... . . . ........................... . .. 18 104 
26. Limes tone, dark to light gray. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54.5 158.5 
25. Sa ndstone, while to yellow, loosely cemented, with some gray lime-
stone and shale ' " . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5 159 
24 . Limes tone, dolomitic, gray, partly crystalline ............ . . . . . . . 18 177 
23. Limes tone, sandy, dolomitic . .................... .... ...... . . 24 201 
R OOT V ALLEY SANDSTONE 
22. Sand stone, white, with calcareous gray shale. . . . . . . . . . . . . . . . . . . 15 216 
RICE COUNTY 19J 
THICKNESS 
(in feet) 
DEPTH 
(in feet) 
ONEOTA DOLOMITE 
21. Dolomite, light bluish gray and yellow, with some shale ......... . 
20. Limestone, dolomitic. gray .................................. . 
19. Shale, calcareous, gray ...................................... . 
18. Shale, dark gray, calcareous ............................. . 
17. Shale, calcareous, light gray ................................ . 
.JORDAN SANDSTONE 
16. Sandstone, gray to white; grains medium, rounded ............. . 
ST. LAWRENCE FOR~IATIOX 
1.5. Sandstone, while, fine-grained, with a large amount of fine-grained, 
calcareous material ........................................ . 
H. Shale, poorly consolidated, porous, highly calcareous ......... . 
FRANCONIA FOR2\IATION 
13. Shale, sandy, greenish. calcareous. with greensand .............. . 
12. Sandstone. fine-grained, glauconitic ........................... . 
11. Sandstone, fine-grained. white. with calcareous material 
DRESBACH FORMATION 
10. Sandstone. very fine-grained, calcareous. white to buff .......... . 
9. Shale, sandy. calcareous ..................................... . 
8. Shale. green, glauconitic .................................... . 
7. Shale, arenaceous, reddish brown ....... . ......... . 
6. Sandstone, medium-grained .............................. . 
HINCKLEY SANDSTONE 
.5. Sandstone, medium ........................................ . 
4. Sandstone, medium-grained. brownish 
3. Sandstone, medium-grained, yellowish 
FOND DU LAC BEDS 
2. Shale, sandy, dark reddish brown ............ . 
1. Shale, sandy, hard, calcareous, yellowish ............... . 
FARIBAULT. RICE COTJNTY 
Section at the Lieb Quarry 
24. Drift, with large boulders, variable in thickness 
GALENA FORMATION 
Decorah Shale Member 
Guttenberg Submember 
25 
.50 
26 
4 
6 
90 
25 
.50 
100 
60 
50 
13 
42 
24 
4.5 
81 
21 
79 
30 
170 
285 
241 
291 
317 
321 
327 
417 
442 
492 
.592 
642 
692 
70.5 
747 
771 
816 
897 
918 
997 
1,027 
1.197 
1,482 
THICKKESS 
(in feet) 
12.0 
23. Shale, blue. argillaceous. with occasional la~'ers of limestone ........ 6.0 
22. Shale. blue, argillaceous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 
21. Shale, blue. argillaceous. with an occasional limestone lens. . . . . . . . . . . 4.0 
20. Limestone. blue. shaly, fucoidal ....... . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 
19. Shale. blue. argillaceous ........................................ 1.0 
18. Shale. blue, argillaceous, with two 3-inch layers of gray limestone. . . . . 2.3 
17. Limestone. shaly. blue. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 
16. Shale, blue, argillaceous ........................................ 1.0 
1.5. Shale, blue, ani·illaceous. with limestone lenses .................... 1.8 
14. Shale. brown. '\'ith light gray to white layers and nodules of pyrite. . . . 0.3 
PLATTEYILLE FORMATION 
Spechts Ferro' Member 
13. Limestone, gray to bluish. highly calcareous. hard. compact. . . . . . . . 2.,:! 
12. Shale, brO\Y!l to bluish, with much pyrite. .. .. .. .. .. .. .. . . . . . .. . . . 0.6 
19'1 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
McGregor Member 
II. Limestone, bluish .......................................... . 
10. Shale. blue. argillaceous. soft ................................... . 
9. Limestone, blue, argillaceous ................................... . 
Glen\\'ood :Member 
R. Shale. bluish to brownish, argillaceous, slighLly sandy. much-weathered 
7. Sandstone, brown, iron-stained ................................. . 
6. Shale. blue. argillaceous ........................................ . 
5. Shale, bluish to yellow. argillaceous. sandy ....................... . 
4. Shale. greenish blue. argillaceous, with a few sand grains ........... . 
3. Sandstone, bluish. highly pyritized .............................. . 
2. Shale. arenaceous ............................................. . 
1. Sandstone. yello\\' to white. mostly coyered, to level of Straig'ht River. 
The lo\\'er part may be St. Peter sandstone ................ . 
FARIBAULT, RICE COUNTY 
Section at the Hallet Quarry, .2 Miles East of Town 
15. Drift ...... . 
GALENA FORMATION 
Decorah Shale Member 
Guttenberg Submember 
H. Shale. blne to green, alternating with layers of bluish. argillaceous lime-
THICKNESS 
(in feet) 
7.0 
1.3 
4.0 
2.0 
0.;) 
1.0 
0.3 
1.3 
0.7 
4.0 
11.9 
THICKNESS 
(in feet) 
30.0 
stone ......................................................... 7.0 
l'LATTEYILLE FOn;\lATION (top at 1,049.4 ft. A.T.) 
Spechts Ferry Member 
13. Limestone, gray, hard, full of fossils. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . O.S 
1'2. Shale. brOl\'ll . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . 0.'2 
11. Shale. argillaceous, pale green or blue to white. An altered bentonite. . 0.'2 
10. Shale, brown .................................................. 0.3 
9. Limestone, gray, containing pyrite and fucoids. . . . . . . . . . . . . . . . . . '2.1 
8. Shale. brown. calcareous ....................................... 0.8 
McGregor Member 
7. Limestone, gray. weathering brown to buff. . . . . . . . . . . . . . . . . . . . . . . . 7.5 
6. Shale, bluish green, nodular . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 
.5. Limestone, brown to gray, with conchoidal fracture ................ 3.0 
Glell\\'Ood NIember 
4. Shale, blue to green, with thin, nodular beds and lenses of impure lime-
~one ........................................................ 6n 
3. Sandstone. calcareous. with much pyrite. . . . . . . . . . . . . . . . . . . . . . . . . . 0.4 
'l. Shale, blue Lo green, nodular, sandy ........... . . . . . . . . . . . . . . . . . . . 4.0 
1. Sandstone. highly iron-stained, ~·ellow, to level of Straight River 5.0 
NORTHFIELD, RICE COUNTY 
Well at St. Olaf College (Drilled in 19,')4; UJlO Ft. A.T.) 
THICKNESS 
(in feet) 
31 7. Drift ........................................ . 
6. St. Peter sandstone ........................................ . 
;). Oneota and Shakopee dolomites .............................. . 
4. Jorclan sandstone ........................................... . 
3. St. Lawrence formation ...................................... . 
'2. Franconia formation ........................................ . 
1. Dresbach formation ......................................... . 
51 
2.53 
95 
76 
1.50 
13,5 
IJ!,;PTH 
(in feet) 
31 
82 
33,; 
430 
.505 
655 
790 
ST. LOUIS COUNTY 
FOND DU LAC, ST. LOUIS COUNTY 
Section along Mission Creek 
193 
THICKNESS 
(in feet) 
FOND DU LAC BF:DS 
8. Sandstone, light gray to red, fine-grained. coherent. massive. beds 01' variable 
thickness ............................................... ,............ 14.0 
7. Shale. with green and red, sandy layers .................................. '2.'2 
(i. Sandstone, massive, gray, medium to fine. cross-bedded ................... 5.5 
.5. Shale. red. thinly laminated .... , ...... ' ............... ,................ 4.0 
4. Sandstone. gray to red, with micaceous partings ......................... 3.4 
3. Shale. chocolate brown. thinly laminated. . . . . . . . . . . . . . . . . . . . . . . . '2.5 
'2. Sandstone. ferruginous. massive ............ , . . . . . . . . . . . . . . . . . . 4.0 
1. Sandstone, gray, medium to fine, thin-bedded, slabby. with green an(1 red shale 
sean1S .. 
FOND DU LAC, ST. LOUIS COUNTY 
Section along ''''est Bank of the St. Louis River, at Ahandoned Quarry 
THICKNESS 
(in fpet) 
FOND DU LAC BEDS 
9. Sandstone, massive, cross-bedded, red to brown, medium to fine. . . . . . . . . . . . 5.0 
8. Conglomerate of shale and slate pebbles, thin-bedded, light green to red. '2.8 
7. Sandstone, coarse-grained, with micaceous parting planes .... 4.6 
6. Sandstone, reddish brown. medium-grained, partly thin-bedded ....... 6 q 
5. Sandstone, coarse, white to light yellow, cross-bedded . . . . . . . . . . . . . . . . 4.0 
4. Sandstone. massive. red . , . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8 
3. Sandstone, conglomerate, with flat red shale pebbles ................ , 1.8 
2. Sandstone, massive, salmon-colored ............. ................. 4.6 
1. Sandstone, massive, buff, with green, shaly partings ................. 4.8 
FOND DU LAC' BEDS 
FOND DU LAC, ST. LOUIS COUNTY 
Section of East Bluff of the St. Louis RiYer, 
SEn Sec. (), T. ·IS N., R. 15 'V. 
THICKNESS 
(in feet) 
6. Sandstone, massive, medium-grained, dark red "'ith white motlling' . . . . .. ... !Ul 
5. Sandstone, cross-bedded, gray to yellow ................................ 8.!) 
4. Sandstone, massiw, cross-bedded, gra~' to reddish brown ........ , . . 6.3 
3. Sandstone, massive, cross-bedded, ferruginous, with thin layers of coarse sand 
and grit ........................................... ,......... 8.2 
2. Sandstone, massive. A conglomerate zonc near the top, ,,·ith flat pebbles of 
quartz. basalt, and slate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.4 
1. Talus-covered inten'al to level of St. Louis River ...................... , 3.5 
FOND DU LAC, ST. LOUIS COlTNTY 
Section along the St. Louis River, Downstream from the Power Hom;e 
(see page 14) 
HIBBING, ST. LOUIS COUNTY 
Section at the Sellers Open-Pit Mine 
10. Drift, hardpan, boulder-bearing' 
9. Drift. sands and gravels. . . ~ 
THICKNESS 
(in feet) 
34.0 
194 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MI NESOTA 
COLORADO SERIES (COLERAI NE F O Hl\IATI ON ?) 
THICK NESS 
(in feet ) 
8. Conglomerate, a white matrix containing unpolished , angula r red hematite 
pebbles and a few taconite pebbles .. . .. .... .... . ........... . .......... . 
BIWABIK FOR.MATION 
7. Limonite, brown to yellow, mass ive, cherty ......... . .. .. . . ............ . 
6. Covered interval ................. . . .. .................. .. ... .... .. .. . 
5. Taconite, mass ive, unaltered, with sla ty banding .. . ... .. ..... .. ... . . .. . . 
4. Covered interva l ... . .......... ... ....... . ............... . . . . .. ..... . 
3. Taconite, brown to red; some layers sandy and white, others slaty and much-
altered ...... . . . ..... ... .................. . .................... . ... . 
2. Covered interva l ... ...... .. ..... .. . . ....... . .......... . .......... . .. . 
1. Hematite, blue and red , mass ive. cherty , with some bands of hard blue chert 
and taconite. To level of water in middle of pit .. .. . .......... .... ...... . 
T 
114 
N 
12.0 
22.3 
8.0 
11.2 
10.3 
24.0 
5.0 
37.5 
FICU RE .57. - Outline map of Scott County, showing locations of measured 
tratigraphic sec tions (so lid trian gles). 
JORDAN, SCOTT COUNTY 
Composite Type Section of the Jordan Sandstone 
( ee page 49) 
MERRIAM JUNCTION, SCOTT COUNTY 
Section at the Lindhoff Quarry, 1fz Mile North of the Pumping Station 
THICK NESS 
(in feet ) 
SHAKOPEE D OLOMITE 
10. Dolomite, gray to buff, rough, cherty, oolitic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 
9. Dolom ite, gray to buff or brown , arenaceous. . . . . . . . . .. . . . . . . . . . . . . . .. . . . 1.5 
8. Dolomite, gray, thin-bedded, shaly .... . ... . . .......... ... . . . ..... ..... 0.7 
7. Dolomite, gray to pink, rough .. ..................................... . . 1.8 
6. Dolomite, buff, compac t, thin-bedded ... .. . .............. ......... ..... 1.5 
5 . Dolomite. gray to brown , rough, mass ive. often with pink streaks and cav ities 
fi lled with pink crys ta ls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 .3 
SCOTT COUNTY 
4. Dolomite, gray to buff streaked with pink, compact ..................... . 
3. Dolomite, pink, weathering gray, massive, porous, to bottom of quarry .... . 
2. Covered interval .................................................... . 
1. Dolomite, brown to buff, compact to porous, with streaks of sand near the 
bottom. To level of railroad track (757 ft. A.T.) ....................... . 
ST. LAWRENCE, SCOTT COUNTY 
Section at the Hewitt and Beason Quarries 
(see page 43) 
SHAKOPEE, SCOTT COUNTY 
Section at the J. B. Conter Quarry 
(see page 64) 
SHAKOPEE. SCOTT COUNTY 
Well at the Rohr Malting Company (Drilled in 1936) 
195 
THICKNESS 
(in feet) 
2.0 
7.7 
17.0 
11.0 
THICKNESS DEPTH 
(in feet) (in feet) 
SHAKOPEE DOLOMITE 
12. Dolomite, broken 
ONEOTA DOLOMITE 
11. Dolomite, somewhat broken ................................. . 
JORDAN SANDSTONE 
10. Sandstone ................................................. . 
ST. LAWRENCE FORMATION 
9. Shale, sandy ............................................... . 
8. Shale, gray .................................... " ........... . 
FRANCONIA FORMATION 
7. Shale, gray to green ........................................ . 
6. Shale, green ............................................... . 
5. Sandstone, white ........................................... . 
DRESBACH FORMATION 
4. Sandstone ................................................ . 
3. Shale, soft, gray ........................................... . 
2. Sandstone ................................................ . 
1. Shale. red ................................................. . 
SHAKOPEE. SCOTT COUNTY 
27 27 
65 92 
88 180 
20 200 
15 215 
15 230 
H5 37;'; 
45 420 
15 435 
80 515 
193 708 
5 713 
City Well (Drilled in 19I1; Elevation of Well-Cap, Top of Curbing, 
725 Ft. A.T.) 
SHAKOPEE DOLOMITE 
THrcKNESS 
(in feet) 
11. Dolomite, gray to buff. Removed by hand; space now filled with 
cinders around curbing ..................................... . 
10. Dolomite, gray to brown. Beginning of the drilling log .......... . 
9. Sandstone, friable. medium to fine, vellow to white. Source of the 
springs at river level ............ : .......................... . 
ONEOTA DOLOMITE 
12 
2:3 
DEPTH 
(in feet) 
12 
37 
39 
8. Dolomite, gray to drab ..... , ...... , ...... ,.................. 31 70 
7. Sand and sandy gray dolomite, water-bearing, reported as sandstone 35 105 
196 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTER MINNESOTA 
J OR DAN SANDSTONE 
6. Sandstone, buff to white 
ST. LA WRENCE FORMATION 
THI CKNESS 
(in feet) 
100 
DEPTH 
(in feet ) 
205 
5. Shales, arenaceous, with dolomite ... . . ........ . . .. ..... ...... 33 238 
FRA NCONIA FORMATION 
4. Shales and glauconitic white sandstone . . .... . . . . . . . .. ...... ... III 349 
3. Sandstone, white .. ..... . . .... ........... . . .. ........ . ... . . . 95 444 
DRESBACH FORMATION 
Q. Sandstone. gray, with gray shales .... ....... .. . . . . . . . . . . . . . . .. 173 617 
I . Sandstone. while and red ... .... ... . . . ... .. . . . ........... 98 71.5 
SHAKOPEE, SCOTT COUNTY 
Section at the John Wambach Quarry, P4, Mile West of Town 
THICKNESS 
5. Soil .. .. .......................... . . .. .. . ............ . .. . ... . . ... . . . . 
SHAKOPEE DOLOMITE 
(in fee t) 
0.5 
4. Limestone, dolomitic, gray to pink, thin-bedded . ... . . . . . . . . . . . . . . . . . . . . . . . 2.0 
3. Dolomite, brown to pink, thin-bedded, cavernous . . . . . . . . . . . . . . . . . . . . . . . . . 8.0 
FIGURE 58. - Outline map of western Stearns County, showing locations of measured strati-
graphic sect ions (solid triangles). 
STEARNS COUNTY 197 
2. _Dolomite, gray to brown, compact, with some solution cavities . . ......... . . 
T HICK NESS 
(in fee t) 
4.4 
1. Dolomite, gray , mass ive, co mpact to crysta lline. T o bottom of quarry at level of 
Mi lwaukee Railroad tracks .. , .. . ........ . . ... . ... ............... . .. . . . 
RICHMOND , STEAR NS COUNTY 
Section of the H . Sieverding Well 
(see page 105) 
SAUK RIVER, STEARN S COUNTY 
Section a t West End of Highway Bridge over Sauk Ri ver, 
SWl,4 NE l,4 Sec. 23, T . 123 N ., R. 31 W. 
4.0 
THICK NESS 
(in fee t ) 
8. Dri ft, with boulders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34.0 
D AKOTA F ORM ATION 
7. Shale, red, pebbly, with roar e red sandstone and conglomera te in t he upper 
pa rt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 
6. Shale, gray. hard . somewha t slumped . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 .1 
5. Shale, gray, a rgillaceous, pebbly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7 
4. Shale, black, a rgillaceous, iignitic, with marcasite and limonite concretions. . . 2.0 
3. Shale, blue-gray, lignitic, passing into seams of lignite. . . . . . . . . . . . . . . . .. . . . 1.2 
2. Shale, gray to whiLe. argillaceous, partly concealed . . . . . . . . . . . . . . . . . . . . . . . . 1.5 
1. Covered by reworked clay, with fragment of lign ite from above . . . . . . .. . . . .. 3.2 
T 
108 
N 
T 
10 
N 
T 
106 
N 
T 
10~ 
N 
o 
R 21W 
FICUHE .59. - Outlin e map of Steele County, 
showing locations of measured t ratigraphic sec-
t ions (solid triangles). 
198 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
CLINTON FALLS, STEELE COUNTY 
Section in Klemmer Rock Quarry, 1 Mile South of Town, SE Cor. Sec. 28 
THICKNESS 
(in feet) 
:MAQUOKETA FORMATION 
Dubuque :Member 
6. Limestone, tan, thin-bedded, with cystoid sterns and heads, also Rafi.ne-
squ;.na alternata, Rhynchotrema, sp., Orthoceras sociale, and others. . . . . . . 4 
5. Limestone, gTay to yellow, thin-bedded, shaly, with interstratified beds of 
blue shale. Crinoid sterns. Rhynchotrema, and others common .......... 7 
4. Limestone, in 3- to 5-inch layers, blue, thin-bedded, containing fucoids and 
Lingula. sp. ....................................................... 6 
3. Shaly beds, gray. arenaceous; and thin-bedded limestones containing fncoids 
and Lingula (Pseudolingula) ;0/l'en5';8 .............................. 3 
2. Limestone, gray to bluish, hard. in 6- to 12-illch beds. Contains crinoid 
stems, fucoids, Streptela.sma. n~~ticum, Lingula. (Psemdoiingula) ;OWCIlS;S. 
Endoceras JiTote;forme, and others. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 
GALENA FORMATION 
Stewartville .Mem bel' 
1. Shale, arenaceous, blue, with thin lenses of hard blne to gray limestone. 
Tracks and trails through the shales. Receptaculites owen; in the limestone 8 
OWATONNA, STEELE COUNTY 
City Well (Drilled in 1935; 1,137 Ft. A.T.) 
12. Drift and allU\'ium 
THICKNESS 
(in feet) 
32 
GALENA FORMATION 
Stewartville and Prosser Nlembers 
11. Limestone, gray ........................................ . 
Decorah Shale Member 
10. Shale, gray and green ................................... . 
PLATTEVILLE FORMATION 
Spechts Ferry Member 
9. Shale, with layers of limestone 
McGregor Member 
8. Limestone, hard, gray 
Glenwood Member 
7. Shale, light green ....................................... . 
ST. PETER SANDSTONE 
6. Sandstone, white, soft ................................... . 
ONEOTA AND SHAKOPEE DOLOMITES 
.5. Limestone, sandy, buff .................................. . 
.JORDAN SANDSTONE 
4. Sandstone. medium-grained 
ST. LAWRENCE FORMATION 
3. Limestone. sandy ....................................... . 
FRANCONIA FORMATION 
2. Shale, green, sandy 
DRESBACH FORMATION 
1. Sandstone and sandy shale 
68 
75 
10 
21 
5 
110 
266 
90 
100 
1.50 
180 
DEPTH 
(in feet) 
32 
100 
175 
185 
206 
211 
321 
587 
677 
777 
927 
1,107 
WABASHA COUNTY 199 
FIGU RE 60. - Outlille map of Wabasha County, showing localions of measured slrati-
graphic sec tions (solid triangles). 
KELLOGG, WABASHA COUNTY 
Section along P lainview R oad, State Highway No. 42 , through Town 
THICKNESS 
14 . Covered to lop of hill .... . ... ... . . . . ..... .. . ... ....... . ............. . 
13. Covered, but showing blocks of typical Root Valley sandstone, none in place 
ONEOTA DOLO~IlTE 
12. Dolomite, gray, massive, with some quartz-fill ed cavities and masses of chert. 
Upper portion much-weathered ..................... ... ............... . 
II. Dolomite, gray, massive . . . ... ... ....................... . ... . ........ . 
10. Dolom ite, sha ly, gray, thin-bedded .... . . ............................. . 
9. Dolomite, gray to drab, massive, even-bedded, sandy throughout. Some joints 
are calcite-fi lled ........ . ...... . ....................... . ............ . 
J ORDAN SANDSTONE 
8. Sandstone, yellow to white, mass ive, cross-bedded, medium- to fine-grained .. 
7. Sandstone, yellow, conglomerate, cross-bedded, with pebbles of a fin e-gra ined , 
sandy shale ............................. . ................. . ........ . 
6. Sandstone. yellow, mass ive, cross-bedded, friah le, with ha rd layer- and streaks 
5. Sandstone, brown to yellow, mass ive, fairly well cemented; some laye rs are 
very hard ... . . ....... . . . ............... . ..................... . ..... . 
4. Sandstone, yellow to buff. cross-bedded. usua lly soft and friable but with hard 
layers and masses. This is ver~' near the base of the formation .......... . 
ST. LAWRENCE F ORMATION 
3. Covered interval, St. Lawrence float, some very nearly in place . .......... . 
(in feet ) 
40.6 
5.0 
17.6 
43 .3 
19 .1 
7 .0 
ft7.1 
3.0 
22.ft 
34.5 
16 .'1 
73.8 
200 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
FRA:<fCONIA FORl\IATION 
2. Coyered for the most part, but with scattered outcrops of glauconitic sands 
and shales in the fields ............................................... . 
1. Coyered to level of Zumbro RiYer at bridge on Highway No. 61, 14, mile north 
of Kellogg (670.5 ft. A.T.) .......................................... . 
KELLOGG, WABASHA COUNTY 
THICKNESS 
(in feet) 
90.6 
98.6 
Section at the Outlet of Snake Creek, 3% Miles South of Town 
THICKNESS 
6. Coyered to top of riYer terrace 
FRA:<fCONIA FORMATION 
Taylors Falls Member 
5. Sandstone. fine-grained, laminated, glauconitic. mostly thin-bedded. Trilo-
(in feet) 
4.0 
bites and brachiopods common, especially in lower part . . . . . . . . . . . . . . . . . 11.0 
Ironton :Member 
4. Sandstone. coarse to medium, brown, cross-bedded, full of Dicellomu8 in 
streaks often following the cross-bedding ............................. 1. 7 
DRESBACH FOR:.\IATION 
Galesyille Member 
3. Sandstone, white to yellow, even-bedded, cross-bedded, medium to coarse. 
No fossils found ................................................... 16.0 
G) Covered to level of Milwaukee Railroad tracks. . . . . . . . . . . . . . . . . . . . . . . . 14.0 
1. Covered to pool len I (660 ft. A.T.) ................................. 10.0 
ONEOTA DOLO~IITE 
LAI\.~ CITY, WABASHA COUNTY 
Section of Bluff at the Baker-Harrison Quarry 
9. Dolomite, gray to buff and brown. massiYe, with quartz geodes 
JORDAN SANDSTONE 
8. Sandstone, yellow to white, massi"e, cross-bedded. Part is well cemented 
THICKNESS 
(in feet) 
53.8 
and stands out in relief on the wind-eroded cliff . . . . . . . . . . . . . . . . . . . . . . . . 77.7 
7. Sandstone, \"hite to ~'ellow, loosely cemented ......................... 34.0 
ST. LAWRENCE FORMATION 
Lodi Member 
6. Shale, gray to buff, sandy. with arenaceous dolomite ................... 28.3 
5. Shale, dolomitic. blue to gTay, weathering buff to cream. The trilobite bed 2.0 
Nicollet Creek Member 
4. Dolomite. gray to buff. arenaceous. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3U! 
FRANCONIA FORMATION 
3. Covered interval below the quarry .................................. 51.0 
2. Greensand and sandy shales, partly covered .......................... 11.3 
1. Cm'ered interval to le"el of Mississippi River (667 it. A.T.) . . . . . . . . . ... 130.0 
LAKE CITY. WABASHA COUNTY 
Well of the Milwaukee Railroad (Drilled in 1882; 7H? Ft. A.T.) * 
THICKNESS 
(in feet) 
207 
DEPTH 
(in feet) 
207 
* After C. W. Hall, O. E. Meinzer. and M. L. Fuller. Geology and Underground \Vaters 
of Southern Millnesota (U. S. Geological Survey, Water Supply Paper 256), p. 358. 
WABASHA COUNTY 
FRANCONIA FORMATION 
4. Shale, blue, sandy ...... . 
DRESBACH FORMATION 
THICKNESS 
(in feet) 
68 
201 
DIOPTH 
(in feet) 
'l75 
3. Sandstone and sandy gray shale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 127 402 
2. Sandstone, gray and yellow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 490 
1. Shale, red, with quartzite .................................... 320 810 
LAKE CITY, WABASHA COUNTY 
Section at Riley's Coulee, 4 Miles Southeast of Town 
29. Covered to top of hill ............................................ . 
ONEOTA DOLOMITE 
28. Dolomite, gray to buff or tan, massive, weathered surface pitted, with chert 
THICKNESS 
(in feet) 
50.0 
and quartz crystals in cavities. Cherts fossiliferous. . . . . . . . . . . . . . . . . . . . 65.0 
re7. Dolomite, gray, massive to thin-bedded, compact. Conglomerate near base 25.0 
.JORDAN SANDSTONE (top at 969.0 ft. A.T.) 
26. Sandstone, yellow to brown, massive, with hard, dense layers or lenses 3.5.0 
re5. Sandstone, yellow to gray and white, massive, cross-bedded, medium-
grained .......................................................... 43.0 
24. Sandstone, yellow to white, massive, soft, with hard quartzitic beds. . . . . . 6.0 
23. Sandstone, yellow to brown and white, massive, medium-grained, cross-
bedded .......................................................... 16.0 
2re. Sandstone, hard, brown to yellow, medium to coarse, soft at base. Sharp 
contact at base. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 
ST. LAWRENCE FORMATION (top at 866.0 ft. A.T.) 
Lodi Member 
21. Dolomite, sandy, gray to buff, thin-bedded to massive, with vermicular 
markings .............. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.1 
20. Siltstone. dolomitic, gray to buff. The Dike/ocephalus minnesoiensis zone 
(top at 844.9 ft. A.T.) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.0 
Nicollet Creek Member 
19. Dolomite, arenaceous, gray to buff, massive to thin-bedded, glauconitic, 
with vermicular markilJD's . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28.0 
18. Dolomite, arenaceous, g-~y to buff or brown, hard, thin-bedded to massive, 
,,,ith a few fine grains of glauconite . . . . . . . . . . . . . . . . . . . 9.2 
FRANCONIA FORMATION (top at 802.7 ft. A.T.) 
Bad Axe Member 
17. Sandstone, dolomitic, shaly, gray to brown, fine-grained, glauconitic, with 
some vermicular markings ......................................... \20.0 
16. Sandstone, gray to brown, thick-bedded. . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 
1.5. Sandstone, gray to brown, laminated, cross-bedded, with much glauconite 5.0 
14. Sandstone, laminated, soft, shaly, with streaks of glauconite and beds show-
ing vermicular marking-s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 
13. Sandstone. gra.v to brown, massive, cross-bedded, with much sandy g'lau-
conite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7 
12. Sandstone, gray, with vermicular gray shale streaked with glauconite. . . . 19.3 
11. Glauconite, sandy ................................................ 0.3 
10. Shale, sandy, with thin beds of gray to brown sandstone containing o'lau-
conite. Vermicular markings common ........................... ~... 4.0 
Hudson Member 
9. Sandstone, gray, laminated. with some glauconite throughout. The Idalloia 
zone. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.'2 
8. Shale, salld~', gray, vermicular ...... , .. , . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 
202 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
7. Sandstone. gray, laminated, glauconitic. with an abundant fauna ....... . 
6. Shale. gray to yellow or brown. sandy, lumpy, vermicular ............. . 
5. Sandstone, gray to brown, laminated. fine-grained. vermicular; also sandy, 
vermicular gray shale with grains of glauconite and scattered beds of sandy 
glauconite ...................................................... . 
4. Shale, gray to brown, vermicular. sandy; also glauconitic sandstones alter-
nating with layers of sandy, cross-bedded glauconite ................. . 
3. Sandstone, gray to buff, laminated, glauconitic. The PtYChMpis zone .... . 
'2. Sandstone, gray to buff. glauconitic, fine-grained, alternating with gray to 
brown. nodular. vermicular. glauconitic shale ....................... . 
1. Covered inten'al over U. S. Highway No. 61 and Milwaukee Railroad 
tracks to level of Lake Pepin (667 ft. A.T.) .......................... . 
LAKE CITY, WABASHA COUNTY 
THICKNESS 
(in feet) 
0.3 
5.0 
7.0 
5.0 
10.0 
1.5.0 
27.1 
Section along Old Highway No.3 (Now U. S. Highway No. 61), 
S Miles Southeast of Town 
17. Covered to top of hill ............................................ . 
16. Covered, but with much brown sandstone float from the Root Valley sand-
stone ..................................................... .' ..... . 
ONEOTA DOLOMITE 
15. Dolomite, gray to buff, massive. shaly, containing cryptozoons ........ . 
14. Dolomite, gray, massive and thin-bedded layers, with large cavities and a 
layer of cryptozoons at the bottom ................................ . 
13. Dolomite, gray to buff and brown, massive, porous, with quartz geodes and 
cherty masses ................................................... . 
12. Dolomite, partly covered ......................................... . 
.JORDAN SANDSTONE 
11. Covered interval ................................................ . 
10. Sandstone, yellow to brown, with thin streaks of green to blue, argillaceous 
shale ........................................... · .. ············· . 
9. Sandstone, white to yellow, cross-bedded, very poorly cemented, but with 
spots or lenses like well-cemented layers ............................ . 
8. Sandstone, buff to brown, medium to coarse, loosely consolidated ...... . 
7. Sandstone, white to yellow, fine-grained, loosely consolidated .......... . 
ST. LAWRENCE FORMATION 
6. Covered interval ................................................. . 
FRANCONIA FORMATION 
Bad Axe Member 
5. Covered interval ................................................. . 
4. Sandstone. gray to pink. fine-grained, laminated. glauconitic. partly ver-
micular; also beds of cross-bedded, sandy glauconite ................. . 
Hudson Member 
3. Covered interval ................................................ . 
2. Sandstone. gray to pink. thick-bedded, glauconitic, with trilobites and 
small brachiopods. The Ptycha.spis fauna ........................... . 
I. Sandstone. gray, thin-bedded, cross-bedded, glauconitic. containing scat-
tered trilobites. To level of Lake Pepin (667.0 ft. A.T.) ............... . 
MINNEISKA, WABASHA COUNTY 
Section of Ravine and Bluff % Mile Southeast of Town 
THICKNESS 
(in feet) 
32.1 
4.5.0 
51.3 
28.2 
56.7 
6.0 
21.0 
16.0 
22.0 
26.7 
21.3 
70.0 
32.0 
32.7 
22.4 
6.0 
26.0 
THICKNESS 
(in feet) 
20. Covered to to.]1 of bluff ........................................... 20.0 
WABASHA COUNTY 
ONEOTA DOLOMITE 
19. Dolomite, gray to drab, massive, with calcite-filled ca\·ities and much chert 
203 
THICKNESS 
(in feet) 
toward the top .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 137.5 
JORDAN SANDSTONE (top at 1.048.5 ft. A.T.) 
18. Sandstone, white to yellow, medium to coarse, massive, cross-bedded, with 
numerous thin calcite-cemented lavers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40.4 
17. Sandstone, yellow Lo white, mediu~ to rather coarse, with rounded masses 
and lenses of calcite-cemented sands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.9 
ST. LAWRENCE FORMATION (top at 946.2 ft. A.T.) 
Lodi Member 
Hi. Sandstone, dolomitic, gray to buff, wiLh some glauconite and numel'OUS 
vermicular markings; also shale. . . . . . . . . . . . . . . . . . . . . . . . . . 35.9 
Nicollet Creek Member 
15. Dolomite, sandy, thin-bedded to shaly, gray, glauconitic. .. .. . . . . . . . . . 6.0 
14. Conglomerate zone, dolomitic and glauconitic beds interbedded with 
bands of conglomerate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.0 
FRANCONIA FORMATION (top at 898.3 ft. A.T.) 
Bad Axe Member 
13. Sandstone, fine-grained, glauconitic. Vermicnlar layers alternate \"ith lami-
nated beds and gray shale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (N.5 
Hudson Member 
12. Sandstone, fine-grained, laminated. The Idahoia zone. . . . . . . . . . . . . . 2.0 
11. Sandstone, thin-bedded, glauconitic, fine-grained, vermicular, with inter-
bedded layers of finely laminated glauconitic sandstone ............ 30.0 
10. Sandstone, gray to pink, glauconitic, fine-grained. The Ptychaspis zone, 
containing an abundance of the usual fossils ....................... 3.5 
9. Sandstone, fine-grained, glauconitic, \'ermicular, gray. Some beds contain 
numerous trilobites ...... ,................................... 12.0 
8. Sandstone, e\'en-bedded, fine-gTained, glauconitic, gray, interbedded with 
laminated layers. Billinysella and Ptychas]Yis still common ............. 11.4 
Taylors Falls Member (?) 
7. Sandstone, fine-grained, pink to gray, glauconitic, \"ith interbedded, fine-
grained, vermicular sandstone ......... . . . . . . . . . . . . . . . . 22.2 
6. Covered interval, with basal Ironton showing . . . . . . . . . . . . . . 33.3 
DRESBACH FORl\IATION (top at 721.4 ft. A.T.) 
Galesville Member 
5. Sandstone, gray to white, coarse, massive, cross-bedded 4.0 
4. Covered interval ........................... . 17.4 
Eau Claire Member 
3. Sandstone, shaly, yellow to brown, weathered. Dicellomus po/ifll" and Lin-
guiella. sp. common ............................................... 20.0 
2. Sandstone, white to browll, coarse, rather massive. Dicellomlls politlls com-
mon ....... ....................................... 11.3 
1. COYered to level of Mississippi River (660.0 ft. A.T.) ........ 8.7 
ONEOTA DOLOMITE 
READS LANDING, WABASHA COUNTY 
Section Exposed in the Village 
THICKNESS 
(in feel) 
21. DoJo1111te, Inassive~ grn,Y-, ll10re or less covered .... . . . . . . . . . . . . . . . . . . . . 20.0 
!'l0. Dolomite, massive to medium-bedded, gray .......................... 92.0 
19. Dolomite, sand~·, gray to brown, hcm·y-bedded. C'rypfozoon sp. in base. . 14.0 
~O~ PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
JORDAN SANDSTONE 
18. Sandstone. massive. white to yellow. with hard lenses and layers 
17. Sandstone. massive. white, exposed at intervals .......... . 
ST. LAWRENCE FORMATION 
Lodi Member 
16. Covered interval ................................................ . 
Nicollet Creek Member 
THICKNESS 
(in feet) 
~O.O 
90.0 
50.S 
15. Covered interval ................................................. ~;).O 
14. Dolomite. glauconitic. gray to pink and brown. .. . . . . .. 5.0 
13. Conglomerate, gray to brown. dolomitic, glauconitic ............... 3.0 
FRANCONIA FORMATION 
Bad Axe Member 
1~. Sandstone. fine-grained. thin-bedded. laminated. glauconitic. gray... 15.0 
11. Covered intel'\'al ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50.7 
Hudson Member 
10. Sandstone, partly covered, gray to green. fine-grained. glauconitic. strewn 
with loose blocks. containing the Idahoia hamulus fauna (in float) 15.0 
9. Sandstone. fine-grained, gray to pink. glauconitic. containing the Pty-
chaspis granulosa fauna. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Q.O 
8. Sandstone, fine-grained. laminated. glauconitic. gray, with beds of green-
sand ............................................................ 17.8 
Tavlors Falls Member 
7." Sandstone. gray, glauconitic. Billingsella common . . . . . . . . . 10.0 
G. Sandstone, thin-bedded. fine-grained, glauconitic. The Conaspis fauna 
abundant ...................................................... Q.O 
.~. Sandstone. thin-bedded. glauconitic. gray. largelo' rough-bedded 5.0 
4. Sandstone, fairly massive, dolomitic, glauconitic, gray to mottled. . . . 6.0 
3. Sandstone, thin-bedded to fairly thick-bedded, glauconitic. dolomitic. some 
beds with worm borings. Common fossils include JlJonocheillls sp. and Ida-
hoia sp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0 
2. Sandstone. fine-grained. glauconitic. cross-bedded, with shale beds and 
partings ............................... . . . . . . . . . . . . 24.0 
1. Covered to Mississippi River level (667.0 ft. A.T.) . 10.0 
WABASHA. WABASHA COUNTY 
Section along State Highway No. 60 at Southwest Edge of Town 
THICKNESS 
(in feet) 
18. Covered to top of hill. A few blocks of Root Valley sandstone float neal' 
the hottom . . . . .. ......................................... 46.3 
ONEOT A DOLOlHITE 
17. Dolomite, gray. very cherty. much-weathered, with quartz-lined holes. . . 15.0 
16. Dolomite, gTay. massive. with nodules and lenses of gny flint tending to 
follow bedding planes. Great holes and cawrns are partly filled by brOWll 
c1av; some of smaller cavities suggest fossils ...................... 50.4 
15. D010mite. gray to buff, very massive. . . . . . . . . . . . . . . . . . . . . . . 30.0 
14. Dolomite. thin- to medium-bedded. arenaceous .................. 14.6 
JORDAN SANDSTONE (Jordan-Oneota contact fair) 
13. Sandstone. yellow to white. also thin, sandy dolomite. with partings of olive 
green shale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.3 
12. Sandstone. vellow to white. cross-bedded, with numerous thin streaks of 
olive gTeen ~hale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6 
II. Sandstone, yellow to white, massive, cross-bedded, medium- to coarse-
grained, with occasional streaks and pockets of sandy olive green shale .. 21.1 
WASHINGTON COUNTY :!05 
THICKNESS 
(in feet) 
10. Sandstone, yellow to while, Yer.)' maSSIve, even-bedded, but with some 
cross-bedding ............................................... 6'2.8 
9. Sandstone, yellow to white, massive, cross-bedded, medium- to fine-grained 6.0 
ST. LA WRE:-ICE FOR~lATJON (St. Lawrence-,Jordon contact excellent) 
Lodi Member 
8. Dolomite, gray, massi"e, sandy, especially at the top, vermicular through-
out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.1 
7. Siltstone. blue to buff, compact, arenaceous. Sallkie!.la typicalis and D:kel-
acephalus minnesotensis in the middle. This bed seems to be broken into 
three parts, with massive dolomitic layers inten-elling. Fossils found at 
904.1 ft. A.T. ..................................................... 17 .. ; 
Nicollet Creek Member 
6. Dolomite, gray, with bluish shale partings, massi"e to thin-bedded. are-
naceous 
FRANCO:-lIA FOR::\IATJOc-I 
Bad Axe Member 
28.1 
5. Covered by slump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40.';! 
4. Shale, gray. glauconitic. sandy, with glauconitic sandstone. . . . . . . . . . . 29.4 
Hudson member 
3. Sandstone. gray. thin-bedded. laminated. glauconitic, with sandy. glau-
conitic, gray shales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.0 
'2. Sandstone. gray to buff with a pink cast. dolomitic. glauconitic. laminated. 
with sandy gray shales. Some beds ripple-marked and finely cross-bedded. 
All show wormlike boring'S. Fossils in the upper part, including Ptyclwspis 
granulosa, Idaho;a sp .. and others ............ 37.0 
1. Covered to Mississippi Riwr level (667 ft. A.T.) ...................... 62.9 
AFTON, K\SHINGTON COUNTY 
Section along the Creek at South Edge of Town 
12. Cm'ered to top of hill 
ONEOTA DOLOMITE 
THICKNESS 
(in feet) 
13.2 
11. Dolomite. gray to drab. massive, much of it covered ..... . . . . . . . . . . . . . 53.3 
JORDA:\," SANDSTONE 
10. Sandstone, white to yellow, medium to fine .......................... 10.0 
9. Sandstone, white to yellow, massive, coarse to medium ................ 72.:! 
8. Sandstone. yellow to white. thin-bedded, fine-grained. . . . . . . . . . . . . . . . . . 15.0 
ST. LAWRENCE FORMATIO:-I 
Lodi Member 
7. Dolomite, gray. sHndy. with gra~', dolomitic. sandy shales 
6. Dolomite, gra~' to buff. fine. even-textured. with glauconite. Graptolites 
at 780.6 ft. A.T. .. . ........................................ . 
Nicollet Creek Member 
.5. Sandstone. gray, massiye to thin-bedded. g'lauC'onitic. with thin beds of 
nearly pure glauconite and salldy g-ray dolomite ,yith shaly blue partings 
4. Sandstone, dolomitic, gra~' to buff, irregularly bedded. glauconitic, vennicll-
lar ............ . 
FRA:-ICOc-lIA FORl\lATION 
Bad Axe Member 
3. Sandstone. gray to buff, mHssi,'c, fine-grained. cross-bedded. very glauco-
nitic .................................................. , ........ . 
34.6 
3.0 
5.6 
7.n 
30.7 
~06 PALEOZOIC A D RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
FIGURE 61 . - Outline map of Washi ngton 
County, showing locations of measured 
stratigraphic sections (solid triangles). 
THICKNJ::SS 
(in feel) 
2. Sandston~, gray to ye llow and buff, soft , massive to shaly, fine-grained, 
glaucoDltlc ...... .... ........ .... ....... . ......................... 14.6 
1. Covered to level of Lake St. Croix (675 ft. A.T.) .. . .... . ............. 46.9 
AFTON, WASHINGTON COUNTY 
Section 4 Miles West of Town along the West Line of Afton Township 
THICKNESS 
(in feet) 
10. Soil and drift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.0 
WASHINGTON COUNTY 207 
THICKNESS 
(in feet) 
PLATTEVILLE FORMATION 
McGregor Member 
9. Limestone, blue weathering to gray or brown. fossiliferous .. . . . . . . . . . . . 21.3 
Glenwood Member 
8. Shale, bluish gray ................................................ 0.5 
7. Shale, brown. soft, with thin layers of hard brown shale . . . . . . . . . . . . . . . . 2.3 
6. Shale, brown. sandy .............................................. 0.9 
5. Shale, brown. argillaceous ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 
4. Sandstone, yellow to brown with interrupted streaks of red. Worm borings 
common......................................................... 2.0 
3. Sandstone. yellow to brown. with worm tubes and some sandy, blue to 
ween, argillaceous shale ........................................... 1.7 
ST. PETER SANDSTONE 
C) Sandstone. white to yellow. medium-grained . . . . . . . . . . . . . . . . . . . . . . . 5.5 
1. Sandstone, white. friable, partly covered to bottom of outcrop along road 4.0 
ARCOLA. WASHINGTON COUNTY 
Section at the Arcola Schoolhouse 
15. Covered to top of hill back of schoolhouse .......................... . 
ONEOTA DOLOMITE 
14. Dolomite, gray to drab. massiw. irregular. roug'h, III old quarry on hill 
THICKNESS 
(in feet) 
13.3 
back of schoolhouse . . . . . . . . . . . . . . 8.0 
JORDAN SANDSTONE 
13. Sandstone, white to vellm\'. massive. medium to coarse. with hard lavers 10.5 
12. Sandstone. vellow to brm\'11 and white. cross-bedded. massive t; thin-
bedded lay~rs .................................................... 31.4 
II. Covered interval .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26.7 
10. Sandstone. white. friable. medium-grained ............... 2.0 
9. Sandstone. covered 2(;.0 
ST. LAWRENCE FORMATION 
Locli Member 
8. Covered inteJ'\'al ........... . 
Nicollet Creek Member 
7. Dolomite, massive. arenaceous. cross-bedded. gray; also sandstones. dolo-
10.0 
mitic. glauconitic. fine-grained. gray ........................... 29.1 
FRANCONIA FORMATION 
Bad Axe Member 
6. Sandstone. white to yellow. m"ssive. ('liff-forming. medium- to fine-grained. 
with fine grains of glau('onite anel some vermicular beds. . . . . . . . . . . . . . . . 20.S 
5. Sandstone. white tu yellow. medium to coarse. cross-bedded. . . . . . . . . . . . 5.4 
4. Sandstone. blue Lo g;·ay. massi\'e to shaly. glauconitic. vermicular. dolomi-
tic. A 3- to 4-inch glauconite la~'er at the base .... , . . . . . . . . . . . . . . . . . . . 1(L4 
Hudson :MemLer 
3. Sandstone, g-ray to yellow, massive, cross-bedded, medium-grained. fossil-
iferous , .. ,..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34.9 
2. Sandstone. yellow to brown. massive. medium-g-rained. Fossils abundant at 
the top. The Ptychaspis zone. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7 
1. Coveredlu level of SL Croix Ri\'er pool (675 ft. A.T.) . . . . . . . . . . . . . . . . . . 3.0 
208 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
ARCOLA. WASHINGTON COUNTY 
Section at the Soo Line High Bridge 
THICKNESS 
(in feet) 
14. Drift-covered to top of hill back of old lime kiln. . . . . . . . . . . . . . . . . . . . . . . . . 12.0 
ONEOTA DOLOMITE 
13. Dolomite. gray to drab. massive. rough. Upper beds pitted, with quartz-lined 
cavities ............................................................. 20.0 
12. Dolomite. gray, arenaceous. massive to thin-bedded ...................... 74 
II. Covered to bottom of old quarry. (Partly Jordan) ....................... 35.4 
JORDAN SANDSTONE 
10. Covered to prominent bench below quarry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47.9 
9. Sandstone, white to yellow. massive. friable. with thin streaks of greenish shale 3.0 
ST. LAWRENCE FORMATION 
8. Sandstone. white to yellow. mostly covered by sodded slope but showing in 
nearby gullies. (Partly Jordan) ........................................ 45.0 
7. CO\'ered interval. probably sandy shale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.9 
FRANCONIA FORlHATION 
6. Sandstone, yellow to gray and white. massive, cross-bedded ............... 18.6 
5. Sandstone, gray to yellow, coarse, well cemented. weathering to thin beds. . . . 11.0 
4. Sandstone. white to yellow, massive, cross-bedded, medium- to fine-grained. 
with grains of glauconite and a few trilobites. A spring at the base . . . . . . . . . 14.0 
3. Sandstone, gray to buff, shaly, vermicular. glauconitic, somewhat calcareous. 
A 3-inch layer of glauconite at the base ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26.2 
2. Sandstone. gray, massive, glauconitic, cross-bedded. Oboloid brachiopods 
scattered throughout ................................................. 30.0 
I. Sandstone. gray, fine- to medium-grained. well cemented. Trilobites abundant. 
The Ptychaspis zone. To level of St. Croix River pool (67.5 ft. A.T.) ........ 4 .. 5 
12. Glacial drift 
ONEOTA DOLOMITE 
COPAS. WASHINGTON COUNTY 
Section along Creek and up the West Road 
II. Dolomite, gray to buff. much-weathered; upper parl massive. lower part thin-
THICKNESS 
(in feet) 
5.0 
bedded and sandy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.0 
10. Covered interval .................................................... 30.0 
JORDAN SANDSTONE 
9. Sandstone, white to brown, cross-bedded, thin-bedded. with varying degrees 
of cementation. Scolith1J,.~ tubes common ................................ 27.0 
8. Covered interval ..................................................... 24.7 
7. Sandstone, brown to purple. well cemented ............................. 7.1 
6. Sandstone, white to yellow or brown, cross-bedded, massive. friable. Abundant 
Scolithu.Y tubes ...................................................... 26.7 
ST. LAWRENCE FORMATION 
5. Shale, gray to buff, sandy; also irregularly bedded, shaly gray sandstone and 
dolomite with argillaceous green partings. Fucoids common ............... 33.0 
FRANCONIA FORMATION 
4. Sandstone, gray to green. fine-grained, cross-bedded. . . . . . . . . . . . . . . . . . . . . . . 10.7 
3. Sandstone, gray to gray mottled with brown, fine-grained, massive to thin-
bedded ............................................................. 10.7 
2. Sandstone, brown, even-bedded. thin to massive, with fragments of trilobites 10.7 
1. Shale. buff, calcareous. irregularly bedded, hard. with soft, blue, shaly part-
ings. To level ofSt. Croix River (679 ft. A.T.) ................ .. . . . . . . . . . 5.0 
WASHINGTON COUNTY 
COPAS, WASHINGTON COUNTY 
Section in Ramsey's Gorge 
10. Covered to Soo Line tracks 
JORDAN SANDSTONE 
9. Sandstone, white to brown, fine-grained. somewhat massive, cross-bedded. 
~09 
THICKNESS 
(in feet) 
8.0 
Upper beds vermicular, top layers dolomitic ............................ 30.0 
8. Sandstone, gray to white. glauconitic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0 
7. Sandstone, white to yellow, thin-bedded, fine-grained, glauconitic, with gray-
green to brown shale partings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.0 
ST. LAWRENCE FORMATION 
6. Sandstone, white to brown, shaly ...................................... 19.0 
5. Sandstone, gray to bluish and brown, thin-bedded, fine-grained, glauconitic, 
with shaly partings showing mud cracks and ripple marks on the surfaces; also 
occasional thin layers of sandy dolomite. Upper part is somewhat vermicular 11..5 
FRANCONIA FORMATION 
4. Sandstone, gray, fine-grained, glauconitic. cross-bedded ................... 5.8 
3. Sandstone, white to tan, fine-grained. micaceous. cross-bedded, weathering to 
thin-bedded. Locally upper part is somewhat dolomitic. Occasional brachiopods 10.0 
2. Sandstone, fine-grained, white to buff, containing the Ptychaspi.s fauna .... 6.0 
1. Covered to level of St. Croix River (679 ft. A.T.) ........... . . . . . . . . . . . . . 17.5 
FISH LAKE, WASHINGTON COUNTY 
Section on the E. Schmidt Farm, Fish Lake, near NW Cor. NE% Sec. 15, 
Woodbury Twp. 
1~. Drift, clay and boulders 
PLATTEVILLE FORMATION 
McGregor Member 
THICKNESS 
(in feet) 
16.0 
11. Limestone, gray, weathered to yellow and brown, fossiliferous ... ,. ... .. 10.7 
Glenwood Member 
10. Shale, gray to brown, fossiliferous. argillaceous, with some calcareous layers 
near the bottom ................................................. 1. 7 
9. Shale, brown, calcareous ........................................... 0.3 
8. Sandstone. hard, brown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.7 
7. Shale, green to blue, argillaceons, soft, containing some sand grains . . . . . . 1.0 
6. Sandstone, yellow to white and gray, well cemented .................. 1.7 
5. Sandstone, yellow to brown and green, with worm tubes .............. 0.9 
4. Sandstone. yellow to brown ........................................ 4.7 
3. Sandstone, yellow to white, with some argillaceous green shale . . . . . . . . . . ~ . .5 
ST. PETER SANDSTONE 
2. Sandstone, white with yellow patches. medium to fine. . . . . . . . . . . . . . . . . 10.0 
1. Covered to level of pond, 20 rods south of road. . . . . . . . . . . . . . . . . . . . . . . ~1.3 
16. Drift 
JORDAN SANDSTONE 
MARINE, WASHINGTON COUNTY 
Section Starting at the Ferry in the Village 
THICKNESS 
(in feet) 
60.0± 
15. Sandstone, massive to thin-bedded, white to yellow. medium-grained. . . . I!O.O 
14. Sandstone, in thi('k, even beds, cross-bedded, medium-grained, white. 
Gastropods abundant at places ..................................... 4.0 
210 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
13. Sandstone, thiek-bedded, friable, white to yellow, medium-grained 
12. Sandstone, white to brown, partly covered ................... . 
ST. LAWRENCE FORMATION 
Lodi Member 
11. Covered interval ................................................. . 
Nicollet Creek Member 
THICKNESS 
(in feet) 
22.4 
8.2 
18.0 
10. Sandstone, dolomitic, with sandy. shaly dolomites. . . . H.O 
9. Dolor:'i~e. s~ndy, gray to brow;" thin'-bedded. cross-bedded, glauconitic, 
contallllllg loss11 fragments ........................................ 9.8 
FRANCONIA FORMATION 
Bad Axe Member 
8. Sandstone. gray to white. friable, with some glaueonite ........ 10.2 
7. Sandstone. massive to thin-bedded or shaly. cross-bedded. gray to buff or 
brown, medium- to fine-grained, glauconitic. Some layers are hard, others 
soft. argillaceous. and full of burrows ...... . . . . . . . . . . . . . 10.9 
6. Sandstone. fine-gTained. gray to bluish gray, glauconitic, vermicular 11.4 
5. Sandstone. massive, cross-bedded. friable, yery glauconitic, some layers 
more resistant, vermicular . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.7 
Hudson Member 
4. Sandstone. white, massive, fine-grained. cross-bedded. with some fine 
grains of glauconite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.7 
3. Sandstone, gray. mostly covered .. . . . . . . . . . . . . . . . . . . . . . . . 5.0 
2. Sandstone. gray to buff, fairly massive, fine- to medium-grained. well shown 
in small quarry near ferry. Trilobites abundant. The Ptychaspis zone '23.8 
1. Sandstone. dolomitic, gray to red-brown, thin-bedded, laminated. with 
interbedded gray shales and shaly partings. Trilobite fragments occasionally 
found to river lenl (677 ft. A.T.) ................................... 15.4 
MERIDIAN LAKE, WASHINGTON COUNTY 
Section 1 Mile North of Marine 
12. Glacial drift ........................... . 
.JORDAN SANDSTONE 
11. Smldstone, light buff to brown, thin-bedded. friable. witk an abundant fauna, 
chiefly trilobites. Common forms include Billingsella coloradoens';s. Finkelnbur-
gia o:yceola, Osceolia osceola, Illaen"Tlls qua.dratus. Tel/erina !cueosia, and 
THICKNESS 
(in feet) 
38.0 
SaukieUa p!}Tene ................................................... 1~3.5 
ST. LAWRENCE FORi\fATION 
10. Covered interval. (Partly .Jordan and Franconia) ;jH.S 
FRANCONIA FORMATION 
9. Sandstone, buff to brown, friable, heayy-beclded. ,scolithns common 1(;.0 
8. Sandstone, green. increasingly buff toward the top, with occasional gray to 
green, shaly partings .................... . . . . . . . . . . . . . . . . . . . . . . . 14.8 
7. Shale, blue-green, sandy; also greensand with similar shaly partings toward 
the bottom. Bedding irregular. Shales fucoidal ..................... 6 .. 5 
6. Shale, gray to bluish, passing downward into thin-bedded greensand 8.0 
5. Sandstone, white. thin, eyen-bedded, friable. with brown iron oxide concen-
trated in veins and concretions ............. 17.3 
4. Sandstone, light red to nearly purple, streaked with green and gray, firmly 
cemented, with interbedding of more friable white sandstone .............. 5.1 
3. Sandstone, brown to buff. fiue-grained, medium- to thin-bedded, with streaked 
and mottled coloration. Trilobites common. The Ptychaspis granulosa zone 4.0 
2. Sandstone, buff to gray, partly mottled, massive, medium-grained. with a few 
small iron concretions ................................................ 17.7 
'WASl-IINGTON COUNTY 211 
THICKNESS 
(in feet) 
1. Shale, buff, thin and irregularly bedded, sandy, with light blue to gTeenish 
clay partings and some conglomerate. Contains abundant fucoids and some 
trilobite frag·ments. To level of St. Croix River (678 ft. AT.) . . . . . . . . . . . . . . 8.1 
SOO LINE DRA WBRlDGE, WASHINGTON COUNTY 
Section at Falls West of Water Tank and Drawbridge 
1.5. Drift ............ . 
SHAKOPEE DOLOMITE 
14. Dolomite, buff, irregularly bedded, arenaceous 
13. Sandstone, coarse, brown ............................................ . 
ONEOTA DOLO:MITE 
THICKNESS 
(in feet) 
67.0 
1.9 
l.l 
12. Dolomite, gray ting-ed with pink, irregularly bedded. thick to thin. . . . . . . . . . 8.5.0 
11. Dolomite. gray to buff. even-bedded. Small quartz geodes common 11.0 
10. Dolomite, buff to pinkish gray. sandy. thin and irregularly bedded. . . . . . . . . ;).0 
9. Dolomite, gTay to buff, sandy, with rounded pebbles of well-cemented sand-
stone at base ........................................................ 1.0 
JORDAN SANDSTONE 
8. Sandstone, white. massive, ripple-marked. mostly well cemented 1.5 
7. Sandstone, white to buff. coarse, rough, broken, poorly cemented. containing 
rounded, flat pebbles of well-cemented sandstone ........................ 1..5 
6. Sandstone. white to brown. coarse. massive. "'eathered surface is case-hard-
ened but interior is friable. Complexly jointed or cracked. upper part with 
small anastamosing veins ............................................. 19.8 
5. Sandstone, white. poorly cemented. heavy-bedded, fine-grained, but with some 
large. clear quartz grains. Contains a few poorly preserved trilobite fragments 3.0 
4. Sandstone, white to yellow or brown, massive. poorly cemented, fine-grained. 
Complex cross-bedding and color-banding common. . . . . . . . . . . . . . . . . . . . . . . 34.0 
3. Sandstone, like that above, but mostly covered. . . . . . . . . . . . . . . . . . . . . . . . . . . 15.5 
ST. LAWRENCE FORMATION 
2. Shale, sandy, buff, with argillaceous blue partings, irregularly bedded. Contains 
fragments of inarticulate brachiopods ............................ 1.1 
1. Shale, sandy, buff to blue, similar to that above. exposed along the river 
about 100 feet from no. 2. To Je,'el of St. Croix River (682 ft. A.T.) ....... 25.0 
STILLWATER. WASHINGTON COUNTY 
Section at Boom Hollow 
18. Covered to top of hill ............................................ . 
ONEOTA DOLOl\IITE 
THICKNESS 
(in feet) 
20.0± 
17. Dolomite. gray to buff. thick-bedded. rough. weathered surface pitted. 
Sharp contact at base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50.0 
JORDAN SANDSTONE 
16. Sandstone. coarse. gray to brown. with some reconstructed qnartz grains 6.0 
1.5. Sandstone. white to yellow. cross-bedded. medium to coarse, fairly massive. 
with thin lenses of arg-illaceous blue shale. Contains a few Sc.olithus tubes 
and fragments of trifobites ........................................ 16.0 
14. Sandstone. white to pink and brown. medium-grained. Trilobites abundant 6.0 
13. Sandstone. massive to thin-bedded. white to yellow ancl brown. medium-
to fine-grained, occasionally cross-bedded ............................ 37.3 
12. Sandstone. gray, rather fine-grained. with many trails or burrows. . . . . . . 10.7 
11. Sandstone, thin-bedded. fine-grained, white to gray and brown. . . . . . . . . 20.0 
'lI'l PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
ST. LAWRENCE FORMATION 
Lodi Member 
10. Shale, sandy, blue to gray, compact, dolomitic ...................... . 
9. Shale, gray to buff, silty. The Dikelocephallt8 m.innesoten~,y zone ...... . 
8. Shale, sandy, gray ............................................... . 
Nicollet Creek Member 
7. Dolomite. sandy. glauconitic, cross-bedded, gray to brown ........... . 
6. Dolomite, sandy, glauconitic. gray to buff .......................... . 
5. Dolomite, sandy. gray; also sandstone, dolomitic. gray, glauconitic, includ-
ing lenses and layers of dolomitic conglomerate ...................... . 
4. Sandstone, cross-bedded. medium to fine, gray to white .............. . 
3. Conglomerate, gray to pink, weathering yellow, sandy, dolomitic. Con-
tains some fossils ................................................. . 
FRANCONIA FORMATION 
Bad Axe Member 
2. Sandstone, massive. cross-bedded. fine- to medium-grained, white and light 
gray to ~'ellow and brown ......................................... . 
I. Sandstone. gray. glauconitic, vermicular, thick-bedded. To level of St. Croix 
Rinr (675.0 ft. A.T.) ............................................ . 
STILLWATER, WASHINGTON COUNTY 
THICKNESS 
(in feet) 
8.5 
3.0 
8.0 
6.0 
5.7 
18.7 
4.0 
2.0 
6.8 
7.0 
Section at the Twin City Foundry. up the Bluff and through the 
C. H. Carli Quarry THICKNESS 
15. Soil and drift 
ONEOT A DOLOMITE 
14. Dolomite. gray to buff. thin-bedded to massive. Bottom on floor of quarry 
(in feet) 
2.5 
in upper part . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.0 
13. Dolomite. gray. massive, rough ..................................... 5.0 
1'l. Dolomite. gray to pink ............ , .................... " ... " . .. . 1.0 
II. Dolomite. gray to buff. even-bedded, with fucoids and rarely a gastropod 3.3 
10. Shale and thin-bedded dolomite, yellow to buff. . . . . . . . . . . . . . . . . . . . . . 1.0 
9. Dolomite. gray to buff. rough, massive. pitted. Bottom at lowest quarry 
floor. which shows mud cracks and great billowy rolls ................ 4.5 
8. Dolomite, gray to reddish gray, massive, compact. showing in crusher pit 8.0 
7. Dolomite, gTay to buff, massive, hard, arenaceous. Sharp contact. . . . . . . . 6.0 
JORDAN SANDSTONE 
6. Sandstone. white to yellow or brown, massive. hard, medium to coarse ... 'l3.0 
5. Sandstone, white to yellow. massive. cross-bedded. medium- to fine-grained 31.0 
4. Sandstone. white to yellow. massive, cross-bedded. fine-grained. vermicular 6.0 
3. Sandstone, yellow to white, massive, medium-grained. vermicular ...... 28.0 
ST. LAWRENCE FORMATION 
Lodi Member 
'l. Sandstone, shaly. gray to yellow, probably including the trilobite beds 10.0 
1. Covered to level of St. Croix River (675 ft. A.T.) . . . . . . . . . . . . . . . . . . . . . . 15.9 
STILLWATER, WASHINGTON COUNTY 
Deep Well (Drilled in 1889; Original Elevation Probably 762 Ft. A.T.; Adjacent 
Filling Brings Present Level [October 12. 1934] of Sill of Well 
House to 780.64 Ft.) 
ONEOTA DOLO~lITE 
(781 ft. A.T.) Dolomite. thick-bedded. gray to brown and bufl'. Lower 
part is sandy but shows a sharp contact with the underlying formation 
THICKNESS 
(in feet) 
10.1 
DEPTH 
(in feet) 
10.1 
WASHINGTON COUNTY 
JORDAN SANDSTONE 
(770.9 ft. A.T.) Sandstone. haro, coarse. brown to white, grading into 
loose sand below. Sand grains show reconstructed quartz crystals 
(762 ft. A.T.) Sandstone, coarse, yellow; grains poorly assorted, well 
rounded to subangular, stained mostly on outside. (Sample 1 *) ... 
(744ft. A.T.) Sandstone. yellow to white. No sample preserved. 
ST. LAWRENCE FORl\IATION 
(696 ft. A.T.) Shales. arenaceous. gray, dolomitic ............... . 
(661 it. A.T.) Shale. fine-grained. argillaceous to siliceous. dolomitiC'. 
The Stillwater trilobite bed of Owen. (Sample '2) .......... . 
FRANCONIA FOR;>,IATION 
(659 ft. A.T.) Sandstone. with fine. rounded, frosted grains. glauconitic. 
(Sample 3) ............................................. . 
(6'20 ft. A.T.) Sandstone. with fine. white to colorless. partly rounded. 
slightly frosted grains of quartz, with some pyrite and glauconite. 
(Sample 4) . . ........................................... . 
(600 ft. A.T.) Sandstone. fine-grained. calcareous. silty. gray to green-
ish. with glauconite and some pyrite. (Sample 5) ................ " 
(559 ft. A.T.) Sandstone. medium to fine. white. with scattered grains 
of glauconite. (Sample 6) ...................................... . 
(547 ft. A.T.) Sandstone. fine-grained. with sandy gray shale and some 
fine grains of glauconite. (Sample 7) ......................... . 
(491 ft. A.T.) Sandstone. with medium to fine. subangular, poorly as-
sorted white grains. with scattered grains of glauconite. Contains frag-
ments of fossils. probably trilobites. (Sample 8) .................. . 
DRESBACH FORMATION 
(460 ft. A.T.) Sandstone. medium to coarse. gray to white. with some 
shale and scattered grains of glauconite. Contains fragments of fossils, 
probably trilobites. (Sample 9) .................. . 
(450 ft. A.T.) Sandstone. medium to coarse. white. composed of well-
rounded. frosted grains; also a few grains of pyrite and scattered grains 
of glauconite. (Sample 10) ... . ............................ . 
(440 ft. A.T.) Sandstone. gray to white. with medium. subangular 
grains. with a few scatlereo grains of glauconite. Contains fragments 
of fossils. probably trilobites. (Sample 11) .......... . 
(413 ft. A.T.) Sandstone. very fine-grained. white. with sandy, calcare-
ous gray shale. (Sample 12) ................................... . 
(382 ft. A.T.) Sandstone, coarse to medium, gray to white. dolomitic. 
with scattered grains of glauconite. (Sample 13) ................. . 
(31'2 ft. A.T.) Sandstone, white. coarse to meoium, with fine. rounded. 
grains. with scattered grains of glauconite. A calcareous cement. 
(Sample 14) ............ ........................... . .. 
(30'2 ft. A.T.) Shale, pink and reo to gray and buff. Apparently with 
a few garnets. (Sample 15) ....................... . ........... . 
HINCKLEY SANDSTONE 
(22'2 ft. A.T.) Sandstone, gray to white, with \"ery coarse, subangular to 
rounded grains. (Sample 16) ................................. . 
(132 ft. A.T.) Sandstone, white, poorly assorted. coarse. with some 
large grains. (Sample 16a) .................................... . 
(8'2 ft. A.T.) Sandstone, with \"ery coarse, subangular grains of yellow 
to pink and white sand. (Sample 17) ... 
FOND DU LAC BEDS 
(74ft. A.T.) Shale. sandy, dark red. calcareous. (Sample 18) . 
(61 ft. A.T.) Sanostone. coarse. subangular. red to brown and white. 
(Sample 19) ................................................. . 
* Samples in Department of Geology, Uni\'ersit~, of Minnesota. 
THICKNESS 
(in feet) 
8.9 
18 
4H 
36 
39 
20 
12 
56 
31 
10 
1U 
27 
31 
70 
10 
80 
90 
6() 
S 
13 
;) 
~13 
DEPTH 
(in feet) 
19 
37 
H5 
120 
IG1 
181 
234 
290 
3'21 
331 
341 
368 
3!J9 
469 
479 
;;59 
G49 
699 
707 
720 
7~;) 
214 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
(56 ft. A.T.) Shale, sandy, dark red, calcareous. (Sample 20) 
(45 ft. A.T.) Sandstone, dark red to brown, medium- to fine-grained. 
heavy, iron-bearing, calcareous. (Sample 21) .................... . 
(-34 ft. A.T.) Sandstone, dark red to brown, with much iron and 
calcareous matter. (Sample 22) ................................ . 
(-130 ft. A.T.) Arkose, dark red to brown, sandy, calcareous. Thin 
section shows quartz, feldspar, calcite, and various forms of iron. 
(Sample 23) ................................................ . 
(-161 ft. A.T.) Sandstone, arkosic, coarse, dark red-brown, with much 
iron. (Sample 23a) ........................................... . 
(-190 ft. A.T.) Arkose, medium to coarse, red to brown. Thin section 
shows quartz, feldspar, and such alteration minerals as chlorite, kaolin, 
and various oxides of iron. (Sample 24) ......................... . 
(-1,488 ft. A.T.) Arkose, like that above. Described by Winchell. 
No sample preserved ........................................ . 
(-1,808 ft. A.T.) Sandstone, arkosic, with angular fragments of quartz 
and pink feldspar. Also "arious alteration products, gray to brown in 
color. (Sample 25) ............................................ . 
(-2,138 ft. A.T.) Arkose. quartz, and feldspar, the quartz partly 
rounded and waterworn. (Sample 26) ........................... . 
(-2,184 ft. A.T.) Sandstone, dark red to brown, arkosic. Thin section 
shows little quartz but many rounded opaque grains. (Sample 27) .. 
(-2.188 ft. A.T.) Sandstone, brownish quartz with fresh feldspar. 
(Sample 28) ................................................ . 
(-2,338 ft. A.T.) Diabase, very dark brown, with pieces of kaolinized 
feldspar and some green grains. Described by Meeds. No sample pre-
served ...................................................... . 
(-2.413 ft. A.T.) Igneous rock. brown quartz with fresh feldspar and a 
pale green mIneral. probably prehnite. (Sample 28a) .............. . 
(-2.468 ft. A.T.) Igneous rock. unaltered, dark basic material showing 
excellent crystals and quartz veins. (Sample 28b) ............... . 
(-2,483 ft. A. T.) Igneous rock, unaltered, similar to that above. 
(Sample 28c) ................................................ . 
(-2,501 ft. A.T.) Igneous rock, similar to that above. (Sample 28d) .. 
(-2,509 ft. A.T.) Diabase. dark brown. similar to sample 28. Thin 
section shows calcite, kaolin, and slender fibers of a green mineral, 
probably serpentine. Described by Meeds. No sample preserved ..... . 
(-2,513 ft. A.T.) Diabase, fine-grained, slate-colored, with fresh feld-
spar. Meeds reported copper in this sample. (Sample 29) ......... . 
(-2,.538 ft. A.T.) Diabase, similar to that above but with much white 
material identified as kaolin. Described by M('eds. No sample pre-
served ...................................................... . 
(-2,543 ft. A.T.) Diabase, fine-grained, gray, with fresh minerals. 
Similar to that above. (Sample 30) ............................. . 
(-2,548 ft. A.T.) Diabase, similar to that above. Described by Meeds. 
No sample preserved ......................................... . 
(-2,639 ft. A.T.) Diabase, very fine-grained, drab, with some white 
and green minerals. Described by Meeds. No sample preserved ..... . 
(-2.678 ft. A.T.) In "May, 1889, the drillings indicated that the drill 
had entered gabbro, though of a rather finer grain than most of that 
which appears in the hills of the Mesabi range north and east of 
Duluth." * No sample preserved. (Bottom of hole at -2,738 ft. A.T.) 
TIIICKNESS DEPTH 
(in feet) (in feet) 
11 736 
79 815 
96 911 
31 942 
29 971 
1.298 2,269 
320 2,589 
330 2,919 
46 2,965 
4 2,969 
150 3,119 
75 3,194 
55 3,249 
15 3,264 
18 3,282 
8 3,290 
4 3.294 
2.5 3,319 
5 3,324 
5 3,329 
91 3,420 
39 3,459 
60 3,519 
* N. H. Winchell. Natural Ga.~ in Minne.mta (Geological and Natural History Survey of 
Minnesota, Bulletin ,5, 1889). p. 27n. 
WASHINGTON COUNTY 
STILLWATER, WASHINGTON COUNTY 
Section in Fairy Glen 
15. Soil covering in field 
ONEOTA DOLOMITE 
14. Dolomite, massive, gray to buff ................................... . 
JORDAN SANDSTONE (sharp contact) 
13. Sandstone, massive. white, medium-grained ........................ . 
12. Sandstone. fine-grained, buff to white. Several intral"ormational conglom-
erates show on bluff .............................................. . 
II. Sandstone, thin-bedded, somewhat dolomitic, gray to tan and light buff 
10. Sandstone, cross-bedded, fine-grained, white ......................... . 
ST. LAWRENCE FORMATION (sharp contact) 
Lodi Member 
9. Shale, fine, sandy, gray ........................................... . 
8. Shale (or coarse, hard gray siltstone). No fossils .................... . 
7. Shale, fine-grained, sandy, gray to buff .... , , , , . , ... , .. , , . , , . , ... , , .. 
6, Siltstone, gray, shaly, breaking with conchoidal fracture. Full of fossils. 
The Dikelocephalus minnesotensis zone ., .. , , .. , . , . , . , .... , , ..... , .. , 
5, Shale, gray to buff, mottled, slightly dolomitic ,.,.", ... ,."., ... , . , . 
Nicollet Creek Member 
4, Dolomite. rough, sandy, gray to buff ."."" .. , .... ", ... ", .. , ... , 
3, Dolomite, gray to yellow, thin-bedded, with several beds of conglomerate 
~. Sandstone. fine-grained. gray to buff. with fine grains of glauconite and 
interbedded dolomitic layers ... """ .... ,.", .. ,., .. , ..... ,., ..... 
1. Covered to level of St. Croix RiYer (pool leyel at 675.0 ft. A,T.) 
STILLWATER, WASHINGTON COUNTY 
Section through the William McNaughton Quarry 
15, Soil and drift covering """"""""""""""""""""""'" 
SHAKOPEE DOLOMITE 
14, Dolomite, gray to buff. massive to thin-bedded, porous. many of the holes 
showing dolomitic crystals, Fossiliferous; new fauna , . , .. , . , , ... , .. , ..... . 
13. Dolomite. gray, thin-bedded. sandy, with thin layers of sandstone. Ripple 
marks in some of the sand. Contains fucoids and an occasional slender 
Ilonnotoma sp. , .. , .. " .... , .. ", ... ,., .... , ... , ... , .. ", .. ,., ... , .. , 
12, Dolomite, gray. partly covered. , . , , , . , , , , , , , .. , , , , .... , . , , ... , .... , , . , 
II. Covered interval .. ,." ... , ... ".,.".,.,.".".", ... " .. " .. , ... "., 
10. Dolomite, gray, oolitic (probably Shakopee) """""""""""""'" 
ONEOTA DOLOMITE 
9. Dolomite, gray to brown. massive. making up most of the quarry wall .. ",. 
8. Dolomite. drab to gray. massive , .. " .. "", .... " .. ",."" .... , , . , ... 
JORDAN SANDSTONE 
7, Sandstone. white to yellow or brown. coarse. massive. cross-bedded, with hard 
white qnartzitic lenses and layers ,.," ...... " .. ," .. ".,. , .. , . , ... , , , , 
6. Sandstone, white to yellow, medium to coarse. massive, cross-bedded, Trilo-
bites common ".",.",.""""" ... ""., .... """.".""." ... , 
5. Sandstone, white to yellow, medium-grained. massive, cross-bedded .. , ... , . , 
4, Conglomerate. yellow. massive, with flat sandstone pebbles, mostl~· flat-lying 
3. Sandstone. white, fine-grained. with thin streaks of green clay, most of them 
filling worm holes ... '" . , .. , .. , , .. , .. , .... , , ....... , , .. , .. , , . , , , , ... . 
~. Sandstone. yellow to white. massive, banded. fine-grained, full of trails and 
burrows. Grades into dolomitic sandstone and includes several pebble horizons 
1. Covered to level of St. Croix RiYer (675 f1. A.T.). S1. Lawrence-Jordan con-
tact covered ,.,., ..... "."",., ... ,., .. ,.""" .... "" ... , .... , .. , 
THICKNESS 
(in feet) 
5.0 
50.0 
3;';,0 
35.0 
12.0 
.5.0 
3,0 
l..5 
4.0 
2,0 
8.0 
7,0 
3,0 
17.0 
8.0 
THICKNESS 
(in feet) 
1.0 
4,0 
4.4 
10.0 
33.6 
1.0 
28.'2 
25.0 
1'2.0 
6.0 
30,5 
3 . .5 
q,O 
18,0 
1'2.0 
~ I6 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
STILLWATER, WASHINGTON COUNTY 
Section of Bluff at the Wolfe Brewery 
15. Soil 
......... . ....... . . . . ' . . . ...... . .. .. . .... ..... ............. . ... . 
ONEOTA DOLOMITE 
THICKNESS 
(in reet) 
0.5 
14. Dolomite. thin-bedded. pitted to dense. gray to yellow . . . . . .. . . . . . . .. . .. . 10.0 
13. Dolomite, even-bedded. fairl y dense, gray. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 
I 'l. Dolomite. massive, rough, pitted, gray . . . . .. . .. .. .. . . . . .. . . . . . . . . . . . ... . 3.5 
II. Dolomite. mas ive to thin-bedded. dense, gray . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5 
10. Dolomite. massive, rough, pitted, gray to brown ............... . ...... '" . 6.0 
9. Dolomite. massive, dense. even-bedded , gray .... . ........... . ........... 80 
8. Dolomite, mass ive, rough, porous, arenaceous, gray to brown. . .. . . .. . ... .. 10.7 
JORDA N SANDSTONE (sharp contac t) 
7. Sandstone, mass ive, cross-bedded. coarse, yellow to brown , with recons tructed 
quartz grains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5 
6. Sandstone, mass ive, cross-bedded, medium to coarse, white to yellow. . . . . . . . 3'l .0 
5. andstone, mass ive to thin-bedded, often cros~-bedded , yellow to white . . . . . 6.7 
4. Conglomerate, massive, yellow. Sandstone pebbles Aat and mostly in a hori-
zontal position .. . .. . ....... . ........ . ..... . ........................ . 3.5 
3. Sandstone, fine-grained , wh ite. with vermicul ar markings fill ed with green 
~ak ...... . ....... . . . ........ . ......... . .......... . ...... . ...... .. . I~ 
I. Sandstone, mass ive, fine-grained, dolomitic in lower part, yellow to white, 
vermicular ............. . .... . . . .......... . ... .. ....... . . ... .. .. ..... 18.0 
I . Covered to level of St. Croix River (675ft. A.T.) .. . ..... . .... .. ........ . 18.0 
F rGURE 61. - Outline map of Winona County, showing locat ions of measured stratigraphic 
section (solid triangles). 
'WINONA COUNTY 
Winchell's General Section of the St. Croix ian 
(see page ~5) 
WINONA COUNTY 
DAKOTA, WINONA COUNTY 
Section at Cemetery Hill 
217 
THICKNESS 
(in feet) 
ONEOTA DOLOMITE 
21. Dolomite, massive to thin-bedded, gray to drab. Contains cryptozoons in 
upper part ....................................................... 55.0 
JOHDAN SANDSTONE 
~O. Sandstone, massive. white to yellow, with hard lenses and layers becoming 
more abundant in upper part ...................................... 40.0 
19. Covered interval, mostly sodded .................................... 65.0 
ST. LAWRENCE FORMATION 
18. Covered interval 
FRANCONIA FORMATION 
Bad Axe Member 
17. Covered interval 
Hudson Member 
50.0 
50.0 
16. Sandstone, covered at cemetery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3~.9 
15. Sandstone. thin-bedded, laminated, glauconitic. gray to brown. The 
Ptychaspis fauna ................................................. 5.0 
14. Sandstone. thin-bedded. glauconitic, gray. . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.9 
13. Sandstone, gray, thin-bedded, worm-bored. with occasional layers of lami-
nated gray to pink sandstone. Contains trilobites ..... . . . . . . . . . . . 15.0 
Taylors Falls Member 
1~. Sandstone, cross-bedded, glauconitic, buff to pink. fine- to medium-grained, 
dolomitic. Trilobites abundant, brachiopods common. . . . . . . . . . . . . . . . . . 16.0 
Ironton l\1ember 
11. Sandstone, pink to brown, coarse to medium, cross-bedded. Oboloid 
brachiopods abundant. Sandstone pebbles in base ................... 10.6 
DRESBACH FORMATION 
Galesville Member 
10. Sandstone, thick-bedded. cross-bedded. coarse- to medium-grained. white 
to gray and buff or yellow ......................................... 24.0 
Eau Claire Member 
9. Shale. gray to drab, argillaceous. with sandy streaks. Contains linguloid 
brachiopods ...................................................... 0.4 
8. Sandstone, coarse to medium. gray, with partings of argillaceous gTay shale 
containing thin streaks of coarse sand ............................... 8.0 
7. Sandstone. massive. e,-en-bedded. coarse-gTained, gray to yellow. . . . . . . . 17.0 
6. Sandstone. medium to coarse. cross-bedded. white to yellow. with verv few 
or no fossils except a few indefinite forms near base ~f cliff back of t~urist 
park ............................................................ 40.0 
5. Partly covered. but some sandstone along side road. . . . . . . . . . . . . . . . . . . 9.0 
4. Sandstone, massive to thin. even-bedded, tan to buff. Fossils common. . . . 10.0 
3. Sandstone. tan to buff, massive. fine-grained, somewhat laminated. occa-
sionally ripple-marked. Very fossiliferous. . .. . . . . . .. . . . .. . . . . ... . . . . . 12.0 
2. Sandstone. gray to buff. medium- to fine-grained. in thick beds weathering 
to thinner beds. Very fossiliferous, especially in thin streaks; the typical 
Dresbach fauna. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 .. 5 
1. Sandstone, fine-grained. thin-bedded. gray to buff, very fossiliferous. To 
level of Mississippi River (pool b'e! at 639.0 ft. A.T.) ................ 3.0 
218 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
DRESBACH, WINONA COUNTY 
Section at the Tostevin Quarry 
3'!. Coyered interval. weathered sandstone ........................... . 
ROOT V ALLEY SA:\'DSTONE 
31. Sandstone, brown to white, medinm-grained, with hard, flinty masses .... 
ONEOTA DOLOMITE (top at 1,'13'1.2 ft. A.T.) 
30. Chert, gray. rough, massiye, with cherty gray dolomite. Fossiliferous; 
common fossils include ClaTkoceras newton-winche.li.i, Rhachopea leiosomel-
/zun, and Ophilcta pc pinen.~e ...................................... . 
29. Dolomite, gray to drab, massive, with little chert ..................... . 
28. Dolomite, gray to buff, fairly massive, rough ......................... . 
'17. Dolomite, gray to buff, massiYe, fairly even-bedded ................... . 
26. Dolomite, massive to thin-bedded, with much sand and sandy beds .... . 
JORDAN SANDSTONE (top at 1.090.1 ft. A.T.) 
25. Sandstone, white to yellow and brown, massive, with hard lenses or la~'ers 
24. Sandstone, friable, white to yellow ................................ . 
23. Sandstone, white to yellow'and brown, massiYe, fine-grained to coarse, 
cross-bedded .................................................... . 
'22. Sandstone. white to yellow, mostly covered but showing occasionally 
ST. LAWRENCE FOR!\IATION 
Lodi and Nicollet Creek Members 
THICKNESS 
(in feet) 
4.7 
24.0 
32.4 
9.7 
36.0 
38.0 
26.0 
23.,5 
14.4 
32.4 
40.8 
'21. Covered. but showing some float characteristic of this shale. . . . . . . . . . . . 10.0 
20. Siltstone, gray to buff, fine-grained ..................... 1.0 
19. Covered interval, with some siltstone float and residual blocks of gray 
glauconitic dolomite .............................................. 39.0 
FRANCO~IA FORMATION 
Bad Axe Member 
18. Sandstone, pink to gray and buff, banded by glauconite and with glauconite 
layers ........................................................... 11.0 
17. Sandstone, gray to buff, with thin layers or bands of glauconite. . . . . . . . . 41.8 
Hudson Member 
16. Sandstone and shale. badly slumped and covered. . . . . . . . . . . . . . . . . . . . . 65.8 
Tavlors Falls Member 
15.' Sandstone, mostly coyered by slump ............................... 15.0 
Ironton :lVIember 
14. Covered interyal. Some coarse sandstone float with numerous fossils. . . . . . 5.0 
13. Sandstone, gray to brown, coarse to medium . . . . . . . . . . . . . . .5.0 
DRESBACH FORMATION (top at 785.4 ft. A.T.) 
Galesville Member 
12. Sandstone, coarse, yellow to white, massive . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.0 
Eau Claire Member 
11. Sandstone, with gTay shaly partings containing linguloid brachiopods . . . . 2.0 
10. Sandstone, gray to yellow, massive to thin-bedded. . . . . . . . . . . . . . . . . . . . 8.4 
9. Sandstone, massive. medinm- to coarse-grained, gray, brown to reddish 
brown. Some beds are very hard, some are crowded with Dicellomus politu.s 21.3 
8. Sandstone. white to brown. cross-bedded, fine- to medium-grained. . . . . . . 26.6 
7. Sandstone, white to yellow, cross-bedded, fine- to medium-grained, thin-
to massiye-bedded ............. .................................. 23.0 
6. Sandstone, partly covered .......... . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3 
5. Sandstone, gray to buff, massive, shown on the 'Vebster property ...... 5.'2 
4. Sandstone, gray to buff, quite fossiliferous. Quarry rock in Tostevin Quarry 
(top at 668.,5 ft. A.T.) ............................................. 14.0 
3. Shale, sandy, gray, with mud cracks and shaly gray sandstone. Common 
fossils include Dicellomu.s politu8. Lingulella amp/.a, Hyolithes primordialis, 
WINONA COUNTY 
Crepicephalus iuwen"is, Anollwcarella? winona, Lonchocephalu.y minor, and 
£19 
THICKNESS 
(in feet) 
Dresbachia amaia ................................................ 12.1 
2. Sandstone, gray, massive, containing a few fossils ..................... 3.0 
1. Shale, sandy, gray, mud-cracked, with irregular layers of gray sandstone. 
Dicellomu-y ]Jolitu.~, Lingttlella ampla, and others common. Extending to 
Mississippi River (old) level at 632.5 ft. A.T. . . . . . . . . . . . . . . . . . . . . . . . . . 7.0 
DRESBACH, WINONA COUNTY 
Section of Mineral Bluff, North End of the Village 
19. Soil 
ONEOTA DOLOMITE 
18. Dolomite, rough, cherty, brown to gray, containing some fossils. Chert 
masses mostly float .............................................. . 
17. Dolomite, massive, gray, weathering into great castellated bluffs and 
promontories .................................................... . 
JORDAN SANDSTONE 
16. Sandstone, medium- to fine-grained, white, with occasional small nodules 
of calcite crystals ................................................ . 
15. Sandstone, medium to coarse, massive, rough. brown ................. . 
14. Sandstone, massive. white to yellow, with hard layers that stand out in 
relief on the face of the cliff ....................................... . 
ST. LAWRENCE FORMATION 
Lodi Member 
13. Siltstone and sandy gray shales 
Nicollet Creek Member 
12. Sandstone, thin-bedded, dolomitic, mostly covered .................. . 
FRANCONIA FORMATION 
Bad Axe and Hudson Members 
11. Sandstone and shales, mostly covered. Glauconitic gray sandstone blocks 
are strewn over the slope ......................................... . 
Taylors Falls Member 
10. Sandstone, gray to white, medium- to fine-grained .................... . 
Ironton Member 
9. Sandstone. massive. gray to white with yellow stains, medium- to fine-
grained. Dicellomu... sp. and Lingulel.la sp. numerous .................. . 
DRESBACH FORMATION 
Galesville Member 
8. Sandstone. massive, white to gray or brown, fine-grained, friable ...... . 
Eau Claire Member 
7. Sandstone. medium- to fine-grained. white to yellow, partly co\"ered ..... . 
6. Sandstone, white to yellow, mostly covered ......................... . 
5. Sandstone, massive, white to yellow or brown. Common fossils are Dicel-
l.omus politus and Hyolithes primordialis ........................... . 
4. Sandstone and shale, gray to buff or brown. DicelionlU-s poliiu$ abnndant 
and Lingttlella am.pla, Hyolithes primordialis, trilobite fragments, and 
others common .................................................. . 
3. Sandstone. shaly, gray, very fossiliferous. Mostly covered but slope is 
st~e"-:n .wi~h l?Ose blocks of sandy shale to water's edge and old level of 
MISSISSIPPI River ................................................ . 
2. Sandstone, medium to fine. gray, exposed during excavation of mine shaft 
of Winona Mining Company late in the last century ................. . 
1. Sandstone, shaly, gray, with beds of gray shale. Shown in the drilling made 
by the Davis brothers below the shaft level .......................... . 
THICKNESS 
(in feet) 
1.0 
2.0 
113.0 
22.0 
28.3 
55.0 
25.0 
31.0 
131.7 
15.0 
10.0 
'.H.O 
51.0 
22.0 
13.3 
18.0 
11.3 
20.0 
68.0 
220 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
LA MOILLE, WINONA COUNTY 
Section at the Spring 21/2 Miles Northwest of Town, Opposite the 
North End of Trempealeau Mountain 
FRANCONIA FORl\IATION 
Bad Axe Member 
Slumped and poorly shown. 
Hudson 'Member 
Partly covered. Loose blocks of fossiliferous, glauconitic gray sandstone. 
The Ptychaspis zone. 
Taylors Falls Member 
5. Sandstone. gray to buff. fossiliferous, with gray shale. Wilburnia and Con-
THICKNESS 
(in feet) 
aspis common, but beds are poorly shown ............................ 3.5.0 
Ironton :Member 
4. Sandstone, hard, brown, medium to coarse, with numerous Dicellornns sp. 
in lower part ..................................................... 10.0 
DRESBACH FORl\[ATION (top at 759.5 ft. A.T.) 
Galesville Member 
3. Sandstone, white to yellow, thin-bedded to massIve. No fossils found ..... 50.0 
Eau Claire Member 
52. Sandstone, massive to thin-bedded. white to gray and yellow. fine-grained 
to coarse. Dicellollltls politlls and Lingulepis acurninatus common ....... . 
1. Covered to pool level of Mississippi River (64.5.5 ft. A.T.) ............. . 
JOHN A. LATSCH STATE PARK, WINONA COUNTY 
Section .7 to 1 :Mile above Dam No.5 
6. Covered by slump 
FRANCONIA FORMATION 
Ironton :Member 
5. Sandstone, glauconitic. coarse, brown, full of Dicel/omus sp. Sharp basal 
58.0 
8.0 
THICKNESS 
(in feet) 
50.0 
contact ........................................................... 5.0 
DRESBACH FORl\IATION 
Gales\'iIle Member 
4. Sandstone, coarse. white to :I·ellow, thick-bedded. No fossils found 523.5 
3. Cm'ered to level of U. S. Highway No. 61 ............................ 10.0 
2. Cm'ered from entrance of park to level of Milwaukee Railroad tracks. . . . ,5.3 
1. Covered to level of pool above Dam No.5 (660.0 ft. A.T.) .............. 10.7 
LEWISTON, 'WINONA COUNTY 
Section at the Chicago and Northwestern Railroad Quarry 
(see page 58) 
WHITEWATER STATE PARK, WINONA COUNTY 
Section along State Highway No. 74 
(see page 62) 
WINONA COUNTY 
WINONA, WINONA COUNTY 
Section of Bluff at the Biesanz Quarry 
221 
29. Soil and residual material 
THICKNESS 
(in feet) 
0.5 
ONEOTA DOLOMITE 
2S. Dolomite, hard, gray. "Bastard rock". . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . 4.0 
27. Dolomite. close-grained. buff. Works easily. "The freestone ledge". . . .. . . 2.3 
26. Dolomite, gray to drab, used for crushing' only. . . . . . . . . . . . . . . . . . . . . . . . 10.0 
25. Dolomite, buff. "The cream ledge". . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 
24. Dolomite, buff to gray, rough. . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 
23. Dolomite, sOlllewhat pitted, buff. "The yellow ledge". . . . . . . . . . . . . . . . . . 2.5 
22. Dolomite, gray to light gray. fossiliferous. "The white ledge". .. .. .. . . . . 2.0 
21. Dolomite, gray to drab, fossiliferous. "The upper gray ledge". ... ... .. . 0.7 
20. Dolomite, gray, fossiliferous. "The lo,Yer gray ledge". . . . . . . . . . . . . . . . . . . O.S 
19. Dolomite, massive, gray to pink, with ~astropods and cavities or holes that 
may have been fossils. "The main .pink ledge". . . . . . . . . . . . . . . . . . . . . . . . 3.3 
IS. Dolomite, gray to pink. "The lower or light pink ledge". . . . . . . . . . . . . . . . 1.2 
17. Dolomite, rough, gray to drab, used for rubble. Bottom at quarry floor. . 5.0 
16. Dolomite, rough, arenaceous, gray, containing several layers of sandstone. 
Not used .............................................. " . . . . . . . . . 24.0 
JORDAN SANDSTONE 
15. Sandstone, white to yellow, with lenses and irregular layers of hard dolo-
mitic sandstone and some beds of coarse sandstone near the middle. . . . . . 60.0 
14. Sandstone, white to yellow, with flat, rounded concretions but with very 
few hard layers .................................................. 34.5 
ST. LAWRENCE FORMATION 
Lodi Member 
13. Sandstone, thin-bedded, ripple-marked, cross-bedded. glauconitic. dolo-
mitic; also blue to gray shale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25.0 
Nicollet Creek Member 
12. Dolomite, sandy, glauconitic, gray. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.0 
FRANCONIA FORMATION 
Bad Axe Member 
II .. Sandstone, glauconitic, gray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5.0 
10. Covered interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39.0 
Hudson Member 
9. Covered interval ................................................... 20.0 
S. Sandstone, glauconitic, gray. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.0 
7. Covered interval. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . 27 .. 5 
Taylors Falls Member 
6. Covered interval ................................................. 35.0 
Ironton Member 
5. Covered interval 
DRESBACH FORMATION 
Galesville Member 
4. Covered interval 
Eau Claire Member 
12.0 
6.5 
3. Covered interval ................................................. 14.7 
2. Sandstone. coarse, gray to brown. thick-bedded. fossiliferous. Sand grains 
well rounded. Outcrop at lower end of old quarry road ................ 9.S 
1. Covered to U. S. B. M. at 662.S ft. A.T ......................... '" . . II.:; 
222 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
WINONA, WINONA COUNTY 
Section of Stockton Hill and City Well 
34. Soil, weathered residual material to top of hill. Contains blocks of Root 
Valley sandstone ................................................ . 
O~EOTA DOLOMITE (top at 1,191.9 ft. A.T.) 
33. Dolomite, gray to drab, rough, cavernous, pitted. Calcite crystals fill 
cavities; chert nodules common. Upper 20 feet badly weathered ....... . 
32. Dolomite, gray to buff, in thick, even beds, with some calcite-fillings but 
few open cavities ............................................... . 
31. Dolomite, gray to drab and buff, with streaks of glauconite. Lower portion 
is a conglomerate with shale pebbles ............................... . 
30. Shale, blue to greenish, argillaceous, but often sandy or pinching out en-
tirely ........................................................... . 
29. Dolomite, arenaceous, gray. oolitic, with pockets of calcite crystals and 
zones of pebbles ................................................. . 
JORDAN SANDSTONE (top at 1,010.1 ft. A.T.) 
28. Sandstone, white to yellow, alternating with streaks or irregular layers of 
hard, calcareous sandstone. These calcareous streaks follow the bedding 
planes, the cross-bedding, and in some cases even the joint planes ...... . 
27. Sandstone, white to yellow, mostly soft and friable but with some hard, 
flat masses or lenses .............................................. . 
26. Sandstone, dolomitic, gray, loose, white to yellow, with numerous pear-
shaped concretions ......................................... . 
ST. LAWRENCE FORl\fATION (top at 914.7 ft. A.T.) 
Lodi Member 
25. Dolomite, sandy, gray, with thinly laminated sandstones and seams of mud-
THICKNESS 
(in feet) 
30.0 
100.3 
61.0 
16.0 
1.0 
3.5 
64.7 
20.0 
10.7 
cracked blue shale. Some silt beds and chert near the top. . . . . . . . . . 23.8 
24. Shale or silt bed, compact, fine-grained, dolomitic, drab to buff. containing 
brachiopods and trilobites. The Dikelocephalus minnesotensis fauna . . . . . 2.0 
Nicollet Creek Member 
23. Dolomite, sandy, gray to buff and pink. with grains of glauconite and 
interbedded gray shale. Some 10wN layers appear identical with those of 
the type section .................................................. 18.5 
22. Sandstone, fine-grained, dolomitic, glauconitic. gray to buff. . . . . . . . . . . . 5.6 
21. Conglomerate zone. Sandy gray dolomitic beds with interbedded glauconitic 
sandstones and beds of conglomerate ............................... 8.0 
FRANCONIA FORl\IATION 
Bad Axe Member (top at 856.9 ft. A.T.) 
20. Sandstone, fine-grained, argillaceous, glauconitic. partly cross-laminated, 
with beds of gray shale and greensand .............................. 38.5 
19. Shale and sandstone, gray to greenish, glauconitic, fine-grained. mostly a 
vermicular mudstone. Sandstone beds are finely laminated. . . . . . . . . . . . . 13.5 
Hudson Member 
18. Sandstone. micaceous, gray. glauconitic. containing the ldahoia hamulus 
fauna ........................................................... 2.0 
17. Sandstone, gray to greenish gTay, medium- to thick-bedded, with gray 
shales ........................................................... 020.0 
16. Sandstone, gray with a pink cast, carrying the Piychaspis granulosa fauna 3.0 
15. Sandstone, gray, fine-gTained, glauconitic, with gray shales ............ 28.0 
Taylors Falls Member 
14. Covered interval ................................................. 34.3 
Ironton lVlember 
13. Sandstone, thin-bedded, cross-bedded, shaly, glauconitic, crowded with 
oboloid shells .................................................... '2.0 
12. Sandstone, coarse. cross-bedded, poorly sorted, gray to yellow. Oboloid 
fossils common ................................................... 10.5 
WINONA COUNTY 
DRESBACH FORMATION (top at 705.1 ft. A.T.) 
Galesville Member 
II. Sandstone, massive, yellow (ferruginous), coarse. poorly sorted ......... . 
Eau Claire Member 
10. Sandstone, yellow to white. coarse. poorly sorted, with layers (% to % or 
more inches) of bluish. argillaceous shale carrying linguloid fossils ..... . 
9. Sandstone, massive. cross-bedded. poorly sorted, white to yellow, in inter-
bedded, fine-grained layers. Contains abundant fossils, Lingulella and 
oboloids ........................................................ . 
8. Sandstone, thin-bedded, fine-grained, white to yellow. Linguloid fossils 
common ........................................................ . 
7. Covered to level of U. S. B. M. at 66~.8 ft. A.T ...................... . 
6. Covered to level of city well no. ~ at 6.56.5 ft. A.T ................... . 
5. River fill of sand and gravel. Includes much of the Eau Claire horizon .. . 
4. Sandstone and shale, mostly medium- to fine-grained white sand with well-
rounded and frosted grains. Lower part probably Mt. Simon ........... . 
Mt. Simon Member 
3. Sandstone, white to brown, with sharp, medium to fine grains ......... . 
PRE-CAMBRIAN: ARCHEOZOIC (?) (surface at 169 .. 5 ft. A.T.) 
~. Granite, weathered .............................................. . 
1. Biotite granite, seemingly fresh. to bottom of city well no. ~ (l5~ .. 5 ft. A.T.) 
ONEOTA DOLOMITE 
WINONA, WINONA COUNTY 
Section of Sugar Loaf Hill 
18. Dolomite, rough, cavernous, buff to brown. with quartz-lined cavItIes and 
much chert ........................................................ . 
17. Dolomite, massive, brown to buff. Exposed in the quarry ................. . 
16. Dolomite, massive, drab to buff; upper part knotty .. probably of algal origin 
15. Dolomite, compact, buff to gray, also green mottled with pink. Contains shell 
fragmen ts ......................................................... . 
14. Dolomite. buff with green and pink streaks ............................ . 
13. Dolomite. buff to pink. A cryptozoon bed .............................. . 
1~. Dolomite, compact, even-bedded, oolitic, gray to buff. with occasional calcite 
crystals ........................................................... . 
II. Dolomite, thin-bedded. oolitic. with scattered grains of sand ............. . 
10. Sandstone. buff, dolomitic, thin-bedded. with angular sandstone pebbles and 
calcite crystals ...................................................... . 
9. Sandstone. brown to buff, with calcite crystals and some angular pebbles of 
sandstone .......................................................... . 
8. Sandstone, friable, yellow. with some hard, nodular lumps of sandstone .... . 
7. Dolomite, a cryptozoon layer ......................................... . 
JORDAN SANDSTONE (top at 1,033.8 ft. A.T.) 
6. Sandstone. poorly cemented. cross-bedded. white to yellow .............. . 
5. Sandstone. in layers of very firmly cemented sandstone. alternating with layers 
of poorly cemented white to yellow or brown sand ...................... . 
4. Sandstone, with layers of yellow to brown dolomitic sandstone ............ . 
ST. LAWRENCE AND FRANCONIA FORMATIONS 
3. Covered interval .................................................... . 
DRESBACH FORMATION (?) 
~. Sandstone. coarse, yellow to white, poorly cemented .................... . 
1. Covered to level of Mississippi River at Winona (pool level at 645.5 ft. A.T.) 
THICKNESS 
(in feet) 
6.5 
~.5 
~~.O 
10.0 
1.3 
6.3 
15~.O 
~30.0 
105.0 
5.0 
1~.0 
THICKr;ESS 
(in feet) 
~5.0-
30.0 
7.5 
1.0 
0.8 
0.8 
5.0 
1.5 
1.8 
1.3 
~.O 
0.7 
4.0 
75.0 
11.3 
~31.5 
1.5 
65.0 

PART FOUR 
FAUNAL LIST 
A PRELIMINARY LIST OF FOSSILS FROM MINNESOTA FORMATIONS 

FAUNAL LIST 
CRETACEOUS 
COLERAINE FORMATION (Benton) 
Pol,vchaeta 
Serpula bicarinata Bergquist ms. 
Brachiopoda 
Lingula subspatulata? Hall and Meek 
Pelec,vpoda 
Anatina marblensis Bergquist ms. 
Anatina plicata Bergquist ms. 
Anomia propatoris White 
Barbatia micronema (Meek) 
Camptonectes platessa (White) 
Cardium engstromi Bergquist ms. 
Corbula kanabensis Stanton 
Cymbophora emmonsi? (Meek) 
Cymbophora utahensis? (Meek) 
Exogyra boveyensis Bergquist ms. 
Exogyra laeviuscula Roemer 
Exogyra lamellosa Bergquist ms. 
Exogyra mesabiensis Bergquist ms. 
Inoceramus fragilis Hall and Meek 
Inoceramus fragilis mesabiensis 
Bergquist ms. 
Inoceramus sp. 
Legnmen cf. planulatum (Conrad) 
Leptosolen biplicata Conrad 
Lima utahensis Stanton 
l\'lodiola arcturusensis Bergquist ms. 
Nucula coloradoensis Stanton 
Ostrea congesta Conrad 
Ostrea gilei Bergquist ms. 
Ostrea prudentia White 
Ostrea rugosa Bergquist ms. 
Ostrea (Alectryonia) staufferi 
Bergquist ms. 
Parapholas sphenoideus White 
Pholadomya colerainensis Bergquist ms. 
Pinna sp. 
Pteria gastrodes (Meek) 
Pteria hillannexensis Bergquist ms. 
Siliqua huerfanensis Stanton 
Tapes cyprimeriformis Stanton 
Tellina calumetensis Bergquist ms. 
Teredolites sp. 
Yoldia calumetensis Bergquist ms. 
Gastropoda 
Actaeon propinquus Stanton 
Anchura grouti Bergquist ms. 
Calliomphalus d. american us Wade 
Fusus shu mardi Hall and Meek 
Gyrodes conradi Meek 
Lispodesthes nuptialis (White) 
Lunatia concinna (Hall and Meek) 
Nerita minnesotensis Bergquist ms. 
Rostellites dalli (Stanton) 
Scalaria sp. 
Volutoderma sp. 
ScaphopoJa 
Dentalium sp. 
Cephalopoda 
Acanthoceras sp. 
Epengonoceras cf. dumblei (Cragin) 
Metacalycoceras' sp. 
Metoicoceras swallovi (Shumard)? 
Scaphites sp. 
Decapoda 
Callianassa sp. 
Hoploparia sp. 
Pisces 
Acrodus sp. 
Coelodus sp. 
Corax falcatus Agassiz 
Galeus sp. 
Lamna appendiculata (Roemer) 
Lamna cuspidata Agassiz 
Lamna elegans Agassiz 
Odontaspis sp. 
Onchopristis sp. 
Scapanorhynchus sp. 
Reptilia 
Clidastes sp. 
Hyposaurus sp. 
SHALE (probably Benton) 
Foraminifera 
Bolivina punctata d'Orbigny 
Bulimina pupoides d'Orbigny 
Gaudryina pupoides d'Orbigny 
Globigerina bulloides d'Orbign~' 
Globigerina cretacea d'Orbigny 
Globigerina marginata Reuss 
Globigerina sacculifera Bradv 
Lagena favoso-punctata Bra~ly 
Lagena hispida Reuss 
Operculina complanata Defrance 
Operculina complanata granulosa 
Leymerie 
Orbulina universa d'Orbigny 
Pu.lvinulina hauerii (d'Orbigny) 
Splroplecta americana Ehrenberg 
Textularia agglutinans d'Orbign,v 
Textularia globulosa Ehrenberg 
Textularia turris d'Orbigny 
Trochammina infiata (Montagu) 
DAKOTA FORl\IATION 
Plants 
Acer macrofolia Lesquereux 
Alnites crassus Lesquereux 
~~8 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Alnites cuniata Lesquereux 
Andromeda parlatori Heer 
Aralia radiata Lesquereux 
Bumelia marcouana (Heer) 
Capsulocarpus dakotensis Berry 
Cinnamomum scheachzeri Heer 
Cissus browniana Lesquereux 
Crataegus atavina Heer 
Dewalquea primordalis Lesquereux 
Diospyros pseudoanceps Lesquereux 
. Ficus austiniana Lesquereux 
Ficus halliana Lesquereux 
Ficus laurophylla Lesquereux 
.Juglans debeyana (Heer) 
Laurophyllum reticulatum Lesquereux 
Laurus nebrascensis Lesquereux 
Laurm. plutonia Heer 
LirlOdendron meeki Heer 
l\Ia2'''olia alternans Heer 
Phyllites moorei Heel' 
Phyllites vanonae Heer 
Pinus quellstedti Heel' 
Platanus primaeva Lesquereux 
Popuiites cyclophyllus Heel' 
Populites elegans Lesquereux 
Populites greeri Lesquereux 
Populites lancastriensis Lesquereux 
Populites litigiosus Heel' 
Populites winchelli Lesquereux 
Populus berggreni Heel' 
Protophyllocladus subintegrifolnus 
(Lesquereux) 
Protophyllum credneroides Lesquereux 
Protophyllum integerrimum Lesquereux 
Salix lanceolata Newberry 
Salix proteifolia Lesquereux 
Sapindus morrisoni Lesquereux 
Sassafras acutilobum Lesquereux 
Sequoia winchelli Lesquereux 
Pelecypoda 
Margaritana nebrascensis 
Meek and Hayden 
Unio danae Meek and Hayden 
Uniosp. 
Reptilia 
Dinosauria (gastroliths) 
DEVONIAN 
Cf.DAn V ALLEY LIl\lESTONE 
Anthozoa 
Acervularia da\'idsoni 
Edwards and Haime 
Cladopora magna Hall and Whitfield 
Favosites sp. 
Hederella filiformis (Billings) 
Zaphrentis sp. 
Hydrozoa 
Dictyonema sp. 
Idiostroma sp. 
Stromatoporella erratica 
(Hall and Whitfield) 
Bryozoa 
Polypora sp. 
Semicoscinium rhomhicum? Ulrich 
Teaniopora sp. 
Brachiopoda 
Athyris coloradoensis Girty 
Athyris fulton ens is (Swallow) 
Atrypa histryx Hall 
Atrypa reticularis (Linnaeus) 
Atrypa spinosa Hall 
Camarotoechia sp. 
Chonetes manitobensis Whitea"es 
Chonetes scitulus Hall 
Cranaena iowensis (Calvin) 
Cyrtina hamiltonensis Hall 
Gypidula comis (Owen) 
Gypidula laeviuscula? Hall 
Leptaena rhomboidalis? (Wilckells) 
Martinia sp. 
Nucleospira sp. 
Pelltamerella mullicosta? Cleland 
Productella subalata Hall 
lleticularia fimbriata (Conrad) 
Schizophoria striatula (Schlotheim) 
Schuchertella chemungensis arctistria.ta 
(Hall) 
Spirifer asper Hall 
Spirifer bimesialis Hall 
Spirifer euryteines Owen 
Spirifer iowensis? Owen 
Spirifer orestes Hall and Whitfield 
Spirifer pinonensis? Meek 
Spirifer sp. 
Stropheodonta arcuata Hall 
Stropheodonta demissa (Conrad) 
Stropheodonta halli musculosa? Cleland 
Stropheodonta perplana (Conrad) 
Stropheodonta variabilis? Calvin 
Stropheodonta sp. 
Tropidoleptus occidens Hall 
Pelecypoda 
Conocardium sp. 
Nuculites sp. 
Nyassa parva Walcott 
Palaeoneila sp. 
Paracyclas sp. 
Gastropoda 
Bellerophon perplexa Walcott 
Bellerophon sp. 
Coleolus sp. 
Cyclonema sp. 
Eunemia sp. 
Hyolithes alatus? Whiteaves 
Loxonema sp. 
Murchisonia dowlingi? Whiteaves 
Murchisonia sp. 
Pleurotomaria sp. 
Raphistoma disciformis? Tschernyschew 
Raphistoma terrelli Cleland 
FAUNAL LIST 
Straparollus clymenoides? Hall 
Tentaculites sp. 
Trochonema monroei? Cleland 
Trochonema sp. 
Cephalopoda 
Orthoceras sp. 
Poterioceras sp. 
Trilobita 
Phacops sp. 
Proetus sp. 
Conodonts 
Acodina conca va Stauffer 
Acodina covina Stauffer 
Acodina curvata Stauffer 
Acodina cuspidata Stauffer 
Acodina delata Stauffer 
Acodina lanceolata Stauffer 
Acodina Iirata Stauffer 
Acodina ursa Stauffer 
Acodina velva Stauffer 
Acodina zionensis Stauffer 
Angulodus elongatus Stauffer 
Belodus devonicus Stauffer 
Bryantodus brickeri Stauffer 
Bryantodns hickoki Stanffer 
Bryantodus hormeli Stauffer 
Bryantodus versus Stauffer 
Cervicornoides minnesotensis Stauffer 
Ctenognathus elegans Stauffer 
Hindeodella austinensis Stauffer 
Hindeodella moweri Stauffer 
Icriodus brevis Stauffer 
Icriodus cymbiformis? 
Branson and Mehl 
Icriodus expansus Branson and Mehl 
Ligonodina armena Stanffer 
Ligonodina atana Stauffer 
Ozarkodina congesta Stauffer 
Pandorina bam bona Stanffer 
Pandorina gratiosa Stauffer 
Pandorina insita Stauffer 
Plectodina tilbara Stauffer 
Polygnathus angulosus Stauffer 
Polygnathus Imlkus Stauffer 
Polygnathus juvensis Stauffer 
Polygnathus porcillus Stauffer 
Polygnathus sanduskiensis Stauffer 
Polygnathus strongi Stauffer 
Polygnathus varcus Stauffer 
Polygnathus xylus Stauffer 
Prioniodella mulata Stauffer 
Prioniodina tortus Stauffer 
Prioniodus remus Stauffer 
Prioniodus taritus Stauffer 
Synprioniodus forsenta Stauffer 
Synprioniodus tropa Stauffer 
Trichognathus blanda Stauffer 
ORDOVICIAN 
MAQUOKETA FORMATION: Wykoff Member 
Spongiae 
Heterospongia subramosa Ulrich 
Hindia parva? Ulrich 
Ischadites iowensis (Owen) 
Receptaculites sp. 
Anthozoa 
Columnaria vacua Foerste 
Protaraea vetusta (Hall) 
Streptelasma rusticum (Billings) 
Hydrozoa 
Diplograptus peosta Hall 
Cystoidea 
Glyptocystites sp. 
Lichenocrinus affinis Miller 
Pleurocystites sp. 
Crinoidea 
Carabocrinus sp. 
Bryozoa 
Bythopora gracilis (Nicholson) 
Homotrypella rustica Ulrich 
Rhombotrypa quadrata (Rominger) 
Brachiopoda 
Dalmanella corpnlenta (Sardeson) 
Dalmanella futilis (Sardesoll) 
Dalmanella ignota (Sardeson) 
Dalmanella macrior (Sardeson) 
Dalmanella meeki (Miller) 
Daimanella porrecta (Sardeson) 
Dalmanella rogata (Sardeson) 
Dalmanella tersa (Sardeson) 
Dinorthis proavita (Winchell and 
Schuchert) 
Dinorthis (Plaesiomys) subquadrata 
(Hall) 
Hebertella (Glyptorthis) illsculpta 
(Hall) 
Leptaella ullicostata 
(Meek and Worthen) 
Lingulasp. 
Lingulasma schucherti Ulrich 
Orbiculoidea lamellosa (Hal!) 
Platystrophia biforata (Schlot-
heim) 
Platystrophia crassa (James) 
Plectambonites recedens (Sardeson) 
Plectambonites saxeus (Sardeson) 
Plectambonites sericeus (Sowerby) 
Plectorthus (Austillella) whitfieldi 
(N. H. Winchel!) 
Rafinesquina alternata (Emmons) 
Rafinesquilla deltoidea (Conrad) 
Rafiuesquina kingi (Whitfield) 
Rhynchotrema capax (Conrad) 
Schizotreta pelopea (Billings) 
Strophomena acuta (Winchell and 
Schuchert) 
Strophomella fluctuosa occidelltalis 
Foerste 
Strophomena neglecta (James) 
229 
Q30 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Strophomena planodorsnta Winchell 
and Schuchert 
Strophomena planum bona (Hall) 
Strophomena planum bona subtenta 
(Hall) 
Zygospira modesta Hall 
Pelecypod a 
Byssonychia tenuistriata Ulrich 
Ctenodonta recurva (Ulrich) 
Ctenodonta similis (Ulrich) 
Ctenodonta simulat~ix Ulrich 
Cyrtodonta grandis luculenta 
(Sardesoll ) 
L~'rodesma major (Ulrich) 
;\'Iodiolopsis excellens Ulrich 
Orthodesma canaliculatum Ulrich 
Saffordia suleodorsata (Ulrich) 
Saffordia ventralis Ulrich 
WhitelJa obliquata Ulrich 
"'hitclla quadrangularis (Whitfield) 
"'hi tella sterlinge!1sis 
(Meek and Worthen) 
Gastropoda 
Conularia sp. 
Cyrtolites disjunctus 
Ulrich and Scofield 
Hormotoma gracilis (Hall) 
Hormotoma gracilis multivolvis 
Ulrich and Scofield 
Liospira micula (Hall) 
Lophospira acuminata 
Ulrich and Scofield 
Lophospira bicincta (Hall) 
Lophospira obliqua Ulrich 
Lophospira pulchella 
Ulrich and Scofield 
Lophospira quadriculca ta 
Ulrich and Scofield 
lVIeekospira subconica 
Ulrich and Scofield 
Phragmolites dyeri (Hall) 
Salpingostoma imbricatum 
Ulrich and Scofield 
Sinuites cancellatus (Hall) 
Sinuites concinnus (Ulrich and Scofield) 
Cephalopoda 
Diestoceras staufieri Foerste 
Orthoceras sociale Hall 
Spyroceras perroti (Clarke) 
Trilobita 
Amphilichas bicornis (Ulrich) 
Bumastus sp. 
Cah'mene meeki Foerste 
En~rinurus cristatus Clarke 
lllaenus sp. 
Isotelus gigas De Kay 
Isotelus maximus Locke 
Onchometopus susae (Whitfield) 
Ostracoda 
Aparchites fimbrialus (Ulrich) 
Ceratopsis robusta (Ulrich) 
:MAQUOKETA FORJ\lATION: Dubuque Member 
Anthozoa 
Streptelasma rusticum (Billings) 
Hydrozol> 
Climacograptus (lVlesograptus) putillus 
(Hall) 
Polychaeta 
Cornulites sp. 
Bryozoa 
Spatiopora iowensis Ulrich 
Brachiopoda 
Dalmanella corpulenta (Sardeson) 
Dalmanella futilis (Sardeson) 
Dalmanella meeki (Miller) 
Dalmanella rogata (Sardeson) 
Dinorthis (Plaesiomys) subquadrata 
(Hall) 
Leptobolus occidentalis Hall 
Lingula beltrami Winchell and 
Schuchert 
Lingula (Palaeoglossa) deflect a 
(Winchell and Schuchert) 
Lingula (Pseudolingula) 10\\'enS1S 
(Owen) 
Lingula modesta Ulrich 
Lingula philomela Billings 
Lingula sp. 
Lingulasma schucherti tnrich 
Oxoplecia ulrichi (Winchell and 
Schuchert) 
Plectambonites precosis (Sardesoll) 
Plectambonites sericeus (Sowerby) 
Rafinesquina alternata (Emmons) 
Rafinesquina kingi (Whitfield) 
Rhynchotrema sp. 
Schizotreta minutula 
"'inchell and Schuchert 
Strophomena fluctuosa Billings 
Zygospira modesta Hall 
Pelecypod a 
Clidophorus neglectus Hall 
Ctenodonta fecunda Hall 
Ctenodon ta filistriata Ulrich 
Gastropoda 
Archinacella rotunda 
Ulrich and Scofield 
Conularia trentonensis Hall 
Hormotoma gracilis (Hall) 
Liospira micu!a (Hall) 
Plethospira semele (Hall) 
Sinuites cancellatus (Hall) 
Cephalopoda 
Endoceras protei forme Hall 
Orthoceras sociale Hall 
Trilobita 
Isotelus gigas De Kay 
Isotelus maximus Locke 
Ostracoda 
Ceratopsis chambcrsi (Miller) 
Primitia gibbera Ulrich 
Primitia tumidula Ulrich 
FAUNAL LIST 231 
GALENA FOHMATION: Stewartville lVlember 
Hydrozoa 
Ischadites cf. iowensis (Owen) 
Receptaculites oweni Hall 
Brachiopoda 
Rhynchotrema capax? (Conrad) 
Rhynchotrema increbescens (Hall) 
Gastropoda 
Coelocaulus oehlerti Ulrich and Scofield 
Fusispira angusta Ulrich and Scofield 
Fusispira inflata (Meek and Worthen) 
Fusispira inflata ventricosa (Hall) 
Fusispira intermedia Ulrich and Scofield 
Fusispira subbrevis Ulrich and Scofield 
Fusispira subfusiformis (Hall) 
Hormotoma gracilis (Hall) 
Hormotoma? major (Hall) 
Hormotoma trentonensis 
Ulrich and Scofield 
Lophospira augustina (Billings) 
Lophospira augustina minnesotensis 
Ulrich and Scofield 
Lophospira perforata Ulrich and Scofield 
Madurina cuneata (Whitfield) 
l\1aclurina manitobensis (Whiteaves) 
Maclurina subrotunda (Whitfield) 
Maclurites crassus (Ulrich and Scofield) 
Smuites sp. 
Trochonema urn bilica tum (Hall) 
Cephalopoda 
Charactoceras cf. rotundum Troedsson 
Endoceras sp. 
Lambeoceras confertum Foerste 
Lambeoceras lambii (Whitea"es) 
Orthoceras sp. 
Teichertoceras d. husseyi Foerste 
'Vestonoceras minnesotense (Clarke) 
Whitfieldoceras mumiaforme <,Yhitfield) 
Trilobita 
IlIaenus sp. 
Isotelus gigas De Kay 
GALENA FORl\lATIOX: Prosser :Member 
Algae 
ticrophycus ottawaense Billings 
Spongiae 
Hindia parva Ulrich 
Ischadites iO\\'ensis (Owen) 
Receptaculites oweni Hall 
Anthozoa 
Lichenaria minor Ulrich 
Protaraea wtusta (Hall) 
Streptelasma corniculum Hall 
Streptelasma profundum (Conrad) 
Graptiloidea 
Climacograptns typicalis Hall 
Polvchaeta 
Comnlites sp. 
Cystoidea 
'Edrioaster bigsbyi (Billing's) 
Glyptocystites sp. 
Lichenocrinus craterifonnis Hall 
Pasceolus globosus Billings 
Pleurocystites squamosus Billings 
Pleurocystites sp. 
Crinoidea 
Carabocrinus sp. 
Dendrocrinus sp. 
Bryozoa 
Arthroclema armatum Ulrich 
Arthroc!ema pulchellum Billings 
Arthropora bifurcata Ulrich 
Arthropora reversa Ulrich 
Aspidopora elegantula (Ulrich) 
Batostoma humile Ulrich 
Ceramoporella inc! usa Ulrich 
Ceramoporella interporosa Ulrich 
Chasmatopora reticulata (Hall) 
Coeloclema trentonense (Ulrich) 
Constellaria varia Ulrich 
Corynotrypa delicatula (James) 
Corynotrypa inflata (Hall) 
Crepipora snbaequata Ulrich 
Cyphotrypa acervulosa (Ulrich) 
Dekavella trentonensis cmrich) 
Dian~lites petropolitanus Dybowski 
Diastoporina flabellata Ulrich 
Diplotrypa limitaris Ulrich 
Diplotrypa negleeta Ulrich 
Eridotrypa aedilis (Eicl1\vald) 
Eridotrypa aedilis minl)r (l1rich) 
Eridotrypa exigua mrich 
Eridotrypa trentonensis (Nicholson) 
Escharopora recta Hall 
Eurydictya multipora (Hall) 
FayositeIIa laxata (Ulrich) 
Graptodict~'a proava (Eic!n"ald) 
Hallopora ampla (Ulrich) 
Hallopora dumalis (Ulrich) 
Hallopora goodhuensis (Ulrich) 
Hallopora multitabulata (Ulrich) 
HaJIoporina crenulata (Ulrich) 
Helopora mucronata Ulrich 
Helopora quadrata Ulrich 
Helopora sp. 
Hemiphragma irrasum (Ulrich) 
Hemiphragma ottawaense (Foord) 
Hemiphragma tenuimurale Ulrich 
Homotrypa callosa Ulrich 
Homotrypa similis Foord 
Homotr~'pa subramosa Ulrich 
Homotrypa subramosa insigllis (Ulrich) 
Homotrypa sp. 
Homotrypella hospitalis crassa (Ulrich) 
Homotrypella mundula Ulrich 
HomotrypelIa? oyata Ulrich 
l\fesotrypa discoidea Ulrich 
Mesotrypa quebecensis Ulrich 
l\fesotrypa? rotunda Ulrich 
Mitoclema? mundulum Ulrich 
J\Ionotr~'lxl intabulata Ulrich 
l\Ionticulipora arborea Ulrich 
l\fonticulipora cannonensis Ulrich 
Nematopora conferta Ulrich 
232 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Nematopora consueta Bassler 
Nematopora delicatula Ulrich 
Nematopora granosa Ulrich 
Nematopora ovalis Ulrich 
Pachydictya acuta (Hal!) 
Pachydictya elegans Ulrich 
Pach~'dictya fimbriata Ulrich 
Pachydictya magnipora Ulrich 
Pachydictya occidentalis Ulrich 
Pachydictya pumila Ulrich 
Pachydictya pumila sublata Ulrich 
Phaenopora incipiens Ulrich 
Prasopora affinis Foord 
Prasopora conoidea Ulrich 
Prasopora grandis (Ulrich) 
Prasopora insularis Ulrich 
Prasopora insularis fillmorensis Ulrich 
Prasopora oculata Foord 
Prasopora selwyni (Nicholson) 
Prasopora simulatrix Ulrich 
Prasopora sp. 
Rhinidictya minima Ulrich 
Rhinidictva minima modesta Ulrich 
Rhinidictya mutabilis (Ulrich) 
Rhinidictya mutabilis major (Ulrich) 
Rhinidictya neglecta Ulrich 
Vinella repens Ulrich 
Brachiopoda 
Catazyga uphami 
(Winchell and Schuchert) 
Crania trentonensis Hall 
Cyclospira bisulcata (Emmons) 
Dalmanella rogata (Sardeson) 
Dalmanella sp. 
Dinobolus? pan· us Whitfield 
Dinorthis meedsi 
(Winchell and Schuchert) 
Dinorthis meedsi germana 
(Winchell and Schuchert) 
Dinorthis pectinella (Emmons) 
Dinorthis (Plaesiomys) subquadrata 
(Hall) 
Hebertella bellarugosa (Conrad) 
Hebertella borealis (Billings) 
Hebertella frankfortensis Foerste 
Hesperorthis tricenaria (Conrad) 
Leptaena unicostata 
(Meek and Worthen) 
Lingula? canadensis Billings 
Lingula cobourgensis Billings 
Lingula (Palaeoglossa) deflecta 
(Winchell and Schuchert) 
Lingula (Palaeoglossa) hurlbuti 
(N. H. Winchell) 
Lingula (Pseudolingula) iowensis 
(Owen) 
Lingula riciniformis Hall 
Lingula riciniformis galenensis 
Winchell and Schuchert 
Lingula sp. 
Lingulasma galenense 
Winchell and Schuchert 
Parastrophia hemiplicata Hall 
Parastrophia hemiplicata rotunda 
(Winchell and Schuchert) 
Parastrophia scofieldi 
(Winchell and Schuchert) 
Parastrophia sp. 
Petrocrania ulrichi (Hall and Clarke) 
Pholidops trentonensis minor 
Winchell and Schuchert 
Pianodema amoena (N. H. Winchell) 
Pianodema subaequata (Conrad) 
Platystrophia biforata (Schlotheim) 
Platystrophia sp. 
Plectambonites gibbosus 
Winchell and Schuchert 
Plectambonites minnesotensis 
(Sardeson) 
Plectambonites sericeus (Sowerby) 
Plectorthis plicatella (Hall) 
Plectorthis plicatella trentonensis 
Foerste 
Plectorthis (Austinella) whitfieldi 
(N. H. Winchell) 
Rafinesquina alternata (Emmons) 
Rafinesquina alternata loxorhytis 
(Meek) 
Rafinesqnina deltoidea (Conrad) 
Rafinesquina sp. 
Rhynchotrema increbescens (Hall) 
Rhynchotrema laticostatum 
(Winchell and Schuchert) 
Rhynchotrema sp. 
Schizocrania filosa Hall 
Schizotreta pelopea (Billings) 
Strophomena billingsi 
Winchell and Schuchert 
Strophomena emaciata 
Winchell and Schuchert 
Strophomena fluctuosa occiden talis 
Foerste 
Strophomena incurvata (Shepard) 
Strophomena scofieldi 
Winchell and Schuchert 
Strophomena trentonensis 
Winchell and Schuchert 
Strophomena trilobata (Owen) 
Trematis ottawaensis Billings 
Vellamo diversa (Shaler) 
Vellamo diversa altissima 
(Winchell and Schuchert) 
Zygospira recurvirostris (Hall) 
Pelecypoda 
Allodesma subellipticum (Ulrich) 
Ambonychia affinis Ulrich 
Ambonychia amygdalina Hall 
Ambonychia bellistriata Hall 
Byssonychia intermedia 
(Meek and Worthen) 
Clidophorus consuetus Ulrich 
Clionychia un data (Emmons) 
Clionychia sp .. 
Ctenodonta alta (Hall) 
FAUNAL LIST 233 
Ctenodonta carinata Ulrich 
Ctenodonta intermedia (Ulrich) 
Ctenodonta oviformis Ulrich 
Ctenodonta subnasuta Ulrich 
Ctenodonta subrotunda (Ulrich) 
Ctenodonta sp. 
Cuneamya truncatula Ulrich 
Cvrtodonta a/finis fillmorellsis Ulrich 
Cyrtodonta gibbera Ulrich 
Cyrtodonta grandis (Ulrich) 
Cyrtodonta grandis germana (Ulrich) 
Cyrtodonta obliqna 
(Meek and Worthen) 
Cyrtodonta parva Ulrich 
Cyrtodonta sp. 
Endodesma compressnm Ulrich 
Endodesma cnneatnm Ulrich 
Endodesma postlatum Ulrich 
Lyrodesma cannonense Ulrich 
l\1:atheria rugosa Ulrich 
Modiolodon patulus Ulrich 
Modiolopsis mytiloides Hall 
Modiolopsis nana Ulrich 
Modiolopsis oweni Ulrich 
Modiolopsis sp. 
Orthodesma schucherti Ulrich 
Orthodesma subnasutum 
(Meek and Worthen) 
Orthodesma sp. 
Plethocardia suberecta Ulrich 
Prolobella striatula Ulrich 
Psiloconcha minnesotensis Ulrich 
Rhytimya sinuata Ulrich 
Saffordia modesta (Ulrich) 
Sphenolium striatum Ulrich 
Vanuxemia abrupta Ulrich 
Vanuxemia hayniana (Safford) 
Vanuxemia sp. 
Whiteavesia subcarinata (Ulrich) 
Whitella praecipta Ulrich 
Whitella subcarinata Ulrich 
Whitella truncata Ulrich 
Whitella ventricosa (Hall) 
Gastropoda 
Archinacella semicarinata 
Ulrich and Scofield 
Archinacella valida (Sardeson) 
Bellerophon clausus? Ulrich 
Belleropholl platystoma 
(Meek and Worthen) 
Bellerophon sillliEs Ulrich and Scofield 
Bucania elliptica Ulrich and Scofield 
Bucania Endsleyi (Safford) 
Bucania sublat~ Ulrich and Scofield 
Clathrospim conica Ulrich and Scofield 
Clathrospira subconica (Hall) 
Coelocaulus neglectus 
Ulrich and Scofield 
Conularia quadrat a "'alcott 
Conularia trentonensis Hall 
Cyclonema varicosum Hall 
Cyclonema sp. 
Cyrtolites ornatus minor 
Ulrich and Scofield 
Cyrtospira wykoffensis 
Ulrich and Scofield 
Eccyliolllphalus subrotundus 
Ulrich and Scofield 
Eccyliopterus owen anus 
(Meek and Worthen) 
Eccyliopterus sp. 
Eotomaria sp. 
Fusispira angusta Ulrich and Scofield 
Fusispira angusta subplana 
Ulrich and Scofield 
Fusispira convexa Ulrich and Scofield 
Fusispira inftata (Meek and Worthen) 
Fusispira inftata ventricosa (Hall) 
Fusispira intermedia Ulrich and Scofield 
Fusispira nobiEs Ulrich and Scofield 
Fusispira planulata Ulrich and Scofield 
Fusispira subbrevis Ulrich and Scofield 
Fusispira subfusiforlllis (Hall) 
Fusispira vittata (Hall) 
Fusispira sp. 
Gyronema sp. 
Helcionopsis subcarinata 
Ulrich and Scofield 
Holopea appressa Ulrich and Scofield 
Holopea excelsa Ulrich and Scofield 
Holopea paludiniformis Hall 
Holopea pyrene Billings 
Holopea rotunda Ulrich and Scofield 
Holopea similis Ulrich and Scofield 
Holopea supra plana Ulrich and Scofield 
Holopea sp. 
Hormotoma bellicincta (Hall) 
Hormotoma gracilis' (Hall) 
Hormotoma? major (Hall) 
Hormotoma salteri Ulrich 
Hormotoma trentonensis 
Ulrich and Scofield 
Hormotoma sp. 
Kokenospira costaIis 
(Ulrich and Scofield) 
Liospira americana (Billings) 
Liospira angustata Ulrich and Scofield 
Liospira proglle Billings 
Liospira vitruvia (Billings) 
Liospira sp. 
Lophospira augustina minnesotensis 
Ulrich and Scofield 
Lophospira bicincta (Hall) 
Lophospira elevata Ulrich and Scofield 
Lophospira fillmorensis 
Ulrich and Scofield 
Lophospira medialis Ulrich and Scofield 
Lophospira obliqua Ulrich 
Lophospira perforata 
Ulrich and Scofield 
Lophospira sumnerensis (Safford) 
Lophospira sp. 
l\iaclurites crassus macer 
(Ulrich and Scofield) 
234 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Ophiletina sublaxa sequens 
Ulrich and Scofield 
Oxydiscus subacutus Ulrich 
Phragmolites compressus Conrad 
Phragmolites dyeri cellulosus 
Ulrich and Scofield 
Raphistoma peracutum 
Ulrich and Scofield 
Raphistoma sp. 
Raphistomina rug-ata 
Ulrich and Scofield 
Salpingostoma sculptile 
Ulrich and Scofield 
Scenella affinis Ulrich and Scofield 
Scenella affinis obsoleta 
Ulrich and Scofield 
Scenella radialis Ulrich and Scofield 
Sinuites cancellatus (I-J:all) 
Sinuites cancellatns trentonensis 
(Ulrich and Scofield) 
Sinuites peryolntus (Ulrich and Scofield) 
Sinuites sp. 
Strophostylus textilis 
Ulrich and Scofield 
Subulites elongatus Conrad 
Subulites pergracilis Ulrich and Scofield 
Subulites sp. 
Tetranota bidorsata (Hall) 
Tetranota obsoleta Ulrich and Scofield 
Tetranota sexcarinata 
Ulrich and Scofield 
Trochonema altum Ulrich and Scofield 
Trochonema fragile Ulrich and Scofield 
Trochonema (Eunema) robbinsi 
Ulrich and Scofield 
Trochonema (Eunema) sal teri 
Ulrich and Scofield 
Trochonema (Eunema) simile 
Ulrich and Scofield 
Trochonema snbcrassnm 
Ulrich and Scofield 
Trochonema unbilicatnl1l (Hall) 
Trochonema sp. 
Cephalopoda 
Actinoceras bigsbyi Bronn 
Actinoceras sp. 
Cameroceras hennepini Clarke 
Cameraceras? multicameratum 
(Emmons) 
Cycloceras olorus (Hall) 
Cyrtoceras sp. 
Diestoceras clarki Foerste 
Endoceras proteiforme Hall 
lVlanitoulinoceras? wykoffense Foersle 
Oncoceras douglassi Clarke 
Oncoceras sp. 
Orthoceras beltrami Clarke 
Orthoceras junceum Hall 
Orthoceras socia Ie I-Iall 
Orthoceras sp. 
Plectoceras sp. 
Polywammoceras prestonense Foersle 
Spyroceras bilineatum (IIaIl) 
Spyroceras perroti? (Clarke) 
Teichertoceras husseyi Foerste 
Tripteroceras planOCOllYeXUIll (Hall) 
Tripteroceras sp. 
vVhitfieldoceras exiguum (Billings) 
Trilobita 
Amphilichas cueullus 
(Meek and Worthen) 
Amphiliehas robbinsi (Ulrich) 
Bumastus orbicaudatus Billings 
Bumastus? trentonellsis Emmons 
Calliops brevis Ulrich and Delo 
Calliops schl1lidti (Clarke) 
Calymene sen aria Conrad 
Calymene sp. 
Ceraurus pleurexanthemus Green 
Ceraurus sp. 
Corydocephalus wesenbergensis paulian-
us (Clarke) 
Cybeloides? ",inchelli (Clarke) 
E~harpes minnesotensis (Clarke) 
Eoharpes ottawaensis (Billings) 
Eoharpes rutrellum (Clarke) 
Goldius lunatus (Billings) 
Haploconus galenensis (Clarke) 
lJIaenus americanus (Billings) 
lJIaenus sp. 
Isotelus gigas De Kay 
Isotelus maximus Locke 
Nileus vigilans (Meek and Worthen) 
Odontopleura paryula (Walcott) 
Onchometopus susae (Whitfield) 
Ostracoda 
Aparchites minutissul1lUS lrentonensis 
Ulrich 
Bollia subaequata Ulrich 
Bollia unguloidea Ulrich 
Bythocypris cylindrica (Hal!) 
Ceratopsis chal1lbersi (Miller) 
Ctenobolbina obliqua Ulrich 
Eurychilina yentrosa Ulrich 
Halliella labiosa Ulrich 
Halliella linepunctata Kay 
.Jonesella obscura Ulrich 
Primitia micula Ulrich 
Primitia uphami Ulrich 
Punctaparchites rugosus (.Jones) 
Punctaparchites rugosus aretus (Ulrich) 
Schmidtella affinis Ulrich 
Schmidtella incompla subaequalis 
Ulrich 
Tetradella lunatifera. (Ulrich) 
GALENA FORMATION: Decorah Shale Member 
Algae 
Solenopora compacta (Billings) 
Spongiae 
Camarocladia rugosa Ulrich 
Camarocladia sp. 
Cylindricoelia minnesotensis Ulrich 
H'india par"" Ulrich 
FAUNAL LIST 235 
Ischadites iowensis (Owen) 
Rauffella filosa Ulri~h 
Rauffella palmi pes Ulrich 
Receptaculites oweni Hall 
Anthozoa 
Aulopora? trentonensis 
Winchell and Schuchert 
Lichenaria typa Winchell and Schuchert 
Streptelasma corniculum Hall 
Streptelasma? parasiticum Ulrich 
Streptelasma (Petraia) profundum 
(Conrad) 
Polychaeta 
Arabellites acerbus Stauffer 
Arabellites ignotus Stauffer 
Arabellites modest us Stauffer 
Eunicites eximius Stauffer 
Lumbriconereites cameratus Stauffer 
Lumbriconereites inflexus Stauffer 
Oenonites scelestus Stauffer 
Protarabellites delectus Stauffer 
Protarabellites dubius Stauffer 
Protarabellites fidelis Stauffer 
Cystoidea 
Agelacrinites n. sp. Ulrich 
Eurycystites granosus Ulrich 
Glyptocystites sp. 
Hemicystites paulianus Bassler 
Lichenocrinus crateriformis Hall 
Lichenocrinus sp. 
Pasceolus globosus Billings 
Pyrgocystis sardesoni Bather 
Crinoidea 
Carabocrinus conoideus Sardeson 
Carabocrinus dicyclicus (Sardeson) 
Cremacrinus punctatus Ulrich 
Dendrocrinus sp. 
Glyptocrinus sp. 
Asteroidea 
P alaeaster sp. 
Bryozoa 
Anolotichia impolita (Ulrich) 
Anolotichia sp. 
Arthroclema armatum Ulrich 
Arthroclema cornu tum Ulrich 
Arthroclema pulchellum Billings 
Arthroclema striatum Ulrich 
Arthropora bifurcata Ulrich 
Arthropora simplex Ulrich 
Arthl'ostylus conjunctus Ulrich 
Atactoporella ramosa Ulrich 
Batostoma fertile Ulrich 
Batostoma fertile circulare Ulrich 
Batostoma humile Ulrich 
Batostoma minnesotense Ulrich 
Batostoma Illontuosulll Ulrich 
Batostoma varium Ulrich 
Batosloma winchelli (Ulrich) 
Batostollla winchelli nodosulll Ulrich 
Batostoma winchelli spinnlosum Ulrich 
Berenicea minnesotensis Ulrich 
Bythopora alcicornis Ulrich 
Bythopora herricki (Ulrich) 
Callopora crenulata (Ulrich) 
Ceramophylla frondosa Ulrich 
Ceramoporella inclusa Ulrich 
Chasmatopora corticosa (Ulrich) 
Chasmatopora halli (Ulrich) 
Chasmatopora sublaxa (Ulrich) 
Chasmatopora reticulata (Hall) 
Coeloclellla trentonense (Ulrich) 
Corynotrypa delicatula (James) 
Corynotrypa inflata (Hall) 
Crepipora subaequata Ulrich 
Cyphotrypa inforlllis (Ulrich) 
Dekayella praenuntia echinata Ulrich 
Dekayella trenlonensis (Ulrich) 
Eridotrypa aedilis minor (Ulrich) 
Escharopora confluens Ulrich 
Escharopora subrecta (Ulrich) 
Eurydictya multipora (Hall) 
Fa\'ositella laxata (Ulrich) 
Hallopora ampla (Ulrich) 
Hallopora angularis (Ulrich) 
HaIlopora dumalis (Ulrich) 
Hallopora incontroversa (Ulrich) 
Hallopora multitabulata (Ulrich) 
Hallopora pulchella (Ulrich) 
Hallopora pulchella persimilis (Ulrich) 
Hallopora undulata (Ulrich) 
Halloporina crenulata (Ulrich) 
Hemiphragllla irrasulll (Ulrich) 
Hemiphragma ottawaense (Foord) 
Homotrypa minnesotensis Ulrich 
Homotrypa minnesotensis Illontifera 
Ulrich 
Homotrypa subramosa Ulrich 
Homotrypa tuberculata Ulrich 
Monticulipora arborea Ulrich 
Pachydictya acuta (HalO 
Pachydictya fimbriata Ulrich 
Pachydictya l'oIiata Ulrich 
Prasopora conoidea Ulrich 
Prasopora contigua Ulrich 
Prasopora grandis (Ulrich) 
Prasopora lenticularis Ulrich 
Prasopora silllulatrix Ulrich 
Proboscina tumulosa Ulrich 
Rhinidictya exigua Ulrich 
Rhinidictya fidel is (Ulrich) 
Rhinidictya mutabiIis (Ulrich) 
Rhinidictya mutabilis major (Ulrich) 
Rhinidictya paupera Ulrich 
Stictoporella cribrosa Ulrich 
Stictoporella dumosa Ulrich 
Stictoporella rigida Ulrich 
Trigonodictya conciliatl'ix (Ulrich) 
Vinella repens Ulrich 
Brachiopoda 
Camarella panderi Billings 
Crania setigera Hall 
Crania trentonensis Hall 
Crania sp. 
Dalmanella hamhllrgensis (Walcott) 
'236 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Dalmanella rogata Sardeson 
Dinorthis (Valcourea) deflecta (Conrad) 
Dinorthis pecbnella (Emmons) 
Dinorthis sweeneyi (N. H. Winchell) 
Doleroides gibbosus (Billings) 
Doleroides pervetus (Conrad) 
Hebertella (Glytorthis) bellarugosa 
(Conrad) 
Hesperorthis tricenaria (Conrad) 
Leptaena charloltae Winchell and Schu-
chert 
Lingula cobourgensis Billings 
Lingula riciniformis galenensis Winchell 
and Schuchert 
Pianodema subaequata (Conrad) 
Pianodema circularis (N. H. Winchel!) 
Pholidops trentonensis minor 'Vinchell 
and Schuchert 
Platystrophia biforata? (Schlotheim) 
Plectambonites sericeus (Sowerby) 
Rafinesquina altern at a (Emmons) 
Rafinesquina minnesotensis inquassa 
(Sardeson) 
Rhynchotrema ainsliei N. H. Winchell 
Rhynchotrema increbescens (Hall) 
Rhynchotrema minnesotense (Sardeson) 
Schizocrania filosa Hall 
Skenidioides an thonense (Sardeson) 
Strophomena incurvata (Shepard) 
Strophomena septata Winchell and 
Schuchert 
Slrophomena trentonensis 'Vinchell and 
Schuchert 
Vellamo diversa (Shaler) 
Zygospira recurvirostris (Hall) 
Pelecypod a 
Aristerella nitidula Ulrich 
Colpomya demissa Ulrich 
Ctenodonta aslartaeformis? Salter 
Ctenodonla candens (Sardeson) 
Ctenodonla compressa (Ulrich) 
Ctenodonta cuneiformis Ulrich 
Ctenodonta hamburgensis (Walcott) 
Ctenodonla longa (Ulrich) 
Ctenodonta medialis Ulrich 
Ctenodonta nasuta (Hall) 
Ctenodonta nitida (Ulrich) 
Ctenodonta oviformis Ulrich 
Ctenodonta planodorsata (Ulric·h) 
Ctenodonta scofieldi Ulrich 
Ctenodonta socialis Ulrich 
Ctenodonta sp. 
Cyrlodon ta affinis Ulrich 
Cyrtodonta cingulata (Ulrich) 
Cyrtodonla glabella (Ulrich) 
CyrtodonLa huronensis Billings 
Cyrtodonta obesa Ulrich 
Cvrtodonta rotulata Ulrich 
Cyrtodonta ten ella (Ulrich) 
Lvrodesma acuminatum Ulrich 
Lyrodesma acuminatum intermedium 
'Ulrich 
Matheria rugosa Ulrich 
Modiolodon? gibbus Ulrich 
lVlodiolopsis arguta Ulrich 
lVlodiolopsis chalfield~nsis Ulrich 
Modiolopsis concava Ulrich 
Modiolopsis obsoleta Ulrich 
Modiolopsis similis Ulrich 
Modiolopsis sp. 
Orthodesma minnesotense Ulrich 
Plethocardia umbonata Ulrich 
Technophorus divaricatus Ulrich 
Technophorus extenuatus Ulrich 
Technophorus filistriatus Ulrich 
Vanuxemia crassa Ulrich 
Vanuxemia subrotunda Ulrich 
Vanuxemia umbonata Ulrich 
Vanuxemia sp. 
Whitella compressa Ulrich 
Whitella concentrica Ulrich 
Whitella ruga tina Ulrich 
Whit ella scofieldi Ulrich 
Whitella sp. 
Gastropoda 
Archinacella del eta (Sardesoll) 
Archinacella instabilis incurya Ulrich 
and Scofield 
Archinacella simulatrix Ulrich and Sco-
field 
Archinacella subrotunda Ulrich and 
Scofield 
Bucania emmonsi Ulrich 
Bucania sublata Ulrich and Scofield 
Carinaropsis acuta Ulrich and Scofield 
Carinaropsis minima Ulrich and Scofield 
Carinaropsis phalera (Sardeson) 
Clathrospira conica Ulrich and Scofield 
Clathrospira subconica (Hall) 
Conularia quadrata? Walcott 
Conularia trentonensis Hall 
Cyrtolites dilatatus Ulrich and Scofield 
Cyrtolites retrorsus fillmorensis Ulrich 
and Scofield 
Eotomaria supracingulala (Billings) 
Eotomaria sp. 
Fusispira? spicula Sardeson 
Fusispira sp. 
Gyronema pulchellum Ulrich and Sco-
field 
Gyronema semicarinatum (Salter) 
Hormotoma gracilis (Hall) 
Hormotoma gracilis angus tala (Hall) 
Hormotoma gracilis goodhuensis Ulrich 
and Scofield 
HOl"motoma subangulata Ulrich and 
Scofield 
Hyolithes haconi Whitfield 
Hyolithes sp. 
Liospira abrupla Ulrich and Scofield 
Liospira americana (Billings) 
Liospira angustata Ulrich and Scofield 
Liospira modesta Ulrich 
Liospira vitruvia (Billings) 
:FA UN AL LIST ZS7 
Lophospira bicincla Hall 
Lophospira concinnula Ulrich and Sco-
field 
Lophospira oweni Ulrich and Scofield 
Lophospira peracuta Ulrich and Scofield 
Lophospira pulchella Ulrich and Sco-
field 
Lophospira serrula ta (Saller) 
Lophospira spironema Ulrich and Sco-
field 
Lophospira sp. 
Ophiletina angularis Ulrich and Scofield 
Palaeacmaea humilis Ulrich and Scofield 
Phragmolites obliquus (Ulrich and Sco-
field) 
PIa tyceras depressum Ulrich and Sco-
field 
Raphistoma peracntum Ulrich and Sco-
field 
Salpingostoma buelli (Whitfield) 
Salpingostoma sp. 
Scenella a/finis Ulrich and Scofield 
Sinuites cancellatus (Hall) 
Sinuites pervolutus (Ulrich and Scofield) 
Strophostylus textilis Ulrich and Sco-
field 
Subulites sp. 
Tetranota bidorsata (Hall) 
Tetranota bidorsata minor (Ulrich and 
Scofield) 
Tetranota obsoleta Ulrich and Scofield 
Tetranota sexcarinata Ulrich and Sco-
field 
Trochonema? (Eunema) divosa (Sarde-
son) 
Trochonema retrorsum Ulrich and Sco-
field 
Trochonema umbilicatum (Hall) 
Trvblidium modestum Ulrich and Sco-
field 
Cephalopoda 
Actinoceras bigsbyi Stokes 
Actinoceras tenuifilum (Hal!) 
Cameroceras? multicameratum (Em-
mons) 
Cyrtoceras tenuistrialum Hall 
Cyrtoceras sp. 
Cyrtocerina? schoolera fti Clarke 
Endoceras annulatum? Hall 
Endoceras proteiforme Hall 
Manitoulinoceras? 'nnsawense Foerste 
Nanno aulema Clarke 
Oncoceras sp. 
Orthoceras amplicameratum Hall 
Orthoceras junceum Hall 
Orthoceras tenuistriatllm (Hall) 
Orthoceras sp. 
Scofieldoceras? depressulll Foerste 
Spyroceras anellus (Conrad) 
Spyroceras bilineatum (Hall) 
Spyroceras iowense Foerste 
Tripteroceras planoconvexum (HalO 
Whitfieldoceras c1arkei Foerste 
Zitelloceras hallianum (d'Orbigny) 
Trilobita 
Calliops schmidti (Clarke) 
Calliops sp. 
Calymene senaria Conrad 
Calymene sp. 
Ceraurus pleurexanthemus Green 
Corydocephalus wesenbergensis pauli-
anus (Clarke) 
Eomonorachus intermedius (Walcoll) 
1sotelus gigas De Kay 
1sotelus maximus Locke 
Nileus yigilans (Meek anu ,,'orthen) 
Ostracoda 
Aechmina ionensis Kay 
Aparchites arrectus Ulrich 
Aparchites chatfieldensis Ulrich 
Aparchites granilabiatus Ulrich 
Aparchites trentonensis Ulrich 
Apatochilina? subaequata (Ulrich) 
Bollia subaequata Ulrich 
Bollia unguloidea Ulrich 
Bromidella depress a Kay 
Bromidella rhomboides Kay 
Bythocypris cylindrica (H~Il) 
Bythocypris granti Ulrich 
Ceratopsis chambersi Miller 
Ceratopsis humilinoda Kay 
Ceratopsis quadrifida (Jones) 
Conchoprimitia symmetrica (Ulrich) 
Ctenobolbina fulcrata Ulrich 
Ctenobolbina crassa Ulrich 
Dicranella marginata Ulrich 
Dilobella typa Ulrich 
Eridocollcha oboloides Ulrich and Bass-
ler 
Euprimitia linepunctata (Kay) 
Euprimitia sanctipauli (Ulrich) 
Eurychilina incurva Ulrich 
Eurychilina partifimbriata Kay 
Eurychilina parvifrons Kay 
Eurychililla reticulata Ulrich 
Eurychililla subaequata Ulrich 
Eurychilina subradiata Ulrich 
Eurychilina symmetrica Ulrich 
Eurychilina ventrosa Ulrich 
Halliella labiosa Ulrich 
Halliella linepunctata Kay 
Halliella mag11apuncta Kay 
Kieso"'ia yerrucosa I{a v 
Krausella arcuata Ulri~h 
Laecoprimitia fillmorensis (Ulrich) 
Leperditella macra Ulrich 
Leperditella persimilis Ulrich 
Leperditia fabulites (Conrad) 
]\Iacronotella rugosa (Jones) 
ThIaratia mieula (Ulrich) 
Opikatia rotunda Kay 
Parabolbinu anteced~ns 1\:u,' 
Parabolbina staufferi Ka,' . 
Paraschmidtella centipm;ctata Kay 
238 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Paraschmidtella ovata (Kay) 
ParaschmidteUa planilateralis Kay 
ParaschmidteUa? uphami (Ulrich) 
Parenthatia punctata (Ulrich) 
Primitia mammata Ulrich 
Primitia saintpauli Ulrich 
PrimitieUa constricta Ulrich 
Primitiopsis? beUa Kay 
Punctaparchites oyatus Kay 
Punctaparchites rugosus (Jones) 
Rayella calvini Kay 
Raymondatia goniglypta Kay 
Saccelatia angularis (Ulrich) 
Saccelatia arcuamuralis Kay 
Saccelatia arrecta (Ulrich) 
Saccelatia cletifera Kay 
Schmidtella affinis Ulrich 
Schmidtella incompta Ulrich 
SC'hmidteUa sub rotunda Ulrich 
SchmidteUa umbonata Ulrich 
Scofieldia bilateralis (Ulrich) 
Tetradella ellipsilira Kay 
Tetradella quadrilirata (Hall and Whit-
field) 
Tetradella ulrichi Kay 
Thomasatia falcicosta Kav 
Conodonts . 
Barbarodina typicala Stauffer 
Belodus gl.·andis Stauffer 
Belodus wykoffensis Stauffer 
Cyrtoniodus complicatus Stauffer 
Dichognathus typicus Branson and 
Mehl 
Dichognathus variabilis Stauffer 
Distacodus falcatus Stauffer 
Gyrognathus primus Stauffer 
Heterognathus idoneus Stauffer 
Heterognathus simplex Stauffer 
Lonchodus spinuliferus Stauffer 
Lonchodus sp. a 
Microcoelodus obliquus Stauffer 
Neocoleodus breyiconus? Branson and 
Mehl 
Oistodus abundans Branson and Mehl 
Oistodus brevis Stauffer 
Oistodus cun"atus Branson and l\-Iehl 
Oistodus excelsus Stauffer 
Oistodus fornicalus Stauffer 
Oistodus inclinatus Branson and Mehl 
Oistodus suberectus Branson and Mehl 
Ozarkodina concinna Stauffer 
Ozarkodina pauperata Stauffer 
Ozarkodiua robusta Stauffer 
Paltodns cornutns Stanffer 
Paltodus elegans Stauffer 
Paltodns striatus Stauffer 
Phragmodns cognitus Stanffer 
Pleclodina dilata Stanffer 
Polycaulodns chatfieldensis Stauffer 
Pol;'placogl1athus ramosus Stauffer 
Prioniodus aculeatus Stauffer 
Prioniodus cristalus Stauffer 
Prioniodus sp. 
Pteroconus robustus Stauffer 
Subcordylodus? inaequalis Stauffer 
Subcordylodus rectilineatus Stauffer 
Subprioniodus hamatus Stauffer 
Trichognathus iIlustris? Stauffer 
Trichognathus minnesotensis Stauffer 
Trichognathus recurvus Branson and 
Mehl 
Trichognathus symmetricus Stauffer 
PLATTEVILLE FORl\IATION: Spechts Ferry 
Member 
Spongiae 
Cylindricoelia minnesotensis Ulrich 
Hindia inaequalis Ulrich and Everett 
RauffeUa filosa Ulrich 
RauffeUa palmi pes Ulrich 
Anthozoa 
Anlopora? trentonellsis Winchell and 
Schuchert 
Columnaria haUi Nicholson 
Lichenaria typa Winchell and Schuchert 
Streptelasma cf. breve 'Winchell and 
Schuchert 
Streptelasma? parasiticum Ulrich 
Streptelasma (Petraia) profundum 
(Conrad) 
Tetradium fibratum Safford 
Graptiloidae 
Climacograptus typicalis Hall 
Polychaeta 
Arabellites armillaris Stauffer 
Arabellites brevidentatus Stauffer 
Arabellites contritus Stauffer 
Arabellites digonus Stauffer 
Arabellites giganteus Stauffer 
Arabellites gregalis Stauffer 
Arabellites minutus Stauffer 
Arabellites priscus Stauffer 
Arabellites tantus Stauffer 
Arabellites tumidus Stauffer 
Arabellites sp. b 
Eunicites sp. a 
Eunicites? sp. d 
Hyalinaecites aequidelltatus Stauffer 
Hyalinaecites aureatus Stauffer 
Hyalinaecites delectus Stauffer 
Hyalinaecites parvus Stauffer 
Hyalinaecites plenus Stauffer 
Hyalinaecites subulatus Stauffer 
Hyalinaecites typical is Stauffer 
Hyalinaecites sp. a 
Lumbriconereites arcuatus Stauffer 
Lumbriconereites cameratus Stauffer 
Lumbriconereites cognilus Slauffer 
Lumbriconereites crenatus Stauffer 
Lumbriconereites modestus Stauffer 
Lumbriconercites perfectus Stauffer 
Lumbriconereites potellsus Stauffer 
Lumbriconereites speciosus Stauffer 
Lumbriconereites webbi Stauffer 
FAUNAL LIST 239 
Lumbriconereites sp. a 
Lumbriconereites sp. b 
Nothriles elegans Stauffer 
Nothrites gratus Stauffer 
Oenonites dignus Stauffer 
Oenonites excelsus Stauffer 
Oenonites inornatus Stauffer 
Oenonites magnificus Stauffer 
Oenonites paratus Stauffer 
Oenonites propinquus Stauffer 
Oenonites recuryus Stauffer 
Oenonites spiculatus Stauffer 
Oenonites subquadratus Stauffer 
Oenoniles tacitus Stauffer 
Oenonites sp. b 
Paleonereites cervicornis Stauffer 
Paleonereites sp. 
Protarabellites humilis Stauffer 
Protarabellites maturensis Stauffer 
Protarabellites productus Stauffer 
Protarabellites sp. 
Rhabdochitina? minnesotensis Stauffer 
Staurocephalites acutidentatus Stauffer 
Staurocephalites antiquus Stauffer 
Staurocephalites dentatus Stauffer 
Thalenessites lobutus Stauffer 
Thalenessites sp. 
Ungulites aculeatus Stauffer 
Ungulites bicuspidatus Stauffer 
Ungulites hystricosus Stauffer 
Cystoidea 
Agelacrinites n. sp. Ulrich 
Eurycystites granosus Ulrich 
Foerstediscus splendens Bassler 
Glyptocystites sp. 
Lichenocrinus crateriformis Hall 
Pyrgocystis sardesoni Bather 
Crinoidea 
Carabocrinus conoideus Sardeson 
Carabocrinus dicydicus (Sardeson) 
Carabocrinus sp.' 
Cremacrinus punctatus Ulrich 
lVlerocrinus sp. 
Porocrinus sp. 
Asteroidea 
Protopalaeaster narrawayi (Hudson) 
Bryozoa 
Anolotichia illlpolita (Ulrich) 
Arthroclema cornutum Ulrich 
Arthroclellla striatum Ulrich 
Arthroclema sp. 
Arthropora simplex Ulrich 
Arthrostylus conjullctus Ulrich 
Arthroslylus obliquus Ulrich 
Aspidopora parasitica (Ulrich) 
Atactoporella insueta Ulrich 
Atactoporella typiculis praecipta Ulrich 
Batostomur decipiens Ulrich 
Batostoma fertile Ulrich 
Batosloma fertile circulare Ulrich 
Batostoma magnopora Ulrich 
Batostoma minnesotense Ulrich 
Batostoma varium Ulrich 
Batostoma winchelli (Ulrich) 
Batostoma sp. 
Berenicea miunesotensis Ulrich 
Bythopora herricki (Ulrich) 
Bythopora subgracilis (Ulrich) 
Ceramoporella inclusa Ulrich 
Corynotrypa delicatula (James) 
Cyphotrypa informis (Ulrich) 
Dekayella praenuntia Ulrich 
Dekayella praenuntia echinata Ulrich 
Dekayella praenuntia multipora Ulrich 
Dekayella praenuntia naevigera Ulrich 
Dekayella praenuntia simplex Glrich 
Escharo[Jora angularis Ulrich 
Escharopora confluens Ulrich 
Escharopora' limitaris Ulrich 
Escharopora ramosa (Ulrich) 
Escharopora subrecla (Ulrich) 
Hallopora ampla (Ulrich) 
HaJlopora angularis (Ulrich) 
Hallopora incontroyersa (Ulrich) 
Hallupora multitabulata (Ulrich) 
Hallopora undulata (Ulrich) 
Helopora alternata Ulrich 
Helopora di\'aricata Ulrich 
Hemiphragma irrasnm (Ulrich) 
Homotrypa exiIis Ulrich 
Homotrypa intercalaris Ulrich 
Homotrypa minuesotensis Ulrich 
I-Iomotrypa separata Ulrich 
Homotrypa subramosa Ulrich 
Homotrypella instabilis Ulrich 
Homotrypella Illultiporata Ulrich 
Homotrypella' o\'ata Ulrich 
Mesotrypa infida Ulrich 
Mesotrypa? spinosa Ulrich 
MonticuIipora incompta Ulrich 
Nicholsonella laminata Ulrich 
Nicholsonella ponderosa Ulrich 
Pachvdictya fimbriala rIrich 
Pach;'dict:ya foliata Ulrich 
Phvllodict\'a frondosa' Ulrich 
Ph)'1l0dict3'a varia Ulrich 
Prasopora grandis (Ulrich) 
Rhinidictya exigua Ulrich 
Rhinidicto'a fidelis (Ulrich) 
Rhinidictya mutabilis (Ulrich) 
Rhinidictya mutabilis major (Ulrich) 
Rhinidictva mntabilis senilis Ulrich 
Rhinidict~'a trentonensis Ulrich 
Spatiopol:a labeculosa Ulrich 
Spatiopora sp. 
Stictoporella angularis Ulrich 
Stictoporella angnlaris intermedia Ulrich 
Sticloporella crib rosa Ulrich 
Stictoporella frondifera Ulrich 
Stigmatella claviformis (Ulrich) 
Stomatopora sp. 
Stromatotrypa ovata Ulrich 
Trematopora primagenia Ulrich 
\2-to PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Trematopora primagenia ornata 
(Ulrich) 
Trematopora? primagenia spinosa 
Ulrich 
Brachiopoda 
Crania seligera Hall 
Doleroides gibbosus (Billings) 
Doleroides peryetus (Conrad) 
Hebertella (Glytorthis) bellarugosa 
(Conrad) 
Hesperorthis tricenaria (Conrad) 
uptaena charlottae 'Vinchell and Schu-
chert 
Lingula clathrata Winchell and Schu-
chert 
Lingula elderi Whitfield 
Lingula eya Billings 
Petrocrania ulrichi (Hall and Clarke) 
Pianodema conradi (N. H. Winchell) 
Pianodema minnesotensis Cooper 
Pianodema subaequata (Conrad) 
Pianodema uniplicata Cooper 
Plectambonites sericeus (Sowerby) 
Rafinesquina alternata (Emmons) 
Rafinesquina minnesotensis (N. H. 
'''inchell) 
Rafinesquina minnesotensis inquassa 
(Sardeson) 
Rafinesquina sp. 
Rhynchotrema ainsliei N. H. Winchell 
Rhynchotrema minnesotense (Sardeson) 
Schizocrania filosa Hall 
Strophomena incurYata (Shepard) 
Trematis huronensis Billings 
Zygospira nicolleti Winchell and Schu-
chert 
Zygospira recurvirostris (Hall) 
Pelecypod a 
Ambonychia sp. 
Ctenodonta nasuta (Hall) 
Ctenodonta nitida (Ulrich) 
Cyrtodonta cingulata (Ulrich) 
Cyrtodonta glabella (Ulrich) 
Cyrtodonta huron ens is Billings 
Cyrtodonta obesa Ulrich 
Cyrtodanta rotulata Ulrich 
lViodiolopsis arguta Ulrich 
Orthodesma minnesotense Ulrich 
Technophorus extenuatus Ulrich 
Vanuxemia crass a Ulrich 
Whitella compressa Ulrich 
WhitelJa concentrica Ulrich 
vVhitella rugatina Ulrich 
Gastropoda 
Archinacella deleta (Sal·desOll) 
Carinaropsis acuta Ulrich and Scofield 
Carinaropsis phalera (Sardeson) 
Clathrospira conica Ulrich and Scofield 
Clathrospira subconica (Hall) 
Fusispira? spicula Sardeson 
Hormotoma subangulata Ulrich and 
Scofield 
Lophospira bicincta Hall 
Lophospira cOllcinnula Ulrich and Sco-
field 
Lophospira oweni Ulrich and Scofield 
Lophospira peracuta Ulrich and Scofield 
Lophospira sp. 
Phragmolites obliquus (Ulrich and 
Scofield) 
Pterotheca attenuata (I-lall) 
Raphistoma sp. 
Scenella obtusa (Sardeson) 
Sinuites cancelJatus (Hall) 
Sinuites pervolutus (Ulrich and Scofield) 
Tetranota bidorsata (Hall) 
Tetranota sexcarinata Ulrich and Sco-
field 
Cephalopoda 
Beloitoceras houghtoni (Clarke) 
Beloitoceras janesvillense Foerste 
Cameroceras? multicameratum (Em-
mons) 
Cycloceras olorus (Hall) 
Endoceras proteiforme Hall 
Gonioceras anceps Hall 
Metaspyroceras clarkei Foerste 
Metaspyroceras minneapolis Foerste 
Metaspyroceras perlineatum Foerste 
Scofieldoceras shumardi (Clarke) 
Spyroceras bilineatum (Hall) 
Tripteroceras planoconvexum (Hall) 
Tripteroceras sp. 
Trilobita 
Bathyurus extans (Hall) 
Bumastus? trentonensis Emmons 
Calliops plattevillensis Ulrich and Dela 
Calliops sp. 
Ceraurus pleurexanthus Green 
Eomonorachus intermeduis (Walcott) 
Isotelus gigas De Kay 
Nileus vigilans (Meek and Worthen) 
Ostracoda 
Aparchites ellipticus Ulrich 
Aparchites millepunctatus Ulrich 
Aparchites neglectus Ulrich 
Aparchites trentanensis Ulrich 
Bythocypris curta Ulrich 
Bythocypris granti Ulrich 
Cera tops is chambersi Miller 
Dicrallella bicornis Ulrich 
Dicranella marginata Ulrich 
Dicrallella spinosa Ulrich 
Dilobella simplex Kay 
Euprimitia? celata (Ulrich) 
Eurychilina reticulata Ulrich 
Eurychilina subradiata Ulrich 
Eurychilina ventrosa Ulrich 
Haliatia? duplicata (Ulrich) 
Haploprimitia minutissima (Ulrich) 
Krausella arcuata Ulrich 
Leperditia fabulites (Conrad) 
Moorea? perplexa Ulrich 
Primitia mammata Ulrich 
FAUNAL LIST 241 
Primitiella constricta Ulrich 
Primitiella limbata Ulrich 
Primitiella simulans Ulrich 
Saccelatia angularis (Ulrich) 
Schmidtella brevis Ulrich 
Schmidtella iucompta Ulrich 
Schmidtella subrotunda Ulrich 
Tetradella ellipsilira Kay 
Tetradella quadrilirata (Hall and Whit-
field) 
Winchellatia initialis (Ulrich) 
Winchellatia minnesoteusis Kay 
Conodonts 
Acontiodus alveolaris Stauffer 
Anchyrognathus? sp. a and b 
Barbarodina grandis Stauffer 
Barbarodina typicala Stauffer 
Belodus grandis Stauffer 
Belodus Iineatus Stauffer 
Belodus wvkoffeusis Stauffer 
CordyIodu"s serratus Stauffer 
Cyrtoniodus apicalis Stauffer 
Cyrtoniodus complicatus Stauffer 
Dichognathus typicus Branson and 
Mehl 
Dichognathus variabilis Stauffer 
Dichognathus? sp. 
Distacodus arcuatus Stauffer 
Distacodus falcatus Stauffer 
Euprioniodina dubia Stauffer 
Euprioniodina futilis Stauffer 
Gyrognathus planus Stauffer 
Gyrognathus primus Stauffer 
Heterognathus brevis Stauffer 
Heterognathus idoneus Stauffer 
Heterognathus simplex Stauffer 
Hibbardella? gracilis Stauffer 
Hibbardella? sp. 
Lonchodus aequidentatus Stauffer 
Lonchodus dentatus Stauffer 
Lonchodus spinuliferus Stauffer 
Lonchodussp. b 
Lonchodus sp. 
Microcoelodus obliquus Stauffer 
Microcoelodus sp. 
Neocoleodus spicatus? Branson and 
Mehl 
Oistodus abundans Branson and Mehl 
Oistodus brevis Stauffer 
Oistodus curvatus Branson and Mehl 
Oistodus erectus Stauffer 
Oistodus excelsus Stauffer 
Oistodus fornicalus Stauffer 
Oistodus giganteus Stauffer 
Oistodus inclinatus Branson and Mehl 
Oistodus suberectus Branson and l\'lehl 
Ozarkodina concinna Stauffer 
Ozarkodina pauperata Stauffer 
Ozarkodina robusta Stauffer 
Paltodus arcuatus Stauffer 
Paltodus cornutus Stauffer 
Paltodus elegans Stauffer 
Paltodus striatus Stauffer 
Phragmodus cognitus Stauffer 
Plectodina dilata Stauffer 
Polycaulodus irregularis Stauffer 
Polycaulodus sp. 
Polygnathus? sp. 
Polyplacognathus expansus Stauffer 
Polyplacognathus ramosus Stauffer 
PoIypiacognathus sp. a and b 
Prioniodus aculeaius Stauffer 
Prioniodus calcaratus Stauffer 
Prioniodus cristulus Stauffer 
Prioniodus cornutus Stauffer 
Prioniodus cultellatus Stauffer 
Prioniodus liratus Stauffer 
Prioniodus? macrodentus Stauffer 
Prioniodus? obliquus Stauffer 
Pteroconus gracilis Branson and Mehl 
Pteroconus robustus Stauffer 
Scyphiodus primus Stauffer 
Subcordylodus? inaequalis Stauffer 
Subcordylodus restilineatus Stauffer 
Subcordylodus sp. 
Suhprioniodus latus Stauffer 
Trichognathus deformis Stauffer 
Trichognathus gyro ides Stauffer 
Trichognathus illustris? Stauffer 
Trichognathus minnesotensis Stauffer 
Trichognathus recurvus Branson and 
Mehi 
Egg cases? 
PLATTEVILLE FORMATION: McGregor Mem-
ber 
Algae (marine) 
Chaetocladus sardesoni Ruedemann 
Spongiae 
Hindia inaequalis Ulrich and Everett 
Rauffella? fucoida Sardeson 
Anthozoa 
Streptelasma breve Winchell and Schu· 
chert 
Streptelasma? parasiticum Ulrich 
Streptelasma (Petraia) profundulll 
(Conrad) 
Hydrozoa 
ClimacogTaptus (Mesograptus) putillus 
(Hall) 
Climacograptus typicalis Hall 
Diplograptus amplexicaulis? (Hall) 
Polychaeta 
Arabellites acuridentatus Stauffer 
Arabellites sp. a 
Dinoscolites mirabilis Stauffer 
Lumbriconereites affinis Stauffer 
Lumbriconereites cameratus Stauffer 
LUlllbriconereites plattevillensis Stauffer 
LUlllbriconereites superbus Stauffer 
Oenonites sp. a and b 
Protarabellites grandis Stauffer 
Protarabellites intermedius Stauffer 
Serpulites dissolutus Billings 
024'2 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Ungulites aculeatus Stauffer 
Ungulites tridentatus Stauffer 
Cystoidea 
Cheirocrinus sp. 
Crinoidea 
Cremacrinus arctus Sardeson 
Lichenocrinus sp. 
Asteroidea 
Urasterella ulrichi Schuchert 
Bryozoa 
Batostoma fertile Ulrich 
Batostoma fertile circulare Ulrich 
Batostoma? decipiens Ulrich 
Chasmatopora sublaxa (Ulrich) 
Crepipora perampla Ulrich 
Dekayella praenuntia simplex Ulrich 
Escharopora angularis Ulrich 
Fayositella laxata (Ulrich) 
Hallopora al'gularis? (Ulrich) 
Homotrypa minnesotensis Ulrich 
Homotrypa sp. 
Leptotrypa hexagonalis Ulrich 
Monotrypa magna Ulrich 
Nicholsonella ponderosa Ulrich 
Orbignyella wetherbyi (Ulrich) 
Rhinidictya grandis Ulrich 
Rhinidictya mutabilis (Ulrich) 
Rhinidictya nicholsoni Ulrich 
Rhinidictya pediculata Ulricb 
Rhinidictya trentonensis (Ulrich) 
Stromatotrypa ovata Ulrich 
Brachiopoda 
Crania granulosa N. H. Winchell 
Crania setigera Hall 
Dalmanella rogata (Sardeson) 
Dalmanella sp. 
Dinorthis (Valcourea) deflect a (Conrad) 
Dinorthis pectinella sweeneyi? (N. H. 
Winchell) 
Dinorthis (Plaesiomys) subquadrata 
(Hall) 
Doleroides pervetus (Conrad) 
Hebertella (Glytorthis) bellarugosa 
(Conrad) 
Hesperorthis tricenaria (Conrad) 
Leptaena chalottae Winchell and Schu-
chert 
Lingula cobourgensis Billings 
Lingula elderi Whitfield 
Lingula morsei (N. H. Winchell) 
Lingula sp. 
Orbiculoidea lamellosa (Hall) 
Pianodema subaequata (Conrad) 
Pianodema conradi (N. H. Winchell) 
Plectambonites sericeus Sowerby 
Rafinesquina altern at a (Emmons) 
Rafinesquina minnesotensis (N. H. 
Winchell) 
Rhynchotrema inc reb esc ens (Hall) 
Rhynchotrema minnesotense (Sardeson) 
Scenidium anthonense Sardeson 
Siphonotreta? minnesotensis Hall and 
Clarke 
Strophomena incurvata (Shepard) 
Strophomena winchelli Hall and Clarke 
Trematis huronensis Billings 
Zygospira nicolleti Winchell and Schu-
chert 
Zygospira recurvirostris (Hall) 
Pelecypoda 
Ambonychia planistriata Hall 
Clionychia ereda (Hall) 
Clionychia lamellosa (Hall) 
Clionychia nitida Ulrich 
Clionychia rhomboidea (Ulrich) 
Ctenodonta compressa? (Ulrich) 
Ctenodonta gibberula Salter 
Ctenodonta nasuta (Hall) 
Ctenodonta scofieldi Ulrich 
Cyrtodonta ampla Ulrich 
Cyrtodonta billingsi Ulrich 
Cyrtodonta glabella (Ulrich) 
Cyrtodonta huronensis Billings 
Cyrtodonta persimilis Ulrich 
Endodesl1la orthonotum (Meek and 
Worthen) 
Eurymya plana (Hall) 
Modiolopsis cf. simi lis Ulrich 
Modiolopsis sp. 
Technophorus subacutus Ulrich 
Vanuxel1lia decipiens Ulrich 
Vanuxemia dixonensis Meek and 
Worthen 
Vanuxemia dixonensis insueta Ulrich 
Vanuxemia media Ulrich 
Vanuxemia obtusifrons (Ulrich) 
Vanuxemia rotundata (Hall) 
Vanuxemia sardesoni (Ulrich) 
Vanuxemia terminalis (Ulrich) 
Whiteavesia modioloforl1lis (Meek and 
Worthen) 
Whiteavesia superba (Hall) 
Whitella megambona (Whitfield) 
Gastropoda 
Archinacella depress a Ulrich and Sco-
field 
Archinacella perovalis (Whitfield) 
Archinacella powersi Ulrich and Scofield 
Bucania emmonsi Ulrich and Scofield 
Bncania halli Ulrich and Scofield 
Bucania minnesotensis Ulrich and Sco-
field 
Bucania sublata Ulrich and Scofield 
Clathrospira convexa Ulrich and Sco-
field 
Clathrospira subconica (Hall) 
Conularia quadrata Walcott 
Conularia sp. 
Eccyliomphalus undulatus (Hall) 
Eccyliopterus beloitensis Ulrich and 
Scofield 
Ectomaria prisca (Billings) 
Eotol1laria dryope (Billings) 
FAUNAL LIST 'BS 
Eotomaria supracingulala (Billings) 
Eolomaria vic ina Ulrich and Scofield 
Fusispira? spicula Sardeson 
Gyronema duplicatum Ulrich and Sco-
field 
Helicotoma planulata Salter 
Helicoloma planulala robusta Ulrich 
and Scofield 
Helicoloma umbilicala Ulrich and Sco-
field 
Holopea ampla Ulrich and Scofield 
Holopea C'ollC'inllula Ulrich ancl Scofield 
Holopea insignis Ulrich and Scofield 
Holopea rotunda Ulrich and Scofield 
Hormotoma gracilis (Hall) 
Hormotoma gracilis angustata (Hall! 
Hyolithes baconi Whitfield 
Liospira abrupta Ulrich and Scofield 
Liospira angustata Ulrich and Scofield 
Liospira obtusa Ulrich and Scofield 
Liospira vitru"ia (Billings) 
Lophospira bicincta (Hall) 
Lophospira conrad ana Ulrich and Sco-
field 
Lophospira decursa Ulrich 
Lophospira helicteres wisconsinensis 
Ulrich and Scofield 
Lophospira perangulata (Hall) 
Lophospira serrulata (Salter) 
Lophospira sp. 
Maclnrites bigsbyi (Hall) 
Maclurites depress us Ulrich and 
Scofield 
Maclurites nitidus Ulrich and Scofield 
Omospira laticincta? Ulrich 
Ophiletina sublaxa Ulrich and Scofield 
Oxydiscus subacutus Ulrich 
Palaeacmaea humilis Ulrich and Sco-
field 
Phragmolites fimbriatus (Ulrich and 
Scofield) 
Phragmolites triangularis (Ulrich and 
Scofield) 
Platyceras? wisconsinense Ulrich and 
Scofield 
Pterotheca attenuata (Hal!) 
Salpingostoma buelli (Whitfield) 
Seen ella beloitensis Ulrich and 
Scofield 
Scenella compressa Ulrich and Scofield 
Scenella magnifica Ulrich and Scofield 
Scenell" montrealensis (Billings) 
Seen ella superba (Billings) 
Sinuiles rectangularis (Ulrich and 
Scofield) 
Stenotheca exserta (Sardeson) 
Subulites conradi Ulrich and Scofield 
Subulites dixonensis Ulrich and 
Scofield 
Subulites regularis Ulrich and Scofield 
Tetranota macra Ulrich and Scofield 
Tetranota obsoleta Ulrich and Scofield 
Tetrallola ,('xcminata Ulrich and Sco-
field 
Tetranota wisconsin ens is (Whitfield) 
Trochonema beachi Whitfield 
Trochonema beloitense Whitfield 
Trochonema lirata Ulrich and Scofield 
Trochonema percarinatum Hall 
Trochonema rugosum Ulrich and 
Scofield 
Trochonema umbilicatum (Hall) 
Trochoneml1 "agrans Ulrich and Sco-
field 
Trochonema sp. 
Cephalopoda 
Actinoceras bigsbyi Bronn 
Actinoceras j anesyillense Foerste 
Actinoceras remotiseptum (Hall) 
Allumetloceras' planodorsatum (Whit-
field) 
Beloitoceras caryeri (Clarke) 
Beloiloceras houghtoni (Clarke) 
Beloitoceras janesyillense Foerste 
Beloitoceras nonyoodi (Clarke) 
Cameroceras' multicameratum (Em-
mons) 
Cameroceras '2 undetermined species 
Clinoceras mumiaforme (Wllltfield) 
Cycloceras olorus (Hall) 
Cycloceras sp. 
Cvrtoceras featherstonhaughi Clarke 
C:rrtoceras houghtoni Clarke 
Cyrtoceras shumardi Clarke 
C)Ttoceras sp. 
Cyrtorizoceras minneapolis (Clarke) 
Deiroceras scofieldi Foerste 
Endoceras protei forme Hall 
Eurostomites occidental is Hall 
Geisonoceras scofieldi Foerste 
Gonioceras anceps Hall 
Gonioceras occidentale Hall 
Laphamoceras scofieldi Foerste 
IVIaelonoceras neleus (Hall) 
]VIanitoulinoceras' wykoffense Foerste 
l\Ietaspyroceras c1arkei Foerste 
:Metaspyroceras? nicolleti (Clarke) 
Oncoceras carveri Clarke 
Oncoceras Iycns Hall 
Oncoceras pandion Hall 
Orthoceras beltrami Clarke 
Orthoceras junceum Hall 
Orthoceras sociale? Hall 
Orthoceras sp. 
Plectoceras bondi? (Safford) 
Plectoceras undatum occidentale 
(Hall) 
Richardsolloceras? scofieldi? (Clarke) 
Scofieldoceras shumardi (Clarke) 
Spyroceras bilineatum (Hall) 
Spyroceras lesueuri (Clarke) 
Spyroceras scofieldi Foerste 
Staufferoceras featherstonhaughi 
(Clarke) 
~44 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Tripteroceras oweni (Clarke) 
Tripteroceras planoconvexum (Hall) 
Tripteroceras scofieldi Foerste 
Tripteroceras sp. 
Westonoceras minnesotense? (Clarke) 
Whitfieldoceras mumiaforme (Whit-
field) 
Zitelloceras billingsi (Salter) 
Zitelloceras hallianum (d'Orbigny) 
Trilobita 
Amphilichas sp. 
BasiliC'us barrandi (Hall) 
Bathyurus extans (Hall) 
Bathyurus schucherti Clarke 
Bathyurus sp. 
Bumastus trentonensis Emmons 
Calliops plattevillensis Ulrich and Delo 
Calliops sp. 
Ceraurinus scofieldi (Clarke) 
Ceraurus pleurexanthemus Green 
Corydocephalus wesenbergensis 
paulianus (Clarke) 
Encrinurus vannulus Clarke 
Eomonorachus intermedius (Walcott) 
Goldius lunatus (Billings) 
Illaenus americanus? (Billings) 
Isotelus gigas De Kay 
Isotelus sp. 
Nileus vigilans (Meek and Worthen) 
Onchometopus simplex Raymond and 
Narraway 
Thaleops o~·atus Conrad 
Ostracoda 
Drepanella bigeneris Ulrich 
Eurychilina reticulata Ulrich 
Eurychilina subradiata Ulrich 
Krausella arcuata Ulrich 
Leperditella canalis Ulrich 
Leperditia fabulites (Conrad) 
Macronotella scofieldi Ulrich 
Primitiella constricta Ulrich 
Arachnida (order Eurypterida) 
Eurypterus sp. 
PLATTEVILLE FORMATION: Glenwood 
Member 
PoI~'chaeta 
Arabellites eccentricus Stauffer 
Arabellites erectus Stauffer 
Arabellites exiguus Stauffer 
Arabellites gregalis Stauffer 
Arabellites ignotus Stauffer 
Arabellites tenuidentatus Stauffer 
Eunicites sp. band c 
Lumbriconereites affinis Stauffer 
Lumbriconereites cameratus Stauffer 
Lumbriconereites similis Stanffer 
Oenonites sp. b 
Pronereites primus Stauffer 
Protarabellites concavus Stauffer 
Protarabellites glenwoodensis Stauffer 
Bryozoa 
Vinella sp. 
Brachiopoda 
Doleroides pen'eta? (Conrad) 
Lingula morsei (N. H. Winchell) 
Lingula sp. 
Orthis tricenaria Conrad 
Pianodema subaequata (Conrad) 
Platystrophia sp. 
Rafinesquina sp. 
Rhynchotrema minnesotense 
(Sardeson) 
Rhynchotrema sp. 
Strophomena incurvata (Shepard) 
Strophomena sp. 
Pelecypoda 
Modiolopsis fountainensis Sardeson 
Gastropoda 
Conularia sp. 
Lophospira sp. 
Trilobita 
Calliops sp. 
Conodonts 
Belodus lineatus Stauffer 
Bryantodina compacta Stauffer 
Bryantodina digna Stauffer 
Bryantodina dissimilis Stauffer 
Bryantodina excelsa Stauffer 
Bryantodina inaequalis Stauffer 
Bryantodina incurvata Stauffer 
Bryantodina informis Stauffer 
Bryantodina levicula Stauffer 
Bryantodina linata Stauffer 
Bryantodina maxima Stauffer 
Bryantodina parva Stauffer 
Bryantodina typicalis Stauffer 
Bryantodina sp. 
Chirognathus admirandus Stauffer 
Chirognathus alternatus Branson and 
Mehl 
Chirognathus delicatulus Stauffer 
Chirognathus duodactylus Branson 
and Mehl 
Chirognathus eucharis Stauffer 
Chirognathus expatiatus Stauffer 
Chirognathus hamatus Stauffer 
Chirognathus idoneus Stauffer 
Chirognathus invictus Stauffer 
Chirognathus irregularis Stauffer 
Chirognathus lanesboroensis Stauffer 
Chirognathus magnificus Stauffer 
Chirognathus multidens Branson and 
Mehl 
Chirognathus quadridactylus Stauffer 
ChirognaLhus radiatus Stauffer 
Chirognathus scalenus Stauffer 
Chirognathus tenuidentatus Stauffer 
Chirognathus unguliformis Stauffer 
Cyrtoniodus complicatus Stauffer 
Cyrtoniodus erectus Stauffer 
Dichognathus peculiaris Stauffer 
FAUNAL LIST 24.5 
Dichognathus typicus Branson and 
Mehl 
Dichognathus variabilis Stauffer 
Distacodus bicurvatus Stauffer 
Distacodus falcatus Stauffer 
Distacodus longus Stauffer 
Erismodus tantus Stauffer 
Euprioniodina in signa Stauffer 
Euprioniodina robusta Stauffer 
Gyrognathus primus Stauffer 
Lonchodus dentatus Stauffer 
Lonchodus spinuliferus Stauffer 
Lonchodus sp. 
Microcoelodus expansus Branson and 
Mehl 
Oistodus abundans Branson and Mehl 
Oistodus acuminatus Stauffer 
Oistodus curvatus Branson and Mehl 
Oistodus inclinatus Branson and Mehl 
Oistodus ovatus Stauffer 
Oistodus suberectus Branson and Mehl 
Oistodus venustus Stauffer 
Ozarkodina amorphina Stauffer 
Ozarkodina concinna Stauffer 
Ozarkodina crenulata Stauffer 
Ozarkodina delecta Stauffer 
Ozarkodina insolita Stauffer 
Ozarkodina reperta Stauffer 
Ozarkodina sp. 
Paltodus compressus Branson and 
Mehl 
Phragmodus cognitus Stauffer 
Phragmodus inflexus Stauffer 
Phragmodus singularis Stauffer 
Phragmodus varians Stauffer 
Plectodina dilata Stauffer 
Plectodina glenwoodensis Stauffer 
Prioniodus liratus Stauffer 
Stereo corn us gracilis Branson andl'vIehl 
Subcordylodus elongatus Stauffer 
Subcordylodus paratus Stauffer 
Subcordylodus rectilineatus Stauffer 
Subcordylodus sinuatus Stauffer 
Tortoni~dus politus Stauffer 
Trichognathus barbarus Stauffer 
Trichognathus deformis Stauffer 
Trichognathus illustris Stauffer 
Trichognathus inopinatus Stauffer 
Trichognathus recun'us Branson and 
Mehl' 
ST. PETER SANDSTONE 
Brachiopoda 
Crania? reversa Sardesoll 
Pelecypoda 
Ctenodonta? absimilis (Sardeson) 
Ctenodonta novicia (Sardeson) 
Cyrtodonta descriptus (Sardeson) 
Cyrtodonta dignus (Sardeson) 
Modiolopsis affinis Sardeson 
Modiolopsis contig1!a Sardeson 
Modiolopsis gregalis Sar'deson 
Modiolopsis litoralis Sardeson 
Psiloconcha senecta (Sardeson) 
Vanuxemia fragosa Sardeson 
Gastropoda 
Holopea obliqua Hall 
Holopea paludiniformis Hall 
Hormotoma gracilis (Hall) 
Lophospira tricarinata (I-IaIl) 
Ophileta faust a Sardeson 
Platyceras vetulum Sardeson 
Pleurotomaria aiens Sardeson 
Cephalopoda 
Orthoceras minnesotense Sardeson 
Orthoceras sp. 
SHAKOPEE DOLO~I1TE 
Algae 
Cryptozoon giganteum Chaney 
Cryptozoon minnesotense N. H. 
Winchell 
Cryptozoon minnesotense libertatis 
N. I-I. Winchell 
Palaeophycus tubulare Hall 
Gastropoda 
Archinacella simplex (Billings) 
Ceratopea pygmaea Stauffer 
Eccyliomphalus transyerso-cordatus 
Stauffer 
Euomphalopsis depressa Stauffer 
Helcionopsis sp. 
Hormotoma argylensis (Sardeson) 
Hormotoma artemesia (Billings) 
Hormotoma cannonensis Stauffer 
Hormotoma cassina (Whitfield) 
Lophospira pereiegans Stauffer 
Lophospira vetusta Stauffer 
Ophileta canadensis (Billings) 
Ophileta sp. 
Plethospira cassina (Whitfield) 
Raphistoma pan-urn Stauffer 
Raphistoma ruidum Sardeson 
Rapbistoma shakopeense Stauffer 
Subulites exact us Sardeson 
Turritoma melaniformis (Shumard) 
Cephalopoda 
Cameroceras inopinatum Stauffer 
Cameroceras stillwaterense Stauffer 
Cotteroceras compressum Ulrich and 
Foerste 
Cyciostomoceras minimum? (Whitfield) 
Cyptendoceras ruedemanni Ulrich and 
Foerste 
Cyrtoceras confertissimum? Whitfield 
Deltoceras tantillum Stauffer 
Endoceras COllsuetum Sardesoll 
Eurystomites kelloggi (Whitfield) 
Orygoceras eburneolum Stauffer 
Conodonts 
DistaC'odus? gracilis Furnish 
Ihepallodus subarC'uatus Furnish 
2.J,6 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Scolopodus quadriplicatus Furnish 
Scolopodus skakopeensis Furnish 
Ulrichodina? deflexus Fnrnish 
ONEOTA DOLOMITE 
Algae 
Cryptozoon sp. 
Hydrozoa 
Stromatopora sp. 
Cystoidea 
Cystoid plates 
Brachiopoda 
Apheoorthis vicina Walcott 
Clarkella calcifera (Billings) 
Clarkella nonus (Walcott) 
Lingula sp. 
Lingulella sp. 
Obolus dolatus (Sardeson) 
Syntrophina campbelli (Walcott) 
Syntrophina sp. 
Amphineura 
Priscochiton? gibberosum (Sardeson) 
Gastropoda 
Cinctaspira conica Powell 
Dirhachopea calvini Bridge ms. 
Euomphalopsis intralobata (Sardeson) 
Euomphalopsis involuta Ulrich and 
Bridge 
Euomphalus winonensis Sardeson 
Gasconadia putilla (Sardeson) 
Helicotoma uniangulata (Hall) 
Hormotoma sp. 
Lecanospira alturensis (Sardeson) 
Lecanospira profnnda Powell 
Lecanospira tenuis Powell 
Murchisonia? putilla Sardeson 
Ophileta alturensis Sardeson 
Ophileta grandis Ulrich 
Ophileta meeki Powell 
Ophileta multivolyatum (Calvin) 
Ophileta pepinense (Meek) 
Ophileta sardesoni Powell 
Ophileta trochiscus (Meek) 
Ozarkina parva Powell 
Platyceras sp. 
Raphistoma lewistonense Sardeson 
Raphistoma minnesotense (Owen) 
Raphistoma oweni Sardeson 
Raphistoma pepinense (Meek) 
Rhachopea conica Powell 
Rhachopea coronata Powell 
Rhachopea grandis Ulrich and Bridge 
Rhachopea leiosomellum (Sardeson) 
Rhachopea typica Ulrich and Bridge 
Sinnopea obesa (Whitfield) 
Sinuopea turgid a (Hall) 
Sinnopea typicalis Ulrich ms. 
Sinuopea vera Ulrich and Bridge 
Sinuopea virginia Powell 
Cephalopoda 
Burenoceras cornucopia forme Powell 
Clarkoceras claytonense Foerste ms. 
Clarkoceras lnthei (Calvin) 
Clarkoceras newton-winchelli (Clarke) 
Cyrtoceras dresbachense Sardeson 
Ellesmeroceras winonicnm (Sardeson) 
Oneotoceras loculosnm (Hall) 
Piloceras corniculum Sardeson 
Walcottoceras 3hannonense Ulrich and 
Foerste ms. 
Trilobita 
Asaphus sp. 
Bellet'ontia non ius Walcott 
Hystricurus on eo tens is Powell 
Platycolpus eatoni? (Whitfield) 
Symphysurina spicata Ulrich 
S.I'mphysurina woosteri Ulrich 
Xenostegium shepardi (Raymond) 
Conodonts 
Acanthodus uncinnatus Furnish 
Acodus oneotensis Furnish 
Acontiodus iowensis Furnish 
Acontiodus propinquus Furnish 
Clavohamulus densus Furnish 
Cordylodus intermedius Furnish 
Cordylodus subangulatus Furnisb 
Distacodus? simplex Furnish 
Drepanodus lineatus Furnish 
Drepanodus subarcuatus Furnish 
Loxodus bransoni Furnish 
Oistodus concayus Furnish 
Oistodus erectus Furnish 
Oistodus inclinatus Furnish 
Oistodus mehli Furnish 
Oistodus pandus Furnish 
Oistodus? triangularis Furnish 
Paltodus bassleri Furnish 
Paltodus variabilis Furnish 
Scolopodus sulcatus Furnish 
BLUE EARTH SILTSTONE 
Brachiopoda 
Lingulella sp. 
KASOTA SANDSTONE 
Gastropoda • 
Dirhachopea normalis Ulrich and 
Bridge 
Dirhachopea sp. 
Gasconadia sp. 
Matthevia sp. 
Ophileta minnesotense (Owen) 
Ophileta sp. 
Pelag-iella staufferi Powell 
FAUNAL LIST 
CAMBRIAN 
~47 
JORDAN SAI'DSTO:\E: Van Oser Member 
Brachiopoda 
Eoorthis sp. 
Orusia sp. 
Gastropoda 
Dirhachopea sp. 
Trilobita 
Calvin ella sp. 
Plethopeltis sp. 
Saukia sp. 
Saukiella sp. 
Stenochilina sp. 
Stenopilus sp. 
Tellerina sp. 
Prozacompsus sp. 
Several undescribed genera 
JORDAN SANDSTONE: Norwalk Member 
Upper Norwalk 
Polychaeta 
Scolithus sp. 
Brachiopoda 
Billingsella sp. 
Syntrophia sp. 
Gastropoda 
H~'olithes sp. 
Owenella antiquata (Hall) 
Rhachopea sp. 
Trilobita 
Acheilops? sp. 
"Atopina·' sp. 
Bowmania n. sp. 
Chariocephalus sp. 
Corbinia sp. 
Dikelocephalus cf. halli Ulrich and 
Resser 
Euptychaspis? sp. 
Hardyia sp. 
Plethometopus? n. sp. 
Prozacompsus n. sp. 
Saukia imperatrix Ulrich and Resser 
Saukia sp. 
Saukiella pyrene (Walcott) 
Stenopilus sp. 
Tellerina leucosia (Walcott) 
Arachnida 
Aglaspis sp. 
Lower N onval k 
Polychaeta 
Scolithus ,,"oodi Whitfield 
Brachiopoda 
Billingsella coloradoensis (Shumard) 
Finkelnburgia finkelnburgi (Walcott) 
Finkelnburgia osceola (Walcott) 
Lingu!ella ampla (Owen) 
I_ingulella mosia (Hall) 
Lingulella oweni (Walcott) 
Linguiella sp. 
Obolella sp. 
Obolus? sp. 
"'estonia aurOl·a (Hall) 
Westonia stoneanus (Whitfield) 
Gastropoda 
Hyolithes sp. 
Owenella antiquata (Hall) 
Rhachopea? sp. 
Sinuopea sweeti (Whitfield) 
Trilobita 
"Atopina·· sp. 
Corbinia sp. 
Dikelocephalus halli Ulrich and Resser 
Dikelocephalus norwalkensis Ulrich 
and Resser 
Euptychaspis sp. 
Eurekia sp. 
IlIaenurus quadratus Hall 
Osceolia osceola (Hall) 
Plethometopus sp. 
Prozacompsus sp. 
Saukiella pyrene (Walcott) 
Stenochilina sp. 
Tellerina leucosia (Walcott) 
Triarthropsis sp. 
An undescribed genus 
Arachnida 
Aglaspis sp. 
ST. LAWRENCE FOR:\IATIOX: Lodi Member 
Algae 
Cryptozoon sp. 
Graptiloidea 
Acanthograptus priscus Ruedemann 
Callograptus staufl'eri Ruedemann 
Dendrograptus edwardsi Ruedemann 
Dendrograptus hallianus (Prout) 
Dendrograptus sparsus Ruedemann 
Dict~·onema minnesotense Ruedemann 
Haplograptus wisconsinensis Ruede-
mann 
Brachiopoda 
Lingulella convexa (Walcott) 
Lingulella mosia (Hall) 
Lingulella osceola (Walcott) 
Lingulella winona (Hall) 
Lingulella sp. 
Obolus sp. 
"'estonia aurora (Hall) 
Gastropoda 
Hyolithes attenuatus Walcott 
Hyolithes sp. 
Owen ella vaticina Hall 
Owenella sp. 
Sinuopea sp. 
Trilobita 
"Atopina"? sp. 
Calvinella spiniger (Hall) 
Calvinella wisconsillensis Ulrich and 
Ressel' 
Dikelocephalus granosus Ulrich and 
Ressel' 
'WI P.\LEOZOIC AND RELATED ROCKS OF SOUTHK\STERN l\UNNESOTA 
Dikelocephalus minnesotensis Owen 
Dikelocephalus raaschi Ulrieh and 
Ressel' 
IlIaenurus quadratus Hall 
Osceolia lodensis Ulrich and Resser 
Osceolia osceola Hall 
Osceolia sp. 
Saukia sp. 
Saukiella pepinensis (O"'en) 
Saukiella typical is Ulrich and Resser 
Saukiella sp. 
Tellerina lata Ulrich and Ressel' 
Tellerinll strigosll Ulrich and Resser 
Tellerina sp. 
Triarthrella auroralis Hall 
Walcottaspis vallhornei (Walcott) 
Arachnida 
Aglaspis barrandei Hall 
Polychaeta 
Serpulites murchisoni Hall 
Worm trails? 
ST. LAWHENCE FOIDIATION: Nicollet Creek 
Member 
Algae 
Cryptozoon sp. 
Cystoidea 
Cystoid plates 
Brachiopoda 
Archeoorthis sp. 
Billingsella coloradoensis? (Shumard) 
Billingsella? sp. 
Palaeostrophia barabuensis (A. 
Winchell) 
Palaeostrophia primordialis (Whitfield) 
Palaeostrophia sp. 
Gastropoda 
Owenella? sp. 
Scaevogyra sp. 
Triblidium sp. 
Trilobita 
Dikelocephalus cf. minnesotensis Owen 
Dikelocephalus sp. 
Corbinia sp. 
Platycolpus sp. 
FRANCONIA FORMATION: Bad Axe :Member 
Trilobita 
Briscoia sp.* 
Dikelocephalus sp. 
Illaenurus sp. * 
Monocheilus sp.* 
Osceolia sp. 
Prosaukia sp. 
Saukiella sp. 
FRA~CONIA FORIIIATION: Hudson :Member 
Brachiopoda 
Billingsella sp. 
Obolella sp. 
Gastropoda 
cf. Pelagiella minulissima (Walcott) 
Trilobita 
Agnostus josephus Hall 
"Ellipsocephalus" curtus Whitfield 
Idahoia hamulus (Owen) 
Idahoia hera (Walcott) 
Idahoia latifrons (Hall) 
Idahoia wisconsinensis (Owen) 
Menomonia oplata (Hall) 
Monocheilus anatinus (Hall) 
Prosaukia misa (Hall) 
Ptychaspis granulosa (Owen) 
Saukaspis sp. 
Saukia leucosia Walcott 
Stigmacephalus oweni (Hall) 
Taenicephalus bipunctatus (Shumard) 
Wilburnia diademata (Hall) 
Wilburnia halli Ressel' 
FRANCONIA FOR:\IATIO~: Taylors Falls 
Member 
Brachiopoda 
Acrotreta sp. 
Billingsella coloradoensis (Shumard) 
Dicellomus sp. 
Eoorthis sulcata (Walcott) 
Lingulella similis (Walcott) 
Gastropoda 
Hypseloconus franconensis Berkey 
Pelagiella sp. 
Platyceras primordialis (Hall) 
Trilobita 
Agnostus josephus Hall 
Agnostus parilis Hall 
Conaspis eryon Hall 
Conllspis perseus (Hall) 
Idahoia sp. 
Lonchocepbalus bun us? Walcott 
Monocheilus sp. 
Psalaspis patersoni (Hall) 
Taenicephalus bipunctatus (Shumard) 
Taenicephalus shumardi? (Hall) 
Wilburnia cf. halIi Resser 
FRANCONIA FORlIIATION: Ironton l\Iember 
Brachiopoda 
Dicellomus sp. 
Lillgulella sp. 
Lingulepis sp. 
Gastropoda 
Euomphalus strongi sinistrosus Berkey 
Hypseloconus dapuloides Berkey 
Hypseloconus cornutirormis Berkey 
Hypseloconus cylindricus Berkey 
Hypseloconus (Metoptoma) reCllrVUS 
(Whitfield) 
Hypseloconus recurvus elongatus 
Berkey 
Hypseloconus stabilis Berke~' 
Metoptoma? minneiskensis Walcott 
Scae\'ogyr>t minnesotensis Berkey 
* Found in "'isconsin but not yet in Minnesota. 
FAUNAL LIST 
Stenotheca sp. ulldet. 
Tryblidium aduncum Berkey 
Tryblidium convexum Berkey 
Tryblidiulll corpentnlum Berkey 
Tryblidium extensum Berkey 
Tryblidiulll rectilaterale Berkey 
Trilobila 
Berkeia typica Resser 
Caillaraspis conyexus (Whitfield) 
Caillaraspis hemisphericus (Berkey) 
Cheilocephalus st. croixensis Berkey 
Modocia berkeyi Resser 
Wilburnia pero (Walcott) 
DRESBACH FORMATIO,,: Eau Claire Member 
Annelida 
Annelid borings 
Echinodermata 
Crinoid plates 
Eccystites plates 
Brachiopoda 
Acrotreta signalis Walcott 
Curticia elegantula Walcott 
Dicelloillus politus (Hall) 
Lingulella ampla (Owen) 
Lingulella phaon Walcott 
Lingulepis acuillinata (Conrad) 
Obolus matinalis (Hall) 
Gastropoda 
Hyolithes primordial is Hall 
Hyolithes sp. 
Trilobita 
Agnostus sp. 
Anomocarella? winona (Hall) 
Crepicephalns iowensis (Owen) 
Dresbachia amata Walcott 
Lonchocephalns chippewaensis Owen 
Lonchocephalns minor (Shnmard) 
Lonchocephalus sospita Walcott 
l\ienomonia cal \'menoides 
(Whitfield) . 
Millardia optata (Hall) 
"Pagodia" thea (Walcott) 
Pemphigaspis bullata Hall 
Pseudagnostus sp. 
Stenochilina matutina (Hall) 
Arachnida 
Aglaspis sp. 
249 
INDEX 
Accessory minerals. tables of. 7.5 
Acen'lliana beds. 97 
Afton. sections at. 205-7 
Albert Lea. Interstate Power Company well 
at, 154-5.5 
Algae. in fannalEsts. 231,234. 241. 245-48 
Algoman granite. on map. 4 
Algoman Mountains, 3 
Allen. V. T .. 79 
Amphineura. 246 
Analyses of Minnesota limestones. table of. 
II 3-20 
Anoka County. section in, at Columbia 
Heights, 123 
Anthozoa. 228-31. 23.5. 238. 241 
Aphelaspis zone, 15, 33 
in Waconia well, 15 
Arachnida, 244, 247. 249 
Archeozoic, 10, II 
sections of, 164, 183 
Arcola, sections at, 207-8 
Arcola schoolhouse, section at, 207 
Arcturus ]VIine, Taconite, section at, 174 
Armour and Compan:>'. South St. Paul, log of 
well at, 140 
Asteroidea. 235, 239, 242 
Atwater, G. Land G. M. Clement. 13 
and A. C. Trowbridge, see Trowbridge 
Austin, formations at, 57, 94, 9,5, 101 
log of Honnel Packing Company Well at, 
177 
Bad Axe, 28, 29, 30, 40-41. 43, 44 
fauna of, 40-41. 248 
illustrated, 41 
sections of. 133, 150, 161. 168-71, 201-7, 
210, '212. 217-22 
Bad Axe Valley, Wisconsin, type section of 
Bad Axe at, 40 
Bain, H. F., names Platteyille, 70-71 
Barn Bluff, see La Grange Mountain 
Ba;'s, C. A., and G. O. Raasch. 77 
Bear Creek. 58 
sections along, 147, 178 
Beekmantownian series . .53-66 
discussion of. .53 
Belle Plaine-Castle Rock anticline, .5 
Bellechester, section at. 155 
Bennett Open-Pit Mine, Keewatin, section 
at. 173-74 
Bergqnist, Harlan. 99 
Berkey, C. P .. II. 26, III 
Cambrian classification of. '28 
work on Franconia, '26, 29, 30, 3.5-36 
BeY3n. Arthur. 73, 75 
Big Cottomyood River, Cretaceous along, 
99, 103 
sections along, 104, 129-30 
Bigelow Hill, Rochester. deep well on, 182-83 
Biwabik formation, sections of. 10.5, 172-74, 
194 
Blne Earth, cit v well at. 142 
Blue Earth C~unty, Dakota formation in, 
99, 103 
map of. 124 
sections in. at Judson. 1 '23-'24 
Mankato. 126-'27 
Rapidan, 1'28 
sinks and caves in, 97-98 
wells in. 1 '24-'26 
Blue Earth siltstone. 51-53 .. 54-.55 
fauna of, 246 
floor of caves in Oneota. 97-98 
illustrated, .50. 52 
sections of, 55, 127 
Boom Hollow, Stillwater, collections III Jor-
dan at, 48 
section at. 211-1'2 
Brachiopods, in faunal lists, '2'27-3'2, '23.5-36, 
'240, '242, 244-49. See also each formation, 
fauna of 
in Waconia well, 1.5 
Bridge, ,Josiah, 36 
Cam brian classification of. 28 
Bro\yn County, Dakota grayels in, 103 
sections in, at New Ulm, 104, 128-30 
Springfield, 130 
Bryozoa, in faunal lists, '228-32. 235, 239-40, 
242, 244. See also each formation, fauna of 
in Spechts Ferry, 80 
Bunker Hill Well, Mankato, 12, 17-18 
log of, 124-25 
Burch, E. P., see Stauffer 
Caledonia, Oneota fauna at, 58 
sections at, 166-67 
Calumet. Cretaceous in mines at, 99 
sections at, 105, 172 
Calvin, Samuel, 59, 73. 83, 95, 108 
Ca maraspis-Irvil1gella faunule, 30 
Cambrian, 24-49 
classification of, 7-8, 28, 29 
fannal list, 247-49 
Cambrian-Ordovician contact, 50-53 
Cambridg1>, section at, 172 
Canisto Mine, Coleraine, section at, 172-73 
Cannon Falls, Chimney Rock at, illustrated, 
67 
260 
sections at, 155-58 
Shakopee fossils at. 65 
INDEX 251 
Cannon Ril'er, sections along, 140-41. 1.57 
Carli Quarry, Stillwater, section at. 212 
Carlton County, section in, at Fond du Lac, 
14 
Carney Company Qnarry, Mankato, section 
at, 126 
Carthog Gravel Pit, Ostrander. section at. 
103 
Caves, ancient, 50-53, 97-98 
Cedar River, Cedar Valley limestone along. 
94-95 
section at, 177 
Cedar Valley limestone, 94-97 
composition of. 11.5 
faunal list, 228-29 
illnstrated, 96 
iron ore in, 102 
map of, 4 
Maquoketa contact with. 3 
sections of. 92, 95-97, 146-47. 1;)1. 177-79 
well logs showing, 154, 175 
Cedaria zone. 33 
Cemetery Hill, Dakota, section at. 217 
Cenozoi~ in Minnesota, 8, 107-12 
Cephalopoda, in fannallists, 227,229-31. 234, 
237, 240, 243-46. See also each formation. 
fauna of 
Chamberlin, T. C., lOS 
Chase Quarr~', Pleasant Grove, section at. 
182 
Chaska, St. Lawrence in well at, 44-45 
Chasmatopora (Phyl/oporina) bed, 83-85 
in sections, 1.56, 188 
Chatfield, Guttenberg at, illustrated, 84 
Ion at. illustrated. 85 
Kansan at, 109 
Prosser along Lost Creek at, illustrated. 87 
sections at, 7'l, 143-44 
Spechts Ferry at, illustrated, 80 
Chazyan series, 65, 66-69 
Cher~kee Heights, St. Paul, section at the 
Twin City Brick and Tile Plant. 187 
Chicago an~l Northwestern Railroad Qnarry, 
Lewiston, section at, 58 
Chimney Rock. Cannon Falls, illustrated. 67 
Chisago County, Hinckley in lI'ells of, 16 
map of. 131 
sections in, at Franconia, 39-40. 130-3'2 
Osceola Bridge, 132-33 
Taylors Falls, 133-35 
Cincilll;a tian series, 90-93 
Classification (stratigraphic), 7-8 
of Cambrian (St. Croixian series), '28-30 
of Pleistocene, 107-8 
Clay pits, 103 
illustrated, 84 
sections of. 85-86, 130, 189 
Clelll~nt. G. ]\;1.. see Atwater 
('lin tOll Falls, 198 
Coleraine formation (Benton). 99. 104-6 
faunal list, 104, 'N7 
sections of. 105. 17'2-74, 194 
Collection of fossils, see each formation, 
fauna of 
Colorado series, 99. 104-6 
Columbia Hei;,-hts,' section at, 123 
Colvill Park, Red Wing, log of well at, 161 
Conaspi.s zone, 29, 30, 36, 39, 40. 204 
Conodonts, in l'aunallists, '229, 238. '2,U. 
244-46 
in Glenwood, 7.5, 77 
Cooper, William S., 112 
Cop~s, sections at, 208-9 
Corrosion zones, 69-70, 78, 79, 8'1. 83 
Crepicppha/lls zone, 30, 32, 33 
Cretaceous. 4, 99-106. 109. 112 
clays of, 95, 98 
Colorado series in, 104-6 
Dakota series in, 99-1 U4 
faunal list, 227-28 
iron in. 104-6 
rn"p of. + 
sections of, see Colorado series; Dakota 
serIes 
sil t and siltstones of. .52-.53 . .54 
Crinoidea. in faunal lists. 229, '231, 23,;, '239. 
242 
Crowle,". A. -T .• and G. A. Thiel. 18 
Ctenodonta bed, 83. 156, 188 
Curtain Falls Trail, Taylors Falls, section 
along, 133-34 
Cusson .Milling Company, Stewartville, 
section at. 89. 184 
Cystoidea, in faunal list, 229, '231, 235, 239, 
242 .. 246, 248 
Daggett's Gulch. Franconia. section at. 
130-32 
Dake. C. L., 62, 66, 69 
Dakota. Eau Claire member at. 33 
section at, 217 
Dakota County, glacial drift in, 109. no, III 
map of. 136 
sections in. at Hampton, 136 
Hastings, 137-38 
Cannon Falls, 1.58 
Waterford. 140-41 
wells in, at Hastings, 137 
Mendota, 138-39 
Rosemount. 139-40 
South St. Paul. 140 
Dakota Creek Valley. Dakota. illustrated, 7 
Dakota formation, 99-104 
fauna of. 100-1, 2'27-28 
gastroliths in, 100 
gnn-els of. 99-100, 101, 10'2, 103 
iron are in. 10'2 
Ostrander member of. 102-3 
sections of, 103, 104, 1'27-30, 148. 151, L35, 
175. 178, 179, 181-82, 189, 197 
Dakota series, 99-104 
Decapoda, in faunal list, '227 
Decorah. Iowa, type locality of Decorah 
shale, 83 
2.5~ PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Deeorah shale. 8'2-S6 
('omposition 01'. ll5 
fauna of. 83. 85. 23-1,-38 
illustraled. 8-1,. 85 
map of. 4 
relation to Spechts Fel'l'~·. 7'1. 79. 80 
se('tions of. 7'2. S1. 85-S6. 14-1,--45. 154. 156. 
15S. 160. 165. 170. ISO. 183. 188. 191. 19~ 
well logs including. 198 
Deep Well. Stillwater. '21'2-14 
Deer Creek. sections along. 88. 92. 151 
Devonian in Minnesota. 93. 9-1,-!l7. See also 
Cedar Valley limestone 
fauna of. 94. '1'28-29 
iron deposits in. 98 
relation to Maquoketa. 90 
residual fossils of. in the Cretaceous. 101 
sections of. see Cedar Valley limestone 
Dikelocephai-lls minnesotensis' fauna. 26. 30. 
46.133.160.171.201.'205.'212.215.'2'23 
Dikelocephal1ls postrectlls fauna. 30. 40-41 
Diplograptlls bed. 91 
Disconformities in Minnesota. 3 
Ordo\'ician-De\'onian contact. 93 
Shakopee--St. Peter contact. 53. 65-66 
Dodge Connty. map of. 141 
Prosser in. S7 
se('tions in. at Mantorville. 141-4'2 
Wasioja. 142 
Dover. sections at. 180-S1 
Dresbach. Dresbach formation at. 3'1. 33. 
34-35 
illustrated. 31 
Oneota at. 57. 58 
sections at. <e18-19 
type section of Dresbach at. 32 
Dresbach formation. 1.5. 28. 29-35 
Aphelaspis zone of. 15 
Eau Claire member of. 33 
fauna of. 32. 249 
Galesville member of. 34-3.5 
illustrated. 31. 37 . 
Mt. Simon member of. 33 
petrographic analysis of. 17. 18 
sections of. <e.5. 30. 32. 40. 44. 134-3.5. IS6. 
200. '103. 217-'11. 223 
"'ell logs including. 125. 13S-40. 147. 161. 
164. 168. 170. 172. 177. 183. 191. 192. 
195. 196. 198. 201. 213 
Dresbach-Franconia contact. 34-35. 37 
Dubuque. Iowa. type section for Dubuque 
at. 91 
Dubuque member of Maquoketa, 90-92 
fauna of, 91. 230 
illustrated. 91 
sections of. 87. 9<e. 142. 146. 1.52-.53, 198 
Dutton. C. E .. s~e Thiel 
Eau Claire. Wis('ollsin. Eau Claire and Mt. 
Simon type seclions at. 33 
Eau Claire member of Dresbach, 15, 28, 33 
Al'hela.'pis zone of, l.'i 
fauna of. 32, 33, 249 
illustrated, 31 
se(·tions of. 30, 32. 13,5. '103. 217-21. 223 
well logs including, 170 
Edson. F. C .. 69 
Eggleston. sections at. ]:;8-59 
Etna. iron ore at. 98. 102 
Ellrekia-Osceolil, faunule, 30 
Fair~' Glen. Stillwater, -1,6 
section at. 215 
Faribault. Oneota at. 57 
sections at. 192 
Spe('hts Ferry at, 79 
wells at. 44. 190-92 
Faribault Count~·. well Ill, at Blue Earth. 
142 
Farnhill Farm. sec·tion at. HI' 
Faunal list for Minnesota, 225-49 
Faunal zones in classification, 8 
in Mohawkian series, 70 
ill St. Croixian series. 27 
Federal Prison Well. Sandstone, 17 
log of. 186-87 
Fillmore County. formations in .. 59. 87, 89, 
90. 94. 9S. 100. 10'1. 103, 109 
iron ore in. 102 
map of. 143 
sections in. at Chatfield, 72, 143-44 
Fountain. 144-45 
Granger, 146 
Hamilton, 147 
Lanesboro, 147-48 
Lime City, 92 
Ostrander, 148 
Preston, 149 
Rushford. 150 
Spring' Valley. 92-93, 1.51-.52 
Wykoff 152-54 t~'pe 'secti~ns for Prosser and Ostrander in, 
87-88. 103 
wells in, 147 
Fish Lake, section at. 209 
Fond du Lac. Fond du Lac beds at. 12. 13. 14 
sections at. 14. 193 
Fond du Lac beds, 12-15. 19, 24 
(,Olltaet with Hinckley, 16, 17. 23 
fossils in, 14-15 
petrographic analysis of. 17, 18. 19. 7':; 
sections of. 14, 193 
t~'pe section of. 14 
\\'elliogs including, 125. 138, 140, 164. IS3, 
186. 190, 213-14 
Foraminifera. in faunal list. 227 
Formations in Minnesota, geological column 
of. 8-10 
Ford Motor Company Plant, sand mille at, 
67 
,eetiolls at. 81-82. 162-63 
Fort Ridgely, section at Fort Creek. 179 
Fort Snelling. type section of St. Peter at, 68 
Foster. J. W .. and J. D. Whitney. 82 
INDEX 26S 
.Fountain. Glenwood at. 74 
HeC'lions at. 144-4.5 
!<"owl"r and Pay Quarry. LeRoy. ,ecliol! at. 
177 
.Fowler and Pay Quarr.,·. 1I1ankato. ,,,clioll 
a.t. 127 
Franconia. Franconia formation at. 36. 41 
sedions at. 39-40. 130-3'2 
typ .. seetion of Franconia at. 39-40 
]<'ranconia formation. SW. 28. 34-~J5. 35-41. 
43-44 
Bad Axe rnem ber 01'. 40-41 
definitiun and expansion of. 29. 36-37 
faunal list. '248-49 
hea",' Ininerals iu, 75 
Hud~on member of. 40 
illmtrated. 37. 38.41 
IrontolJ member of, 37-39 
seetiolls of. '25. ~30. 39-40,131-33,13.1. 1nI, 
168-72,200-6.207-12.217-'23 
Tayl(,rs Falls member of. 39-40 
type section of. 39-40 
well logs including. 44, It5, 137. 139-+0. 
P7. 16+, 172, 177. 183. 190. 192. HI.'), 
196.198. '201, 213 
}<'reebofll County, Cedar "aile:, limestone in, 
94. 95 
we))s in, at Albert Lea. 154--.5.5 
Freeburg, section near. 167-6R 
Frontenac. Bad Axe at. 41 
Frontenac Quarry, Frontenac. section at, 
159-60 
Fucoid beds. 85. 156. 188 
Fuller. :!VI. L .. see Hall 
Galena, Illinois, type locality, 82 
Galena formation. 73, 80, 8'2-90, 91 
composition of limestones in. 11.5 
Decorah shale member of, 82-86 
faunal list. '231-38 
Illap of. 4 
Prosser member of. 86-88 
sections of. 7'2, 81, 85-86, 88, 89-90, fJ'l, 
141-45. 149, 151-56. 158. 160, 16.5, 170. 
1RO. 18'2-86, 18& 191, 192, 198 
Stewartville member of. 88-90 
"'ell logs including, 142, 1.55, 175-76, 198 
Galesville, Wisconsin, type locality, 34 
Galesville member of Franconia, '28, 31, 3~-
35,40 
f a una 01. 3·1 
heavv minerals in. 75 
Ironton contact with, 34-S5, 38 
sections of, 30, 32. 135, 168, 170, 200. 20:), 
'217-2\1 
Garden City, .Tordan-Oneota contact at, 5'2 
old caves in Oneota at, 98 
Gastrolith" in Dakota formation. 100 
Gastropoda, in faunal list. '227-31, 'l33-3~. 
236-37, 2+0, '242-49. See also each forma-
tion. fauna of 
Geological column of Minnesota, 8-10 
Geology. Ijistorieal. of Minnesota. 3-7 
Geos\'nclille in Minnesota . .5 
Giles'. A. W .. 67 
Gla(·ial drifl, 107-12 
Illap of, III 
Glauconite in the St. Croixian. '26 
Glencoe. wells at. 17 
Glenwood. Iowa, type locality, 73. 75 
Glell\\'oo<l member of Platteville, 71. 7S-77 
contact of. with St. Peter. 67. 73.74, 75-77 
fauna of. 73-7+, 77, 244-~.5 
hea,'\, minerals in, 75 
illustrated. 73 
,cdions 01',68.7'2,76-77.82,123,136,144-
·H. 1+8--19, 154, 167, 1.58, 16'2. 166-67. 
170.181, 184, 188, 189, 192, Q07, '209 
type locality of, 73, 7.5 
well logs including, 142. 1.54. 177. 198 
Gneisses. pre-Cambrian at Redwood Falls, 11 
Goodhue. Cretaceous gTavels and clay near, 
I ()2 
Goodhue County. formations in, !J9. 103. 109 
map of, 1.56 
,cctions in. at Bellechester. l.35 
Cannon Falls. 15,5-.58 
Eggleston. 158--69 
Frontenac. 1.59-{)0 
Kenvon. 160 
Red'Wing, 160-61 
Zumbrota. 85-86 
wells in, 161 
Gcaham, W. A. P., 26, 53 
Granger. Ceclar Valley limestone near, 97 
sections at. 146 
Graptiloidea. in faunal list, 231, '238. '247 
Gravels. in Dakota formation. 99-100 
in drift. 101 
pits. IDS. ]4.8. 151, 181 
illustrated. 100 
Grillllll Farm. section at. 97, 146 
Grindstone River, 22 
Grout. F. F .. 1'2. See also Tyler et al. 
Gruner. .T. W .. ancl G. A. Thiel. 55. 74 
Gunderson Brick and Tile Company. clay 
pit. illustrated. 84 
section at. 86 
Guttenberg. IOIYa, type locality for Gutten-
berg submember, 83 
Guttenberg submember of Decorah shale 
member, 83 
illustrated. 84 
sections of, 72, 81. 85-86, 144, 145, 1.36, 
158, 165, 191, 192 
Half Dome, Winona. illustrated, 6 
Hall. C. W., O. E. Meinzer, anu M. L. Fuller, 
-I-, 12. 13. \28. 43, 44, 45, 1 '25 
and F. ,,'. Sardeson, 6,5, 92 
Hall . .Tames, 68, 8'2 
Hallet Quarry, Faribault, section at. 19'2 
Hamilton. Cedar Valle~- limestone at, 97 
section along- Bear Creek, 147 
~i;')' PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN :MINNESOTA 
Hampton. moraine near. 110 
section at. 136 
Hastings. Oneota fauna at. 58 
sections at. 137-38 
well at. 137-38 
Hastings Dam. section at. 137 
Hastings Stone Company QuarQ'. section at. 
137 
Heayy accessor~' minerals. table. 75 
Hebron. type section of Nicollet Creek mem-
ber at. 45 
Heimann Qnarry and Lime Kiln. sec lions at. 
1~8 
Hell Hollow. Reno. section nt. 169 
Hennepin County. map of. 163 
sections in. at Fort Snelling. 68 
Minneapolis. 76. 16~-66 
type section of 8t. Peter at Fort Snelling. 
68 
wells in. at Minneapolis. 163-6,), 
Hershey, O. H .. 77 
Hewitt and Beason Quarries, St. Lawrence. 
43 
illustrated, 4~ 
Hibbing. Coleraine formation at. 10,), 
section at. 193-94 
Hill-Annex Mine. sections at. 105, 17~ 
Hincklev sandstone. 15-18. ~0-~3. 24. 33 
analy~es of, 16. 17, 18, ~0-~1, 75 
illustrated, 22 
sections of, 2~-23. 25 
type section, 2~ 
well logs including'. 125, 138-40. 161, 164. 
183, 186-87, 190. ~13 
Hokah. section on Mt. Tom, 168 
Hormel Packing Company Well, 57. 95, 175-
77 
Houston County. formations in .. 59. 99 
illustrated. '71 
map of. 167 
sections in. at Caledonia, 166-67 
Freeburg. 167-68 
Hokah, 168 
Reno. 169-70 
Spring Grove, 170 
Hudson member of Franconia formation. ~8, 
~9.40. 44 
fauna of. 248 
sections of. 30. 168-72. ~01-5. 'W7. 210. 
217-22 
type section of. 40 
Hudson trilobite bed of 'Wooster, 40 
ldahoi.a fauna, 30, 40, 169. 201. 203. 20.),. 223 
Interstate Power Company Well, Albert Lea, 
log of, 154-55 
Ion sub member of Decorah shale member. 
83. 85 
fauna of. 85 
illustrated. 85 
sections of. 72. 81, 85-86. 144. 1.56. 1 M~ 
Iron. residual. in Minn'esota, 98. 99. 101-2, 
104-6 
Ironton member of Franconia formation. ~8, 
29. 34-35. 36. 37-39 
fauna of, 40. 248-49 
illustrated. 37 
sections of. 30. 39-40, 13'2. 133. 13,5. 168-
70. 172.~00.203,217-22 
t~'pe section, 34 
Irving. R. D., 12 
Itasca County. map of. 173 
sections in. at Calumet, 10,) 
Coleraine, 172-73 
Keewatin, 173-74 
Taconite, IN 
Jordan. formations at. 43-5.5. 46. 47 
Jordan sandstone. 28, 46-49 
faunal list. 247 
heavy minerals in, 75 
illustrated, 47. 48. 50, 60 
iron deposited in. 98 
Norwalk member of. 48 
relation to Blue Earth siltstone, 50-.53, 54 
sections of, 25. 30. 49. 55. 58. 62. 123. 126-
28. 132-33. 137. 148. 150, 159-61. 167-
69. 171. 174. 199-205. 207-12. 'l};5-19, 
221-23 
type section of. 49 
Van Oser member of. 48-49 
well logs including. 44. 138-40, U7, 1,5.5, 
164. 177. 183, 190, 192. 195. 196. 198. 
213 
Jordan-Kasota contact, 54 
Jordan-Oneota contact. 26-27, 50-53. 57 
illustrated, 50. 56 
Judson. formations at, 45. 46 
sections at. ,),5. 123-24 
Kalb Creek. New Uhn. section at, 129 
Kansan, drift sheet of. 109 
gumbotil in. 110 
sections of, 129, 130 
Kasota, formations at. 54 
illustrated, .50. 51 
section at. 55 
Kasota sandstone, 54 
fauna of, 54. 246 
illustrated. 50 
sections of, 55 
Kay. G. F .. 108. 110 
and J. H. Pearce. 109 
Kay. G. Marshall. 69, 71. 77, 79, 82, 83. 90-
91 
Keewatin. section at, 173-74 
Kellogg. Galesville-Ironton contact near. 
illustrated. 38 
Ironton at. 37 
sections at. 199-200 
Kenyon. section at. 160 
INDEX 2,55 
Kettle Ri\'er, Hinckle.y sandstone along. 15-
16, 17, 22-23 
illustrated, 22 
Kettle RiYer sandstone, 22. See also Hinckley 
sandstone 
Keweenawan laya flows. 11 
map of, 4 
sections of, 40, 132, 134, 135 
Keweenawan sediments in lVlilinesota. 11-'23 
map of, 4 
Klemmer Quarry. Clinton Falls, section at. 
198 
La Grange Mountain (Bal'lI Bluff), Lodi at. 
46 
section on, 160-61 
La Moille. section at, 220 
Lake City, formations at, 41, M. 61 
sections at, 200-2 
well at, 200-1 
Lake Pepin, sections along, at Frontenac, IGO 
Lake City, 201-2 
Lake Supe;ior sandstone, 12 
of Wisconsin, 22 
Lake Superior series, 12-23 
Fond du Lac beds in, 12-1;5 
Hinckley sandstone in, 1.5-23 
Lakewood' Cemetery WelL Minneapolis. log 
of, 163-64 
Lamar, .J. E .. 68 
Lanesboro, formations at. ;;8, 61. 65 
illustrated, 56, 63, 73 
section along highwao' at, U7-4S 
well at, 147 
Lawrence Creek, Franconia, sections along, 
39--40, 130-32 
type section of Franconia formation at. 
39-40 
Le Roy, Cedar Valley limestone at, 97 
ill~strated, 96 ' 
section at, 177 
Le Sueur County, map of. 17;; 
sections in, at Kasota, .';;; 
sinks and caves in, 97, 98 
Le Sueur RiYer, section along', 128 
Leighton, lVI. lVI., and Paul iVlacClintock, 
108, 109 
Lesquereux, Leo, 99 
Leverett, Frank, 108 
Lewiston, section at, 58 
Lime City Quarry, Spring Yalley, illustrated, 
91 
sections at, 91-92 
Limestones in :Minnesota, composition or. 
113-20 
Lithographic limestone, in Cedar Valley for-
mation,94 
Lochman, Christina, 15 
Lodi, Columbia Count v, Wisconsin, type of 
Lodi at, 46 ' 
Lodi member of St. Lawrence formation, 28, 
46 
fauna of. 4G, 247-48 
sections of. 30, 49, 123-24, 132, 150, 160, 
161. 167-69, 171, 200, 201, 203-5, 207, 
210, 212, 215, 218, 219, 221, 2'22 
,,'ell logs including, 147 
Lost Creek, at Chatfield, Prosser along, il-
lustrated, 87 
section at, 143 
"Lower buff" limestone, 79 
Lyle, Cedar Vallev limestone at, 95 
. section at, 177' 
MacClintock, PauL see Leighton and Mac-
Clintock 
Maclurea bed, 88 
Mankato. Bunker Hill Well at, 12, 17-18, 
124-'25 
ca\'es during post-Devonian inten'al, 98 
Dakota formation in region of, 99 
Kasota at, 64 
Oneota and Blue Earth siltstone at, 54. 57, 
58, 59 
illustrated. ,5'2 
sections at, 126-'27 
well at, 124-25 
l\'1ankato time in Minnesota, 111-12 
drift sheet of. 11 0 
Manton'ilk sections at, 141-4'2 
Map, geological, of Minnesota, 4 
Maquoketa formation, 3, 90-93 
composition of limestones in, 115 
Dubuque member of. 90-9'2 
faunal list of. 229-47 
illustrated, 91 
map of. 4 
sections of, 87, 92, 93. 142, 146, H7. 1.;-2-
53, 178, 198 
type locality of. 90 
well logs including, 1.54, 17,) 
Wykoff member of. 92-93 
"Ma~ble layer" of Spechts Ferr.\' , 79 
Marine, formations near, 41. 48 
sections at. 209-11 
Marion, section at, 181 
Marsden, R. 'W .. see Tyler et ai, 
Masonic Park, Spring "alle~', section at. 1.5\ 
l\lazomanie formation, '28, 40-41 
McGee, W. J., 5.5, 94, 10'2 
l\lcGregor member of Platteyille formation, 
77-79 
composition of limestones in, 116 
fauna of, 78, 79, 241--44 
illnstrated, 73 
sections of. 68, 72, 76, 81-82, 123, 136, 144, 
145, 147, 149, 154, 157, ],58, 162, 165-67, 
170.180,181,184,188,189,192,'207,209 
type section of, 77 
well log's including, 142, 1M;, 176, 198 
Meinzer, 0, E., see Hall 
256 PALEOZOIC AND RELATED ROCKS OF SOllTHEASTERN MINNESOTA 
Mendota. well at. 138-39 
"l'I'Iendota limestone:' 44. See ''/.'0 St. Lmn-
ence formation 
Meridian Lake. section at. 210-11 
l'IIerriam Junction. formations at. ·H-45 , "*9. 
59 
section at. 19"*-95 
l'I'Iesabi Range, Cretae-eoll>' in. 99, 104-6 
JHeso7.oic in Minnesota. 8-9. See also Cre-
taceous 
Milwaukee Railroad Well, Hastings, log of. 
J37-38 
Lake Cit v. lcw of. 200-1 
Mineral Bl~ff. Dresbach, Eau Claire at, 33 
section at, 219 
lvIinneapolis. formations at, 12. 31. '1"*-4;), 
57. 67, 69, 73, 75, 79 
illustrated. 66 
sections at. '25. 76, 1 'l3. 16'2-6G 
wells at, 163-64 
l\Iinneapolis and St. Louis Railway Well, 
Jordan, 43-H 
lIIinneiska. section of ravine and bluff at. 
'202-3 
lIEnnesota. general section for Cambrian Ill, 
30 
geological column of. 8-10 
historical geology of, 3-7 
Minnesota Clay Works, Morlon, section at, 
189 
Minnesota Geological Survey, 'lB. 29. 36 
1I1innesota Ri"er, formations along, 11, 43, 
44, 45, 46, 47, 48, 54, 59, 98, 11 '! 
Jordan-Oneota contact along, 50-53, 57 
sections along, 55, 64,123-24.1'16-27,130, 
174, 189 
:Mission Creek, Fond du Lac. section at, 198 
Mississippi River, bluff along. illustrated, 6 
formations along, 34, 37-39. 41, 44. 46, 4R, 
59, 66-67. 82: 11 '2 
Jordan-Oneota contact along .. 50, .).\" 57, 
60 
sections along, 32, 82, 137, 138. 1.59, 160-
61. 162-65. 169-70, 187-89. 200-5. 220, 
223 
~liohawkian series, 69-90 
corrosion wnes in, 69-70 
fauna of. 69-70. 90 
Galena formation of. 8'2-90 
Glenwood belongs in, 74, 77 
Platteville formation of, 70-8'2 
Moore, R. C .. III 
J\'Iora. outcrops of Fond dn Lac beds at, 
13-14 
lIIorrison County, Cretaceous in, 101, 10.J, 
map 0[, 176 
section in, at Two Rivers, 175 
J\'Iorton. section in clay pit at, 189 
11ft. Simon member of Dresbach formation. 
28, 33 
anal,'ses of, 17, 18, 75 
relation to Hincklev sandstone, 16, 17-H'., 
2'2. 33 . 
sections of. 30, 170, 186 
,veil logs including, 2'22 
Mt. Tom, Hokah, section on, 168 
J\Iower County, Cedar Valley limestone in, 
9't' . 
Cretaceous in, 100. 102 
map of. 17R 
",('(ions in, at Le Roy, 177 
LYle 177 
R'aci;Je, 178 
Yarco. 178-79 
wells in, at Austin, 175-77 
Kew Hichmond sandstone, 5n. 61-62 
New Vim, Cretaceous at, 99, 103 
pre-Cambrian outcrops at, 11 
sectiolls at, 103--1. 128-30 
?\icollet County. map of. 179 
sec-tiOllS in, at Fort Ridgel", 179 
Hebron. 45 
Mankato, 127 
Ne\\' VIm. 128 
sinks and cayes in, 97-9R 
Nicollet Creek member of St. Lawrence 
formation. 28. 45, 124 
('ong-Iomerates in. 41, 1'24 
fauna of, 248 
illustrated, 42 
sections of, 30, 4.5, 1 '23. 1 '24, 132, 150, 161, 
167.169.171, '200, 201, 203-5, 207, 210, 
21'2.215,218.219,221, 222 
type section of. 45 
well logs inclnding, 147 
Northfield. Shakopee fossils at, 65 
St. Olaf College well at, log of. 192 
Norton, W. H .. 35, 44 
Xorwalk member of Jordan sandstone, 28, 48 
fauna of. 48. 247 
sections of. 30. 49. 13'2 
type section of. -18 
Olmsted Count.\,. map of. ISO 
Prosser in, 86, R7 
sections in. at Chatfield, 72 
Dover, 180-Rl 
j'darion, 181 
Pleasant Grove, 181-82 
Hochester. 183-84 
Stewartville, 89-90, 184-85 
,veils in, at Rochester, 18'2-83 
Olleota dolomite, 2.5, 53, 55-59. 159 
caves and sinks in, .50-53, 97-98 
illnstrated. ;;2 
composition of. 116 
contact with Jordan. 48. 50-53, 54, 57 
illustrated, 47, 50 
rautHl of. 58. 65, 246 
illustl'ated, 6, 47, 50. 60 
map of. 4 
INDEX £57 
s('('tions of. 25, 65, .sf\. fi2, 126. 127. 137, 
138. 148-,50. 159-fiO, 166, 168. 160. 171, 
174.199-'206. 'W7, 208, 'III. 212. 215-19. 
221-23 
typic-al sectinn of. at Lewiston. Ml 
"ell logs including. 44. 137-39. 147, 155. 
164.177.183.190,192.195. ID8, 212 
Oneota-Shakopee ·contact. 63 .. 59. 62. (H 
"Orange gra\'els," Dakota formation, 100 
Ordovician in l\1innesota, .50-53 
Beekmantown ian series of. .53-66 
Chazvan series of. 66-69 . 
Cinci'~natian series of, 90-97 
eontact with Cambrian, 50-53 
diagram of, 70 
faunal list for, 229-47 
Mohawkian series of. 69, 90 
residual fossils from, in the Cretaceous. 101 
Ordovician-Devonian contact in :Minnesota. 
93 
Oseeola bridge, Norwalk fossils at, 48 
section at, 132-33 
Ostrander member of Dakota formation, 
102-3, 182 
illustrated. 100 
sections of, 103. 127-28. 148, 151. 178. 
181-82 
type section of. 103 
Ottawa. formations at. 52, 54 . .58 
section at, 174 
Owatonna. wells at. 17, 198 
Owen. D. D .. 24. 46, 68. 94 
Cambrian classification of. 28 
O:roplecia (Triplecia) IIlrichi bed, 90-91 
Ozark ian period. 53. 54, 55 
Paleozoic in southeastern l\Iinnesota. 24-98 
geological column for. 9 
histor:v of. 5 
Pearce . .I. H .. see Kay 
Pecatonica beds. 77 
Pelecypoda, in faunal list. 227. 228. 230, 232-
33. 236. 240, 242, 244. 245 
Pettiiohn, Frances. 78 
Phyllo)lorina faunal zone. see Cha.""wtopora 
bed 
PilgTim Rest Cemeter)'. Mankato. section at. 
126 
Pille City, log of. well at, 186 
Pine Count)·. formations in. 15. 16, 17. '2'2-
23. 33, 36 
map of. lS5 
sections in. at Pine Cit,'. 186 
Ri\'erdale Ferry. 186 
Sandstone. 23 
wells in. 186-87 
Pine Point Trail. Taylors Falls, section at. 
135 
Plants. in faunal list. 'N7-Q8 
Platteyille formation, 70-82 
composition of limestone in. II G 
contact with St. Peter. 67, 71-72. 74, 7.5, 
76,77 
definition and correlation of. 70-71. 73. 82 
fauna of, 238--4.5 
Glellwood member of. 73-77 
illustrated. 66. 67, 71, 73. 80 
Magnolia beds in. 77-78 
map of, 4 
:McGregor member of. 77-79 
Pecatonica beds in. 77-78 
relation to Galena and Trenton, 80, 82, 83 
seetions of, 68. 72. 76, 81. 123. 136, IH. 
145, 147-49. 154. 157. 158. 162. 165-67. 
170. ISO. lSI. 184, 188. 189, 191, 192, 
207, 209 
Spechts Ferry member 01', 7n-82 
type location. 70 
well logs including. 142. 156. 176. IS2, 198 
Pleasant Grove. sections at. 181-82 
Pleistocene in southeastern Minnesota. 107-
12 
classification of. 107. 108 
map of drift in. III 
Polychaeta. ill faunal list. 227, 230. 231. 235. 
238-39. 241-42. 2H, 245. 247-49 
Post-Devonian interval. 97-98 
Post-Ordovician interval. 93 
Powell. L. H., 53. 54. 55. 58 
Powers. E. H .. see Trm\'bridge 
Pre-Cambrian in southeastern l\Iinnesota. 3. 
7. 1I-23. 97. 10.5. 109. 189 
Pre-Devonian surface in l\Iinnesota. 93 
Preston. Root Yalley at. 61 
sections at. H9 
Productella beds of Cedar Valle)' limestone. 
97 
illustrated. 96 
Prosser Creek. Stewartville formation at. 89 
Prosser member of Galena formation, 83. 
86-88 
composition of. 11.5 
fauna of. 87. 231-34 
illustrated. 87 
sections of. 7'1. 87-88. 92. 143-44. 149, 
151. 154. 160. IS2. IS3, 188 
t,'pe section or.' 87-88 
well logs including. 155. 158. 198 
Prosser's Ravine. 86. 88 
Proterozoic in Minnesota. 10. II 
Pt!!chaspis gran "losa zone in the Hudson. 40 
in sections. 170. 171. 20'2-4. '207-10. 217. 
2!..20. 22~ 
Raasch. G. 0 .. -1.0. See also Bays and Raasch 
Racine, section at Bear Creek. 178 
Ramsey County, map of, lR7 
seetiol1s in. at St. Paul. 81-8'2. IS7-89 
Ramsey's Gorge. Copas. section at, 209 
Rapidan, section at. 128 
RE'ads Landing. section at. 203-4 
Red Clasti" beds, 12. See also Fond du Lac 
hc-ds 
'2,58 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Red Wing, formations nt, 46, 5,1, 58, 109 
illustrated, 47, 48 
sections at, 160-61 
Red\Yood County, old "'eathered surface Ill, 
97 ' 
sections in, 189 
Red"'ood Falls, formations at, 11. 97 
Reno, sections at, 169-70 
Renyille County, section in, at Morton, lS9 
Reptiles, in Mi;lIlesota formations, 100, 106 
Resser, C. E .. Cambrian classification of. '28 
Rhinidictya bed, 83, 1.56, 188 
Rice County, Illinoian drift in, 109 
wells in, at Faribault, 44, 190-91 
Northfield, 19'2 
map of, 190 
sections in, at Faribault, 191-9'2 
Riceford Creek. section on, 171 
Richmond, Cretaceous at, 104 
log' of well at, 104-.5 
Riley's Coulee, Lake City, section at, '201 
RiY~rdale Ferry, section 'at, 186 
Rochester, formations at, 17, 109 
sections at, 183-84 
well at, 18'2-83 
Rohr Malting Company, Shakopee, well at, 
19.5 
Rollingstone, Oneota fanna at, 58 
Rollingstone Creek, section at, 58 
Root River, Root Valley sandstone named 
for, 61 ' 
sections along, 89-90, !-t9, 15'2, 153-54, 
168, 18'2, 185 
Stewartyille member along, 89-90 
Root Valley sandstone, 25, 59-63, 65 
heavv m'inerals in, 75 
illust'rated, 61 
map of. 4 
sections of. ,58, 6'2. 1'16, 1'27, 137, 138, !-t8-
50. 20'2" 204. 218. '22'2 
well logs, 190 
Rose Creek. at Varco, 9.5 
at Austin, Cedar Valley limestone along. 
95 
section along, 178-79 
Rosemount, log of well at, 139-40 
Rushford. sectIon at, 150 
St. Croix RiYer, formations along, '22, 33, 37, 
46, 48, 57, 59 
map of, 134 
sections along. at Afton, '205-6 
Arcola. '207-8 
Copas, '208-9 
Franconia. 132 
Marine, '209-10 
Meridian Lake, '210-11 
Osceola bridge. 13'2-33 
Soo Line Drawbridge, '211 
Stillwater. '211-1'2, '215-16 
Ta~'lors Falls, 133-35 
S1. Croixian Series, 3, 8, '24-49 
contact with Hinckley sandstone, Hi, 17-
IS, '2'2 
fauna of. '27, 247, '249 
general section for Minnesota. 30 
map of. 4 
"'inchell's section in Winona County. 
'24-~5 
St. Lawrence, type section at, 43 
St. Lawrence fonnation, '"24, ~;3. ':2(1, ':2H. 3;), 
4'2-46 
composition of. 116 
faunal list of. '247-48 
illustrated, 42 
Lodi member of. 46 
Nicollet Creek member of. 4,:; 
sections of. 25, 30, 43, 45, 49, 1023-24, 132, 
150, 159-61. 167-69, 171. 199-~05, '207-
1'2, 215, 217-19, 221-'~3 
well logs inclnding. 44. 1~5, 137-40, 147, 
164, 177, 183, 190, 19'2, 19,;, Hl6, 198. 
'213 
Winchell's type section of. 43 
St. Louis Count~~. sections in, at Fond du 
Lac, 193 
Hibbing. 193-94 
St. Louis River, Fond dn Lac beds along, It, 
13, 14. 75 
sections along, 14, 193 
St. Olaf College WelL Northfield, log of, 192 
St. Paul, forn;ations at, 67, 69, 83, 85 
sections at, 81-S'2, 187-89 
well at, 140 
St. Paul Crushed Stone Company Quarr~', 
section at, 189 
St. Peter, formations at, .5'2, 54 
8t. Peter sandstone, 66-69, 77, 98 
disconformity at base. 53, 65-66 
fossils in, 68: 69, '245 
heavy nlinerals in. 75 
illustrated, 66. 67 
map of, 4 
sections of. '2.5, 6'2, 68, 72, 76, 77, 8\!, 123. 
136, 144, 145. 148, 149, 157, 158, 162, 
165.166,170-71,181. 184, 188,189,192, 
207, '209 
type section of, at Fort Snelling, 68 
well logs including, 44, 138, 139, L;5, 164. 
177, 183, 190. 19'2, 198 
S1. Peter-Platteyille contact, 70-71. 71-7'2. 
73. 74, 7.5-76, 77 
illustrated, 66 
St. Peter's River, St. Peter sandstone named 
for, 68 
Sand Creek, at .Jordan. formations along, 43-
44, 46. 47, 49 
Sand pit. North Minneapolis, section at. 1\!3 
Sandstone. Hinckley sandstone at. 15, 16, 17. 
22-'23.7.5 
illustrated, '2'2 
t~'pe section of Hinckley at. '22, '13 
\Yell of Federal Prison at. 186-87 
INDEX 259 
Sandstones of Minnesota, analysis 01', 75, 
Sardeson, F, W" !l6, .59, 64. 69. 7.5. 90, 91. 92, 
108. 11!l 
on the Mohawkian series. 70. 71, 73. 77, 79, 
R3.94 
Sauk River. Cretaceous along', 10l, 104 
section along. 197 ~ 
Scaevogyra~Billingsella faunule. 30 
Scaphopoda.227 
Schmidt Farm. Fish Lake. section on, 209 
Schwartz Farm, Ottawa, section of river 
bluff at. 174 
Schwm'tz, G, M,. 12. 15, 17.61-62. ll!l, See 
also Thiel; Stauffer et ai, 
Scott County. map of, 194 
St. La\\Tence in, 4!l, 43 
sections in. at Jordan. 49 
;\1errian~ Junction. 194-9.5 
St. Lawrence. 43 
Shakopee. 64, 196-97 
wells in. logs of. 195-96 
Sedimentar~' analyses. as guides to forma~ 
tions. 26 
of Fond du Lac beds. 18. 19 
of Glenwood. 74-75 
of Hincklev. 18.21-22 
of Mt. Sim'on. 18 
of St. Peter. 67 
of sandstones in 'Minnesota, 75 
Sellars Open-Pit Mine. Hibbing. section at. 
193-94 
Shakopee. formations at. 59. 65 
,<ection at. 64 
well at. 64 
Shakopee dolomite. 63-66 
beds at base of. 53. 59. 62 
composition of. 116 
fauna of. 59. 65. 245-46 
illustrated. 61. 63 
map of. 4 
sections of. 25. 62. 64. 68. 126. 127. 137. 
138. 140-41. 148. 149. 157~ 159. 171. 
194-97. 2Il. 215 
well logs including. 44. 138. 139. 142. 155. 
164.177.183.190.192.195-96.198 
Shakopee-St. Peter contact. 6.5-66. 68 
Shumard. B, F .. -t2. 54. 101 
Siblev Park. section at. 127 
Siev~rding's Well. Stearns County. 104. 105 
Silurian. lack of. in 'Minnesota. 93. 94 
Sinks in Oneota. 50-53. 97-98 
illustrated. 51 
Snake Creek. Galesville-Ironton contact at. 
illustrated. 38 
8ection at outlet of. 200 
Snake Rin"r. Fond du Lac (lutcrops alollg'. 
at ;'Ilora. 13-14 
section along. at Ri,'erdale FelT~'. 186 
Soldiers Home. Minneapolis. Platteyille and 
St, Peter at. illustrated. 66 
Soo Line Drawbridge. section at. '211 
Soo Line High Bridge. Arcola. section at. ':208 
Spechts Ferry member of the Platteville for-
mation. 71. 79-82 
fauna of. 80, 238 
illustrated. 80 
sections of, 7'2. 76, 81, 144-45. 154, 1.57, 
1.58. 16'2, 165, 166. 170, 180, 184. 188, 
191. 19'2 
well logs including, 142, 155. 176. 188 
Spongiae, in faunal list, 229. 231, 234-3.5, 
238,241 
Spring Grove, Platteville at, illustrated. 71 
section at. 170-71 
Spring Valley. formations at. 92. 9,5. 97. 98, 
101 
illustrated, 91. 96 
sections at. 91-93. 151-52 
Springfield. Cretaceous at. 99. 103-4 
section at. 130 
Stainbrook. M, A .. 9.5 
State Fish Hatch~rv. Lanesboro, Root Val-
ley at, 61 ' 
State Hospital Quarry. Rochester. section at, 
184 
Stauffer. C. R. 14-1.5, 33. 44. 48. 49. 64, 65. 
73-74. 77, 79. 95 
E. p, Burch, and G, M, Schwartz. II 
G, M, Schwartz. and G, A, Thiel. '28. 30, 
36. 48 
and G, A, Thiel. 63. 115 
Stearns County. Cretaceous in. 104 
log of well in, 104. 105 
map of. 196 
section in. on Sauk River. 197 
Steele County, map of. 197 
section in. at Clinton Falls. 198 
',ell in. at Owatonna. 198 
Stewartville. sections at. 89-90. 184 
Ste"artville dolomite at. 88-90 
Stewartville member of Galena formation, 
88-90 
composition of. 11.5 
fauna of. 89, 231 
illustrated. 89. 91 
sections of. 88--90. 9~, HI--H, 149. 1.51-.53. 
18'2. 184-85. 198 
lype sections of. 89-90 
well loi!'s including, 155. 198 
Stictoporella bed. 71. 79. 80. 83. 157. 188 
Still,Yater. 11. 13. 46. 48. 57. 58. 62. 65 
sections at. 'Ill-I'!. 215-16 
',ell at. 2h'-14 . 
Stillwater trilobite bed of Owen. 46. 213 
Stockton HilL Winona. illustrated. -1<1. .50 
section. 2'1Q-23 
Straight Riwr. sections along. 192. 198 
Stratigraphic classification of Minnesota for-
mations. 7-10. 30 
Stromatoporcl/a beds of Cedar Valley lime-
stone. 96 
illustrated. 97 
Sugar Loaf Hill. 'Yinona. section at. 2'23 
S',an well at l\Tanknto. log of. 138-39 
~60 PALEOZOIC AND RELATED ROCKS OF SOUTHEASTERN MINNESOTA 
Taconite. section at Arcturus Mine. 17-1, 
Taylors Falls. formations at. II, 3~. 33. 3,;. 
39, 41, 75 
illustrated. 37. 38 
sections at. 133-35 
Taylors Falls member of the Franeonia for-
mation, 28, 36. 38, 39--40 
fauna of. 40. ~48 
illustrated, 37 
sections of. 30. 39. 131-33. 13;;. 168-70. 
172. 200. 203. 204. 217-~2 
Taylors Falls Region, map of. 13-1, 
Tellerina-Saukiella faunule. 30. 49 
Thatcher Farm. Preston. section at. l-t9 
Thiel. G. A .. 67. 68. 74. 7.5-76. 77. See also 
Crowley; Gruner; Stauffer: T~'ler et al. 
and C. E. Dutton. 16.57 
and G. M. Schw~rtz, 5 
Thwaites. F. T .. 12.48.66.102. 108 
Tostevin Quarries. Dresbach. Dresbaeh in. 
32. 33, 218-19 
illustrated. 31 
sections at. 3~. 218-19 
Trempealeau. in Cambrian classification. 28 
Trilobite beds. 28, 29. 46. 79, 81 
Trilobites. in faunal list. ~29-31. ~34. 240. 
244. 246-49 . 
Triplecia ulrichi beds, 90. See al.w Oxoplec;ct 
ulric hi beds 
Trowbridge. A. C .. 40. 66 
and G. I. Atwater. 29, 3-1,. 64 
and E. H. Powers. 33 
Troy Road, Chatfield. section along. l-t4 
Twenhofel. W. H., 27. 29 
G. O. Raasch, and F. T. Thwaites. 28, 29. 
30. 33, 34. 35. 36. 40 
Twin City Brick and Tile Plant. St. Paul. 
section ·at. 187 
Twin City FoundQ'. Stillwater. section at. 
21~ 
Twin City Region. formations in, 17. 59. 61-
62, 64: 68, 77. 78. 112 
Two Rivers, section at. 175 
Tyler. S. A .. R. W. Marsden. F. F. Grout. 
. and G. A. Thiel, 13, 19-21. ~~ 
Ulrich, E. 0 .. 1.5. ~8. 29, 30. 33. 36, 37, 40-41. 
46. 48, 53. 57, 6~. 65. 86, 88 
Cambrian classification of. ~8 
University of Minnesota Campus. section at. 
164-6,5 
Upham. Warren. 16. 101. 104, 12.5 
Van Oser Creek. 47, 49 
Van Oser member of Jordan sandstone. 28. 
48--49 
fauna of, 49. 247 
sections of. 30. 49. 13~ 
Vanuxemia bed, 79 
Varco. Cedar Valley along Rose Creek. 9.5 
section. 178-79 
Vel/aII/o (Clit(tlnbonites) bed. in section, 15.5 
Vermillion River. at Eggleston, seetion at. 
159 
Vermillion River Gorge. Hastings. seetion at, 
138 
Virginia. Cretaceous at. 104 
"·abasha. Oneota at. 54 
section at. 204-5 
Wabasha County, map of. 199 
section in. at Kellogg. 199-200 
Lake City. 200-~ 
Minneisk~. 202-3 
Reads Landing. 203-4 
Wabasha. 204-,; 
wells in. at Lakf' City, ~00-1 
Waconia. well at. Vi. 33 
Walcott-Ulrich. Cambrian classification. 28 
Washington Avenue Bridge. Minneapolis. 
section at, 76 
Washington County. map of. 206 
sections in. at Afton. ~05-7 
Arcola. ~07-8 
Copas, ~08-9 
Fish Lake, 209 
Hastings Dam, 137 
Marine. ~09-10 
Meridian Lake. 210-11 
Soo Line Drawbridge. ~11 
Stillwater. 211-12. 215-16 
well in. at Stillwater. 212-14 
Wasioja. section at. 142 
·Waterford. section along Cannon River at. 
140-41 
Well logs. see list for each county 
White. C. A .. 90 
\Yhitewater River. section at, 62 
"'hitewater State Park. formations at. 
illustrated. 61 
section at, 6~ 
Wilder Well. Shakopee. log of. 64 
Willow Creek. Preston. section along. 149 
Winchell. Alexander. 42 
Winchell. N. H .. 12, 15. 16.22.2.5.29.30.31. 
46. 47. 48 .. 5~ .. 59. 63, 95. 97. 98, 101. 139, 
1.59. 214 
and E. O. Ulrich. 70. 79, 86. 88. 90 
and Warren Upham, 1~. 13. 44-45 
"'eneral section of the St. Croixian. ~.S ~n St. Lawrence formation. 29. 4~. 43-4;; 
St. Croixian classification of. 24-26. 28 
type section of St. Lawrence by. 43 
Windrow formation, 10~-3 
Winkelmann Quarry. New Ulm, section at. 
130 
Winneshiek County. Iowa. Glenwood type 
locality, 73, 75 
Winona, city well of. 223 
formations at. lR. 22, 32. 41, 57, 58 
illustrated. 50. 60 
sf'ctions at. 221-23 
INDEX 261 
Winona Connt~', formations in. IX. 22. ~H . .59, 
109 
map of, 216 
sections in, at Dakota. '217 
Dresbach, 32, '218-19 
La Moille, '220 
La tsch State Park, 220 
Lewiston, .58 
Whitewater State Park, 62 
Winona. 2'21-'23 
type section of Dresbach formation at 
. Dresbach, 3'2 
wells in, at Winona, 223 
Winchell's general section or St. Croixian 
in, 24-2.5 
Winona Mining Company, shaft, section of. 
219 
'Visconsin, formations compared to :Ylinne-
sota, 1'2, 13, 22, 33, 34, 36, 40, 66, 77, 82, 
83, 102 
Wisconsin drift in Minnesota, 1l0-1'2 
sections of. 129, 130, 16.5 
substages of, 108, 1l0-12 
Wolfe Brewery, Stillwater. section at, '2 Hi 
,,'ooster, L. C., 40, .59 
Worthen, A. H., 82, 102 
"',Ykoff, formations at. 87, 88. 9'2 
sections at. 86, 87-88. 93, 152-.54 
type section of Prosser near. 87-88 
W,"koff member of _Maquoketa formation, 
92-93 
fauna of, 92. 229-30 
sections of. 146, 147, 1;52. ];53. 178 
Zumbro River, section along. at Kellogg, 
199, 200 
Kenvon.I60 
Ma~ton·ille. I-H. 14'2 
,,'asioja, 142 
Zumbrota, Gunderson cia.,' pit at, illustrated, 
84 
sections at. 8.5-86