Bulletin of the Minnesota Geological and Natural History Survey (1887-2000)

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Bulletin No. 48. Frederick William Sardeson, Geologist 1866-1958
(Minnesota Geological Survey, 2000) Weiss, Malcolm P.
Frederick W. Sardeson was a highly capable, innovative, productive, and fascinating figure in geology, yet he never enjoyed admiration from most of his contemporaries or lasting distinction in his chosen field. Cut adrift from his teaching post in middle age, he had to live by nip and tuck thereafter. Nevertheless, his legacy of published geology is of interest still to students of the Lower Paleozoic rocks and fossils of the Upper Mississippi Valley, and to students of Ordovician fossils from several phyla. This report attempts to explain something of Sardeson's qualities and behavior, to give balance to the record of his professional accomplishments, and to throw some light on the practice of geology in the half century prior to World War II. How is it that one undertakes to study and report on such a person in detail? As a graduate student in geology at the University of Minnesota in 1949, I was assigned by W. Charles Bell to prepare a brief account of Sardeson and his contributions to the science of geology. Bell turned me on to Sardeson to help me prepare for my dissertation work on the lithoand biostratigraphy of the Middle Ordovician rocks of Fillmore County in southeastern Minnesota. Charlie Bell had told his students stories from his short acquaintance with Sardeson (1946-47), between Bell's arrival in Minneapolis and Sardeson's departure for Seattle, and I was able to recall those accounts. In addition, in 1949, I interviewed several persons who had known Sardeson. Among those were Frank F. Grout, recently retired from the Department of Geology and, as I now know, a major antagonist of Sardeson early in this century; plant ecologist William S. Cooper, who skirmished with Sardeson over the Anoka sandplain; and Frederick K. Butters, also of the Botany Department. Some biographical information came from the Minnesota Alumni office, and the President's office gave some details of his dismissal from the University. For the early orientation to Sardeson's work I also consulted some of his published works and the standard reference volumes.
Bulletin No. 47. Bibliography of Minnesota Geology 1981-1985
(Minnesota Geological Survey, 1987) Swanson, Lynn; Balaban, N.H.; Morey, G.B.
This bibliography contains references to the geologic literature on the State of Minnesota issued from 1981 through 1985, as well as omissions from the previous two bibliographies of Minnesota geology: Bulletin 34 (published in 1951), with coverage through 1950; and Bulletin 46 (published in 1981), with coverage for 1951-1980. The references in the bibliography section cover most geologic topics but exclude those confined to the last 10,000 years, to surface hydrology, and to mining and metallurgy. Most unpublished maps and reports were excluded from this bibliography, because they are not readily available to users. Notable exceptions are theses and dissertations and open-file reports issued in established and accessible series, such as the U.S. Geological Survey's Open-File Report series. An effort was made in the bibliography section to preserve the spelling, capitalization, and punctuation of the original sources; usage in the index reflects current Minnesota Geological Survey style. The last bibliography, Bulletin 46, covered 30 years. Bulletin 47 covers only 5 years, but contains nearly 1,100 references, more than half the number in its predecessor. Much of this inflation may reflect the increased number of abstracts published in recent years. The next bibliography (for 1986-1990) will differentiate between abstracts and more substantive work. The index section, with a few minor changes, closely follows the design of the index in Bulletin 46. It has in one alphabetical listing topical (Ground Water; Petrology; Sedimentation), geographic (Mesabi range; Lake County; Southwestern Minnesota), lithostratigraphic (Duluth Complex; Lake Vermilion Formation), and chronostratigraphic (Paleozoic; Quaternary) indexing. Care was taken to index references to the closest applicable index classifications. For this reason, users of the index are encouraged to search flexibly, to check both broader and narrower index classifications. For example, someone wanting references for Aitkin County may also wish to search a narrower index classification-Cuyuna range, as well as the broader East-central Minnesota. The increased number of cross references in this index should help users with this type of search. Several of the Survey staff were especially helpful in the preparation of the index, and also reviewed the entries in their respective fields: M.J.P. Kuhns and S.J. Mills (economic geology and Duluth Complex); P.L. McSwiggen (petrology and uranium); H.C. Hobbs (glacial geology); and D.J. Bergstrom (Paleozoic rocks and Sioux Quartzite). V. W. Chandler reviewed the geophysics entries; D.R. Setterholm, Cretaceous rocks; R.S. Lively, geochemistry and geochronology; and M.C. Hoyer, ATES. Linda McDonald typed and updated the bibliography through most of its existence. Denise Fletcher typed the index and inserted the typesetting codes. J. F. Splettstoesser proofread the final typescript.
Bulletin No. 46. Bibliography of Minnesota Geology 1951-1980
(Minnesota Geological Survey, 1981) Morey, G.B.; Balaban, Nancy; Swanson, Lynn
This bibliography brings Minnesota Geological Survey Bulletin 34, "Bibliography of Minnesota Geology," by T.G. Melone and L. W. Weis, published in 1951, up to date. A supplement in 1962, by John F. Splettstoesser and Sally A. Sloan, included literature for the period 1951-1961. The present bibliography incorporates the latter into a compilation of literature from 1951 through 1980. The literature covered includes essentially all geologic topics, but excludes surface hydrology, mining, and metallurgy. Masters theses and Ph.D. dissertations are included, but some omissions of these and other kinds of literature are inevitable. We hope that omissions and errors will be brought to our attention. The bibliography is the result of efforts by numerous individuals over a period of several years. If anyone has been omitted from the alphabetic list that follows, we apologize: Douglas Bergstrom, Reta Bradley, Susan Brostrom, Amy Bumberg, Lucinda Hruska-Claeys, Dana Noonan, John Splettstoesser, and Lynn Swanson. G. B. Morey directed the final selection of the citations and the preparation of the index by Nancy Balaban and Lynn Swanson. The index, designed by Morey, is based in large part on his knowledge of the pertinent literature. Howard Hobbs reviewed the indexing of the Quaternary citations, and Val Chandler, the indexing of the geophysics citations. Lynn Swanson and Nancy Balaban were responsible for copy editing and proofreading. Leonora Bauer, Ruth Harter, Vera Jean Holmberg, and Linda McDonald typed successive generations of the manuscript on a word processor.
Bulletin No. 45. Progressive Contact Metamorphism of the Biwabik Iron-fomation, Mesabi Range, Minnesota
(Minnesota Geological Survey, 1968) French, Bevan M.
The recent, spectacular growth of the taconite industry, and the expansion of taconite operations from the eastern to the central and western parts of the Mesabi range, emphasizes the importance of knowledge of the geology of the range. The earliest taconite plants were established in the Eastern Mesabi district, in areas in which the Biwabik Iron-formation was metamorphosed by the Duluth Gabbro Complex; most of the recent plants are in the Main and Western Mesabi districts, in areas of "unaltered" iron-formation. This report describes the changes in mineralogy and texture from "unaltered" taconite in the Main Mesabi district to highly metamorphosed taconite in the Eastern Mesabi district. It describes not only the silicate minerals, but also the opaque iron oxides, carbonate minerals, and carbonaceous material. Knowledge of the mineralogic changes is extremely important to the practical problems related to beneficiating characteristics of the magnetic taconites. The report is modified from a Ph.D. thesis submitted to the Graduate School at Johns Hopkins University by Bevan M. French. The Biwabik Iron-formation, on the Mesabi range in northern Minnesota, extends for about 120 miles in a generally east-northeast direction, from west of Grand Rapids on the Mississippi River to Birch Lake, east of Babbitt. The formation is the middle unit of the Animikie Group of Middle Precambrian age. On the eastern end of the Mesabi range, the Animikie Group has been metamorphosed by the intrusive Duluth Gabbro Complex; mineralogical changes in the sediments, particularly in the iron-formation, appear to have been caused by the gabbro. From the data of the present study, four metamorphic zones may be distinguished within the Biwabik Iron-formation by changes in mineralogy along the strike of the formation toward the gabbro contact:
Bulletin No. 44. Geology of the Duluth Gabbro Complex near Duluth, Minnesota
(Minnesota Geological Survey, 1964) Taylor, Richard B.
Multiple intrusions at Duluth, Minnesota, form a rock series that is here called the Duluth Gabbro Complex. Each of the principal rock types transgresses one or more of the older units. The oldest rock, a coarsegrained anorthositic gabbro that was intruded into the Keweenawan flows, makes up the upper part of the complex. It was intruded by basaltic magma of a second period of magmatic activity which formed rocks that commonly are banded, and hence called the layered series. The gabbroic rocks of the layered series as well as the older anorthositic gabbro are cut by intrusive bodies of ferrogranodiorite and granophyre and by late dikes of basalt and aplite. The lower two-thirds of the complex, the layered series. is composed chiefly of troctolite, olivine gabbro, feldspathic gabbro, and syenogabbro. About 15,000 feet of layered rocks is exposed, locally with rhythmic banding, fluxion structure, and gravity stratification demonstrating bottom accumulation by crystallization under conditions of active magma circulation. A series of samples collected from bottom to top of the layered series shows only limited development of cryptic layering. This lack of cryptic layering may be explained as the result of periodic renewal of magma in the crystallizing chamber or by multiple small intrusions. Cross-cutting relations between the different types of gabbro in the layered series show that the mass originated by multiple intrusion. The lack of chilling effects indicates that the successive intrusions were not greatly separated in time. Near the top of the series a transition exists from gabbro to syenogabbro, and a similar transition may exist from syenogabbro to ferrogranodiorite. The rock series is similar in many respects to that of the Skaergaard Intrusion, but there are important differences that can be explained by dissimilar tectonic history. The poor development of cryptic layering and the absence of ferro gabbro at Duluth, in contrast to their remarkable development in the Skaergaard Intrusion, can be explained by differing tectonic stability. The Skaergaard magma apparently crystallized in a chamber under stable conditions, whereas the Duluth magma seems to have crystallized in an environment of tectonic instability manifested by multiple intrusions of magma. The various rocks of the Duluth Gabbro Complex can be explained by crystallization-differentiation of basaltic magma, although the origin of some, such as the anorthositic gabbro and intrusive peridotite, is puzzling. The rocks of the layered series probably were derived from a basaltic magma approaching the composition of analyzed late basalt dikes. Compared with the analyses of "marginal olivine gabbro" from the Skaergaard Intrusion, the Duluth parent magma seems to have been notably richer in K2O, TiO2, MnO, and P2O5. The Duluth Gabbro Complex is an immense sill-like mass that extends for 150 miles northeast from Duluth, and relations in other parts may differ from those at Duluth.
Bulletin No. 43. The Geology of the Metamorphosed Biwabik Iron-Formation, Eastern Mesabi District, Minnesota
(Minnesota Geological Survey, 1962) Gundersen, James Novotny; Schwartz, George M.
The construction of large concentrating plants and opening of pits for large-scale mining and milling of taconite during the past decade has emphasized the importance of all aspects of the geology of the Eastern Mesabi district. It had been known from the earliest explorations in the Mesabi district that the eastern twenty-mile portion was characterized by a hard, siliceous, magnetite rock which Winchell called "taconyte." It was soon learned that this rock had not yielded to natural enrichment as had many areas in the main part of the range. Later, as the large complex concentrating plants went into operation, it became evident that intensive study of certain aspects of the geology, including detailed lateral as well as vertical stratigraphic variations, together with mineralogical and petrographic characteristics, would be extremely important to the successful operation of the huge pits and concentrating plants. The only detailed publication on the Eastern Mesabi was by Grout and Broderick in 1919, a study that necessarily depended mainly on outcrops, whereas large amounts of diamond drill core and extensive vertical exposures in the pits are now available. The earlier mineralogical work was done before x-ray methods were well developed and before the complex amphibole and pyroxene groups were well understood. It was therefore obvious to the Director of the Minnesota Geological Survey that a modern detailed study was needed to supplement the excellent earlier work of Grout and Broderick. Fortunately, Dr. E. W. Davis, who had spent much of a lifetime on developing a process to concentrate taconite, was a consultant for the Reserve Mining Company. He fully understood the significance of a detailed knowledge of taconite, and as a result of his suggestions the company established an excellent postgraduate fellowship at the University of Minnesota to aid in fundamental research on the characteristics of taconite. Dr. James N. Gundersen, currently of the Department of Geology, Los Angeles State College, was appointed to the fellowship. The Minnesota Geological Survey agreed to assume field and other expenses and to direct the work. The results published in this bulletin speak for the character of the work accomplished. The bulletin is adapted from Dr. Gundersen's thesis submitted for the degree of Doctor of Philosophy. He deserves the highest praise for the energy and devotion he has given to the problem. The economically important Eastern Mesabi district of Minnesota is the type locality for the iron-formation rock type taconite, a stratified quartzose rock containing significant amounts of iron-bearing oxides, hydroxides, silicates, and, locally west of the district, carbonates. Five basic types of taconite massive, layered, laminated, shaly bedded, and shaly are delineated for detailed classification of the stratified structure and mineralogy of the Biwabik iron-formation in this district.
Bulletin No. 42. Lower Upper Cretaceous Plant Microfossils from Minnesota
(Minnesota Geological Survey, 1961) Pierce, Richard L.
Spores and pollen from the pre-marine Cretaceous clays and lignites of Minnesota indicate that the probable age of these deposits is Cenomanian. Forests of conifers appear to have been the main type of vegetation; however, these forests contained a diversity of species that do not occur in modern conifer forests of the State. Many of the conifer pollen species found appear to be referable to the Podocarpaceae, a family of Eastern Asiatic, Mexican, and Southern Hemispheric distribution. Dicotyledonous angiosperms were present in the flora, but their pollen is seldom abundant in the Cretaceous deposits of Minnesota. The morphological simplicity and lack of diversity of the angiosperm pollen in these rocks indicate that the angiosperms were at a lower stage of evolution than that often ascribed to them on the basis of leaf impressions from the same rocks. The physiognomy of the flora reflected by the spores, pollen, and previously described leaf impressions can be reconciled with the physiognomy of floras that occur in moist, warm-temperate areas such as Seattle, Washington. A moist, warm-temperate climate, in an area of little relief, is postulated to have prevailed in Minnesota during Cenomanian time.
Bulletin No. 41. The Precambrian Geology and Geochronology of Minnesota
(Minnesota Geological Survey, 1961) Goldich, Samuel S.; Nier, Alfred O.; Baadsgaard, Halfdan; Hoffman, John H.; Krueger, Harold W.
This bulletin is an outstanding example of the cooperation of several scientists and scientific organizations. Without the cooperation of all concerned, such a comprehensive correlation of age determinations and regional geology would have been impossible short of many years of work. The results are a particularly important demonstration of cooperation among geologists, chemists, and physicists. Radioactivity dating of a large number of igneous and metamorphic rocks by the potassium-argon and the rubidium-strontium methods is the basis for revision of the classification of the Precambrian rocks of Minnesota. The major divisions of the three-fold classification are made at time boundaries of 2.5 and 1.7 billion years (b.y.), corresponding to the time of two major orogenies, the Algoman and the Penokean, respectively. The eras are referred to as Early, Middle, and Late Precambrian in preference to the older terminology of Earlier, Medial, and Later Precambrian. The division between the Early and Middle Precambrian is placed at the time of the Algoman rather than of the older Laurentian orogeny. The division between the Middle and Late Precambrian is made on the basis of the Penokean orogeny which resulted in a mountain chain that extended from central Minnesota through Wisconsin into Michigan. The Penokean Mountains formerly were assigned erroneously to late Keweenawan time. The Early Precambrian rocks are divided into the Ontarian and the Timiskamian systems. The Ontarian rocks include the Keewatin group of Minnesota and the Coutchiching metasediments which underlie the Keewatin greenstones in Ontario. Some of the gneisses in the Giants Range and the Vermilion granite regions of Minnesota probably were derived by metamorphism of ancient sediments that were deposited prior to the great outpouring of basalt flows assigned to the Ely greenstone of the Keewatin group.
Bulletin No. 40. Pleistocene Geology of the Randall Region, Central Minnesota
(Minnesota Geological Survey, 1961) Schneider, Allan F.
The systematic investigation of the glacial history of Minnesota goes back sixty to eighty years, to the days of N. H. Winchell and Warren Upham, who were as competent in the interpretation of the terrain and surface deposits as they were in working out the relations of the bedrock. A resurvey of the glacial history of the State was completed just before World War I by Frank Leverett of the U.S. Geological Survey, whose comprehensive report, however, was not published until 1932. Leverett had already mapped most of the other states in the Great Lakes region, so the picture for Minnesota fitted consistently with the others. Each successive generation of geologists, however, has different approaches, based on new techniques and on increased understanding of geological processes. After World War II the Minnesota Geological Survey initiated a program of re-examination of the glacial deposits of the State, which has an exceptionally fine record of the complex interactions of ice lobes that invaded the area from different directions. The recent Bulletin 39 on the Geology of Cook County incorporated a modern study of the glacial history of the northeastern corner of the State by Robert P. Sharp, and the present Bulletin by Allan F. Schneider describes a detailed study of an area in central Minnesota northwest of Little Falls. To this problem Dr. Schneider brought the necessary energy and enthusiasm to do the detailed field work required to unravel the complex relationships. In work on a problem of this sort a broad background on the region as a whole is necessary. This was furnished by H. E. Wright, Jr., who has supervised the work on the Pleistocene geology of Minnesota since 1947. Although the field work was supported by the Minnesota Geological Survey, it should be emphasized that untold hours were spent by Dr. Schneider on laboratory work and on drafting and writing the report while he was otherwise employed. The Minnesota Geological Survey is indebted to both Dr. Schneider and Professor Wright for their devoted service.
Bulletin No. 39. The Geology of Cook County Minnesota
(Minnesota Geological Survey, 1959) Grout, Frank F.; Sharp, Robert P.; Schwartz, George M.
Cook County covers a triangular-shaped area at the extreme northeastern tip of Minnesota between Lake Superior on the south and the province of Ontario, Canada on the north. Its area is approximately 1680 square miles, of which about 274 square miles is covered by several hundred lakes. Its position north of Lake Superior is responsible for a rather moist and cool climate favorable to the growth of timber rather than agriculture. As a result, most of the area is covered by second-growth forest and this, together with the numerous rock-bound lakes, makes it an important vacation area. The area is hilly with a minimum elevation above sea level of 602 feet at Lake Superior and 2232 feet in the Misquah Hills. Much of the northern part of the county is characterized by long narrow lakes separated by prominent ridges. The geology is controlled, in a broad way, by its position on the north limb of the Lake Superior syncline. With the exception of glacial deposits the rocks are all of Precambrian age, with the youngest in a general way occurring along the coast of Lake Superior and the oldest in the Gunflint district and near Saganaga Lake. The older rocks consist of the Ely greenstone, Saganaga granite and Knife Lake group of slates, graywackes, metamorphosed tuffs and various minor types. These form an area of exceedingly complex geology, limited to four townships at the northwest corner of the county. The next group in age, commonly called the Animikie rocks, consists of a thin quartzite followed by the Gunflint iron formation and this, in turn, by the Rove formation. These are correlated with the Biwabik iron formation and Virginia formation of the Mesabi district. The Gunflint formation is mainly limited to two of the four northwest townships noted above, but the Rove formation forms a narrow belt along the international boundary from Gunflint Lake to Pigeon Point, a distance of seventy miles. The beds of the Rove formation dip southward at low angles and have been intruded by numerous diabase sills. Erosion has left the sills standing as asymmetrical ridges between valleys occupied by long narrow lakes. Over two thirds of the county is underlain by rocks of Keweenawan age, consisting of a thin sandstone and conglomerate at the base overlain by an exceedingly thick series of lava flows. These, in turn, are intruded by the eastern part of the huge Duluth gabbro complex and by an extensive series of diabase sills, dikes, and irregular intrusions. The lava flows consist mainly of somewhat variable basalt plus a much smaller percentage of rhyolite. The oldest flows crop out near Grand Portage Bay and trend inland so that successive flows occur along shore to the west as far as Tofte, where the sequence is reversed. A total of 92 flows were mapped between Grand Portage and Tofte with an estimated thickness of over seventeen thousand feet. In the northwestern part of the gabbro exposed in Cook County there is a group of three granite and granodiorite masses of somewhat uncertain origin, but apparently of later age than the gabbro. During Pleistocene time glaciers probably invaded Cook County several times, but the drift now exposed to view represents deposits from the Rainy Lobe, which probably covered the entire county, and the Superior Lobe which covered only a narrow strip along Lake Superior. Drift is of sufficient thickness in some parts of the county to rather effectively mask the underlying rocks and leave unanswered questions about their detailed relations. Glacial lakes covered parts of the county during the waning stages of the glaciers and left abandoned beaches at several levels, as well as glacial-lake clay soils. In spite of the complex geology, Cook County has not furnished productive mineral deposits. Deposits of iron formation, titaniferous magnetite, copper sulfides, and lesser nickel and cobalt sulfides have been investigated from time to time. Forest resources and the resort business are the main sources of revenue, but fishing in Lake Superior and limited agriculture have added to the income. Recently the establishment of Taconite Harbor and a steam power plant by the Erie Mining Company at the end of their railroad from the Mesabi district has been an important addition to the economy.
Bulletin No. 38. The Stratigraphy and Structure of the Mesabi Range, Minnesota
(Minnesota Geological Survey, 1954) White, David A.
The later Precambrian Animikie group in northeastern Minnesota consists of three sedimentary units: the Pokegama (quartzite), Biwabik (iron-rich rock), and Virginia (argillite) formations. "Mesabi range" designates the preglacial outcrop belt, 1/4 to 3 miles wide and 120 miles long, of the Biwabik formation. Varieties of iron-rich rock ("taconite") are either granular or slaty and consist dominantly of chert, iron silicates, magnetite, and siderite. The Lower Cherty, Lower Slaty, Upper Cherty, and Upper Slaty members of the Biwabik formation, which averages 600 feet in thickness, can be further subdivided as shown on a detailed longitudinal stratigraphic section. These members are fairly uniform along most of the range, but only one cherty and one slaty member exist on the Westernmost Mesabi, where the lithic units are intertongued. The areal distribution of rock units on the Westernmost Mesabi is shown on a geologic map. The Biwabik, Pokegama, and Virginia formations are considered conformable. Mesabi rocks probably correlate with those of the Emily district 30 miles away. Chert, greenalite, minnesotaite, stilpnomelane, magnetite, some hematite, and siderite probably formed either during deposition or diagenesis. The rocks are essentially unmetamorphosed. The Pokegama and Biwabik formations were probably produced by the migration of a series of coexisting environments of deposition during an advance, a retreat, and a second advance of the Animikie sea. The deposits formed, during the retreat, in successive environments seaward from shore, were clastic material, carbonaceous-pyritic mud, chert-siderite, chert-magnetite, and iron silicate. Fine clastics of the Virginia formation, perhaps furnished by an outburst of volcanic activity, spread across the former environments of chemical sedimentation. Possible conditions of iron sedimentation were as follows: derivation of iron and silica by weathering of a low-lying land mass, perhaps under an atmosphere rich in carbon dioxide, and a seasonal climate; tectonic stability; and deposition in a shallow, quiescent epicontinental sea. The Animikie beds strike about N. 75 degrees E. and commonly dip 6-12 degrees SE. A structure contour map on the base. of the Biwabik formation shows numerous small anticlines, synclines, monoclines, and faults. Three major joint sets are present. The few rocks intrusive into the Biwabik formation include diabase sills, the Duluth gabbro, and the Aurora syenite sill. Contact metamorphism by the soda-rich Aurora sill has produced crocidolite in adjacent taconite. Minor internal folding of Animikie beds seems to be more prevalent where the underlying rocks are volcanic or sedimentary rather than granitic. The Mesabi range is covered by glacial drift which thickens southward, commonly from 20 to 200 feet, away from a ridge known as the Giants Range. Drift is as much as 500 feet thick over the Westernmost Mesabi. A map of the thickness of drift shows many drift-buried preglacial bedrock valleys that extend from notches in the Giants Range southward across the Mesabi range. Cretaceous iron-ore conglomerates, which at places overlie the Biwabik formation, occur as erosional remnants on bedrock ridges. The scattered soft iron-ore bodies in the Biwabik formation are residual concentrates of oxidized iron minerals formed by the leaching of silica from the chert and iron silicates in taconite. Conditions favoring ore concentration are thought to be as follows: accentuated fracturing at folds and faults allowing ready circulation of leaching solutions; a high iron content in taconite; reducing rather than oxidizing conditions of deposition of the original taconite; the fine size of the grains in taconite and the intimate intermixing of different minerals; a lack of metamorphism, which coarsens the grain; and the availability of large amounts of solutions. The soft ores may have been concentrated by downward-circulating ground waters.
Bulletin No. 37. Minnesota's Rocks and Waters A Geological Story
(Minnesota Geological Survey, 1963) Schwartz, George M.; Thiel, George A.
This volume has been prepared in an attempt to make available to the citizens of Minnesota a general summary of the major geological features of the state and to stimulate a greater interest in, and appreciation of, their natural surroundings. Ability to interpret the landscape requires knowledge of the forces that produced it. One may admire the beauty of a waterfall or marvel at its grandeur, but to appreciate it fully, one must know how it was formed. Man draws from the earth many materials which are necessary for life and happiness, and he deals with geological conditions in many of his daily activities. For example, he plows the soil, which is composed largely of weathered rock materials, and cuts the surface rocks as he grades roads and railroads and excavates foundation places for his skyscrapers and his great plants in which to exploit the earth's resources. Yet how many of the thousands of citizens of Minnesota employed in these enterprises understand the geological relationships of the materials with which they labor? How much greater would be their interest in their assigned tasks if they knew more about the formation of the materials which occupy their attention? An understanding of geological processes guides us in the search for mineral resources and aids us in understanding the forces which produced them. Soil erosion, one of our most important problems, is closely related to the geology of the area involved. The resources of any region determine to a marked degree the activity of its inhabitants. They are the foundation of our well- being, the hope of our future. Minnesota, though known as an agricultural state, has great mineral wealth, and many of its citizens are engaged in mineral industries. All of the mineral substances produced from the rocks of the state may be classified as industrial minerals even though some are metals and others nonmetals. :Metal mining is restricted to the iron ranges, but the nonmetals include a great variety of materials-such as limestone for agricultural lime. marl, sand and gravel, clays and shales, wool rock, and structural and architectural stone-which are excavated and processed at many places in the state. The authors of this book have had many years of experience in educational work in Minnesota. It is their opinion, based upon observation and experience, that in the curriculums in our schools not enough time is devoted to a study of our own state and its resources. It is hoped that this volume will furnish science teachers 'with accurate information which they can in turn pass on to their students at the appropriate time, and that citizens at large will find it a source of information regarding their state. Technical terms have been held to a minimum in order to make the text intelligible to those unfamiliar with detailed geological terminology. The authors know that this method inevitably results in generalities that may not always take into account all detailed scientific information available to the geologist. We hope, however, that geologists will recommend the book to their friends and that they will not hesitate to explain some of the exceptions that are bound to appear where such broad generalizations are employed for the sake of simplicity. Geology is the science that weaves all the other natural sciences together into a comprehensive whole and this results in great complexity. The authors, with full awareness of the magnitude of the task, have attempted to resolve complex geological details by employing a nonscientific assistant who screened out much of the detail and obtained a residue that is sufficiently free of technicalities to be comprehensible to the general reader.
Bulletin No. 37. Minnesota's Rocks and Waters A Geological Story
(Minnesota Geological Survey, 1954) Schwartz, George M.; Thiel, George A.
This volume has been prepared in an attempt to make available to the citizens of Minnesota a general summary of the major geological features of the state and to stimulate a greater interest in, and appreciation of, their natural surroundings. Ability to interpret the landscape requires knowledge of the forces that produced it. One may admire the beauty of a waterfall or marvel at its grandeur, but to appreciate it fully, one must know how it was formed. Man draws from the earth many materials which are necessary for life and happiness, and he deals with geological conditions in many of his daily activities. For example, he plows the soil, which is composed largely of weathered rock materials, and cuts the surface rocks as he grades roads and railroads and excavates foundation places for his skyscrapers and his great plants in which to exploit the earth's resources. Yet how many of the thousands of citizens of Minnesota employed in these enterprises understand the geological relationships of the materials with which they labor? How much greater would be their interest in their assigned tasks if they knew more about the formation of the materials which occupy their attention? An understanding of geological processes guides us in the search for mineral resources and aids us in understanding the forces which produced them. Soil erosion, one of our most important problems, is closely related to the geology of the area involved. The resources of any region determine to a marked degree the activity of its inhabitants. They are the foundation of our well- being, the hope of our future. Minnesota, though known as an agricultural state, has great mineral wealth, and many of its citizens are engaged in mineral industries. All of the mineral substances produced from the rocks of the state may be classified as industrial minerals even though some are metals and others nonmetals. :Metal mining is restricted to the iron ranges, but the nonmetals include a great variety of materials-such as limestone for agricultural lime. marl, sand and gravel, clays and shales, wool rock, and structural and architectural stone-which are excavated and processed at many places in the state. The authors of this book have had many years of experience in educational work in Minnesota. It is their opinion, based upon observation and experience, that in the curriculums in our schools not enough time is devoted to a study of our own state and its resources. It is hoped that this volume will furnish science teachers 'with accurate information which they can in turn pass on to their students at the appropriate time, and that citizens at large will find it a source of information regarding their state. Technical terms have been held to a minimum in order to make the text intelligible to those unfamiliar with detailed geological terminology. The authors know that this method inevitably results in generalities that may not always take into account all detailed scientific information available to the geologist. We hope, however, that geologists will recommend the book to their friends and that they will not hesitate to explain some of the exceptions that are bound to appear where such broad generalizations are employed for the sake of simplicity. Geology is the science that weaves all the other natural sciences together into a comprehensive whole and this results in great complexity. The authors, with full awareness of the magnitude of the task, have attempted to resolve complex geological details by employing a nonscientific assistant who screened out much of the detail and obtained a residue that is sufficiently free of technicalities to be comprehensible to the general reader.
Bulletin No. 36. The Geology of the Cuyuna District, Minnesota
(Minnesota Geological Survey, 1955) Grout, Frank F.; Wolff, J.F., Sr.
This report emphasizes initially the subdivision of the Cuyuna district into a North and a South Range, the former containing iron-bearing rocks comparable with those of the Mesabi district and its Michigan and Wisconsin equivalents and the latter being the equivalent of the younger Michigan iron-formations. The manganiferous iron ores produced on the Cuyuna Range, in east- central Minnesota, have been much desired for use in iron furnaces. The geology of the ore formations and their correlations with ore formations in other districts have been subjects of considerable disagreement, largely because the iron formations on the Cuyuna lie under 50 to 300 feet of glacial deposits. J. F. Wolff, Sr. has a lifelong familiarity with the rocks of the nearby Mesabi Range, and recognizes divisions of the iron formation into four members. He has also had years of work on the Cuyuna area and recog-nizes the same four members, with analogous subdivisions inside the members, and similar sequences of other formations above and below the iron formation. Other men have not wholly agreed on the sequence because of the scarcity of exposures, and the lack of drill cores and records over much of the area. There are also geologists who question the correlation of Mesabi and Cuyuna series, because the "South Range" iron ores on the Cuyuna lie some thousands of feet up in the slates above the main iron-bearing beds of the North Range; and no such high beds of ore have been found in the slates thousands of feet above the Mesabi ore horizons. Only a few hundred to a thousand or more feet of the thickness of the slates overlying the Mesabi iron formation have been penetrated by drills in the Mesabi district, and these were not high enough to encounter the possible South Cuyuna member. This report presents the maps and sections prepared by Wolff, and his interpretation of the sequence, and a comparison with other districts. Some drilling planned by Grout to check the underground sequence of beds was generously supported by funds allotted by the Legislature to the University for research. These two studies of detail are here reported, with scattered data from outlying areas, and suggestions of correlations with the more remote iron ore districts south of Lake Superior. The possible use of the lean manganiferous iron formation of the Cuyuna Range as an emergency resource of manganese, should foreign supplies on which we normally depend be cut off during wartime, is here recommended for further research.
Bulletin No. 35. The Lakes of Minnesota Their Origin and Classification
(Minnesota Geological Survey, 1952) Zumberge, James H.
The most distinctive features of the surface of Minnesota are the thousands of lakes scattered irregularly over the state. Even casual observation reveals the fact that these lakes vary greatly in their character. This means that they have been formed in different ways closely related to the geologic history of the region. There are scattered references to the origin of specific lakes particularly in the Annual Reports and the volumes of the Final Reports of the Geological and Natural History Survey of Minnesota. There has been, however, a lack of any single systematic treatment of the geologic factors involved in the formation of the lakes. It is evident that such a geologic basis is desirable for all scientific and practical work on the lakes which form such a valuable resource. For this reason Dr. Zumberge was supported in his field work by funds allotted by the University of Minnesota to the Minnesota Geological Survey, a unit in the College of Science, Literature, and the Arts. Appreciation is due Dr. Zumberge for his painstaking work, particularly in revising his doctoral thesis to make it into a bulletin for the Geological Survey series - a task performed without remuneration. The Director also wishes to express his thanks to all who helped Dr. Zumberge in his work.
Bulletin No. 34 Supplement. Bibliography of Minnesota Geology
(Minnesota Geological Survey, 1962) Splettstoesser, John F.; Sloan, Sally A.
The following bibliography is limited to titles on the geology of Minnesota and is intended to supplement M. G. S. Bulletin 34, Bibliography of Minnesota Geology through 1951. This supplement covers the period from 1951-1961 plus some items that were missed in the first bibliography. Most of the titles have been taken from Bibliography of North American Geology with some references found in other lists and by searching through periodicals. Thanks are extended for the aid given by the faculty of the Department of Geology of the University of Minnesota. Special assistance, suggestions, and comments were provided by Miss Theodora Melone, co-author of the Bibliography of Minnesota Geology, M. G. S. Bulletin 34, and librarian of the Winchell Library of Geology, and to her the compilers are deeply indebted. Special appreciation is also extended to Charlene Hirsch and Marilyn Reinke for their helpful work in typing and proofreading this Supplement.
Bulletin No. 34. Bibliography of Minnesota Geology
(Minnesota Geological Survey, 1951) Melone, Theodora G.; Weis, Leonard W.
The following bibliography is limited to titles on the geology and mineralogy of Minnesota and is not intended to cover mining and metallurgy. Most of the titles have been taken from Geologic Literature on North America, 1785-1918 and Bibliography of North American Geology, published 1919-1948 as United States Geological Survey Bulletins 746, 747, 823, 937, 938, 949, 952, 958, 968; Annotated Bibliography of Economic Geology, 1928-1949 (except 1944-1945, not published); and Bibliography of Minnesota Mining and Geology and Supplement by Winifred Gregory, published in 1915 and 1920, respectively, as Minnesota School of Mines Experiment Stations Bulletins 4 and 8. Some references were found in private lists and in bibliographies and indexes of societies and journals which ordinarily are not concerned with North American geology. For many valuable suggestions and additions to the bibliography the compilers wish to express their cordial thanks to Dr. George A. Thiel, Chairman of the Geology Department of the University of Minnesota, and Dr. George M. Schwartz, Director of the Minnesota Geological Survey. Special appreciation is also extended to Mrs. Marilyn Jensen for her helpful work in typing and proof-reading, and to Mrs. Nancy Press of the University of Minnesota Press for her technical assistance.
Bulletin No. 33. The Geology of the Duluth Metropolitan Area
(Minnesota Geological Survey, 1949) Schwartz, George M.
The Duluth area is one of the most interesting parts of Minnesota. It is also a critical area in determining the relationship between various rocks of Keweenawan age in the Lake Superior district. The area, therefore, has received more or less detailed study from time to time. Most of these studies, however, referred only to special phases of the geology of the region and no general description has appeared since Winchell published volume four of his final report, which contains a special chapter on the Duluth area. The object of this project was to map the metropolitan area in as much detail as practicable, accompanied by such laboratory studies as seemed desirable. This work was followed by a compilation of all available geological knowledge on the Duluth area into a readable summary for interested residents, as well as for engineers and others who need geological knowledge of the area in their work. The field work was begun in 1937, and the major portion of the field seasons through 1940 was spent in the Duluth area and adjacent portions of the region. Other projects, mostly a result of the war, interfered with the completion of the field work and compilation of the results. The writer is indebted to many persons for innumerable courtesies during the work. The engineering staffs of St. Louis County and the city of Duluth furnished maps and information that aided greatly in the work. Dr. A. E. Sandberg and Mr. Ray Knutsen each served as field assistant for two years and much of the credit for the field work is due to them. Dr. Sandberg had previously spent a great deal of time on field work in connection with a thesis presented to the University of Cincinnati. Professor Thomas W. Chamberlin of the University of Minnesota, Duluth Branch, kindly prepared the chapter on economic geography which is published under his name. The writer is especially indebted to his colleague, Professor Frank F. Grout, for continued suggestions and advice.
Bulletin No. 32, The Geology and Underground Waters of Northeastern Minnesota
(Minnesota Geological Survey, 1947) Thiel, George A.
In 1924 the Minnesota Geological Survey began the task of compiling up-to-date information on the underground waters of Minnesota. Dr. Ira S. Allison carried on much of the work for the northwestern portion of the state and prepared Bulletin 22, The Geology and Water Resources of Northwestern Minnesota, which was published in 1932. Shortly thereafter, Professor Thiel began the revision of the data for the southern half of Minnesota which had originally been discussed in the United States Geological Survey Water-Supply Paper 256 by C. W. Hall, O. E. Meinzer, and M. L. Fuller. Dr. Thiel's revision appeared as Minnesota Geological Survey Bulletin 31 in 1944. The present bulletin completes the series on the underground waters of Minnesota and makes available in published form data on the underground water resources of every county in the state. These bulletins cannot be considered final because water will continue to be developed as long as people inhabit the state. The Minnesota Geological Survey will therefore welcome cooperation in keeping up its file of data on underground waters and will be pleased to answer inquiries not covered by the published material. The state owes a debt to Professor Thiel for the very large amount of painstaking work which has gone into Bulletins 31 and 32. The three bulletins arc available from the University of Minnesota Press at a moderate price. Attention should also be called to the fact that all legal matters regarding underground, as well as surface waters, are by act of the legislature placed under the jurisdiction of the Department of Conservation.
Bulletin No. 31. The Geology and Underground Waters of Southern Minnesota
(Minnesota Geological Survey, 1944) Thiel, George A.
The first reports on the water supplies of southern Minnesota were made late in the past century by my distinguished predecessor, Dr. N. H. Winchell, and his associates. The latest report before the present bulletin was by Professor C. W. Hall, Dr. O. E. Meinzer, and Mr. M. L. Fuller, and was issued in 1911. These two reports were excellent and included essentially all the data available at the time of their preparation. The supply of these reports was soon exhausted, and many requests for information on water supplies of the region were received at the office of the Minnesota Geological Survey from officers of municipalities, railroad companies, canning and packing plants, creamery operators, fanners, well drilling engineers, and from industrial plants. New data were steadily becoming available, chiefly by the sinking of new wells, and it soon became apparent that if the State Geological Survey were to answer these inquiries adequately it must obtain and utilize the information as it became available. Notwithstanding his other heavy university duties, Dr. George A. Thiel agreed to undertake the collection and correla tion of the increasing volume of well records. The results of his researches, together with water analyses and other data supplied by the State Board of Health and by the Division of Lands and Minerals of the State Department of Conservation, are presented herewith. References to papers treating the water supplies of southern Minnesota may be found in this report and also in Bulletin 30 of the Survey, issued in 1943.