Browsing by Author "Grout, Frank F."
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Item Bulletin No. 11. Preliminary Report on the Clays and Shales of Minnesota(Minnesota Geological Survey, 1914) Grout, Frank F.; Soper, E.K.This bulletin is a preliminary paper outlining the principal results of an investigation of the clay resources of Minnesota, which was carried on during the summer of 1912. A more comprehensive report is now in progress and will be issued later. In general, the object of the work has been to assist in the development of the clay resources of Minnesota. The broader problems of ceramics are treated only incidentally. Some of the important scientific conclusions of the American Ceramic Society, of the Bureau of Standards, and of surveys of other states are briefly reviewed here in order that they may be more readily available to those whose chief interests are technical and commercial. A more extended treatment of the scientific results of the investigation will appear later. Specifically, the object has been (1) to investigate the sources of clay for every town of 1,000 or more inhabitants, and for each county of the State; (2) to ascertain the extent of several deposits now developed at only a few points; (3) to find new deposits; and (4) to determine the qualities of these deposits and of certain mixtures, to ascertain whether it is possible to produce some refractory wares, pottery, paving brick, and certain other high-grade products that are now carried considerable distances to the Minnesota markets.Item Bulletin No. 17. The Magnetite Deposits of the Eastern Mesabi Range Minnesota(Minnesota Geological Survey, 1919) Grout, Frank F.; Broderick, T.M.The Mesabi range is a belt of iron-bearing formation about 100 miles long, located about 80 miles north of Duluth, which is situated at the west end of Lake Superior. The trend of the belt is east-north- east. The iron-bearing formation, commonly called taconite, is largely drift covered throughout the main range and has few of the topographic features of a "range." It is called a range because iron-bearing formations in other districts form ranges; and at the east end of the Mesabi district there are some rocky hills rising 200 to 400 feet above the general level. This report is a discussion of the eastern end of the range-that part which lies between the town of Mesaba and Birch Lake, a distance of about 20 miles. This portion of the range is commonly called the "east Mesabi." It is distinguished from the rest of the range by several features, besides the topography above mentioned. In this area, outcrops are numerous; most of the iron is in magnetic form; recrystallization has increased the size of grain and reduced the porosity; there has been very little leaching or enrichment; and in places the beds are more highly tilted. These several peculiarities make the east Mesabi a logical unit for separate study. The field work was done in the summer of 1917, by Frank F. Grout and T. M. Broderick. The Mesabi Syndicate (D. C. Jackling, and Hayden-Stone and Company) were at that time actively exploring certain parts of the area and Mr. W. G. Swart, in charge at the Duluth office, made the work much more effective by rendering many drill records accessible to the Survey. A large number of samples have been assayed in their laboratories.Item Bulletin No. 21. The Geology and Magnetite Deposits of Northern St. Louis County, Minnesota(Minnesota Geological Survey, 1926) Grout, Frank F.This bulletin treats the geology and mineral deposits of a large area in northern St. Louis County, extending northward to the Canadian boundary. It lies north of the Mesabi iron range and includes most of the Vermilion iron range. It lies south of the Rainy Lake area of Canada. Because it adjoins the world's greatest iron-producing area it has been the subject of much interest to explorers and prospectors seeking new deposits of iron ore and parts of the area have been surveyed by the United States Geological Survey and the earlier Minnesota state surveys. Much of the area, however, had not been surveyed in detail. The report includes a general map of the area (Plate I) several detailed maps of small areas of economic interest and 88 township plats. These township plats are essentially outcrop maps and cover the entire area. approximately 2800 square miles.Item Bulletin No. 24. The Geology of the Rove Formation and Associated Intrusives in Northeastern Minnesota(Minnesota Geological Survey, 1933) Grout, Frank F.; Schwartz, George M.In the large area of Rove formation along the boundary of north- eastern Minnesota and Ontario there have been two important silver mines, both on the Ontario side of the boundary - Silver Islet and Silver Mountain. The existence of a number of smaller mines and prospects makes it certain that mineralization of this kind occurred over a wide area, and several other mineral occurrences have long been known; but no other important deposits have been developed. Since much of the area is concealed under glacial deposits and since only a reconnaissance geological survey had been made in the part of the area that lies in Minnesota, it seemed advisable to survey the area in more detail. An effort was made to map and study all large outcrops and most of the smaller ones, to record where the veins are and what is their nature, to map the formations more closely than before, and on these records to base an estimate of the probable mineral prospects of the district. The Gunflint iron-bearing formation, which has been treated before, is here referred to only incidentally. The Minnesota area of Rove slate is a narrow strip south of the international boundary from Pigeon Point to a few miles west of Gunflint Lake in Cook County. Since the base of the formation trends northeast into Ontario and the beds dip south, it is believed that eastern outcrops in Minnesota are at a higher horizon than those near Gunflint Lake.Item Bulletin No. 28. The Geology of the Anorthosites of the Minnesota Coast of Lake Superior(Minnesota Geological Survey, 1939) Grout, Frank F.; Schwartz, George M.The northeast corner of Minnesota, lying north of Lake Superior and comprising Cook and Lake counties and part of St. Louis County, is underlain by Keweenawan rocks except for a narrow strip along the Canadian border. Early studies of these rocks were made principally by Winchell and by Irving, as shown by the list of publications given below. Because of the size and inaccessibility of much of the region, these early studies were confined to a narrow strip along the shore of Lake Superior. Later Grout and other members of the Minnesota Geological Survey made detailed studies of the Duluth gabbro. Between the areas covered by these workers lies a region in which only reconnaissance work had been done previous to the mapping presented in this report. It is planned eventually to map in detail this entire area, but as it embraces approximately 4,000 square miles of forested or brushy country, much of it not easily accessible for detailed work, it will take many field seasons to complete the task. The particular region mapped in this survey was selected because of unusual plagioclase feldspar masses of very high purity, for which it is hoped uses may be found, but the results are also significant as an example of the geology of a great Keweenawan area. The Keweenawan of this region consists almost entirely of igneous rocks. and even the few sedimentary rocks known are closely connected with extrusive igneous activity. It is about centrally located in the Keweenawan area of the north shore of Lake Superior and lies above the thickest part of the Duluth gabbro, but probably is not connected with it by continuous intrusive masses below the drift.Item Bulletin No. 30. Mineral Resources of Minnesota(Minnesota Geological Survey, 1943) Emmons, William H.; Grout, Frank F.This resume of the mineral resources of Minnesota is introduced by a brief discussion of the physiography and general geology of the state to furnish a background for a discussion of its economic geology. Since iron ores are Minnesota's most important mineral resources, they receive the most attention. Other mineral resources are discussed approximately in the order of their commercial importance, and the origin, distribution, and chief commercial uses of each are briefly noted. Four factors determine the economic importance of Minnesota's minerals--quality, quantity, accessibility, and market. Iron ores. for example, are of high quality, they are easily mined and cheaply transported by way of the Great Lakes to the coal regions of the industrial East, and the demand for iron has been and is tremendous -- that of a pioneering, progressive people. It is very likely. however, that the high-grade iron ores will be nearing exhaustion within the next thirty or forty years, and therefore the future of the iron ore industry in Minnesota depends largely upon how well the technical, economical, and political problems connected with the industry are solved. The Mesabi range has probably reached its zenith in less than fifty years since the first discovery of ore at Mountain Iron. Yet there are many billions of tons of low-grade iron-bearing material on that range, and it is not too early to plan for its utilization. This problem, and other problems of mineral resources, are considered and discussed herein. The Minnesota Geological Survey has been studying the mineral resources of the state for many years. The present bulletin makes use of data published in greater detail in earlier reports. brings up to date certain descriptions given in those reports. and adds descriptions of several resources not previously considered.Item 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.Item 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.Item The Granites and Associated Quartz Basalts of Stearns County, Minnesota(1908) Grout, Frank F.