Browsing by Author "Schwartz, George M."
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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. 27. The Geology of the Minneapolis-St. Paul Metropolitan Area(Minnesota Geological Survey, 1936) Schwartz, George M.Geology, or a knowledge of the rocks and surface features of a region, becomes increasingly important as the region is settled and develops into a center of population. This bulletin is the outgrowth of repeated requests to the director of the Minnesota Geological Survey for detailed data on various geologic phases of the area in and near Minneapolis and St. Paul. The immediate requests resulting in the work came from the Metropolitan Regional Planning Association, the Metropolitan Drainage Commission, and the 1932 Water Commission appointed by the City Council of Minneapolis. Most earlier reports, being written primarily for the geologist, employed many technical terms; also they gave generalizations rather than the specific data most useful to the engineer. There is need, therefore, of a summary of the detailed knowledge of the geology of the region and a tabulation of quantitative data. This report is an attempt to answer that demand.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. 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.Item 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.Item 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.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 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.Item Minnesota Limestone Suitable for Portland Cement(Minnesota Geological Survey, 1956) Prokopovich, Nikola; Schwartz, George M.Item On Geologic Values(Minnesota Department of Natural Resources, 1964-06) Schwartz, George M.An analysis of how geological processes have contributed to the natural beauty of Minnesota State Parks.Item Preliminary Survey of Bloating Clays and Shales in Minnesota(Minnesota Geological Survey, 1957) Prokopovich, Nikola; Schwartz, George M.