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Research about Minnesota

Source-linked reports with geographic coverage including Minnesota.

At least 919 records · Page 51Linked to original sources
USGS1962

Pollen sequence at Kirchner Marsh, Minnesota

A pollen diagram from Kirchner Marsh, southeastern Minnesota, records a continuous vegetation sequence from the time of Late Wisconsin ice retreat from the region. The late-glacial and early postglacial portions of the diagram are correlated with a radiocarbon-dated diagram from Madelia, Minnesota. Both diagrams show a series of maxima of pollen types in the early postglacial that suggest a significant climatic change at that time. The Kirchner diagram, in addition, shows high percentages of nonarboreal pollen later in the postglacial that indicate an advance of prairie elements into the area between 7200 and 5000 years ago.

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USGS1962

Use of thermometry in hydrogeologic studies of glacial deposits at Worthington, Minnesota

Precise measurements of fluctuations of ground-water temperature based on monthly readings in shallow glacial -outwash aquifers may be used to study ground-water movement and recharge. An increase in storage in the shallow basin of Okabena Lake, Worthington , Minnesota , permits the water to cover a much larger area and probably increases the opportunity for infiltration of lake water into aquifers connected with the lake. In a shallow artesian aquifer confined by relatively impervious glacial till, water moves toward the land surface in response to steep temperature gradients in the winter, and cool water descends to the aquifer when the upward temperature gradient is lowered or eliminated. Thermometry may also be used in hydrogeologic studies of limestone terrane.

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USGS1962

Magnetic anomalies and magnetizations of the Biwabik iron-formation, Mesabi area, Minnesota

In a study of the relationship of magnetic anomalies to the magnetite content and structure of layered Precambrian iron-formations, the effective induced and remanent magnetizations of the Biwabik iron-formation were determined by analyses of aeromagnetic anomalies recorded 1,000 ft above the Biwabik in areas of known geology. The induced magnetization along the layers is relatively insignificant because the formation is almost perpendicular to the earth's magnetic field. For the relatively unmetamorphosed iron-formation of the Main Mesabi district, the dominant magnetization was found to be across the layers, about 0.012 gauss, and most likely induced. For the strongly metamorphosed iron-formation of the East Mesabi district, the dominant magnetization was found to be along the layers, about 0.100 gauss, and remanent. These values are used as bases for explaining aeromagnetic anomalies from correlatives of the Biwabik iron-formation in the Gunflint, Cuyuna, and Gogebic districts.

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USGS1961

Use of water-well data in interpreting occurrence of aquifers in northeastern Lyon County, Minnesota

In northeastern Lyon County the areal distribution of aquifers of Cretaceous age determined from well-bottom altitudes suggests a series of interbedded sandstones striking northwestward and overlapping one another to the northeast. Probably the numerous thin sandstone aquifers in the area were deposited near the flanks of a Precambrian granite “high” area by a transgressing Late Cretaceous sea.

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USGS1961

Availability of ground water in Lyon County, Minnesota

Lyon County is in southwestern Minnesota, about 150 miles southwest of Minneapolis and St. Paul The basement rocks in the area consist of granite and quartzite of Precambrian age. These materials are in turn overlain by shale and sandstone of Cretaceous age, glacial drift of Pleistocene age, and alluvium of Recent age. Ground water is available primarily from aquifers in Pleistocene and Cretaceous strata from depths ranging from 15 to 500 feet below the land surface. The county is divided into areas of ground-water availability based on the quality and quantity of ground water available from the different geologic units. The glacial drift which covers all of the area, yields very hard water from sands and gravels occurring in melt-water channel deposits or as small, isolated melt-water bodies. Wells in the drift commonly yield from 2 to 30 gpm (gallons per minute), but sustained yields of as much as 500 gpm are obtained in areas where thick melt-water channel deposits occur. Cretaceous strata underlie about two-thirds of the county and yield water from poorly consolidated sandstone, The water ranges in hardness from soft to very hard and is sometimes high in chloride content. Wells in Cretaceous strata commonly yield from 2 to 7 gpm; however, in areas where the sandstone is in contact with the underlying weathered granite, sustained yields of as much as 75 gpm are obtained. The geographic and stratigraphic distribution of the geologic units suggests that additional water supplies may be available from Pleistocene and Cretaceous strata in areas not yet fully explored.

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USGS1961

Exploratory drilling for ground water in the Mountain Iron-Virginia area, St. Louis County, Minnesota

The Mountain Iron-Virginia area is a broad, southwest-trending valley in the central part of the Mesabi Range. The valley, which heads in the Laurentian Divide, and covers about 120 square miles, coincides approximately with a bedrock valley filled with as much as 150 feet of glacial deposits. A complex sequence of glacioaqueous sediments made up of clay, silt, sand, and gravel was delineated from test holes drilled at 238 sites. These sediments range in thickness from 0 to 125 feet and can be considered a hydrologic unit, bounded below by sandy till or bedrock and above by as much as 60 feet of clayey till. The piezometric surface ranges from 0 to about 70 feet below land surface, thus, the glacioaqueous deposits are not everywhere completely saturated. In places, however, the water is under artesian pressure. Within the Mountain Iron-Virginia area about 50 square miles are underlain by deposits 20 feet or more in thickness of silt, sand, or gravel that constitute an aquifer that is a large potential source for additional water supplies. Except for iron and manganese, which are present in excessive amounts in some wells, the water meets U.S. Public Health Service standards for municipal supplies. Pumping tests of wells in the permeable sand or gravel deposits at five sites indicate that yields of several hundred gallons per minute and possibly as much as 2,000 gpm (gallons per minute) can be expected.

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USGS1961

Aquifers in melt-water channels along the southwest flank of the Des Moines Lobe, Lyon County, Minnesota

During the Gary and Mankato substages of Wisconsin glaciation the Des Moines lobe advanced southeastward through the broad lowland of the Minnesota River valley of southwestern Minnesota, and thence southward to central Iowa. Among the most prominent topographic features in Lyon County, Minn., are five southeastward-trending end moraines, two of which are associated with and parallel to belts of surficial outwash that are approximately half a mile to a mile wide. Test drilling indicated that one of the belts of outwash is underlain by a complex system of buried melt-water channels. The other is the upper part of a series of deposits in an incised channel. The channels are filled with till, glaciolacustrine deposits, and outwash, which includes permeable deposits of water-bearing sand and gravel. Associated with the surficial melt-water channels is a pronounced southeastward-trending linear drainage pattern. By studying the lineation of streams and lakes, analyzing the available water-well data, and drilling test holes, several elongate deposits of buried outwash having little or no topographic expression were located. The long axes of the deposits are generally parallel to the lineation of the drainage and the end moraines. The melt-water channels in Lyon County trend southeastward because the flank of the ice sheet was confined by a landmass that sloped to the northeast. Similar buried channels may be present elsewhere along the southwest flank of the Des Moines lobe. If so, they probably can be located by the methods described.

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USGS1960

Occurrence of ground waters of low hardness and of high chloride content in Lyon County, Minnesota

The ground water in Lyon County and elsewhere in southwestern Minnesota is generally hard and low in chloride. It is the purpose of this report to describe briefly the occurrence in Lyon County of waters of low hardness and of high chloride content. The waters are found largely in Cretaceous sandstone. The data were collected in conjunction with a countywide study of the geology and groundwater resources that is being made as part of a statewide investigation in cooperation with the Division of Waters, Minnesota Department of Conservation. The work is under the direct supervision of the junior author, who is district geologist for Minnesota. Hardness and chloride determinations were made with field-testing kits at the time data were obtained on most of the farm wells in the county. Tests were made on wells that were reported to yield relatively soft or "salty" water.

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