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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 109 records · Page 6Linked to original sources
USGS1952

Progress report on geologic study of the Crosby and Ironton area of the Cuyuna Range, Crow Wing County, Minnesota

The detailed geology of part of the Guyana manganiferous iron-ore district was mapped during the summer and autumn of 1951. The only exposures of bedrock in or near this area are in the open-pit and underground mines where two or more layers of iron-formation and associated elastic sediments have been deformed into a complex fold system and have been intruded by large dikes. The accompanying maps and sections show the distribution of the several rock types exposed, brief descriptions of these materials, and data on the geologic structure. For the most part this structural and lithologic information has been generalized from much more detailed maps prepared in the field on scales of 30, 40, or 50 feet equal to one inch.

Minnesota↗
USGS1954

Progress report on studies of salt-water encroachment on Long Island, New York, 1953

Nearly all the water used on Long Island, N. Y., is derived by wells from the thick and extensive water-bearing formations that underlie and compose the entire island. The unconsolidated deposits, consisting of sand, gravel, and clay, range in thickness from a few feet in northern Queens County to more than 2,000 feet in southern Suffolk County. Four main and relatively distinct aquifers, all interconnected hydraulically to a greater or lesser degree, have been recognized and delineated at least in a general way. They are, from younger to older, the upper Pleistocene deposits, in which the ground water is mainly unconfined, and three formations in which the water is generally confined - the Jameco gravel, of Pleistocene age, and the Magothy (?) formation and the Lloyd sand member of the Rartian formation, both of Lake Cretaceous age. Except for some artificial recharge, these aquifers are replenished entirely by infiltration of precipitation. Under natural conditions, the fresh water moves into and through the formations, discharging into the sea. With the growth of population on Long Island and the continuously increasing use of water over the years, not only has the infiltration of precipitation been seriously impeded at places, but the withdrawals from the ground-water reservoir have increased markedly. These factors have upset the natural balance between the fresh surface and ground water of the island and the surrounding sea water, and with increased use of water will do so more and more, thus leading to salt-water encroachment. In a sense, the whole problem of utilization of ground water on Long Island is one of determining how much ground water can be withdrawn without serious salt-water encroachment.

New York↗
USGS1953

Progress report on the Killigwa anticlinorium, 1953

This report was prepared to assist in the planning of seismic profiles to be run across the anticlinorium in the vicinity of the Kiligwa River. The stratigraphy and structure of the mapped area south of the anticlinorium are reviewed. Two facies of the Lisburne formation, a calcarenite-hydroclastic limestone facies and a black shale, black chert and dark limestone facies, have been distinguished. In the southern foothills, the black shale facies appears to have been thrust from the south over the limestone facies. The available evidence indicates that the Lisburne formation, as limestone or a more proximal facies was doposited over the area of the anticlinorium. Following a redefinition of the Torok formation in the type area, strata formerly mapped as Torok have here been designated Castle Mountain formation. The depositional history of the Castle Mountain formation reflects active orogeny. Lenses of coarse clastics appear to have been dumped in local basins; equivalent beds to the north are much finer. A basal zone of sandstone may be more extensive and may correlate with the sandstones noted along and north of the anticlinorium.

Alaska↗