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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 91 records · Page 5Linked to original sources
USGS1978

Geologic map of the Mare Australe area of Mars

The south polar region of Mars is among the most geologically diverse on the planet. The areas is within the heavily cratered hemisphere of Mars bu t is distinguished by a variety of younger, regionally extensive deposits and a n a ssemblage of unique erosional forms. The spectrum of units varies from the oldest to the youngest on the planet. The oldest unit, typif ying t h e cratered hemisphere, is the material of ancient large craters, most of which have undergone advanced degradation. These ancient crater materials are overlain by a variety of regional deposits, including extensive intercrater debris blankets, r i dged volcanic flows, and massive eolian deposits that eroded to form complex cliff-rimmed pits. In the central zone of the polar region, south of roughly 75 ˚ S., these depositional units are, in turn, unconformably overlain by a t remendous sedimentary complex 1,500-2,000 km in diameter, consisting of 40 or more regularly spaced horizontal starta . Each stratum retains apparently uniform thickness (several tons of meters) over hundreds of kilometers; erosional unconformities between starta have not as yet been identified. Resting on the uppermost surface of this layered terrain is the perm anent residual polar ice cap. This complex stratigraphic record may ultimately hold the keys t o the initial atmospheric evolution, climatological fluctuations, and the history, budget, and mobility of wate r on the planet.

IMAP↗
USGS1978

Geologic map of the Thaumasia Quadrangle of Mars

The Thaumasia quadrangle lies on the south flank of the Tharsis dome (Hord and others, 1974), a large bulge in the crust of Mars extending more than 5,000 km northward from the center of the quadrangle. The major structure imposes a generally southward slope across the entire quadrangle. Topography along the east-central border of the Thaumasia quadrangle exhibits curved scarps and lowlands concentric with the Argyre basin. Four regions within the Thaumasia quadrangle are defined on the basis of the dominant geologic unit exposed. Three of these regions form arcuate patterns around the south flank of the Tharsis dome, and the fourth is a arcuate region concentric with the Argyre basin.

IMAP↗
USGS1978

Bedrock topography of north-central Iowa

The bedrock in Iowa (Hershey, 1969) is generally overlain by deposits of glacial drift and alluvium, which range in thickness from less than 1 ft to more than 400 ft, and from less than 1 ft to about 60 ft respectively. The configuration of the bedrock surface is the result of a complex system of ancient drainage courses which were developed during a long period of preglacial erosion and during shorter, but mroe intense, periods of interglacial erosion.

Iowa↗
USGS1978

Channel migration of the White River in the eastern Uinta Basin, Utah and Colorado

The White River is the largest stream in the southeastern part of the Uinta Basin in Utah and Colorado. This map shows the changes that have occurred in the location of the main channel of the river from 1936 to 1974. The map indicated that certain reaches of the river are subject to different rates of channel migration. Also shown is the boundary of the flood plain, which is mapped at the point of abrupt break in slope. This map documents the position of the river channel prior to any withdrawals of water or alteration of the flow characteristics of the white river that may occur in order to meet water requirements principally associated with the proposed oil-shale industry or other development in the area. The channel locations were determined from aerial photographs taken at four different time periods for the following Federal agencies: In 1936, U.S. Soil Conservation Services; 1953, U.S. Corps of Engineers; 1965, U.S. Geological Survey; and in 1974, U.S. Bureau of Land Management. The 1936 delineation, which is actually based upon photographs that were taken in 1936 and 1937, was made by projection of the original photographs on a base map that was prepared from 1:24,000 scale topographic maps. The 1953, 1965, and 1974 delineations were produced from stereographic models. The 1965 delineation was compiled from photographs that were taken during 1962-65. The delineation is labeled as 1965 for simplicity, however, because the photographs for 1965 cover about 60 percent of the study read of the river, and because no changed were discernable in those areas of repetitive photographic coverage.

Colorado, Utah↗