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The USGS provides unbiased, objective, and impartial scientific information upon which our audiences, including resource managers, planners, and other entities, rely.
Browse more than 65,000 articles authored by our scientists over the past 100+ year history of the USGS and refine search by topic, location, year, and advanced search.
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Composition of fluid inclusions, cave-in-rock fluorite district, Illinois, and upper Mississippi valley zinc-lead district
No abstract available.
Authors
W. E. Hall, I. Friedman
Distribution of fluorine in unaltered silicic volcanic rocks of the western conterminous United States
An investigation of more than 170 samples of glass-rich volcanic rocks of rhyolitic or rhyodacitic composition shows marked regional variations in the fluorine content. The uniformity of the class of rocks was controlled by index of refraction determinations on fused beads and by chemical analyses of about one-seventh of the total number. The fluorine content ranges from 20 to 4,900 ppm. The frequ
Authors
R.R. Coats, W.D. Gross, L. F. Rader
Factors influencing the pore volume of fine-grained sediments under low-to-moderate overburden loads
An anomalous increase of pore volume with increasing depth in the range 0—1,900 ft. occurs in fine‐grained sediments along the east side of the San Joaquin Valley of Cali‐ fornia. Several possible causes for the anomaly were inferred from a literature search and from study of the core samples. Statistical analyses of the core sample data suggest the principle causes to be variations in particle si
Authors
R.H. Meade
Hypervelocity impact of steel into Coconino Sandstone
Impact of a 0.4019-g steel sphere at 4.27 km/sec into Coconino Sandstone [Permian] from Meteor Crater, Arizona, produced a crater 11-12 cm across and 2.45 cm deep. The ejecta consist of sandstone fragments, disaggregated sand, splinters of sand grains, strongly shocked aggregates of crushed sandstone grains, and chips, splinters, small amounts of silica glass, and minute spheres of steel. Part of
Authors
Eugene Merle Shoemaker, D. E. Gault, H. J. Moore, R. V. Lugn
The hydraulic geometry of a shallow estuary
An analogy with entropy production in steady-state systems leads to a statement that the geometry of natural waterways is governed by two opposing influences: a) equal work per unit of area of bed, and b) minimum work done in the system as a whole. The resulting calculations applied to shallow, estuaries are verified by field measurements.
Authors
W. B. Langbein
Preliminary results of a study of calcium carbonate saturation of ground water in central Florida
The departure of ground water from equilibrium with calcite is being studied in central Florida. Measurements of pH, temperature, and concentration of bicarbonate made in the field are used with standard laboratory analyses of water samples to calculate an ion activity product (K) for calcium carbonate. The calculated Kiap is compared with the equilibrium constant (Keq) for calcite to determine th
Authors
William Back
Correlations and problems in belt series stratigraphy, Northern idaho and western Montana
A continuous strip of geologic maps has recently been completed along the Idaho-Montana state line between Clark Fork, Idaho, and Superior, Montana. New stratigraphic and petrographic information provides the basis for stratigraphic correlations and for the interpretation of facies changes in this part of the basin of deposition of the Precambrian Belt Series. Identification of facies changes is a
Authors
J. E. Harrison, A.B. Campbell
Anomalous gravity field in east-central California
Bouguer gravity values at about 11,000 stations in east-central California range from -14 mgal near Merced to -274 mgal in Long Valley. Gravity lows in the west and south parts of the San Joaquin Valley and over local basins south and east of the Sierra Nevada are produced by large thicknesses of Upper Cretaceous and Cenozoic deposits. A large regional gravity low over the Sierra Nevada can be exp
Authors
Howard W. Oliver, Don R. Mabey
Facies and types of hydrothermal alteration
No abstract available.
Authors
J.J. Hemley, P. B. Hostetler
Two pollen diagrams from southeastern Minnesota: Problems in the regional late-glacial and postglacial vegetational history
Kirchner Marsh and Lake Carlson are located 3 miles apart in Dakota County about 15 miles south of Minneapolis in the St. Croix moraine, which was formed by the Superior lobe during the Gary phase of the Wisconsin glaciation. During the Mankato phase that followed, the Des Moines lobe advanced to within a few miles of the sites. The region today is in a mixed-oak forest, with a maplebasswood fores
Authors
H.E. Wright, Thomas C. Winter, Harvey L. Patten
Early pennsylvanian currents in the southern Appalachian Mountains
Measurement of more than 1200 cross-beds in lower Pennsylvanian sandstones of the southern Appalachian Mountains reveals a broad pattern of sediment transport to the southwest and west. Most of the sand appears to have been derived from the east and to have moved south-westward parallel to the axis of the Appalachian geosyncline. The pattern has a similar alignment to that in the Illinois basin, b
Authors
John Schlee