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A slice of geologic history is exposed to view in the Denver, Colorado area. Denver is situated on the High Plains near the east front of the Rocky Mountains. As one travels westward from Denver toward the mountains, successively older rocks are crossed from the geologically young rocks of the...

This study of the geometry of limestone solution is based on the following conditions: (1) the limestone is impermeable but contains and transmits water in joints, fractures, bedding‐plane partings, and solution channels; (2) at depth, the limestone aquifer is underlain by impermeable rock; (3) ground water in the limestone is under water‐table conditions; (4) recharge to the limestone is by infiltration of precipitation through the overlying rock...

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Scapolite is a common rock-forming mineral in parts of the Belt Series of Precambrian age in southern Shoshone County and adjoining parts of Clearwater County, Idaho. It is most abundant in moderately metamorphosed calcareous shaly layers of the Wallace Formation but occurs also in their highly metamorphosed equivalents and in...

The Poker Jim Ridge and Fort Warner areas, which are candidate areas for inclusion in the National Wilderness Preservation System, are in the Hart Mountain National Antelope Refuge in east-central Lake County, south-central Oregon. The two areas form part of an upraised and tilted fault block--a structural element that is...

The relation between water quality and water movement within the ground-water reservoir may be better understood if studies of flow systems are used in conjunction with hydrochemical methods. Within small watersheds, local, intermediate, and regional flow systems may develop, depending upon the shape, the relief, and the thickness of the...

Drifts of two pre-Olympia glaciations separated by nonglacial sediments are widespread in the central Puget Lowland of western Washington. The Double Bluff Drift (older) and Possession Drift represent advances of the Puget lobe of the Cordilleran ice sheet more than 40,000 years ago. The nonglacial Whidbey Formation between the drifts...

Guánica and the lower Rio Loco valley lie between the extensive agricultural development in Lajas Valley to the west and the industrial development at Guayanilla to the east. Having a protected deep-water port, the Guánica area is particularly well suited to further development. The economic growth of the area depends,...

No abstract available. ...

The Devonian System, represented predominantly by shallow-water marine carbonate, is widespread in Montana, Wyoming, eastern Idaho, North Dakota, South Dakota, and northwestern Nebraska. It comprises cratonic rocks in the east and miogeosynclinal rocks in the west. The cratonic rocks thicken generally northward from their southern limit in Wyoming across...

The structural framework that controlled Devonian deposition consisted of, from west to east: (1) a eugeosynclinal area in northern California and western Nevada; (2) a miogeosynclinal area in southeastern California, eastern Nevada, and western Utah; and (3) a cratonic area in Arizona, eastern Utah, Colorado, New Mexico, and western...

Water temperature and the distribution of various chemicals measured during surveys from June 7 to October 30, 1956, reflect a highly variable and rapidly changing circulation in Saginaw Bay, Lake Huron. The circulation is influenced strongly by local winds and by the stronger circulation of Lake Huron which frequently causes...

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No abstract available....

Analysis of cores collected from a sequence of lavas in Eastern Iceland has made possible an accurate calculation of the average rate of reversal of the Earth's magnetic field....

The isotopic composition of lead in Red Sea chloride brine containing 0.5 ppm Pb is found to be similar to that of some Cenozoic ore leads such as galena at Rabigh in Saudi Arabia that may have formed during mineralization accompanying Tertiary...

No abstract available....

Rb and Sr contents and87Sr/86Sr values were determined for samples of eugeosynclinal sedimentary rocks, mostly graywackes, from Oregon and California. These data are compatible with the theory of anataxis of eugeosynclinal sedimentary rocks in orogenic belts to produce granitic magmas provided...

Measurements of the longitudinal and shear moduli were made on fused quartz to 10 kb at 24·5°C. The anomalous behavior of the bulk modulus K at low pressure, &#x2202;K&#x2202;P&lt; 0">∂K∂P< 0, begins to approach the “normal” behavior of solids, &#x2202;K&#x2202;P&gt; 0">∂K∂P> 0,...

Melting and subsolidus relations in the system K2SO4MgSO4CaSO4 were studied using heating-cooling curves, differential thermal analysis, optics, X-ray diffraction at room and high temperatures and by quenching techniques. Previous investigators were unable to study the binary MgSO4CaSO4 system and the adjacent area in the ternary system because of the decomposition of MgSO4 and...

Rare-earth contents of 20 allanites and 13 monazites, accessory minerals from a restricted outcrop area of intrusive granitic rocks, are reported. A quantity called sigma (Σ), which is the sum of the atomic percentages of La, Ce and Pr, is used...

The significant known hydrated borate mineral assemblages (principally of the western United States) in the system Na2O-CaO-MgO-B2O3-H2O are expressible in three ternary composition diagrams. Phase rule interpretation of the diagrams is consistent with observation, if the activity of H2O is generally considered to be determined by the geologic environment. The...

A paleomagnetic and K-Ar dating study of 44 upper Miocene and Pliocene volcanic units from the western United States suggests that the frequency of reversals of the earth's magnetic field during Pliocene time may have been comparable with that of the...