Conference Papers

No abstract available

Large vein-like deposits of calcite and opaline silica that infill the Bow Ridge fault are exposed by Trench 14 at the Nevada Test Site. The origin of the deposits has been the center of considerable controversy because the deposits occur on the edge of Yucca Mountain, which is being characterized geologically as a possible site for the nation's first high level nuclear waste repository...

Fully three-dimensional representations of the geologic system at Yucca Mountain have been developed using a Geoscientific Information System, which is an expansion of a traditional Geographic Information Systems. These advanced, three dimensional, representations of Yucca Mountain are required to adequately evaluate the complex geologic and hydrologic conditions surrounding the site...

A method was developed for measuring the spatial distribution of immiscible liquid contaminants in the subsurface. Fluid saturation distributions measured at a crude-oil spill site were used to test a numerical multiphase flow model.

An intensive hydrologic investigation of the North Fork Bens Creek Watershed on Laurel Hill in southwestern Pennsylvania was made during 1984-85. Precipitation was sampled weekly, and stream water was sampled monthly and during selected storms for discharge and chemical composition. The watershed is underlain by sandstone and sandy shale consisting of quartz, feldspar, muscovite...

A study of the barrier islands and wetlands in the deltaic plain of Louisiana is presented. Its purpose was to document rapid changes and to learn more about the processes responsible and the geologic framework within which they operate. It included systematic collection and analysis of precision nearshore hydrographic data, high resolution seismic profiles, surface sediment samples...

The Wyoming Province is an Archean craton which underlies portions of Idaho, Montana, Nevada, Utah, and much of Wyoming. The cratonic block consists of Archean age granite-gneiss with interspersed greenstone belts and related supracrustal terranes exposed in the cores of several Laramide uplifts. Resources found in the Province and in the adjacent accreted Proterozoic terrane include...

The plate tectonic setting, regional geology, and certain aspects of the economic geology of the iron-rare-earth-niobium ore bodies at Bayan Obo, Inner Mongolia, China, were studied by a team of geologists from the Tianjin Geologic Research Academy and the U.S. Geological Survey between 1987 and 1989. These ore bodies were formed by hydrothermal replacement of Middle Proterozoic dolomite...

Borehole geophysical logging for site characterization in the volcanic rocks at the proposed nuclear waste repository at Yucca Mountain, Nevada, requires data collection under rather unusual conditions. Logging tools must operate in rugose, dry holes above the water table in the unsaturated zone. Not all logging tools will operate in this environment, therefore; careful consideration...

Eight months of continuous measurements of tidal current profiles with an acoustic Doppler current profiler (ADCP) were made in Carquinez Strait, California, during 1988 for the purpose of estimating long-term variations in vertical profiles of Eulerian residual currents. Salinity stratification near the ADCP deployment site also was analyzed. The strength of density-driven gravitational

Annual base flows of streams draining Okaloosa County and adjacent areas in northwest Florida were determined through hydrograph separation and correlation techniques for purposes of evaluating variations in ground-water recharge rates. Base flows were least in the northern part of the county and greatest in the southern part. Topographic and soils data were then superimposed on the...

Results from a 2-year study of 149 streams geographically distributed across the corn-producing region of 10 midwestern States show that detectable concentrations of herbicides persist year round in most streams. Some herbicides exceeded proposed maximum contaminant levels for drinking water for periods of several weeks to several months following application. Atrazine was the most...