Publications

This report comprises digital spatial data that constitute a partial transcription of the 1:250,000-scale Geologic map of Washington - southwest quadrant (Walsh and others, 1987); digital base material, symbolsets, and ARC Macro Language (AML) procedures to create a geologic map on a shaded-relief base from the digital spatial data; and Postscript and RTL plotfiles for such a geologic map. The di

This report contains a 250-meter digital elevation model (DEM) for Cascadia (latitude 39N - 53N, longitude 116W - 133W), a region that encompasses the Cascade volcanic arc, the Cascadia subduction zone, and the Juan de Fuca Ridge system. The DEM is distributed as file cascdem.tar.gz (39 MB; 78MB uncompressed).

The relative abundance of minerals that react to generate or consume acid in mineralized areas is critical in determining the quality of water draining from such areas. This work examines the fundamental reactions that influence the pH and composition of drainage from mine adits and tailings piles. We construct triangle diagrams that predict stoichiometric relationships between concentrations of d

We present major- and trace- element geochemical data for 27 amphibolites and six greenstones from three structural packages in the Yukon-Tanana Upland of east-central Alaska: the Lake George assemblage (LG) of Devono-Mississippian augen gneiss, quartz-mica schist, quartzite, and amphibolite; the Taylor Mountain assemblage (TM) of mafic schist and gneiss, marble, quartzite, and metachert; and the

Permits to explore for and (or) develop mineral resources on forest land can be used to indicate locations and types of mineral-related activities on national forests. Permits for these activities require filing at the Forest Service a Notice of Intention (Notice) to conduct mineral exploration activities and (or) a Plan of Operation (Plan). A Plan of Operation is required is significant activitie

The contiguous United States has been well explored for exposed conventional mineral deposits. Therefore, it is likely that many economically viable and strategically significant conventional undiscovered mineral deposits will be found in bedrock concealed beneath basin sediments. Mineral resource assessments must incorporate an understanding of the geometry, structure, and concealed lithology of

No abstract available.

A three-dimensional inversion of gravity data from the Pahute Mesa–Oasis Valley region reveals a topographically complex pre-Tertiary basement surface. Beneath Pahute Mesa, the thickness of the Tertiary volcanic deposits may exceed 5 km within the Silent Canyon caldera complex. South of Pahute Mesa in Oasis Valley, basement is shallower (< 1 km) but between this valley and the Timber Mountain cald

The Puget-Willamette study area is composed of two distinct subareas, the Puget Sound Lowland and the Willamette Lowland. The study area for this report is the Puget Sound Lowland, which is located in western Washington and in a small part of southwestern British Columbia, Canada. The lowland encompasses an area of about 17,610 square miles and contains about 2,615 square miles of saltwater. The u

Truncation of metamorphic isograds and fold axes within coherent terranes of Franciscan metagraywacke by intervening zones of melange indicate that the melange is tectonic and formed after the subduction-related metamorphism and folding. These relations are expressed in two terranes of blueschist-facies rocks of the Franciscan Complex in the Mt. Hamilton area, northern California-the Jurassic Yoll

Removal of Pb, Cu, Zn, and Cd during neutralization of acid rock drainage is examined using model simulations of field conditions and laboratory experiments involving mixing of natural drainage and surface waters or groundwaters. The simulations consider sorption onto hydrous Fe and Al oxides and particulate organic carbon, mineral precipitation, and organic and inorganic solution complexation of

In the southern San Francisco Bay region of California, oblique dextral reverse faults that verge northeastward from the San Andreas fault experienced triggered slip during the 1989 M7.1 Loma Prieta earthquake. The role of these range-front thrusts in the evolution of the San Andreas fault system and the future seismic hazard that they may pose to the urban Santa Clara Valley are poorly understood