Forty years of geologic investigations at the Nevada Test Site (NTS) have been digitized. These data include all geologic information that: (1) has been collected, and (2) can be represented on a map within the map borders at the map scale is included in the map digital coverages. The following coverages are included with this dataset: Coverage Type Description geolpoly Polygon Geologic outcrops geolflts line Fault traces geolatts Point Bedding attitudes, etc. geolcald line Caldera boundaries geollins line Interpreted lineaments geolmeta line Metamorphic gradients. The above coverages are attributed with numeric values and interpreted information. The entity files documented below show the data associated with each coverage.

This map database, identified as Faults, lineaments, and earthquake epicenters digital map of the Pahute Mesa 30' X 60' quadrangle, Nevada, has been approved for release and publication by the Director of the USGS.Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review.Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.This digital map compilation incorporates fault, air photo lineament, and earthquake epicenter data from within the Pahute Mesa 30' by 60' quadrangle, southern Nye County, Nevada (fig.1).The compilation contributes to the U.S. Department of Energy's Yucca Mountain Project, established to determine whether or not the Yucca Mountain site is suitable for the disposal of high-level nuclear waste.Studies of local and regional faulting and earthquake activity, including the features depicted in this compilation, are carried out to help characterize seismic hazards and tectonic processes that may be relevant to the future stability of Yucca Mountain.The Yucca Mountain site is located in the central part of the Beatty 30' by 60' quadrangle approximately 15 km south of the south edge of the Pahute Mesa quadrangle (fig.1).The U.S. Geological Survey participates in studies of the Yucca Mountain site under Interagency Agreement DE-AI08-78ET44802.The map compilation is only available on line as a digital database in ARC/INFO ASCII (Generate) and export formats.The database can be downloaded via 'anonymous ftp' from a USGS system named greenwood.cr.usgs.gov(136.177.48.5).The files are located in a directory named /pub/open-file-reports/ofr-96-0262.This directory contains a text document named 'README.1ST' that contains database technical and explanatory documentation, including instructions for uncompressing the bundled (tar) file.In displaying the compilation it is important to note that the map data set is considered accurate when depicted at a scale of about 1:100,000; displaying the compilation at scales significantly larger than this may result in distortions and (or) mislocations of the data.

This letter documents objections of a group of US Geological Survey Scientists to an article appearing November 18, 1990 in New York Times Magazine. The article was written by William J. Broad and dealt with a hypothesis of Jerry S. Szymanski. The letter addressed areas of concern; including hydrology, geology, tectonics, and the integrity of the scientists and their conclusions. (SM)

Bare Mountain comprises the isolated complex of mountain peaks southeast of the town of Beatty in southern Nye County, Nevada. This small mountain range lies between the alluvial basins of Crater Flat to the east and the northern Amargosa Desert to the southwest. The northern boundary of the range is less well defined, but for this report, the terrane of faulted Miocene volcanic rocks underlying Beatty Mountain and the unnamed hills to the east are considered to be the northernmost part of Bare Mountain. The southern tip of the mountain range is at Black Marble, the isolated hill at the southeast corner of the map. The main body of the range, between Fluorspar Canyon and Black Marble, is a folded and complexly faulted, but generally northward-dipping (or southward-dipping and northward-overturned), sequence of weakly to moderately metamorphosed upper Proterozoic and Paleozoic marine strata, mostly miogeoclinal (continental shelf) rocks. The geology of Bare Mountain is mapped at a scale of 1:24,000.

Yucca Mountain in southern Nye County, Nevada, has been proposed as a potential site for the underground disposal of high-level nuclear waste.An exploratory drill hole designated UE25p#l was drilled 3 km east of the proposed repository site to investigate the geology and hydrology of the rocks that underlie the Tertiary volcanic and sedimentary rock sequence forming Yucca Mountain.Silurian dolomite assigned to the Roberts Mountain and Lone Mountain Formations was intersected below the Tertiary section between a depth of approximately 1244 m (4080 ft) and the bottom of the drill hole at 1807 m (5923 ft).These formations are part of an important regional carbonate aquifer in the deep ground-water system.Tertiary units deeper than 1139 m (3733 ft) in drill hole UE25p#l are stratigraphically older than any units previously penetrated by drill holes at Yucca Mountain.These units are, in ascending order, the tuff of Yucca Flat(?), an unnamed calcified ash-flow tuff, and a sequence of clastic deposits.The upper part of the Tertiary sequence in drill hole UE25p#l is similar to that found in other drill holes at Yucca Mountain.The Tertiary sequence is in fault contact with the Silurian rocks.This fault between Tertiary and Paleozoic rocks may correlate with the Fran Ridge fault, a steeply westward-dipping fault exposed approximately 0.5 km east of the drill hole.Another fault intersects UE25p#l at 873 m (2863 ft), but its surface trace is concealed beneath the valley west of the Fran Ridge fault.The Paintbrush Canyon fault, the trace of which passes less than 100 m (330 ft) east of the drilling site, intersects drill hole UE25p#l at a depth of approximately 78 m (255 ft).The drill hole apparently intersected the west flank of a structural high of pre-Tertiary rocks, near the eastern edge of the Crater Flat structural depression.1,479-1,502