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At least 1,009 records · Page 56Linked to original sources
USGS1978

Stratigraphic test well, Nantucket Island, Massachusetts

The U.S. Geological Survey, in cooperation with the Massachusetts Water Resources Commission and the Nantucket Conservation Foundation, continuously cored 514 m of sediment and volcanic rock in a stratigraphic and water-quality test near the geographic center of Nantucket Island. Stratified sediments were divided texturally into three zones: the upper zone (0-128 m) contains mostly coarse sand and gravel; the middle zone (128-349 m) contains mostly silty clay and a few beds of sand and silt; and the lower zone (349-457 m) contains soft, unconsolidated, clayey sand. Below the lower zone, a saprolite, composed mostly of clay, grades abruptly downward at 470 m into partially altered basalt that extends to the bottom of the hole at 514 m. Calculations based on the Ghyben-Herzberg principle predicted a zone of freshwater 120-150 m thick. This principle is the theory of hydrostatic equilibrium between freshwater and more dense seawater in a coastal aquifer; it states that for each meter of ground-water elevation above sea level, the freshwater lens will depress the saltwater interface about 40 m below sea level. Freshwater or low-salinity brackish water was found in sediments far below the depth predicted by the Ghyben-Herzberg principle. These interstitial waters are probably relict ground water emplaced during times of low sea level during the Pleistocene. (Woodard-USGS)

Circular↗
USGS1979

A study of reservoir characteristics of the Nanushuk and Colville groups, Umiat test well 11, National Petroleum Reserve in Alaska

Cretaceous sandstones in the Umiat Anticline contain the largest volume of oil discovered to date in the National Petroleum Reserve in Alaska. Umiat test well 11, although dry and abandoned, penetrated the most complete sequence of Cretaceous rocks in the Umiat area. Cretaceous formations cored (oldest to youngest) were the Grandstand, Chandler, and Ninuluk Formations of the Nanushuk Group and the Seabee and Prince Creek Formations of the Colville Group. Cores from sandstone beds in each of the formations penetrated were studied to identify the factors influencing porosity and permeability. Based on lithologic, textural, sedimentary-structural, faunal and floral, and regional paleogeographic evidence, the Cretaceous stratigraphic sequence in the Umiat area can be described as complexly interbedded delta-front and delta-plain facies (named the Umiat delta). The Grandstand Formation and Killik Tongue of the Chandler Formation represent one thick progradational sequence of delta-front and delta-plain facies, respectively. This sequence was followed by deposition of transgressive marine facies of the Ninuluk and Seabee Formations, which were in turn overlain by another progradational delta-plain facies, the Tuluvak Tongue of the Prince Creek Formation. The delta-front sandstone of the Grandstand Formation is well-sorted, fine-grained to very fine grained, angular to subangular chert arenite and phyllarenite. Authigenic cements include dolomite, calcite, siderite, quartz overgrowth, kaolinite, chert, pyrite, and possibly some small flakes of chlorite. The source terrane was southwest of Umiat and, on the basis of the aforementioned petrographic evidence, consisted of low-grade metamorphic rocks and possibly sandstone and cherty limestone. The weighted average porosity, based on well-log analyses, for the lower part of the Grandstand Formation is 15.1 percent and for the upper part is 15.6 percent; the weighted average permeability is 58.6 md for the lower part and 167 md for the upper part. The average size of visible pores is about 50 ?m. A linear relationship was established between permeability and porosity for sandstone samples from depths less than 405 m and greater than 644 m; the average permeability of these intervals can be estimated with reasonable accuracy not only for the Grandstand but also for the Tuluvak, Seabee, and Killik. The delta-front, delta-plain marginal facies of the Killik Tongue of the Chandler Formation includes sandstone, siltstone, shale, and coal. Sandstone samples studied petrographically are similar to those of the Grandstand Formation; the delta prograded northeasterly across the Umiat area and the source terrane for the sediments remained the same. Well-log analyses indicate that the weighted average porosity for the Killik Tongue is 16.4 percent and the weighted average permeability is 96.2 md. The delta-front sandstone of the Ninuluk Formation is similar to that of the Grandstand and Killik, but is moderately sorted and contains less detrital quartz and significantly more metamorphic rock fragments than chert fragments. Sandstone in the upper part of the formation contains a considerable amount of calcite. Visible pores average about 35 ?m in size. The weighted average porosity for the Ninuluk Formation, based on well-log analyses, is 12.6 percent; the weighted average permeability is 10.7 md. The Seabee Formation is primarily shale deposited in an open-marine environment; sandstone units in the Seabee overlie and are overlain by black marine shale. The mineralogy of these sandstone units differs markedly from that of the older formations. The sandstones are characterized by an abundance of volcanic rock fragments, high content of volcanic plagioclase feldspar, and low content of detrital quartz. Quartz, chert, phyllite, and metaquartzite all appear to be the same petrographically as in the Nanushuk Group. Abundant chlorite and smectite reduce permeability and make sandstones

Circular↗
USGS2006

Database of ground-water levels in the vicinity of Rainier Mesa, Nevada Test Site, Nye County, Nevada, 1957-2005

More than 1,200 water-level measurements from 1957 to 2005 in the Rainier Mesa area of the Nevada Test Site were quality assured and analyzed. Water levels were measured from 50 discrete intervals within 18 boreholes and from 4 tunnel sites. An interpretive database was constructed that describes water-level conditions for each water level measured in the Rainier Mesa area. Multiple attributes were assigned to each water-level measurement in the database to describe the hydrologic conditions at the time of measurement. General quality, temporal variability, regional significance, and hydrologic conditions are attributed for each water-level measurement. The database also includes hydrograph narratives that describe the water-level history of each well.

Nevada↗
USGS2007

Ground-Water Temperature Data, Nevada Test Site and Vicinity, Nye, Clark, and Lincoln Counties, Nevada, 2000-2006

Ground-water temperature data were collected by the U.S. Geological Survey in wells at and in the vicinity of the Nevada Test Site during the years 2000-2006. Periodic ground-water temperatures were collected in 166 wells. In general, periodic ground-water temperatures were measured annually in each well at 5 and 55 feet below the water surface. Ground-water temperature profiles were collected in 73 wells. Temperatures were measured at multiple depths below the water surface to produce these profiles. Databases were constructed to present the ground-water temperature data.

Data Series↗
USGS2014

Construction, water-level, and water-quality data for multiple-well monitoring sites and test wells, Fort Irwin National Training Center, San Bernardino County, California, 2009-12

Because of increasing water demands at the U.S. Army Fort Irwin National Training Center, the U.S. Geological Survey in cooperation with the U.S. Army carried out a study to evaluate the water quality and potential groundwater supply of undeveloped basins within the U.S. Army Fort Irwin National Training Center. In addition, work was performed in the three developed basins—Langford, Bicycle, and Irwin—proximal to or underlying cantonment to provide information in support of water-resources management and to supplement monitoring in these basins. Between 2009 and 2012, the U.S. Geological Survey installed 41 wells to expand collection of water-resource data within the U.S. Army Fort Irwin National Training Center. Thirty-four monitoring wells (2-inch diameter) were constructed at 14 single- or multiple-well monitoring sites and 7 test wells (8-inch diameter) were installed. The majority of the wells were installed in previously undeveloped or minimally developed basins (Cronise, Red Pass, the Central Corridor area, Superior, Goldstone, and Nelson Basins) proximal to cantonment (primary base housing and infrastructure). Data associated with well construction, water-level monitoring, and water-quality sampling are presented in this report.

California↗
USGS2002

Results of test drilling in the Basalt aquifer near Fallon, Nevada

Drilling of two test holes into the Fallon basalt aquifer commenced August 14, 2001. The basalt aquifer is located beneath the Carson Desert, near Fallon, Nevada, and is the sole source of drinking water for the City of Fallon, the Naval Air Station (NAS) Fallon, and the Fallon Paiute-Shoshone Tribe. Basalt comprising the aquifer is exposed at Rattlesnake Hill, an eroded volcanic cone, about 1 mile northeast of Fallon, and the remainder is buried beneath sediments deposited by the Carson River and ancient Lake Lahontan to depths of 600 feet near its edges (fig. 1). The basalt-aquifer system is a mushroom-shaped body of highly permeable volcanic rock. Viewed from above, the lateral extent of the basalt body is oval-shaped, about 4-miles wide and 10-miles long (fig. 1). Drilling was part of a cooperative study between the U.S. Geological Survey (USGS), the Bureau of Reclamation, and NAS Fallon. The study was started because of concern about the continued viability of the basalt-aquifer system as a source of municipal water supply. Increased pumping from about 1,700 acre-feet per year (acre-ft/yr) in the 1970?s to over 3,000 acre-ft/yr in the late 1990?s has caused water levels in the basalt to decline as much as 12 feet (fig. 2). During this same time period, water pumped from the aquifer at NAS Fallon and the City of Fallon wells showed that concentrations of dissolved chloride increased, although chloride concentrations were well within the U.S. Environmental Protection Agency?s (EPA) drinking-water standards; at this rate of increase, it would take decades to exceed the present standard (Maurer and Welch, 2001, p. 46). Concentrations of arsenic in the aquifer are about 0.1 milligrams per liter (mg/L), exceeding the drinking-water standard of 0.01 mg/L, but show no apparent change over time (Maurer and Welch, 2001, p. 10 and 48; U. S. Environmental Protection Agency, 2001). Increasing concentrations of chloride may be caused by increased pumping, that induces inflow of more saline water from aquifers surrounding or underlying the basalt, or from greater depths within the basalt itself. Prior to the drilling on August 14, 2001, few wells penetrated the basalt more than 70 feet below its upper surface (Maurer and Welch, 2001, p. 34). This prevented monitoring changes in water quality deeper in the aquifer that might be moving upward with continued pumping. Purposes of drilling were to fully penetrate the basalt, determine its hydrogeological character, the distribution of water quality in the basalt and in the underlying sedimentary aquifer, install monitoring wells.

Fact Sheet↗
USGS2003

Geophysical, stratigraphic, and flow-zone logs of selected test, monitor, and water-supply wells in Cayuga County, New York

Volatile-organic compounds have been detected in water sampled from more than 50 supply wells between the City of Auburn and Village of Union Springs in Cayuga County, New York, and the area was declared a Superfund site in 2002. In 2001-04, geophysical logs were collected from 37 test, monitor, and water-supply wells as a preliminary part of the investigation of volatile-organic compound contamination in the carbonate-bedrock aquifer system. The geophysical logs included gamma, induction, caliper, wellbore image, deviation, fluid resistivity and temperature, and flowmeter. The geophysical logs were analyzed along with core samples and outcrops of the bedrock to define the stratigraphic units and flow zones penetrated by the wells. This report describes the logging methods used in the study and presents the geophysical, stratigraphic, and flow-zone logs.

Open-File Report↗
USGS2006

A Preliminary Investigation of The Structure of Southern Yucca Flat, Massachusetts Mountain, and CP Basin, Nevada Test Site, Nevada, Based on Geophysical Modeling

New gravity and magnetic data collected in the vicinity of Massachusetts Mountain and CP basin (Nevada Test Site, NV) provides a more complex view of the structural relationships present in the vicinity of CP basin than previous geologic models, helps define the position and extent of structures in southern Yucca Flat and CP basin, and better constrains the configuration of the basement structure separating CP basin and Frenchman Flat. The density and gravity modeling indicates that CP basin is a shallow, oval-shaped basin which trends north-northeast and contains ~800 m of basin-filling rocks and sediment at its deepest point in the northeast. CP basin is separated from the deeper Frenchman Flat basin by a subsurface ridge that may represent a Tertiary erosion surface at the top of the Paleozoic strata. The magnetic modeling indicates that the Cane Spring fault appears to merge with faults in northwest Massachusetts Mountain, rather than cut through to Yucca Flat basin and that the basin is downed-dropped relative to Massachusetts Mountain. The magnetic modeling indicates volcanic units within Yucca Flat basin are down-dropped on the west and supports the interpretations of Phelps and KcKee (1999). The magnetic data indicate that the only faults that appear to be through-going from Yucca Flat into either Frenchman Flat or CP basin are the faults that bound the CP hogback. In general, the north-trending faults present along the length of Yucca Flat bend, merge, and disappear before reaching CP hogback and Massachusetts Mountain or French Peak.

Open-File Report↗
USGS2006

Micrometeorological and Soil Data for Calculating Evapotranspiration for Rainier Mesa, Nevada Test Site, Nevada, 2002-05

Micrometeorological and soil-moisture data were collected at two instrumented sites on Rainier Mesa at the Nevada Test Site, January 1, 2002 - August 23, 2005. Data collected at each site include net radiation, air temperature, and relative humidity at two heights; wind speed and direction; subsurface soil heat flux; subsurface soil temperature; volumetric soil water; and matric water potential. These data were used to estimate 20-minute average and daily average evapotranspiration values. The data presented in this report are collected and calculated evapotranspiration rates.

Open-File Report↗
USGS2007

Geophysical Logs of Selected Test Wells at the Diaz Chemical Superfund Site in Holley, New York

In June and July 2006, geophysical logs were collected and analyzed along with rock-core samples to define the bedrock stratigraphy and flow zones penetrated by four test wells at the Diaz Chemical Superfund site at Holley in eastern Orleans County, New York. The work was completed as a preliminary part of the investigation of contamination by organic compounds in the shale, mudstone, and sandstone bedrock. The geophysical logs included natural-gamma, caliper, borehole image, fluid properties, and flowmeter data. The orientation of fractures in the boreholes was inferred from the log data and summarized in stereo and tadpole plots; the transmissivity and hydraulic head was also determined for fracture zones that were observed to be hydraulically active through the flowmeter logs. The data are intended in part for use in the remediation of the site.

Open-File Report↗
USGS2007

Modeling the Spatial and Temporal Variation of Monthly and Seasonal Precipitation on the Nevada Test Site and Vicinity, 1960-2006

The Nevada Test Site (NTS), located in the climatic transition zone between the Mojave and Great Basin Deserts, has a network of precipitation gages that is unusually dense for this region. This network measures monthly and seasonal variation in a landscape with diverse topography. Precipitation data from 125 climate stations on or near the NTS were used to spatially interpolate precipitation for each month during the period of 1960 through 2006 at high spatial resolution (30 m). The data were collected at climate stations using manual and/or automated techniques. The spatial interpolation method, applied to monthly accumulations of precipitation, is based on a distance-weighted multivariate regression between the amount of precipitation and the station location and elevation. This report summarizes the temporal and spatial characteristics of the available precipitation records for the period 1960 to 2006, examines the temporal and spatial variability of precipitation during the period of record, and discusses some extremes in seasonal precipitation on the NTS.

Open-File Report↗
USGS2008

Electrical Resistivity and Seismic Surveys at the Nevada Test Site, Nevada, April 2007

In April 2007, the USGS collected direct-current (DC) electrical resistivity data and shear- (S) and compressional- (P) wave seismic data to provide new detail of previously mapped, overlapping fault splays at two administrative areas in the Nevada Test Site (NTS). In NTS Area 7, we collected two-dimensional DC resistivity data along a transect crossing the Yucca Fault parallel to, and between, two transects along which resistivity data were collected in a previous study in 2006. In addition, we collected three-dimensional DC resistivity data in a grid that overlies part of the 2007 transect. The DC resistivity data show that the fault has a footwall that is more conductive than the hanging wall and an along-strike progression of the fault in a location where overlapping splays are present. Co-located with the northernmost of the two 2006 DC resistivity transects, we acquired S- and P-wave seismic data for both reflection and refraction processing. The S-wave data are corrupted by large amounts of converted (P-wave) energy likely due to the abundance of fractured caliche in the shallow subsurface. The P-wave data show minimal reflected energy, but they show clear refracted first arrivals. We have inverted these first arrival times to determine P-wave seismic velocity models. The seismic model for the transect in Area 7 shows low velocities extending to the base of the model at the location of the Yucca Fault, as well as low velocities at the eastern end of the transect, in the vicinity of the adjacent crater. These new surveys provide further detail about the geometry of the Yucca Fault in this location where it shows two overlapping splays. We collected P- and S-wave seismic data along a transect in the southern part of NTS Area 2, corresponding with the location of a 2006 DC resistivity transect that targeted a set of small faults identified with field mapping. Again, the S-wave data are difficult to interpret. The P-wave data show clear first arrivals that we inverted, yielding a velocity model that shows lateral heterogeneity similar to the 2006 DC resistivity models. Finally, we collected P-wave data along a second transect in Area 2, located north of the first line and in an area of a very minor fault that was targeted by another 2006 DC resistivity survey. The P-wave refraction velocity model shows generally high velocities, with a zone of somewhat lower velocities in the central part of the transect. The position of the low velocity zone corresponds with the location of a minor fault, though it is unclear whether the two are related. Together, these results demonstrate the value of geophysical data for mapping the subsurface extent of faults. The 2007 DC resistivity data complement the 2006 data and provide important new detail of the overlapping fault splays. The seismic data demonstrate the ability of P-wave refraction methods to identify the damage zones at faults, and they show the difficulties associated with S-wave methods in areas with caliche. Combining all of the geophysical data from the Area 7 studies, we are able to develop a coherent interpretation of the relation between the site geology, the fault, and the observations.

Open-File Report↗
USGS2009

Results of laboratory testing for diphacinone in seawater, fish, invertebrates, and soil following aerial application of rodenticide on Lehua Island, Kauai County, Hawaii, January 2009

In January 2009, rodenticide bait (Ramik Green pellets) containing the active ingredient diphacinone was aerially applied to Lehua Island. Reported herein are the results of laboratory analyses to determine diphacinone concentrations in samples of seawater, fillet of fish, soft tissue of limpets (opihi), whole-body crabs, and soil collected from Lehua Island, Kauai County, Hawaii, after aerial application of the rodenticide bait. Diphacinone was specifically chosen because of its low toxicity to nontarget organisms. Its use on Lehua Island is the second time it has ever been used for an aerial application to eradicate rodents. Testing of the Lehua Island samples for diphacinone utilized high-performance liquid chromatography with photodiode array detection. No detectable concentrations of diphacinone were found in any of the samples from Lehua Island. The limits of detection for diphacinone were 0.4 nanograms per milliliter (parts per billion) seawater, 15 nanograms per gram (dry weight) soil, 20 nanograms per gram (parts per billion) fish fillet, 13 nanograms per gram whole crab, and 34 nanograms per gram soft tissue limpet.

Hawaii↗
USGS2010

Evaluating the feasibility of modeling the subsurface structure of two volcanic units in drill holes UE-18r and ER-EC-2a using existing magnetic data, Nevada Test Site

The magnetic properties of two volcanic units encountered in two drill holes, ER-EC-2a and UE18r, located in the vicinity of the Nevada Test Site, were investigated to determine if the units were significantly more magnetic than overlying units and, thus, detectable by using aeromagnetic data. Magnetic-susceptibility measurements were made on cuttings from the drill holes and were combined with published data on remanent magnetism to generate two-dimensional magnetic models, based on an interpreted geologic cross-section. The resulting magnetic anomaly calculated from the models was compared with the observed aeromagnetic anomaly and was found to differ significantly from it. Furthermore, the calculated magnetic anomalies were found to be relatively insensitive to changes in the two units of interest.

Nevada↗
USGS2012

Preparation and characterization of "Libby Amphibole" toxicological testing material

The U.S. Environmental Protection Agency (USEPA) began work in Libby, Mont. in 1999 when an Emergency Response Team was sent to investigate local concern and media reports regarding asbestos-contaminated vermiculite. Since that time, the site has been granted Superfund status and site remediation to a safe level of asbestos has been ongoing. The amphibole asbestos from the Vermiculite Mountain vermiculite deposit near Libby, Mont. (Libby amphibole) is unusual in the sense that it is currently not classified as one of the regulated six asbestos minerals—chrysotile (a serpentine mineral) and the amphibole minerals amosite (asbestiform cummingtonite-grunerite), crocidolite (asbestiform riebeckite), asbestiform anthophyllite, asbestiform tremolite, and asbestiform actinolite. The amphiboles from the Vermiculite Mountain vermiculite deposit, primarily winchite and richterite, are related to tremolite and in the past have been referred to as sodium-rich tremolite or soda tremolite (Larsen, 1942; Boettcher, 1966; Wylie and Verkouteren, 2000; Gunter and others, 2003; Meeker and others, 2003). The public health issues in Libby, Mont. have brought to light many of the inconsistencies in the literature regarding fiber characteristics, nomenclature, and toxicology. To better understand the toxicological characteristics of the Libby amphibole, investigators require a sufficient quantity of material representing the range of fibrous amphiboles present in the vicinity of Vermiculite Mountain to use in toxicology studies. The material collected in 2000 (Meeker and others, 2003) has been exhausted and a second collection and preparation effort, funded by the USEPA, was conducted in 2007. Both the 2000 (LA2000) and 2007 (LA2007) materials were generated to support research needs identified by the USEPA and the National Toxicology Program, and new in-vivo and in-vitro toxicology studies are underway. This Open-File Report describes the process of preparation and summarizes the chemistry and mineralogy of the LA2007 toxicological testing material.

Libby, Montana↗
USGS2012

Test drilling and data collection in the Calaveras County portion of the Eastern San Joaquin Groundwater Subbasin, California, December 2009-June 2011

Two multiple-well monitoring sites were drilled in the Calaveras County portion of the Eastern San Joaquin Groundwater Subbasin, about 100 miles east of San Francisco, California, during December 2009 and January 2010. Site 3N/9E-12G1-4 was drilled to a depth of 503 feet below land surface (bls), and four wells were installed. Site 4N/9E-36A1-3 was drilled to a depth of 400 feet bls, and three wells were installed. Lithologic and geophysical data collected during test drilling indicated the presence of volcanic sands interspersed with lahar deposits that are characteristic of the Mehrten Formation to about 420 feet bls at site 12G1-4, and the presence of volcanic sands interspersed with clay that are characteristic of the Valley Springs Formation at site 36A1-3. In January 2010, water levels at site 12G1-4 ranged from 120 to 127 feet bls (the shallowest well at the site, 12G4, screened from 90 to 110 feet bls, was dry). Between May and November 2010, water levels declined as much as 22 feet in wells 12G1 and 12G2, the deepest wells at this site, and declined about 6 feet in shallower well 12G3. During this same period, water-levels declined less than 8 feet in the three wells at site 36A1-3. Water levels in all monitoring wells recovered to near-May-2010 levels by mid-spring 2011. Dissolved solids in the six sampled monitoring wells (residue on evaporation) ranged from 154 to 239 milligrams per liter (mg/L); arsenic concentrations ranged from 1.8 to 13 micrograms per liter (μg/L), and were greater than the U.S. Environmental Protection Agency Maximum Contaminant Level (MCL) for arsenic of 10 μg/L in well 36A2. The oxygen-18 (δ 18 O) and deuterium (δD) stable-isotopic composition of water from the six monitoring wells and from nine domestic and public-supply wells sampled as part of this study ranged from -6.7 to -8.2 per mil (δ 18 O), and -50 to -60 per mil (δD), and was consistent with values expected for water recharged in the lower altitudes of the Sierra Nevada. Well 36A3, the shallowest well at site 36A1-3, was the only well that contained measurable tritium - indicative of water recharged after 1952. Carbon-14 activities from the six monitoring wells ranged from 76.0 to 18.9 percent modern carbon, and groundwater ages (time since recharge), not corrected for chemical reactions, ranged from 2,200 to 13,400 years before present.

California↗
USGS2014

Coalbed natural gas exploration, drilling activities, and geologic test results, 2007-2010

The U.S. Geological Survey, in partnership with the U.S. Bureau of Land Management, the North Slope Borough, and the Arctic Slope Regional Corporation conducted a four-year study designed to identify, define, and delineate a shallow coalbed natural gas (CBNG) resource with the potential to provide locally produced, affordable power to the community of Wainwright, Alaska. From 2007 through 2010, drilling and testing activities conducted at three sites in or near Wainwright, identified and evaluated an approximately 7.5-ft-thick, laterally continuous coalbed that contained significant quantities of CBNG. This coalbed, subsequently named the Wainwright coalbed, was penetrated at depths ranging from 1,167 ft to 1,300 ft below land surface. Core samples were collected from the Wainwright coalbed at all three drill locations and desorbed-gas measurements were taken from seventeen 1-ft-thick sections of the core. These measurements indicate that the Wainwright coalbed contains enough CBNG to serve as a long-term energy supply for the community. Although attempts to produce viable quantities of CBNG from the Wainwright coalbed proved unsuccessful, it seems likely that with proper well-field design and by utilizing currently available drilling and reservoir stimulation techniques, this CBNG resource could be developed as a long-term economically viable energy source for Wainwright.

Alaska↗
USGS2014

Petrophysical properties, mineralogy, fractures, and flow tests in 25 deep boreholes at Yucca Mountain, Nevada

As part of a site investigation for the disposal of radioactive waste, numerous boreholes were drilled into a sequence of Miocene pyroclastic flows and related deposits at Yucca Mountain, Nevada. This report contains displays of data from 25 boreholes drilled during 1979–1984, relatively early in the site investigation program. Geophysical logs and hydrological tests were conducted in the boreholes; core and cuttings analyses yielded data on mineralogy, fractures, and physical properties; and geologic descriptions provided lithology boundaries and the degree of welding of the rock units. Porosity and water content were computed from the geophysical logs, and porosity results were combined with mineralogy from x-ray diffraction to provide whole-rock volume fractions. These data were composited on plates and used by project personnel during the 1990s. Improvements in scanning and computer technology now make it possible to publish these displays.

Nevada↗