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At least 55 records · Page 3Linked to original sources
USGS1998

Structure contours of top of Laramie-Fox Hills aquifer in "Structure, outcrop, and subcrop of the bedrock aquifers along the western margin of Denver Basin, Colorado." Hydrologic Atlas 742

This digital geospatial data set consists of structure contours of the top of the Laramie-Fox Hills aquifer along the Front Range of Colorado. The U.S. Geological Survey developed this data set as part of a project described in the report, "Structure, Outcrop, and Subcrop of the Bedrock Aquifers Along the Western Margin of the Denver Basin, Colorado" (Robson and others, 1998).

Colorado↗
USGS1998

Structure contours of base of upper Arapahoe aquifer in "Structure, outcrop, and subcrop of the bedrock aquifers along the western margin of the Denver Basin, Colorado." Hydrologic Atlas 742

This digital geospatial data set consists of structure contours on the base of the upper member of the Arapahoe aquifer. The U.S. Geological Survey developed this data set as part of a project described in the report,"Structure, Outcrop, and Subcrop of the Bedrock Aquifers Along the Western Margin of the Denver Basin, Colorado" (Robson and others, 1998)

Colorado↗
USGS2013

Geodatabase and characteristics of springs within and surrounding the Trinity aquifer outcrops in northern Bexar County, Texas, 2010--11

The U.S. Geological Survey, in cooperation with the Trinity Glen Rose Groundwater Conservation District, the Edwards Aquifer Authority, and the San Antonio River Authority, developed a geodatabase of springs within and surrounding the Trinity aquifer outcrops in a 331-square-mile study area in northern Bexar County, Texas. The data used to develop the geodatabase were compiled from existing reports and databases, along with spring data collected between October 2010 and September 2011. Characteristics including the location, discharge, and water-quality properties were collected for known springs and documented in the geodatabase. A total of 141 springs were located within the study area, and 46 springs were field verified. The discharge at springs with flow ranged from 0.003 to 1.46 cubic feet per second. The specific conductance of the water discharging from the springs ranged from 167 to 1,130 microsiemens per centimeter at 25 degrees Celsius with a majority of values in the range of 500 microsiemens per centimeter at 25 degrees Celsius.

Texas↗
USGS2001

Outcrop structural data from parts of the Petersburg and Sumdum 1:250,000-scale quadrangles, southeastern Alaska

This report presents a compilation of 4203 measurements of outcrop structures from part of the Petersburg 1:250,000-scale quadrangle in southeastern Alaska. We collected 1966 measurements, and an additional 2237 unpublished measurements were compiled from field notebooks a from a field mapping effort in the late 1970’s and early 1980’s. These data are listed in spreadsheet and derivative formats. The data includes the latitude and longitude of each measurement, the type of measurement and its orientation.

Alaska↗
USGS2001

Outcrop structural data from Wales Group and adjacent rocks, Dall and Prince of Wales islands, southeastern Alaska

This report presents a compilation of 3224 measurements of outcrop structures from Wales Group and adjacent strata on Dall and Prince of Wales Islands, southeastern Alaska. We collected 2230 measurements, an additional 344 were digitized from the map of Eberlein and others (1983), and an additional 650 come from the map of Herreid and others (1978). These data are listed in Excel spreadsheet, tab-delimited, and PDF formats. The data includes the latitude and longitude of each measurement, the type of measurement and its orientation.

Alaska↗
USGS2013

Bedrock geology and outcrop fracture trends in the vicinity of the Savage Municipal Well Superfund site, Milford, New Hampshire

The Savage Municipal Well Superfund site consists of an eastward-directed plume of volatile organic compounds, principally tetrachloroethylene (PCE), in alluvium and glacial sand and gravel in the Souhegan River valley, just south of the river and about 4 kilometers west of the town of Milford, New Hampshire. Sampling of monitoring wells at the site has helped delineate the extent of the plume and has determined that some contaminant has migrated into the underlying crystalline bedrock, including bedrock north of the river within 200 meters of a nearby residential development that was constructed in 1999. Borehole geophysical logging has identified a northeast preferential trend for bedrock fractures, which may provide a pathway for the migration of contaminant under and north of the Souhegan River. The current study investigates the bedrock geologic setting for the site, including its position relative to known regional geologic structures, and compiles new strike and dip measurements of joints in exposed bedrock to determine if there are dominant trends in orientation similar to what was found in the boreholes. The site is located on the northwestern limb of a northeast-trending regional anticlinorium that is southeast of the Campbell Hill fault zone. The Campbell Hill fault zone defines the contact between granite and gneiss of the anticlinorium and granite and schist to the northwest and is locally marked by lenses of massive vein quartz, minor faults, and fracture zones that could potentially affect plume migration. The fault zone was apparently not intercepted by any of the boreholes that were drilled to delineate the contaminant plume and therefore passes to the north of the northernmost borehole in the vicinity of the new residential area. Joints measured in surface exposures indicate a strong preferred direction of strike to the north-northeast corroborating the borehole data and previous outcrop and geophysical studies. The north-northeast preferred direction matches the direction of elongation of the cone of depression formed during a pump test of the bedrock wells and could explain a potential pathway for the migration of contaminant north of the river.

New Hampshire↗
USGS1985

Delineation of the outcrop of the Edwards Aquifer hydrologically associated with Barton Springs in the Austin area, Texas

This report, prepared in cooperation with the City of Austin, delineates the outcrop of the Edwards aquifer that is hydrologically associated with Barton Springs. The Edwards is a regional aquifer system in central Texas that extends in a narrow belt from Kinney County to Bell County (index map) and lies within an area locally known as the Balcones fault zone. Hydrologic boundaries separate the Edwards auifer into several parts. Barton Springs is the major discharge point of the part of the Edwards aquifer in the Austin area (southern Travis and northern Hays Counties).

Open-File Report↗
USGS1996

National Water-Quality Assessment of the Trinity River Basin, Texas - Well and Water-Quality Data from the Outcrop of the Woodbine Aquifer in Urban Tarrant County, 1993

An urban land-use study of the shallow water-bearing zones of the Woodbine aquifer outcrop area began in 1993 as a part of the National Water-Quality Assessment Program for the Trinity River Basin. Thirty-eight wells located within predominantly commercial or residential settings were selected for this study. Water samples were collected from each well and analyzed for 186 waterquality constituents. A brief description of the study area and the Woodbine aquifer, a description of the installation and design of the wells used, and the water-quality data obtained from this study are included in this report. The well description includes the locations of the 38 wells used in the study, the well design of the 28 U.S. Geological Survey-installed wells, and the lithological logs. Laboratory analyses of water samples include major inorganic constituents, nutrients, trace elements, tritium, organic carbon, phenols, methyl blue active substance, pesticides, and volatile organic compounds. Field measurements (specific conductance, pH, water temperature, and dissolved oxygen concentration) were measured at each site.

Open-File Report↗
USGS1997

Map showing outcrop of the coal-bearing units and land use in the Gulf Coast region

This map is a preliminary compilation of the outcrop geology of the known coal-bearing units in the Gulf Coast Coal region. The map has been compiled for use in the National Coal Resource Assessment Project currently being conducted by the U.S. Geological Survey, and will be updated as the assessment progresses. The purpose of the map is to show the distribution of coal-bearing rocks in the Gulf Coastal Plain Region and to show stratigraphic correlations, transportation network, fossil-fuel burning power plants, and federally managed lands in the region. It is hoped that this map may aid coal exploration and development in the region. Geologic contacts were digitized from paper copies of the maps listed in the reference section below. The primary source of information was the 1:500,000-scale state geology map series, but larger scale maps were use to better define certain areas, notably the Jackson-Claiborne contact in western Kentucky and Tennessee for example (Olive, 1980). Contacts along state boundaries were modified to best-fit information available from the border areas. Note that coal distribution in the mapped units is not uniform. For example, the Jackson Group contains coal in Texas, but in Mississippi is not presently known to contain significant coal deposits. The unit is widespread and in part non-marine and thus of potential future interest. In contrast, the Jackson Group is not shown in Georgia where it is mostly marine and residuum (weathered material) at the surface. Tertiary age coal has also been noted in the Vicksburg Group (Oligocene) of Louisiana and Mississippi, but is not shown on this map. Contacts with mapped surficial units are not always shown. The locations of coal mine permit boundaries are based on information available at the time of publication and were obtained from the Division of Surface Mining and Reclamation, Railroad Commission of Texas, Austin, and the Injection and Mining Division, Department of Natural Resources, Baton Rouge, Louisiana. The correlation of map units and formation names generally follow Galloway and others (1991). We have placed the Paleocene-Eocene boundary in the middle of the Calvert Bluff Formation in Texas based on unpublished pollen biostratigraphy reports (N.O. Fredericksen, unpublished data, 1993; D.J. Nichols, unpublished data, 1996).

Alabama, Arkansas, Georgia, Florida, Kansas, Kentu↗
USGS1983

Base flow of streams in the outcrop area of southeastern sand aquifer: South Carolina, Georgia, Alabama, and Mississippi

The base flow component of streamflow was separated from hydrographs for unregulated streams in the Cretaceous and Tertiary clastic outcrop area of South Carolina, Georgia, Alabama, and Mississippi. The base flow values are used in estimating recharge to the sand aquifer. Relations developed between mean annual base flow and stream discharge at the 60- and 65-percent streamflow duration point can be used to approximate mean annual base flow in lieu of hydrograph separation methods for base flows above 10 cu ft/s. Base flow recession curves were used to derive estimates of hydraulic diffusivity of the aquifer which was converted to transmissivity using estimated specific yield. These base-flow-derived transmissivities are in general agreement with transmissivities derived from well data. The shape of flow duration curves of streams is affected by the lithology of the Coastal Plain sediments. Steep flow duration curves appear to be associated with basins underlain by clay or chalk where a low percentage of the discharge is base flow while flatter curves appear to be associated with basins underlain by sand and gravel where a high percentage of the discharge is base flow.

Alabama, Georgia, Mississippi, South Carolina↗
USGS1983

Map showing outcrops of basaltic rocks of early Quaternary and Tertiary age, Basin and Range province, Southern California

This map report is one of a series of geologic and hydrologic maps covering all or parts of States within the Basin and Range province of the western United States. The map reports contain detailed information on subjects that characterize the geohydrology of the province, including the ground-water hydrology/ ground-water quality, surface distribution of selected rock types, tectonic conditions, areal geophysics, Pleistocene lakes and marshes, and mineral and energy resources. This is a part of the U.S. Geological Survey's program for geologic and hydrologic evaluation of the province to identify prospective regions for further study relative to isolation of high-level nuclear waste (Bedinger, Sargent, and Reed, 1984). This map was prepared from published geologic maps and reports utilizing the project guidelines defined in Sargent and Bedinger (1984). As used in this study, basaltic rocks include basaltic andesite and basalt. The map shows the known occurrences of basaltic rocks largely of Tertiary age. Locally, however, where basalts of Quaternary age were not differentiated from those of Tertiary age, the younger basalts have been included on the map. The Description of Map Units includes the geologic and, if available, radiometric age; lithology; thickness where available; and sources of data for the basaltic units in outlined and numbered areas within the counties of the study area. No information was available on the rock outcrops that are unnumbered. The listed radiometric ages do not necessarily represent the entire age range of a unit.

California↗
USGS1983

Map showing outcrops of ash-flow tuffs, Basin and Range Province and vicinity, Trans-Pecos Texas

This map report is one of a series of geologic and hydrologic maps covering all or parts of the States within the Basin and Range province of the western United States, resulting from work under the U.S. Geological Survey's program for geologic and hydrologic evaluation of the Basin and Range province to identify potentially suitable regions for future study relative to isolation of high-level nuclear waste (Bedinger, Sargent, and Reed, 1984) . The map report on the ash-flow tuffs of Trans-Pecos Texas was prepared from published maps and reports and from recent work in progress by geologists of the Texas Bureau of Economic Geology, and was compiled utilizing the project guidelines of Sargent and Bedinger (1984). The map shows the outcrops and localities of measured thicknesses of the ash-flow tuffs that resulted from silicic volcanism 38 to 28 million years ago (Henry and McDowell, 1982). Locally, however, some thin, inadequately studied tuffs of limited distribution have been excluded from the map. Such tuffs are reported in the "lower rhyolite" in the Eagle Mountains (Underwood, 1963), in the southern Davis Mountains (Parker, 1977), within parts of the Shely Group and Morita Ranch Formation in the Chinati Mountains (Cepeda and Henry, 1983) , and in the Rawls Formation in the Bofecillos Mountains (McKnight, 1969). The distribution of most ash-flow tuffs in the northern Davis and Wylie Mountains is not well known. The Chambers Tuff, largely tuffaceous sedimentary rocks, is reported to contain several ash-flow tuffs (Walton, 1972), but their distribution is poorly documented. Metamorphosed ash-flow tuffs of Precambrian age in the Thunderbird Group in the Franklin Mountains (Thomann, 1981) and in the Carrizo Mountain Group near Van Horn (Rudnick , 1983) were not included on the map. In some areas studied in reconnaissance, the definitive lithology of some volcanic units described as lava flows or tuffs has not been determined. In the Description of Map Units, the general location, caldera source and volume of tuff, isotopic age, if available, lithologic data, and the reference sources for each geologic unit are described. The nomenclature of the geologic units is from published reports and does not necessarily conform to U.S. Geological Survey usage.

Texas↗
USGS1995

Physical and hydrologic properties of outcrop samples from a nonwelded to welded tuff transition, Yucca Mountain, Nevada

Quantitative material-property data are needed to describe lateral and vertical spatial variability of physical and hydrologic properties and to model ground-water flow and radionuclide transport at the potential Yucca Mountain nuclear-waste repository site in Nevada. As part of ongoing site characterization studies of Yucca Mountain directed toward this understanding of spatial variability, laboratory measurements of porosity, bull* and particle density, saturated hydraulic conductivity, and sorptivity have been obtained for a set of outcrop samples that form a systematic,two dimensional grid that covers a large exposure of the basal Tiva Canyon Tuff of the Paintbrush Group of Miocene age at Yucca Mountain. The samples form a detailed vertical grid roughly parallel to the transport direction of the parent ash flows, and they exhibit material-property varia- tions in an interval of major lithologic change overlying a potential nuclear-waste repository at Yucca Mountain. The observed changes in hydrologic properties were systematic and consistent with the changes expected for the nonwelded to welded transition at the base of a major ash-flow sequence. Porosity, saturated hydraulic conductivity, and sorptivity decreased upward from the base of the Tiva Canyon Tuff, indicating the progressive compaction of ash- rich volcanic debris and the onset of welding with increased overburden pressure from the accumulating ash-flow sheet. The rate of decrease in the values of these material properties varied with vertical position within the transition interval. In contrast, bulk-density values increased upward, a change that also is consistent with progressive compaction and the onset of welding. Particle-density values remained almost constant throughout the transition interval, probably indicating compositional (chemical) homogeneity.

Water-Resources Investigations Report↗
USGS1952

Stratigraphy of the outcropping formations in southern Florida

The geology of southern Florida, except for the Pliocene deposits, is not widely known among geologists and paleontologists. The popular concept is that there are very few outcrops in this part of the State. It is true that there are very few natural exposures, but the dredging of rivers and the construction of canals have made many exposures. The Tamiami formation is the only formation of Miocene age exposed at the surface that is recognized in southwestern Florida. The Hawthorn formation and the older Tertiary formations have been recognized in samples from wells in southern Florida.

Florida↗
USGS1988

Source-rock evaluation of outcrop samples from Vanuatu (Malakula, Espiritu Santo, Maewo, and Pentecost)

Thirty-nine outcrop samples of mudstones, siltstones, and limestones were collected for source-rock evaluation of the sedimentary column in Vanuatu. Twenty-nine samples showing the least evidence of oxidation were selected for total organic analysis from the Miocene Matanui Group and Port Sandwich Formation in Malakula, and from the Miocene Ilava, Peteao, and Pelapa Formations in Espiritu Santo. An additional 13 samples from the upper Miocene to Pleistocene sequence in the islands of Maewo and Pentecost were taken from the sample collection stored at the Department of Geology, Mines, and Rural WAter Supplies in Port Vila and analyzed for total organic carbon (T.O.C.). Of the 42 samples analyzed for total organic carbon content, four yielded values above the generally accepted minimum for source rock: three from the Peteao Formation (T.O.C. ranging from 0.52% to 1.44%), and one from the Pelapa Formation (T.O.C. = 0.54%). Rock-Eval pyrolysis on the rocks and reflected light microscopy on the separated organic matter indicate that the organic matter is poor in hydrogen and is dominantly type III kerogen; therefore, it is of a chemical type that does not yield liquid hydrocarbons but may havev limited potential for generating gas. The Rock-Eval pyrolysis and the vitrinite reflectance analysis indicate that the organic matter in these samples is thermally immature. The samples collected for the present study represent only a portion of the sedimentary column in the various sedimentary basins of Vanuatu. The characterize only the outer margins of the sedimentary basins and do not necessarily reflect the source-rock potential of the deeper (offshore) parts of the basins.

Book chapter↗