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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 1,639 records · Page 91Linked to original sources

USGS2001

Geologic Map of the Cane Quadrangle, Coconino County, Northern Arizona

This digital map database is compiled from unpublished data and new mapping by the authors, represents the general distribution of surficial and bedrock geology in the mapped area. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the area. The database delineate map units that are identified by age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution of the database to 1:24,000 or smaller.

Miscellaneous Field Studies Map↗

USGS2001

Geologic Map of the House Rock Spring Quadrangle, Coconino County, Northern Arizona

Miscellaneous Field Studies Map↗

USGS2001

Geologic map of the Saint Joseph area, Missouri and Kansas

This map was prepared as a collaborative effort with the Missouri Division of Geology and Land Survey, the Kansas Geological Survey, and the Nebraska Conservation and Survey Division. Map units and preliminary contacts between units were identified using stereoscopic pairs of high altitude, false color infrared, aerial photographs. Contacts were drawn on twelve USGS 7.5-minute topographic maps, and were checked in the field. U.S. Department of Agriculture Soil Survey maps at a scale of 1:62,500 for Buchanan County, Andrew County, Platte County, and Doniphan County were used to provide a general overview of the soils of the area. A U.S. Geological Survey map at a scale of 1:24,000 showing the geohydrology of Doniphan County, Kansas; soil surveys at a scale of 1:24,000 for Buchanan County, Andrew County, and Platte County; and soil survey at a scale of 1:20,000 for Doniphan were used to corroborate map contacts and field observations.

Kansas, Missouri↗

USGS2002

Geologic map of the Hidden Hills and vicinity, Mohave County, northwestern Arizona

This digital map database is compiled from unpublished data and new mapping by the authors and represents the general distribution of surficial and bedrock geology in the mapped area. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the area. The database delineates map units that are identified by age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution of the database to 1:31,680 or smaller.

Arizona↗

USGS2002

Geologic map of Clayhole Wash and vicinity, Mohave County, northwestern Arizona

This digital map database is compiled from unpublished data and new mapping by the authors and represents the general distribution of surficial and bedrock geology in the mapped area. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the area. The database dilineates map units that are identified by age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution of the database to 1:31,680 or smaller.

Miscellaneous Field Studies Map↗

USGS2003

Geologic map of the Lower Hurricane Wash and vicinity, Mohave County, Northwestern Arizona

This digital map database is compiled from published open file reports, and new mapping by the author, and represents the general distribution of surficial and bedrock geology in the mapped area. The map area lies within the Shivwits and Uinkaret Plateaus, subplateaus of the southwestern part of the Colorado Plateau hypsographic province. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the area. The database delineates map units that are identified by age and lithology, following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution of the database to 1:31,680 or smaller.

Miscellaneous Field Studies Map↗

USGS2003

Geologic map of the Rio Puerco quadrangle, Bernalillo and Valencia Counties, New Mexico

The Rio Puerco quadrangle is located southwest of Albuquerque in central New Mexico and covers part of the western part of the Isleta Reservation. The U.S. Geological Survey, the New Mexico Bureau of Geology and Mineral Resources, and the University of New Mexico have conducted geologic mapping on the Isleta Reservation and vicinity as part of the Middle Rio Grande Basin Project. The map area contains surficial deposits, calcic soils, fluvial deposits of the Rio Puerco, deposits of the Santa Fe Group, and three volcanic fields. The area is characterized by predominantly north-trending normal faults with generally down-to-the-east movement. Post-Santa Fe Group deposits are composed of surficial deposits (Pleistocene-Holocene) and fluvial deposits of the Rio Puerco (Pleistocene-Holocene). The surficial deposits are divided into eolian, alluvial, colluvial, and landslide deposits. The fluvial deposits of the Rio Puerco consist of four terrace and present channel deposits. The Santa Fe Group is divided into lower and upper parts. The lower part of the Santa Fe Group is exposed near the southwestern corner of the study area where deposits consist of reddish-brown mudstone and sandstone correlated to the Popotosa Formation (Unit 1) of Lozinsky and Tedford (1991). They interpreted deposition of the unit in a basin-floor playa setting. The Popotosa Formation is in fault contact to the east with deposits of the upper Santa Fe Group. The upper Santa Fe Group is derived from major tributary fluvial systems (ancestral Rio Puerco Puerco and possibly the Rio San Jose drainages) draining the adjacent Colorado Plateau and Sierra Nacimiento and correlated to parts of Kelley's (1977) Ceja Formation of the Santa Fe Group and equivalent to Machette's (1978) Sierra Ladrones Formation, Connell's Arroyo Ojito Formation (Connell and others, 1999, and Maldonado's lithofacies of the Isleta Reservation (Maldonado and Atencio,1998a, b). The group also locally includes a fine- grained unit (lower Pleistocene) referred to here as the sand, silt, and clay of Chavez Grant (Qsc). The Ceja Formation of the Santa Fe Group as defined here is divided into the following units in descending stratigraphic order: (1) upper sand and gravel unit (upper Pliocene), (2) middle silt, sand, and clay unit (upper Pliocene), and (3) lower sand and gravel unit (Pliocene). The three volcanic fields in the map area are: (1) basalt of Cat Hills, dated at 98-110 ka and composed of seven lava flows and four cinder cones; the flows overlie calcic soils that overlie the upper sand and gravel unit of the Ceja Formation; (2) lava flow of Cat Mesa, dated at about 3 Ma and interfingers with the upper part of the Ceja Formation; (3) diabase of Mohinas Mountain, dated at 8.3 Ma (Baldridge and others, 1987) and intrudes the Popotosa Formation. Numerous high-angle faults cut the area but are mostly buried. The faults generally trend north but deviate to the northwest and northeast. The major normal faults are the Cat Mesa and Mohinas Mountain faults.

Miscellaneous Field Studies Map↗

USGS2002

Surficial Geologic Map of The Loop and Druid Arch Quadrangles, Canyonlands National Park, Utah

This geologic map is a product of a cooperative project between the U.S. Geological Survey and the U.S. National Park Service to provide geologic information about this part of Canyonlands National Park, Utah. This digital map database contains bedrock data from previously published data that has been modified by the author. New mapping of the surficial deposits represents the general distribution of surficial deposits of the Druid Arch and The Loop 7.5-minute quadrangles.

Miscellaneous Field Studies Map↗

USGS2003

Geologic map of upper Clayhole Valley and vicinity, Mohave County, northwestern Arizona

Miscellaneous Field Studies Map↗

USGS2004

Geologic map of the Lower Grand Wash cliffs and vicinity, Mohave County, Northwestern Arizona

This digital map database is compiled from unpublished data and new mapping by the authors and represents the general distribution of surficial and bedrock geology in the mapped area. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the area. The database dilineates map units that are identified by age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution of the database to 1:31,680 or smaller.

Miscellaneous Field Studies Map↗

USGS1974

Preliminary report on the geology of the continental borderland of Southern California

Appraisal of the mineral resource potential and assessment of environmental problems of any specific area require an understanding of the regional geology. The geology of t he coastal zone and offshore islands from Point Conception to the Mexican boundary serves as a frame of reference from which rock units and structures can be extrapolated into submerged parts of the borderland (sheet 1). Such extrapolations should be used with caution, for the tectonic evolution and depositional history of parts of the borderland may not have paralleled those of the mainland. On shore, rocks and structures c an be observed directly with supplemental aid from deep drill holes; but in areas covered by deep water, only indirect techniques such as geophysical methods and shallow coring provide information from which geologic intepretations can be made.

California↗

USGS2000

Acoustic mapping of the regional seafloor geology in and around Hawaiian ocean dredged-material disposal sites

During January and February 1998 the U.S. Geological Survey Coastal and Marine Geology Team (USGS) conducted regional high-resolution multibeam mapping surveys of the area surrounding EPA-designated ocean disposal sites located offshore of the Hawaiian Islands of Oahu, Kauai, Maui, and Hawaii. The sites are all located within 5 nautical miles of shore on insular shelves or slopes. Regional maps were required of areas much larger than the disposal sites themselves to assess both the regional seafloor geology and the immediate vicinity of the disposal sites. The purpose of the disposal site surveys was to delimit the extent of disposal material by producing detailed bathymetric and backscatter maps of the seafloor with a ± 1 m spatial accuracy and <1% depth error. The advantage of using multibeam over conventional towed, single-beam sidescan sonar is that the multibeam data are accurately georeferenced for precise location of all imaged features. The multibeam produces a coregistered acoustic-backscatter map that is often required to locate individual disposal deposits. These data were collected by the USGS as part of its regional seafloor mapping and in support of ocean disposal site monitoring studies conducted in cooperation with the US Environmental Protection Agency (EPA) and the US Army Corps of Engineers (COE).

Hawai'i↗

USGS2000

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory-Determination of ammonium plus organic nitrogen by a Kjeldahl digestion method and an automated photometric finish that includes digest cleanup by gas diffusion

The National Water Quality Laboratory (NWQL) determined ammonium plus organic nitrogen (Kjeldahl nitrogen) by using semiautomated, block digester methods for filtered and whole-water samples from 1986 until October 1, 1991. During that time, phosphorus was determined by a persulfate digestion method. In 1991, projected increases in demand for both tests by the U.S. Geological Survey?s National Water-Quality Assessment Program led the NWQL to develop and validate methods for determining both analytes in a common digest. This report describes a rapid and accurate method to determine Kjeldahl nitrogen. The batch, high-temperature (block digester), Hg (II)-catalyzed digestion step used in the new methods I-2515-91/4515-91 is similar to U.S. Geological Survey methods I-2552-85/4552-85 and U.S. Environmental Protection Agency method 351.2 except that sample and reagent volumes are halved. Prepared digests are desolvated at 220 degrees Celsius (oC) and digested at 370oC in separate block digesters set at these temperatures, rather than in a single, temperatureprogrammed block digester. This approach permits 40 calibrants, reference materials, and samples to be digested and resolvated in about an hour. Ammonium ions originally present in samples, along with those released during the digestion step, are determined photometrically by an automated, salicylatehypochlorite Berthelot reaction procedure at a rate of 90 tests per hour. About 100 microliters of digest are required per determination. The upper concentration level is 10 milligrams per liter (mg/L) with a method detection level of 0.05 mg/L. Repeatability for a sample containing about 4.1 mg/L of Kjeldahl nitrogen in a high suspended-solids matrix is 3.1 percent. Between-day precision for the same sample is 4.8 percent. A gas diffusion cell in the air-segmented continuous flow analyzer eliminates particulates and ions that otherwise would interfere in the photometric finish. A singlechannel analyzer can process the resolvated digests from two pairs of block digesters each hour. Statistical analysis of paired data for about 1,500 samples determined by U.S. Geological Survey methods I-2552-85/4552- 85 and I-2515-91/4515-91 during method validation revealed a median concentration difference between the former and the latter methods of about 0.1 mg-N/L. This result was expected because digestion blank concentrations (nearly equal to 0.1 mg/L) were not subtracted from concentrations reported by methods I-2552-85/4552-85. A 10-year record of National Water Quality Laboratory Kjeldahl nitrogen blind blank concentration data also supports a step-change decrease in Kjeldahl nitrogen concentrations of about 0.1 mg/L after methods I-2552-85/4552-85 were replaced by methods I-2515-91/4515-91 on October 1, 1991. Somewhat larger concentration differences between the two methods were observed for a subset of about 350 samples with nitrate plus nitrite concentrations greater than 1 mg-N/L.

Open-File Report↗

USGS2001

Use of structural geology in exploration for and mining of sedimentary rock-hosted Au deposits

Structural geology is an important component in regional-, district- and orebody-scale exploration and development of sedimentary rock-hosted Au deposits. Identification of timing of important structural events in an ore district allows analysis and classification of fluid conduits and construction of genetic models for ore formation. The most practical uses of structural geology deal with measurement and definition of various elements that comprise orebodies, which can then be directly applied to ore-reserve estimation, ground control, grade control, safety issues, and mine planning. District- and regional-scale structural studies are directly applicable to long-term strategic planning, economic analysis, and land ownership. Orebodies in sedimentary rock-hosted Au deposits are discrete, hypogene, epigenetic masses usually hosted in a fault zone, breccia mass, or lithologic bed or unit. These attributes allow structural geology to be directly applied to the mining and exploration of sedimentary rock-hosted Au deposits. Internal constituents in orebodies reflect unique episodes relating to ore formation. The main internal constituents in orebodies are ore minerals, gangue, and alteration minerals that usually are mixed with one another in complex patterns, the relations among which may be used to interpret the processes of orebody formation and control. Controls of orebody location and shape usually are due to structural dilatant zones caused by changes in attitude, splays, lithologic contacts, and intersections of the host conduit or unit. In addition, conceptual parameters such as district fabric, predictable distances, and stacking also are used to understand the geometry of orebodies. Controls in ore districts and location and geometry of orebodies in ore districts can be predicted to various degrees by using a number of qualitative concepts such as internal and external orebody plunges, district plunge, district stacking, conduit classification, geochemical, geobarometric and geothermal gradients, and tectonic warps. These concepts have practical and empirical application in most mining districts where they are of use in the exploration for ore, but are of such broad and general application that they may not represent known or inferred ore formation processes. Close spatial relation among some sedimentary rock- hosted Au deposits and their host structures suggests that the structures and the orebodies are genetically linked because they may have shared the same developmental history. Examples of probable syn-deformational genesis and structural control of sedimentary rock-hosted Au deposits are in the large Betze deposit in the Carlin trend, Nevada and in the Lannigou, Jinlongshan, and Maanqiao Au deposits, China.

Open-File Report↗

USGS2001

Preliminary digital geologic map of the Appalachian Piedmont and Blue Ridge, South Carolina segment

A preliminary geology coverage of the Piedmont and Blue Ridge in South Carolina has been compiled at 1:5000,000 scale and digitized as part of a patchwork of coverages for the analysis of regional and national geochemical patterns that may have environmental and resource implications. It was produced from other compilations that incorporate more detailed geologic maps as well as additional sources. The compilation is designed to meet short-term needs until better coverage of the regional geology is available.

Open-File Report↗

USGS2002

Geologic interpretation of aeromagnetic maps in the Santa Cruz basin: Patagonia Mountains area, south-central Arizona

High resolution aeromagnetic data for the Santa Cruz basin - Patagonia Mountains region of south-central Arizona (USGS, 2000) can be combined with geologic mapped regions to reconfirm known geologic features, extend known features, and suggest new possibilities. These include mapping of lava flows, mapping of igneous intrusions, mapping of faults, and the mapping of basement rocks which lie beneath sediments. The processed maps of interest for a geologic interpretation include the reduced-to-the-pole magnetic map (Phillips, Plate 3), the depth estimate by the horizontal gradient method (Phillips, Plate 6), and the basin depth estimates map.

Arizona↗

USGS2003

A spatial database of bedding attitudes to accompany Geologic Map of Boulder-Fort Collins-Greeley area, Colorado

This digital map shows bedding attitude data displayed over the geographic extent of rock stratigraphic units (formations) as compiled by Colton in 1976 (U.S.Geological Survey Map I-855-G) under the Front Range Urban Corridor Geology Program. Colton used his own mapping and published geologic maps having varied map unit schemes to compile one map with a uniform classification of geologic units. The resulting published color paper map was intended for planning for use of land in the Front Range Urban Corridor. In 1997-1999, under the USGS Front Range Infrastructure Resources Project, Colton's map was digitized to provide data at 1:100,000 scale to address urban growth issues(see cross-reference). In general, the west part of the map shows a variety of Precambrian igneous and metamorphic rocks, major faults and brecciated zones along an eastern strip (5-20 km wide) of the Front Range. The eastern and central part of the map (Colorado Piedmont) depicts a mantle of Quaternary unconsolidated deposits and interspersed Cretaceous or Tertiary-Cretaceous sedimentary rock outcrops. The Quaternary mantle is comprised of eolian deposits (quartz sand and silt), alluvium (gravel, sand, and silt of variable composition), colluvium, and few landslides. At the mountain front, north-trending, dipping Paleozoic and Mesozoic sandstone and shale formations (and sparse limestone) form hogbacks, intervening valleys, and in range-front folds, anticlines, and fault blocks. Localized dikes and sills of Tertiary rhyodacite and basalt intrude rocks near the range front, mostly in the Boulder area.

Colorado↗

USGS2003

Isostatic gravity map with simplified geology of the Los Angeles 30 x 60 minute quadrangle

This isostatic residual gravity map is part of the Southern California Areal Mapping Project (SCAMP) and is intended to promote further understanding of the geology in the Los Angeles 30 x 60 minute quadrangle, California, by serving as a basis for geophysical interpretations and by supporting both geological mapping and topical (especially earthquake) studies. Local spatial variations in the Earth's gravity field (after various corrections for elevation, terrain, and deep crustal structure explained below) reflect the lateral variation in density in the mid- to upper crust. Densities often can be related to rock type, and abrupt spatial changes in density commonly mark lithologic boundaries. The map shows contours of isostatic gravity overlain on a simplified geology including faults and rock types. The map is draped over shaded-relief topography to show landforms.

California↗