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At least 1,405 records · Page 78Linked to original sources
USGS2001

Geologic map and digital database of the San Rafael Mtn. 7.5-minute quadrangle, Santa Barbara County, California

Geologic mapping of the San Rafael Primitive Area (now the San Rafael Wilderness) by Gower and others (1966) and Vedder and others (1967) did not include all of the San Rafael Mtn. quadrangle, and the part that was mapped was done in reconnaissance fashion. To help resolve some of the structural and stratigraphic ambiguities of the earlier mapping and to complete the mapping of the quadrangle, additional field work was done during short intervals in 1980 and 1981 and from 1996 to 1998. Contacts within the belt of Franciscan rocks at the southwestern corner of the quadrangle were generalized from the detailed map by Wahl (1998). Because extensive areas were inaccessible owing to impenetrable chaparral, observations from several helicopter overflights (1965, 1980, 1981) and interpretations from aerial photographs were used as compilation aids. Consequently, some of the depicted contacts and faults are highly inferential, particularly within the Upper Cretaceous rocks throughout the middle part of the quadrangle.

California↗
USGS2002

Fourth international circumpolar arctic vegetation mapping workshop

During the week of April 10, 2001, the Fourth International Circumpolar Arctic Vegetation Mapping Workshop was held in Moscow, Russia. The purpose of this meeting was to bring together the vegetation scientists working on the Circumpolar Arctic Vegetation Map (CAVM) to (1) review the progress of current mapping activities, (2) discuss and agree upon a standard set of arctic tundra subzones, (3) plan for the production and dissemination of a draft map, and (4) begin work on a legend for the final map.

Open-File Report↗
USGS2002

Digital soils survey map of the Patagonia Mountains, Arizona

The ‘Soil Survey of Santa Cruz and Parts of Cochise and Pima Counties, Arizona,' a product of the USDA’s Soil Conservation Service and the Forest Service in cooperation with the Arizona Agricultural Experiment Station, released in 1979, was created according to the site conditions in 1971, when soil scientists identified soils types on aerial photographs. The scale at which these maps were published is 1:20,000. These soil maps were automated for incorporation into the hydrologic modeling within a GIS. The aerial photos onto which the soils units were drawn had not been orthoganalized, and contained distortion. A total of 15 maps composed the study area. These maps were scanned into TIFF format using an 8-bit black and white drum scanner at 100 dpi. The images were imported into ERDAS IMAGINE and the white borders were removed through subset decollaring processes. Five CD-ROM’s containing Digital Orthophoto Quarter Quads (DOQQ’s) were used to register and rectify the scanned soils maps. Polygonal data was then attributed according to the datasets.

Arizona↗
USGS2002

Digital data grids for the magnetic anomaly map of North America

The digital magnetic anomaly database and map for the North American continent is the result of a joint effort by the Geological Survey of Canada (GSC), U. S. Geological Survey (USGS), and Consejo de Recursos Minerales of Mexico (CRM). This integrated, readily accessible, modern digital database of magnetic anomaly data is a powerful tool for further evaluation of the structure, geologic processes, and tectonic evolution of the continent and may also be used to help resolve societal and scientific issues that span national boundaries. The North American magnetic anomaly map derived from the digital database provides a comprehensive magnetic view of continental-scale trends not available in individual data sets, helps link widely separated areas of outcrop, and unifies disparate geologic studies. This open-file report presents three unique, gridded data sets used to make the magnetic anomaly map of North America. Subsets of these three grids that span only the United States were also created, giving a total of six grids. Details on the data processing and compilation procedures used to produce the grids are described in the booklet that accompanies the North American magnetic anomaly map. All three grids have 1-km spacing and are projected to the DNAG projection (spherical transverse mercator, central meridian of 100 o W, base latitude of 0o, scale factor of 0.926 and Earth radius of 6,371,204 m.) More details are given in the metadata files that accompany the gridded data files. These grids are presented in Geosoft binary grid format, with two files describing each of the six grids (suffixes .grd and .gi). This format can be easily converted to numerous other formats using the free conversion software offered by this company at http://www.geosoft.com/. The first grids (NAmag_origmrg.grd and USmag_origmrg.grd) show the magnetic field at 305 m. above terrain. For the second grids (NAmag_hp500.grd and USmag_hp500.grd) we removed long-wavelength anomalies (500 km and greater) from the first grid. This grid was used for the published map. Although the North American merged grid represents a significant upgrade to older compilations, the existing patchwork of surveys is inherently unable to accurately represent anomalies with long (greater than roughly 150 km) wavelengths, particularly in the US and Canada (U.S. Magnetic-Anomaly Data Set Task Group, 1994). The lack of information about long wavelength anomalies is primarily related to datum shifts between merged surveys, caused by data acquisition at widely different times and by differences in merging procedures. Therefore, we removed anomalies with wavelengths greater than 500 km from the merged grid to reduce the effects caused by the spurious long wavelengths but still maintain the continuity of anomalies. The correction was accomplished by transforming the merged grid to the frequency domain, filtering the transformed data with a long-wavelength cutoff at 500 km, and subtracting the long-wavelength data grid from the merged grid. In addition to the 500-km high pass filter, an equivalent source method, based on long-wavelength characterization using satellite data (CHAMP satellite anomalies, Maus and others, 2002), was also used to correct for spurious shifts in the original magnetic anomaly grid (Ravat and others, 2002). These results are presented in the third grids (NAmag_CM.grd and USmag_CM.grd), in which the wavelengths longer than 500 km have been replaced by downward-continued satellite data. The steps used to create the third long-wavelength-corrected grid are: 0. The North American 1-km merged grid was decimated to 5 km. 1. This 5-km grid was converted to a 0.05 degree grid and was low-pass filtered using a Gaussian filter with a 500-km cutoff, then decimated to 1 degree. 2. A joint inversion of this 1-degree low-pass aeromagnetic grid and satellite data, with the aeromagnetic data weighted very low, was used to produce a stabilized downward continuation of the satellite data. 3. The inverted data were interpolated to 0.05 degrees and again low-pass filtered using the same Gaussian 500-km filter to remove short-wavelength artifacts. 4. The low-pass grid from step 1 was subtracted from the original 0.05-degree aeromagnetic grid to create a 500-km high-pass aeromagnetic grid. This grid was added to the low-pass inverted grid from step 3 to get a corrected 0.05-degree aeromagnetic grid. 5. The corrected 0.05-degree aeromagnetic grid was projected to the DNAG projection and regridded to 5 km. This was subtracted from the decimated 5-km aeromagnetic grid to generate a 5-km correction grid. A matched filter was used to remove short-wavelength artifacts resulting from the projection and regridding process. 6. The resulting 5-km correction grid was regridded to the original 1-km grid and subtracted from the original 1-km aeromagnetic grid to generate the final 1-km corrected aeromagnetic grid. The six grids described in this report are available for download. Two metadata files, one for the North American grids and one for the United States grids, are also included with the gridded data.

Open-File Report↗
USGS2003

A digital geologic map database for the state of Oklahoma

This dataset is a composite of part or all of the 12 1:250,000 scale quadrangles that make up Oklahoma. The result looks like a geologic map of the State of Oklahoma. But it is only an Oklahoma shaped map clipped from the 1:250,000 geologic maps. This is not a new geologic map. No new mapping took place. The geologic information from each quadrangle is available within the composite dataset.

Open-File Report↗
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↗
USGS2003

Geologic map and digital database of the Yucaipa 7.5’ quadrangle, San Bernardino and Riverside Counties, California

Introduction This geologic database of the Yucaipa 7.5' quadrangle was prepared by the Southern California Areal Mapping Project (SCAMP), a regional geologic-mapping project sponsored jointly by the U.S. Geological Survey and the California Geological Survey. The database was developed as a contribution to the National Cooperative Geologic Mapping Program's National Geologic Map Database, and is intended to provide a general geologic setting of the Yucaipa quadrangle. The database and map provide information about earth materials and geologic structures, including faults and folds that have developed in the quadrangle due to complexities in the San Andreas Fault system. The Yucaipa 7.5' quadrangle contains materials and structures that provide unique insight into the Mesozoic and Cenozoic geologic evolution of southern California. Stratigraphic and structural elements include: (1) strands of the San Andreas Fault that bound far-traveled terranes of crystalline and sedimentary rock; (2) Mesozoic crystalline rocks that form lower and upper plates of the regionwide Vincent-Orocopia Thrust system; and (3) late Tertiary and Quaternary sedimentary materials and geologic structures that formed during the last million years or so and that record complex geologic interactions within the San Andreas Fault system. These materials and the structures that deform them provide the geologic framework for investigations of geologic hazards and ground-water recharge and subsurface flow. Geologic information contained in the Yucaipa database is general-purpose data that is applicable to land-related investigations in the earth and biological sciences. The term "generalpurpose" means that all geologic-feature classes have minimal information content adequate to characterize their general geologic characteristics and to interpret their general geologic history. However, no single feature class has enough information to definitively characterize its properties and origin. For this reason the database cannot be used for site-specific geologic evaluations, although it can be used to plan and guide investigations at the site-specific level.

California↗
USGS2003

Geologic map and digital database of the Redlands 7.5' quadrangle, San Bernardino and Riverside Counties, California

This geologic database of the Redlands 7.5' quadrangle was prepared by the Southern California Areal Mapping Project (SCAMP), a regional geologic-mapping project sponsored jointly by the U.S. Geological Survey and the California Geological Survey. The database was developed as a contribution to the National Cooperative Geologic Mapping Program's National Geologic Map Database, and is intended to provide a general geologic setting of the Redlands quadrangle. The database and map provide information about earth materials and geologic structures, including faults and folds that have developed in the quadrangle due to complexities in the San Andreas Fault system. The Redlands 7.5' quadrangle contains earth materials and structures that provide insight into the late Cenozoic geologic evolution of the southern California Inland Empire region. Important stratigraphic and structural elements include (1) the modern trace of the San Andreas and San Jacinto faults and (2) late Tertiary and Quaternary sedimentary materials and geologic structures that formed during the last million years or so and that record complex geologic interactions within the San Andreas Fault system. These materials and the structures that deform them provide the geologic framework for investigations of earthquake hazards and ground-water recharge and subsurface flow. Geologic information contained in the Redlands database is general-purpose data that is applicable to land-related investigations in the earth and biological sciences. The term "general-purpose" means that all geologic-feature classes have minimal information content adequate to characterize their general geologic characteristics and to interpret their general geologic history. However, no single feature class has enough information to definitively characterize its properties and origin. For this reason the database cannot be used for site-specific geologic evaluations, although it can be used to plan and guide investigations at the site-specific level. This summary pamphlet discusses major categories of surficial materials in the Redlands quadrangle, and provides a conceptual framework and basis for how geologicmap units containing such materials are recognized and correlated.

California↗
USGS2003

Database and Map of Quaternary Faults and Folds in Peru and its Offshore Region

This publication consists of a main map of Quaternary faults and fiolds of Peru, a table of Quaternary fault data, a region inset map showing relative plate motion, and a second inset map of an enlarged area of interest in southern Peru. These maps and data compilation show evidence for activity of Quaternary faults and folds in Peru and its offshore regions of the Pacific Ocean. The maps show the locations, ages, and activity rates of major earthquake-related features such as faults and fault-related folds. These data are accompanied by text databases that describe these features and document current information on their activity in the Quaternary.

Open-File Report↗
USGS2008

Geologic map of Mount St. Helens, Washington prior to the 1980 eruption

It is rare that a geologic map exists for a volcano prior to such a catastrophic modification as that produced by the eruption of Mount St. Helens in 1980. As such, this map provides an important historical record of the volcano prior to that eruption. The map has not been reviewed or checked for conformity to USGS editorial standards or stratigraphic nomenclature, and it has not been digitized. This version of the map is unchanged from that submitted to the USGS for publication shortly after the 1980 eruption of Mount St. Helens and includes unresolved inconsistencies with the subsequently published work of Crandell (1987) and Mullineaux (1996). Nevertheless, it is the most accurate available depiction of the pre-1980 edifice and is published here for comparison with more recent geologic mapping and historical perspectives.

Open-File Report↗
USGS2003

Maps Showing Inundation Depths, Ice-Rafted Erratics, and Sedimentary Facies of Late Pleistocene Missoula Floods in the Willamette Valley, Oregon

Glacial Lake Missoula, impounded by the Purcell Trench lobe of the late Pleistocene Cordilleran Icesheet, repeatedly breached its ice dam, sending floods as large as 2,500 cubic kilometers racing across the Channeled Scabland and down the Columbia River valley to the Pacific Ocean. Peak discharges for some floods exceeded 20 million cubic meters per second. At valley constrictions along the flood route, floodwaters temporarily ponded behind each narrow zone. One such constriction at Kalama Gap-northwest of Portland-backed water 120-150 meters high in the Portland basin, and backflooded 200 km south into Willamette Valley. Dozens of floods backed up into the Willamette Valley, eroding 'scabland' channels, and depositing giant boulder gravel bars in areas of vigorous currents as well as bedded flood sand and silt in backwater areas. Also, large chunks of ice entrained from the breached glacier dam rafted hundreds of 'erratic' rocks, leaving them scattered among the flanking foothills and valley bottom. From several sources and our own mapping, we have compiled information on many of these features and depict them on physiographic maps derived from digital elevation models of the Portland Basin and Willamette Valley. These maps show maximum flood inundation levels, inundation levels associated with stratigraphic evidence of repeated floodings, distribution of flood deposits, and sites of ice-rafted erratics. Accompanying these maps, a database lists locations, elevations, and descriptions of approximately 400 ice-rafted erratics-most compiled from early 20th-century maps and notes of A.M. Piper and I.S. Allison.

Open-File Report↗
USGS2004

Binational digital soils map of the Ambos Nogales watershed, southern Arizona and northern Sonora, Mexico

We have prepared a digital map of soil parameters for the international Ambos Nogales watershed to use as input for selected soils-erosion models. The Ambos Nogales watershed in southern Arizona and northern Sonora, Mexico, contains the Nogales wash, a tributary of the Upper Santa Cruz River. The watershed covers an area of 235 km2, just under half of which is in Mexico. Preliminary investigations of potential erosion revealed a discrepancy in soils data and mapping across the United States-Mexican border due to issues including different mapping resolutions, incompatible formatting, and varying nomenclature and classification systems. To prepare a digital soils map appropriate for input to a soils-erosion model, the historical analog soils maps for Nogales, Ariz., were scanned and merged with the larger-scale digital soils data available for Nogales, Sonora, Mexico using a geographic information system.

Arizona, Sonora↗
USGS2004

Preliminary geologic map of the El Cajon 30' x 60' quadrangle, Southern California

This data set maps and describes the geology of the El Cajon 30' x 60' quadrangle, southern California. Compilation of the El Cajon quadrangle is based upon published mapping at various scales, unpublished mapping at 1:24,000 scale, and reconnaissance mapping. Mapping was done by fieldwork and the use of aerial photographs at 1:24,000 scale. The El Cajon quadrangle includes parts of two physiographic provinces: the Peninsular Ranges Province on the west underlies the major part of the quadrangle; the western Colorado Desert (locally called the Anza-Borrego Desert) underlies the northeastern corner. The approximate boundary between these two provinces is the Neogene Elsinore Fault Zone, the westernmost on-land strand of the San Andreas Fault System. Movements within the Elsinore Fault Zone are believed to have resulted in the uplift and westward rotation of the Peninsular Ranges block relative to the western Colorado Desert (Gastil and others, 1975). As a result, elevations in the El Cajon quadrangle increase from less than 100 m in the westernmost part of the quadrangle to ~2000 m along the irregular mountainous spine of the Peninsular Ranges (the Cuyamaca, Laguna, Tierra Blanca, and Jacumba Mountains); elevations then decrease rapidly eastward to <100 m in the Anza-Borrego Desert. Southwest of the Elsinore Fault Zone, the El Cajon quadrangle is underlain by Jurassic and Cretaceous plutonic rocks of the composite Peninsular Ranges Batholith, which contains screens of variably metamorphosed Mesozoic supracrustal rocks. Late Jurassic and Early Cretaceous volcanic and volcaniclastic rocks that are exposed in the western part of the quadrangle represent an older, superjacent part of the Peninsular Ranges magmatic arc. Upper Cretaceous and Eocene marine and nonmarine strata were deposited widely upon the eroded batholith but are preserved only in the westernmost part of the quadrangle (the San Diego embayment). Pliocene and Pleistocene coastal terrace deposits rest unconformably upon the early Tertiary rocks in the southwestern corner of the quadrangle. Northeast of the Elsinore Fault Zone, the El Cajon quadrangle exposes extensive Neogene nonmarine and marine sedimentary and volcanic rocks of the Fish Creek-Vallecito basin. Basement uplifts in this region are composed of crystalline rocks of the eastern Peninsular Ranges Batholith (the Vallecito, Fish Creek, and Coyote Mountains).

Open-File Report↗
USGS2005

Generalized geologic map of bedrock lithologies and surficial deposits in the Great Smoky Mountains National Park region, Tennessee and North Carolina

The geology of the Great Smoky Mountain National Park (GSMNP) region of Tennessee and North Carolina was studied from 1993 to 2003 as part of a cooperative investigation with the National Park Service (NPS). This work has been compiled as a 1:100,000-scale map derived from mapping done at 1:24,000 and 1:62,500 scale. The geologic data are intended to support cooperative investigations with NPS, the development of a new soil map by the Natural Resources Conservation Service, and the All Taxa Biodiversity Inventory ( http://www.discoverlifeinamerica.org/ ). At the request of NPS, we mapped areas previously not visited, revised the geology where stratigraphic and structural problems existed, and developed a map database for use in interdisciplinary research, land management, and interpretive programs for park visitors.

North Carolina, Tennessee↗
USGS2006

Geologic map of the Colonial Beach South 7.5-minute quadrangle, Virginia

The Open-File Report includes a geologic map with cross section, and composite stratigraphic section of the Tertiary stratigraphy and of the Quaternary stratigraphy. The Tertiary map units are presented and interpreted for erodability and derived surficial deposits. The map area contains the George Washington Birthplace National Monument. The map facilitates the interpretation of the natural history of the Park including processes such as bog (wetlands) formation and coastal erosion. Two cores of Holocene estuarine deposits are sited on the map. They present the transition from terrestrial to estuarine depositional environments.

Open-File Report↗
USGS2005

Alabama-Mississippi coastal classification maps - Perdido Pass to Cat Island

The primary purpose of the USGS National Assessment of Coastal Change Project is to provide accurate representations of pre-storm ground conditions for areas that are designated high-priority because they have dense populations or valuable resources that are at risk from storm waves. Another purpose of the project is to develop a geomorphic (land feature) coastal classification that, with only minor modification, can be applied to most coastal regions in the United States. A Coastal Classification Map describing local geomorphic features is the first step toward determining the hazard vulnerability of an area. The Coastal Classification Maps of the National Assessment of Coastal Change Project present ground conditions such as beach width, dune elevations, overwash potential, and density of development. In order to complete a hazard vulnerability assessment, that information must be integrated with other information, such as prior storm impacts and beach stability. The Coastal Classification Maps provide much of the basic information for such an assessment and represent a critical component of a storm-impact forecasting capability. The map above shows the areas covered by this web site. Click on any of the location names or outlines to view the Coastal Classification Map for that area.

Alabama, Mississippi, Florida↗
USGS2005

Geologic map of the Great Smoky Mountains National Park region, Tennessee and North Carolina

The geology of the Great Smoky Mountain National Park (GSMNP) region of Tennessee and North Carolina was studied from 1993 to 2003 as part of a cooperative investigation with the National Park Service (NPS). This work has been compiled as a 1:100,000-scale map derived from mapping done at 1:24,000 and 1:62,500 scale. The geologic data are intended to support cooperative investigations with NPS, the development of a new soil map by the Natural Resources Conservation Service, and the All Taxa Biodiversity Inventory ( http://www.discoverlifeinamerica.org/ ). At the request of NPS, we mapped areas previously not visited, revised the geology where stratigraphic and structural problems existed, and developed a map database for use in interdisciplinary research, land management, and interpretive programs for park visitors.

North Carolina, Tennessee↗
USGS2006

Preliminary Surficial Geologic Map of the Mesquite Lake 30' X 60' Quadrangle, California and Nevada

The Quaternary surficial geologic map of the Mesquite Lake, California-Nevada 30'X60' quadrangle depicts deposit age and geomorphic processes of erosion and deposition, as identified by a composite of remote sensing investigations, laboratory analyses, and field work, in the arid to semi-arid Mojave Desert area, straddling the California-Nevada border. Mapping was motivated by the need to address pressing scientific and social issues such as understanding and predicting the effects of climate and associated hydrologic changes, human impacts on landscapes, ecosystem function, and natural hazards at a regional scale. As the map area lies just to the south of Las Vegas, Nevada, a rapidly expanding urban center, land use pressures and the need for additional construction materials are forecasted for the region. The map contains information on the temporal and spatial patterns of surface processes and hazards that can be used to model specific landscape applications. Key features of the geologic map include: (1) spatially extensive Holocene alluvial deposits that compose the bulk of Quaternary units (~25%), (2) remote sensing and field studies that identified fault scarps or queried faults in the Kingston Wash area, Shadow Mountains, southern Pahrump Valley, Bird Spring Range, Lucy Gray Mountains and Piute Valley, (3) a lineament indicative of potential fault offset is located in Mesquite Valley, (4) active eolian dunes and sand ramps located on the east side of Mesquite, Ivanpah, and Hidden Valleys adjacent to playas, (4) groundwater discharge deposits in southern Pahrump Valley, Spring Mountains, and Lucy Gray Mountains and (5) debris-flow deposits spanning almost the entire Quaternary period in age.

Open-File Report↗