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At least 1,621 records · Page 90Linked to original sources

Spatial digital database for the tectonic map of southeast Arizona

A spatial database was created for Drewes' (1980) tectonic map of southeast Arizona: this database supercedes Drewes and others (2001, ver. 1.0). Staff and a contractor at the U.S. Geological Survey in Tucson, Arizona completed an interim digital geologic map database for the east part of the map in 2001, made revisions to the previously released digital data for the west part of the map (Drewes and others, 2001, ver. 1.0), merged data files for the east and west parts, and added additional data not previously captured. Digital base map data files (such as topography, roads, towns, rivers and lakes) are not included: they may be obtained from a variety of commercial and government sources. This digital geospatial database is one of many being created by the U.S. Geological Survey as an ongoing effort to provide geologic information in a geographic information system (GIS) for use in spatial analysis. The resulting digital geologic map database can be queried in many ways to produce a variety of geologic maps and derivative products. Because Drewes' (1980) map sheets include additional text and graphics that were not included in this report, scanned images of his maps (i1109_e.jpg, i1109_w.jpg) are included as a courtesy to the reader. This database should not be used or displayed at any scale larger than 1:125,000 (for example, 1:100,000 or 1:24,000). The digital geologic map plot files (i1109_e.pdf and i1109_w.pdf) that are provided herein are representations of the database (see Appendix A). The map area is located in southeastern Arizona (fig. 1). This report describes the map units (from Drewes, 1980), the methods used to convert the geologic map data into a digital format, the ArcInfo GIS file structures and relationships, and explains how to download the digital files from the U.S. Geological Survey public access World Wide Web site on the Internet. The manuscript and digital data review by Helen Kayser (Information Systems Support, Inc.) is greatly appreciated.

Arizona↗

A model of transmissivity and hydraulic conductivity from electrical resistivity distribution derived from airborne electromagnetic surveys of the Mississippi River Valley Alluvial Aquifer, Midwest USA

Groundwater-flow models require the spatial distribution of the hydraulic conductivity parameter. One approach to defining this spatial distribution in groundwater-flow model grids is to map the electrical resistivity distribution by airborne electromagnetic (AEM) survey and establish a petrophysical relation between mean resistivity calculated as a nonlinear function of the resistivity layering and thicknesses of the layers and aquifer transmissivity compiled from historical aquifer tests completed within the AEM survey area. The petrophysical relation is used to transform AEM resistivity to transmissivity and to hydraulic conductivity over areas where the saturated thickness of the aquifer is known. The US Geological Survey applied this approach to a gain better understanding of the aquifer properties of the Mississippi River Valley alluvial aquifer. Alluvial-aquifer transmissivity data, compiled from 160 historical aquifer tests in the Mississippi Alluvial Plain (MAP), were correlated to mean resistivity calculated from 16,816 line-kilometers (km) of inverted resistivity soundings produced from a frequency-domain AEM survey of 95,000 km 2 of the MAP. Correlated data were used to define petrophysical relations between transmissivity and mean resistivity by omitting from the correlations the aquifer-test and AEM sounding data that were separated by distances greater than 1 km and manually calibrating the relation coefficients to slug-test data. The petrophysical relation yielding the minimum residual error between simulated and slug-test data was applied to 2,364 line-km of AEM soundings in the 1,000-km 2 Shellmound (Mississippi) study area to calculate hydraulic property distributions of the alluvial aquifer for use in future groundwater-flow models.

Mississippi River Valley Alluvial Aquifer↗

Assessing state-wide biodiversity in the Florida Gap analysis project

The Florida Gap (FI-Gap) project provides an assessment of the degree to which native animal species and natural communities are or are not represented in existing conservation lands. Those species and communities not adequately represented in areas being managed for native species constitute 'gaps' in the existing network of conservation lands. The United States Geological Survey Gap Analysis Program is a national effort and so, eventually, all 50 states will have completed it. The objective of FI-Gap was to provide broad geographic information on the status of terrestrial vertebrates, butterflies, skippers and ants and their respective habitats to address the loss of biological diversity. To model the distributions and potential habitat of all terrestrial species of mammals, breeding birds, reptiles, amphibians, butterflies, skippers and ants in Florida, natural land cover was mapped to the level of dominant or co-dominant plant species. Land cover was classified from Landsat Thematic Mapper (TM) satellite imagery and auxiliary data such as the national wetlands inventory (NWI), soils maps, aerial imagery, existing land use/land cover maps, and on-the-ground surveys, Wildlife distribution models were produced by identifying suitable habitat for each species within that species' range, Mammalian models also assessed a minimum critical area required for sustainability of the species' population. Wildlife species richness was summarized against land stewardship ranked by an area's mandates for conservation protection. ?? 2002 Elsevier Science Ltd. All rights reserved.

Journal of Environmental Management↗

California State Waters Map Series — Offshore of Point Reyes, California

This publication about the Offshore of Point Reyes map area includes ten map sheets that contain explanatory text, in addition to this descriptive pamphlet and a data catalog of geographic information system (GIS) files. Sheets 1, 2, and 3 combine data from four different sonar surveys to generate comprehensive high-resolution bathymetry and acoustic-backscatter coverage of the map area. These data reveal a range of physiographic features (highlighted in the perspective views on sheet 4) such as the flat, sediment-covered seafloor in Drakes Bay, as well as abundant “scour depressions” on the Bodega Head–Tomales Point shelf (see sheet 9) and local, tectonically controlled bedrock uplifts. To validate geological and biological interpretations of the sonar data shown in sheets 1, 2, and 3, the U.S. Geological Survey towed a camera sled over specific offshore locations, collecting both video and photographic imagery; these “ground-truth” surveying data are summarized on sheet 6. Sheet 5 is a “seafloor character” map, which classifies the seafloor on the basis of depth, slope, rugosity (ruggedness), and backscatter intensity and which is further informed by the ground-truth-survey imagery. Sheet 7 is a map of “potential habitats,” which are delineated on the basis of substrate type, geomorphology, seafloor process, or other attributes that may provide a habitat for a specific species or assemblage of organisms. Sheet 8 compiles representative seismic-reflection profiles from the map area, providing information on the subsurface stratigraphy and structure of the map area. Sheet 9 shows the distribution and thickness of young sediment (deposited over the last about 21,000 years, during the most recent sea-level rise) in both the map area and the larger Salt Point to Drakes Bay region, interpreted on the basis of the seismic-reflection data, and it identifies the Offshore of Point Reyes map area as lying within the Bodega Head–Tomales Point shelf, Point Reyes bar, and Bolinas shelf domains. Sheet 10 is a geologic map that merges onshore geologic mapping (compiled from existing maps by the California Geological Survey) and new offshore geologic mapping that is based on integration of high-resolution bathymetry and backscatter imagery (sheets 1, 2, 3), seafloor-sediment and rock samples (Reid and others, 2006), digital camera and video imagery (sheet 6), and high-resolution seismic-reflection profiles (sheet 8), as well as aerial-photographic interpretation of nearshore areas. The information provided by the map sheets, pamphlet, and data catalog have a broad range of applications. High-resolution bathymetry, acoustic backscatter, ground-truth-surveying imagery, and habitat mapping all contribute to habitat characterization and ecosystem-based management by providing essential data for delineation of marine protected areas and ecosystem restoration. Many of the maps provide high-resolution baselines that will be critical for monitoring environmental change associated with climate change, coastal development, or other forcings. High-resolution bathymetry is a critical component for modeling coastal flooding caused by storms and tsunamis, as well as inundation associated with longer term sea-level rise. Seismic-reflection and bathymetric data help characterize earthquake and tsunami sources, critical for natural-hazard assessments of coastal zones. Information on sediment distribution and thickness is essential to the understanding of local and regional sediment transport, as well as the development of regional sediment-management plans. In addition, siting of any new offshore infrastructure (for example, pipelines, cables, or renewable-energy facilities) will depend on high-resolution mapping. Finally, this mapping will both stimulate and enable new scientific research and also raise public awareness of, and education about, coastal environments and issues.

California↗

Map showing potential metal-mine drainage hazards in Colorado, based on mineral-deposit geology

This map, compiled by the U.S. Geological Survey (USGS) in cooperation with the Colorado Geological Survey (CGS) and the U. S. Bureau of Land Management (BLM), shows potential mine-drainage hazards that may exist in Colorado metal-mining districts, as indicated by the geologic characteristics of the mineral deposits that occur in the respective districts. It was designed to demonstrate how geologic and geochemical information can be used on a regional scale to help assess the potential for mining-related and natural drainage problems in mining districts, unmined mineralized areas, and surrounding watersheds. The map also provides information on the distribution of different mineral deposit types across Colorado. A GIS (Geographic Information System) format was used to integrate geologic, geochemical, water-quality, climate, landuse, and ecological data from diverse sources. Likely mine-drainage signatures were defined for each mining district based on: (1) a review of the geologic characteristics of the mining district, including mineralogy, trace-element content, host-rock lithology, and wallrock alteration, and; (2) results of site specific studies on the geologic controls on mine-drainage composition.

Colorado↗

Catalog of US GeoData

The development of geographic information systems (GIS) is a rapidly growing industry that supports natural resources, studies, land management, environmental analysis, and urban and transporation planning. The increasing use of computers for storing and analyzing earth science information has greatly expanded the demand for digital cartographic and geographic data. Digital cartography involves the collection, storage, processing, analysis, and display of map data with the aid of computers. The U.S. Geological Survey (USGS), the Nation's largest earth science research agency, through its National Mapping Program, has expanded digital cartography operations to include the collection of elevation, planimetric, land use and land cover, and geographic names information in digital form. This digital information is available on 9-track magnetic tapes and, in the case of 1:2,000,000-scale planimetric digital line graph data, in Compact Disc Read Only Memory (CD-ROM) format. Digital information can be used with all types of geographic and land information systems.

General Information Product↗

Geologic map of the Middendorf quadrangle, Chesterfield County, South Carolina

The Middendorf 7.5-minute quadrangle is located entirely within the Carolina Sandhills region of the upper Atlantic Coastal Plain province in Chesterfield County, South Carolina. The Carolina Sandhills, which has been recognized as a separate region for a long time (e.g., McGee, 1890, 1891; Holmes, 1893), extends from central North Carolina across South Carolina to the western border of Georgia along the updip (inland) margin of the Atlantic Coastal Plain province. In Chesterfield County, the Carolina Sandhills form a relatively high plateau that is bounded to the west by Paleozoic metamorphic rocks of the Piedmont province. This plateau is bounded to the east by the east-facing Orangeburg Scarp, which is interpreted as a shoreline formed by wave erosion during a middle Pliocene time of high sea level (Dowsett and Cronin, 1990). Digital Elevation Models (DEMs) of the Middendorf quadrangle derived from lidar point cloud data reveal a landscape incised by creeks and streams. The highest elevation in the Middendorf quadrangle is 596 ft (182 m) on top of a sandhill in the northwest quadrant of the quadrangle, whereas the lowest elevation is 230 ft (70 m) in the floodplain of Big Black Creek on the southern margin of the quadrangle. Most of the landscape is covered by a mantle of unconsolidated sand that is mapped as the Quaternary Pinehurst Formation. At many locations, the unconsolidated sand is <2 m thick and forms a sand sheet of low relief. In areas of higher elevation, however, the unconsolidated sand can be up to 10 m thick and forms subdued hills (degraded dunes) of up to 6 m relief with steeper sides on the east and southeast. Many of these subdued hills (degraded dunes) are present in the area of closed depressions in the southwest corner of the map. Outcrops within the quadrangle are not common, and are limited mostly to a few exposures of sandstone and clay of the Cretaceous Middendorf Formation in a few road cuts, railroad cuts, and borrow pits as well as some slopes and roadside ditches.

South Carolina↗

Swath Bathymetry Surveys of the Monterey Bay Area from Point Ano Nuevo to Moss Landing, San Mateo, Santa Cruz, and Monterey Counties, California

This report describes swath bathymetry and backscatter data acquired by the U.S. Geological Survey on the continental shelf within the Monterey Bay National Marine Sanctuary between Point Año Nuevo and Moss Landing, in San Mateo, Santa Cruz, and Monterey Counties, Calif. The survey was done for the California Seafloor Mapping Program (CSMP) , in field activities S-7-09-MB and S-10-09-MB , by the Western Coastal and Marine Geology (WCMG) Team of the U.S. Geological Survey (USGS). The data were acquired in two separate surveys: (1) between August 13, 2009 and September 3, 2009, personnel from WCMG completed field activity S-7-09-MB, from Point Año Nuevo south to Table Rock, as well as a block west of Soquel Canyon; (2) between October 12 and December 16, 2009, WCMG conducted field activity S-10-09-MB, surveying between Table Rock and Moss Landing.

Data Series↗

Mapping and vessel-based capabilities

U.S. Geological Survey (USGS) scientists from the Florida Integrated Science Center (FISC) conduct scientific investigations of submerged coastal and marine resources using new and existing technologies. Each contributing technique, method, or product adds to our understanding of coastal and marine resources and provides information for resource-management decisionmaking. In support of this mission, the USGS St. Petersburg office maintains a fleet of research vessels used for inland, coastal, and open-water marine surveys and investigations. Each vessel has advantages and limitations related to water depth, carrying capacity, speed, operation in open water, and other functions. These research platforms are staffed by experienced technical and scientific professionals with expertise in marine navigation, geology, geophysics, engineering, biology, and oceanography.

Fact Sheet↗

Gloria mosaic of the deep sea floor off the Atlantic coast of the United States

This mosaic is a GLORIA (Geological LOng Range Inclined Asdic) view of the deep sea floor off the East Coast of the United States. It covers a surveyed region (fig. 1) of 195,000 square miles, an area nearly as large as Texas. The survey is part of a program to map the entire Exclusive Economic Zone (EEZ) of the United States and its island territories (also including Puerto Rico and the Northern Mariana Islands) carried out by the U.S. Geological Survey in cooperation with the British Institute of Oceanographic Sciences (IOS). A detailed atlas of the East Coast data has been published (EEZ-SCAN 87 Scientific Staff, 1991), and, along with this report, provides an overall view of the morphology and texture of the sea floor in the EEZ beyond the Continental Shelf.

New England↗

Gap Analysis Project (GAP) Terrestrial Vertebrate Species Richness Maps for the Conterminous U.S.

The mission of the Gap Analysis Project (GAP) is to support national and regional assessments of the conservation status of vertebrate species and plant communities. This report explains conterminous United States species richness maps created by the U.S. Geological Survey for four major classes in the phylum Chordata: mammals, birds, reptiles, and amphibians. In this work, we focus on terrestrial vertebrate species and the spatial patterns of richness derived from species’ habitat distribution models. We created species’ habitat distribution models for 1,590 species (282 amphibians, 621 birds, 365 mammals, 322 reptiles) and an additional 129 subspecies (2 amphibians, 28 birds, 94 mammals, 5 reptiles) that occur in the conterminous United States. The 1,590 species level models were spatially combined to create the taxa richness maps at a spatial resolution of 30 meters. Based on those maps we identified the maximum species richness for each of the taxa (43 amphibians, 163 birds, 72 mammals, and 54 reptiles) and show variation in richness across the conterminous United States. Because these habitat models remove unsuitable areas within the range of the species, the patterns of richness presented here are different from the coarse-resolution species’ habitat distribution models commonly presented in the literature. These maps provide a new, more spatially refined richness map. In addition, since these models are logically linked to mapped data layers that constitute habitat suitability, this suite of data can provide an intuitive data system for further exploration of biodiversity and implications for change at ecosystem and landscape scales.

Scientific Investigations Report↗

Following the tug of the audience from complex to simplified hazards maps at Cascade Range volcanoes

Volcano-hazard maps are broadly recognized as important tools for forecasting and managing volcanic crises and for disseminating spatial information to authorities and people at risk. As scientists, we might presume that hazards maps can be developed at the time and with the methods of our discretion, yet the co-production of maps with stakeholder groups, who have programmatic needs of their own, can sway the timing, usability, and acceptance of map products. We examine two volcano hazard map-making efforts by staff at the U.S. Geological Survey. During the 1990s and early 2000s scientists developed a series of hazard assessments and maps with detailed zonations for volcanoes in Washington and Oregon. In 2009, the National Park Service expressed the need for simplified versions of the existing hazard maps for a high-profile visitor center exhibit. This request created an opportunity for scientists to rethink the objectives, scope, content, and map representations of hazards. The primary focus of this article is a discussion of processes used by scientists to distill the most critical information within the official parent maps into a series of simplified maps using criteria specified. We contextualize this project with information about development of the parent maps, public response to the simplified hazard maps, the value of user engagement in mapmaking, and with reference to the abundance of guidance available to the next generation of hazard-mapmakers. We argue that simplified versions of maps should be developed in tandem with any hazard maps that contain technical complexities, not as a replacement, but as a mechanism to broaden awareness of hazards. We found that when scientists endeavor to design vivid and easy-to-understand maps, people in many professions find uses for them within their organization’s information products, resulting in extensive distribution.

Washington↗

Magnetic surveys for locating abandoned wells

Abandoned and unrecorded wells may act as conduits for the contamination of groundwater supplies by oil field brines and other pollutants. The casings of abandoned wells eventually develop leaks, which, if not properly plugged, can allow pollutants to reach freshwater aquifers that supply drinking water. Sources of pollutants include brine ponds, landfill sites, agricultural activities, industrial activities, illegal disposal sites, or accidental spills. The problem is particularly acute in regions where there are old petroleum fields or where water wells have been extensively used for agricultural irrigation. Even urban areas can contain wells that were abandoned and concealed during development. Carefully designed ground magnetic or aeromagnetic surveys can be used to locate abandoned wells by mapping the magnetic disturbances or "anomalies" produced by their steel well casings. The U.S. Geological Survey (USGS) can, at the request of other Federal, State, or local agencies, conduct, process, and interpret such surveys, or it can aid in the design and monitoring of contracts for such surveys.

Fact Sheet↗