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Map and database of Quaternary faults and folds in Colombia and its offshore regions

As part of the International Lithosphere Program’s “World Map of Major Active Faults,” the U.S. Geological Survey (USGS) is assisting in the compilation of a series of digital maps of Quaternary faults and folds in Western Hemisphere countries. The maps show the locations, ages, and activity rates of major earthquake-related features such as faults and fault-related folds. They are accompanied by databases that describe these features and document current information on their activity in the Quaternary. Top date, the project has published fault and fold maps for Costa Rica (Montero and others, 1998), Panama (Cowan and others, 1998), Venezuela (Audemard and others, 2000), Bolovia/Chile (Lavenu, and others, 2000), and Argentina (Costa and others, 2000). The project is a key part of the Global Seismic Hazards Assessment Program (ILP Project II-0) for the International Decade for Natural Hazard Disaster Reduction.

Open-File Report↗

Digital recovery, modification, and analysis of Tetra Tech seismic horizon mapping, National Petroleum Reserve Alaska (NPRA), northern Alaska

We have digitized, modified, and analyzed seismic interpretation maps of 12 subsurface stratigraphic horizons spanning portions of the National Petroleum Reserve in Alaska (NPRA). These original maps were prepared by Tetra Tech, Inc., based on about 15,000 miles of seismic data collected from 1974 to 1981. We have also digitized interpreted faults and seismic velocities from Tetra Tech maps. The seismic surfaces were digitized as two-way travel time horizons and converted to depth using Tetra Tech seismic velocities. The depth surfaces were then modified by long-wavelength corrections based on recent USGS seismic re-interpretation along regional seismic lines. We have developed and executed an algorithm to identify and calculate statistics on the area, volume, height, and depth of closed structures based on these seismic horizons. These closure statistics are tabulated and have been used as input to oil and gas assessment calculations for the region. Directories accompanying this report contain basic digitized data, processed data, maps, tabulations of closure statistics, and software relating to this project.

Open-File Report↗

Multibeam mapping of the Los Angeles, California Margin

The Los Angeles, California Margin was mapped using multibeam echosounders during three separate surveys (Figure 1). In 1996, the USGS surveyed the shelf and slope in Santa Monica Bay from Pt. Dume to south of the Palos Verdes Peninsula. The mapping was accomplished using a Kongsberg Simrad EM1000 multibeam sonar system that provided high-quality bathymetry and quantitative backscatter. In 1998, the USGS continued the mapping to the south and surveyed the outer shelf, slope, and proximal basin off Long Beach and Newport using a Kongsberg Simrad EM300 multibeam sonar system. In 1999, the Los Angeles Margin mapping was completed with the surveying of the inner Long Beach shelf from the Palos Verdes Peninsula, south to Newport. This survey used a dual Kongsberg Simrad EM3000D multibeam sonar system. These three surveys were conducted to support USGS projects studying marine pollution and geohazards along the Los Angeles Margin.

California↗

Fifty-year flood-inundation maps for Catacamas, Honduras

After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of the 50-year-flood inundation at 15 municipalities in Honduras were prepared as a tool for agencies involved in reconstruction and planning. This report, which is one in a series of 15, presents maps of areas in the municipality of Catacamas that would be inundated by a 50-year-flood of Rio Catacamas. Geographic Information System (GIS) coverages of the flood inundation are available on a computer in the municipality of Catacamas as part of the Municipal GIS project and on the Internet at the Flood Hazard Mapping Web page (http://mitchnts1.cr.usgs.gov/projects/ floodhazard.html). These coverages allow users to view the flood inundation in much more detail than is possible using the maps in this report. Water-surface elevations for a 50-year-flood on Rio Catacamas at Catacamas were estimated using HEC-RAS, a one-dimensional, steady-flow, step-backwater computer program. The channel and floodplain cross sections used in HEC-RAS were developed from an airborne light-detection-and-ranging (LIDAR) topographic survey of the area. The 50-year-flood discharge for Rio Catacamas at Catacamas, 216 cubic meters per second, was estimated using a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation because there are no long-term stream-gaging stations on the river from which to estimate the discharge. The drainage area and mean annual precipitation estimated for Rio Catacamas at Catacamas are 45.4 square kilometers and 1,773 millimeters, respectively.

Catacamas↗

Fifty-year flood-inundation maps for Choloma, Honduras

After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of the 50-year-flood inundation at 15 municipalities in Honduras were prepared as a tool for agencies involved in reconstruction and planning. This report, which is one in a series of 15, presents maps of areas in the municipality of Choloma that would be inundated by a 50-year flood of Rio Choloma. Geographic Information System (GIS) coverages of the flood inundation are available on a computer in the municipality of Choloma as part of the in the Municipal GIS project and on the Internet at the Flood Hazard Mapping Web page (http://mitchnts1.cr.usgs.gov/projects/floodhazard.html). These coverages allow users to view the flood inundation in much more detail than is possible using the maps in this report. Water-surface elevations for a 50-year-flood on Rio Choloma at Choloma were determined using HEC-RAS, a one-dimensional, steady-flow, step-backwater computer program. The channel and floodplain cross sections used in HEC-RAS were developed from an airborne light detection and ranging (LIDAR) topographic survey of the area. There are no nearby long-term stream-gaging stations on Rio Choloma; therefore, the 50-year-flood discharge for Rio Choloma, 370 cubic meters per second, was estimated using a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation. The drainage area and mean annual precipitation estimated for Rio Choloma at Choloma are 89.5 square kilometers and 2,164 millimeters, respectively.

Choloma↗

Fifty-year flood-inundation maps for Choluteca, Honduras

After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of 50-year-flood inundation at 15 municipalities in Honduras were prepared as a tool for agencies involved in reconstruction and planning. This report, which is one in a series of 15, presents maps of areas in the municipality of Choluteca that would be inundated by 50-year floods on Rio Choluteca and Rio Iztoca. Geographic Information System (GIS) coverages of the flood inundation are available on a computer in the municipality of Choluteca as part of the Municipal GIS project and on the Internet at the Flood Hazard Mapping Web page (http://mitchnts1.cr.usgs.gov/projects/floodhazard.html). These coverages allow users to view the flood inundation in much more detail than is possible using the maps in this report. Water-surface elevations for 50-year-floods on Rio Choluteca and Rio Iztoca at Choluteca were estimated using HEC-RAS, a one-dimensional, steady-flow, step-backwater computer program. The channel and floodplain cross sections used in HEC-RAS were developed from an airborne light-detection-and-ranging (LIDAR) topographic survey of the area. The estimated 50-year-flood discharge for Rio Choluteca at Choluteca is 4,620 cubic meters per second, which is the drainage-area-adjusted weighted-average of two independently estimated 50-year-flood discharges for the gaging station Rio Choluteca en Puente Choluteca. One discharge, 4,913 cubic meters per second, was estimated from a frequency analysis of the 17 years of peak discharge record for the gage, and the other, 2,650 cubic meters per second, was estimated from a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation. The weighted-average of the two discharges at the gage is 4,530 cubic meters per second. The 50-year-flood discharge for the study area reach of Rio Choluteca was estimated by multiplying the weighted discharge at the gage by the ratio of the drainage areas upstream from the two locations. The 50-year-flood discharge for Rio Iztoca, which was estimated from the regression equation, is 430 cubic meters per second.

Choluteca↗

Fifty-year flood-inundation maps for Comayagua, Hondura

After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of the 50-year-flood inundation at 15 municipalities in Honduras were prepared as a tool for agencies involved in reconstruction and planning. This report, which is one in a series of 15, presents maps of areas in the municipality of Comayagua that would be inundated by 50-year floods on Rio Humuya and Rio Majada. Geographic Information System (GIS) coverages of the flood inundation are available on a computer in the municipality of Comayagua as part of the Municipal GIS project and on the Internet at the Flood Hazard Mapping Web page (http://mitchnts1.cr.usgs.gov/projects/floodhazard.html). These coverages allow users to view the flood inundation in much more detail than is possible using the maps in this report. Water-surface elevations for 50-year-floods on Rio Humuya and Rio Majada at Comayagua were estimated using HEC-RAS, a one-dimensional, steady-flow, step-backwater computer program. The channel and floodplain cross sections used in HEC-RAS were developed from an airborne light-detection-and-ranging (LIDAR) topographic survey of the area. The 50-year-flood discharge for Rio Humuya at Comayagua, 1,400 cubic meters per second, was estimated using a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation. The reasonableness of the regression discharge was evaluated by comparing it with drainage-area-adjusted 50-year-flood discharges estimated for three long-term Rio Humuya stream-gaging stations. The drainage-area-adjusted 50-year-flood discharges estimated from the gage records ranged from 946 to 1,365 cubic meters per second. Because the regression equation discharge agrees closely with the high end of the range of discharges estimated from the gaging-station records, it was used for the hydraulic modeling to ensure that the resulting 50-year-flood water-surface elevations would not be underestimated. The 50-year-flood discharge for Rio Majada at Comayagua (230 cubic meters per second) was estimated using the regression equation because there are no long-term gaging-stations on this river from which to estimate the discharge.

Comayagua↗

Fifty-year flood-inundation maps for El Progreso, Honduras

After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of the 50-year-flood inundation at 15 municipalities in Honduras were prepared as a tool for agencies involved in reconstruction and planning. This report, which is one in a series of 15, presents maps of areas in the municipality of El Progreso that would be inundated by a 50-year flood of Rio Pelo. Geographic Information System (GIS) coverages of the flood inundation are available on a computer in the municipality of El Progreso as part of the Municipal GIS project and on the Internet at the Flood Hazard Mapping Web page (http://mitchnts1.cr.usgs.gov/projects/floodhazard.html). These coverages allow users to view the flood inundation in much more detail than is possible using the maps in this report. Water-surface elevations for a 50-year-flood on Rio Pelo at El Progreso were estimated using HEC-RAS, a one-dimensional, steady-flow, step-backwater computer program. The channel and floodplain cross sections used in HEC-RAS were developed from an airborne light-detection-and-ranging (LIDAR) topographic survey of the area. There are no nearby long-term stream-gaging stations on Rio Pelo; therefore, the 50-year-flood discharge for Rio Pelo, 235 cubic meters per second, was estimated using a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation. The drainage area and mean annual precipitation estimated for Rio Pelo at El Progreso are 47.4 square kilometers and 1,920 millimeters, respectively.

El Progreso↗

Fifty-year flood-inundation maps for Juticalpa, Honduras

After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of 50-year-flood inundation at 15 municipalities in Honduras were prepared as a tool for agencies involved in reconstruction and planning. This report, which is one in a series of 15, presents maps of areas in the municipality of Juticalpa that would be inundated by a 50-year flood of Rio Juticalpa. Geographic Information System (GIS) coverages of the flood inundation are available on a computer in the municipality of Juticalpa as part of the Municipal GIS project and on the Internet at the Flood Hazard Mapping Web page (http://mitchnts1.cr.usgs.gov/projects/floodhazard.html). These coverages allow users to view the flood inundation in much more detail than is possible using the maps in this report. Water-surface elevations for a 50-year-flood on Rio Juticalpa at Juticalpa were estimated using HEC-RAS, a one-dimensional, steady-flow, step-backwater computer program. The channel and floodplain cross sections used in HEC-RAS were developed from an airborne light-detection-and-ranging (LIDAR) topographic survey of the area. The estimated 50-year-flood discharge for Rio Juticalpa at Juticalpa, 1,360 cubic meters per second, was computed as the drainage-area-adjusted weighted average of two independently estimated 50-year-flood discharges for the gaging station Rio Juticalpa en El Torito, located about 2 kilometers upstream from Juticalpa. One discharge, 1,551 cubic meters per second, was estimated from a frequency analysis of the 33 years of peak-discharge record for the gage, and the other, 486 cubic meters per second, was estimated from a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation. The weighted-average of the two discharges at the gage is 1,310 cubic meters per second. The 50-year flood discharge for the study area reach of Rio Juticalpa was estimated by multiplying the weighted discharge at the gage by the ratio of the drainage areas upstream from the two locations.

Juticalpa↗

Fifty-year flood-inundation maps for La Ceiba, Honduras

After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of the 50-year-flood inundation at 15 municipalities in Honduras were prepared as a tool for agencies involved in reconstruction and planning. This report, which is one in a series of 15, presents maps of areas in the municipality of La Ceiba that would be inundated by a 50-year-flood of Rio Cangrejal. Geographic Information System (GIS) coverages of the flood inundation are available on a computer in the municipality of La Ceiba as part of the Municipal GIS project and on the Internet at the Flood Hazard Mapping Web page (http://mitchnts1.cr.usgs.gov/projects/floodhazard.html). These coverages allow users to view the flood inundation in much more detail than is possible using the maps in this report. Water-surface elevations for a 50-year-flood discharge of 1,030 cubic meters per second on Rio Cangrejal at La Ceiba were computed using HEC-RAS, a one-dimensional, steady-flow, step-backwater computer program. The channel and floodplain cross sections used in HEC-RAS were developed from an airborne light-detection-and-ranging (LIDAR) topographic survey of the area. There are no nearby long-term stream-gaging stations on Rio Cangrejal; therefore, the 50-year-flood discharge for Rio Cangrejal at La Ceiba was estimated using a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation. The drainage area and mean annual precipitation estimated for Rio Cangrejal at La Ceiba are 498 square kilometers and 2,306 millimeters, respectively.

La Ceiba↗

Fifty-year flood-inundation maps for Nacaome, Honduras

After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of 50-year-flood inundation at 15 municipalities in Honduras were prepared as a tool for agencies involved in reconstruction and planning. This report, which is one in a series of 15, presents maps of areas in the municipality of Nacaome that would be inundated by 50-year floods on Rio Nacaome, Rio Grande, and Rio Guacirope. Geographic Information System (GIS) coverages of the flood inundation are available on a computer in the municipality of Nacaome as part of the Municipal GIS project and on the Internet at the Flood Hazard Mapping Web page (http://mitchnts1.cr.usgs.gov/projects/floodhazard.html). These coverages allow users to view the flood inundation in much more detail than is possible using the maps in this report. Water-surface elevations for 50-year-floods on Rio Nacaome, Rio Grande, and Rio Guacirope at Nacaome were computed using HEC-RAS, a one-dimensional, steady-flow, step-backwater computer program. The channel and floodplain cross sections used in HEC-RAS were developed from an airborne light-detection-and-ranging (LIDAR) topographic survey of the area and ground surveys at two bridges. The estimated 50-year-flood discharge for Rio Nacaome at Nacaome, 5,040 cubic meters per second, was computed as the drainage-area-adjusted weighted average of two independently estimated 50-year-flood discharges for the gaging station Rio Nacaome en Las Mercedes, located about 13 kilometers upstream from Nacaome. One of the discharges, 4,549 cubic meters per second, was estimated from a frequency analysis of the 16 years of peak-discharge record for the gage, and the other, 1,922 cubic meters per second, was estimated from a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation. The weighted-average of the two discharges is 3,770 cubic meters per second. The 50-year-flood discharges for Rio Grande, 3,890 cubic meters per second, and Rio Guacirope, 1,080 cubic meters per second, were also computed by adjusting the weighted-average 50-year-flood discharge for the Rio Nacaome en Las Mercedes gaging station for the difference in drainage areas between the gage and these river reaches.

Nacaome↗

Fifty-year flood-inundation maps for Olanchito, Honduras

After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of the 50-year-flood inundation at 15 municipalities in Honduras were prepared as a tool for agencies involved in reconstruction and planning. This report, which is one in a series of 15, presents maps of areas in the municipality of Olanchito that would be inundated by a 50-year-flood of Rio Uchapa. Geographic Information System (GIS) coverages of the flood inundation are available on a computer in the municipality of Olanchito as part of the Municipal GIS project and on the Internet at the Flood Hazard Mapping Web page (http://mitchnts1.cr.usgs.gov/projects/floodhazard.html). These coverages allow users to view the flood inundation in much more detail than is possible using the maps in this report. Water-surface elevations for a 50-year-flood discharge of 243 cubic meters per second on Rio Uchapa at Olanchito were estimated using HEC-RAS, a one-dimensional, steady-flow, step-backwater computer program. The channel and floodplain cross sections used in HEC-RAS were developed from an airborne light-detection-and-ranging (LIDAR) topographic survey of the area. There are no nearby long-term stream-gaging stations on Rio Uchapa; therefore, the 50-year-flood discharge for Rio Uchapa was estimated using a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation. The drainage area and mean annual precipitation estimated for Rio Uchapa at Olanchito are 97.1 square kilometers and 1,178 millimeters, respectively.

Olanchito↗

Fifty-year flood-inundation maps for Siguatepeque, Honduras

After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of the 50-year-flood inundation at 15 municipalities in Honduras were prepared as a tool for agencies involved in reconstruction and planning. This report, which is one in a series of 15, presents maps of areas in the municipality of Siguatepeque that would be inundated by 50-year floods on Rio Selguapa, Rio Guique, Rio Celan, Rio Calan, and Quebrada Chalantuma. Geographic Information System (GIS) coverages of the flood inundation are available on a computer in the municipality of Siguatepeque as part of the Municipal GIS project and on the Internet at the Flood Hazard Mapping Web page (http://mitchnts1.cr.usgs.gov/projects/floodhazard.html). These coverages allow users to view the flood inundation in much more detail than is possible using the maps in this report. Water-surface elevations for 50-year-floods on each of the streams studied were computed using HEC-RAS, a one-dimensional, steady-flow, step-backwater computer program. The channel and floodplain cross sections used in HEC-RAS were developed from an airborne light-detection-and-ranging (LIDAR) topographic survey of the area and ground surveys at six bridges. There are no nearby long-term stream-gaging stations on any of the streams studied; therefore, the 50-year-flood discharges were estimated using a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation. The 50-year-flood discharges estimated for Rio Selguapa, Rio Guique, Rio Celan, Rio Calan, and Quebrada Chalantuma are 323, 168, 161, 146, and 90 cubic meters per second, respectively.

Siguatepeque↗

Fifty-year flood-inundation maps for Sonaguera, Honduras

After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of the 50-year-flood inundation at 15 municipalities in Honduras were prepared as a tool for agencies involved in reconstruction and planning. This report, which is one in a series of 15, presents maps of areas in the municipality of Sonaguera that would be inundated by a 50-year flood of Rio Sonaguera and its tributary, Rio Juan Lazaro. Geographic Information System (GIS) coverages of the flood inundation are available on a computer in the municipality of Sonaguera as part of the Municipal GIS project and on the Internet at the Flood Hazard Mapping Web page (http://mitchnts1.cr.usgs.gov/projects/floodhazard.html). These coverages allow users to view the flood inundation in much more detail than is possible using the maps in this report. Water-surface elevations for an estimated 50-year-flood on Rio Sonaguera and Rio Juan Lazaro at Sonaguera were determined using HEC-RAS, a one-dimensional, steady-flow, step-backwater computer program. The channel and floodplain cross sections used in HEC-RAS were developed from an airborne light-detection-and-ranging (LIDAR) topographic survey of the area and a ground survey at the bridge. There are no nearby long-term stream-gaging stations on Rio Sonaguera or Rio Juan Lazaro; therefore, the 50-year-flood discharge for Rio Sonaguera above the confluence with Rio Juan Lazaro, 194 cubic meters per second; for Rio Juan Lazaro at its mouth, 168 cubic meters per second, and for Rio Sonaguera at the downstream end of the study area, 282 cubic meters per second; were estimated using a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation.

Sonaguera↗

Fifty-year flood-inundation maps for Tegucigalpa, Honduras

After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of the 50-year-flood inundation at 15 municipalities in Honduras were prepared as a tool for agencies involved in reconstruction and planning. This report, which is one in a series of 15, presents maps of areas in the municipality of Tegucigalpa that would be inundated by a 50-year flood of Rio Choluteca, Rio Grande, Rio Guacerique, and Rio Chiquito. Geographic Information System (GIS) coverages of the flood inundation are available on a computer in the municipality of Tegucigalpa as part of the Municipal GIS project and on the Internet at the Flood Hazard Mapping Web page (http://mitchnts1.cr.usgs.gov/projects/floodhazard.html). These coverages allow users to view the flood inundation in much more detail than is possible using the maps in this report. Water-surface elevations for an estimated 50-year-flood on Rio Choluteca, Rio Grande, Rio Guacerique, and Rio Chiquito at Tegucigalpa were determined using HEC-RAS, a one-dimensional, steady-flow, step-backwater computer program. The channel and floodplain cross sections used in HEC-RAS were developed from an airborne light-detection-and-ranging (LIDAR) topographic survey of the area and ground surveys at bridges. There are no nearby long-term stream-gaging stations; therefore, the 50-year-flood discharges were estimated using a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation. The estimated 50-year-flood discharge is 922 cubic meters per second at Rio Choluteca at downstream end of the study area boundary, 663 cubic meters per second at the mouth of the Rio Grande, 475 cubic meters per second at the mouth of the Rio Guacerique, and 254 cubic meters per second at the mouth of the Rio Chiquito.

Tegucigalpa↗

Fifty-year flood-inundation maps for Tocoa, Honduras

After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of the 50-year-flood inundation at 15 municipalities in Honduras were prepared as a tool for agencies involved in reconstruction and planning. This report, which is one in a series of 15, presents maps of areas in the municipality of Tocoa that would be inundated by a 50-year flood of Rio Tocoa. Geographic Information System (GIS) coverages of the flood inundation are available on a computer in the municipality of Tocoa as part of the Municipal GIS project and on the Internet at the Flood Hazard Mapping Web page (http://mitchnts1.cr.usgs.gov/projects/floodhazard.html). These coverages allow users to view the flood inundation in much more detail than is possible using the maps in this report. Water-surface elevations for an estimated 50-year-flood on Rio Tocoa at Tocoa were estimated using HEC-RAS, a one-dimensional, steady-flow, step-backwater computer program. The channel and floodplain cross sections used in HEC-RAS were developed from an airborne light-detection-and-ranging (LIDAR) topographic survey of the area and a ground survey at one bridge. There are no nearby long-term stream-gaging stations on Rio Tocoa; therefore, the 50-year-flood discharge for Rio Tocoa, 552 cubic meters per second, was estimated using a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation. The drainage area and mean annual precipitation estimated for Rio Tocoa at Tocoa are 204 square kilometers and 1,987 millimeters, respectively. It was assumed that a portion of the 50-year flood, 200 cubic meters per second, would escape the main channel and flow down a side channel before re-entering the main channel again near the lower end of the study area.

Tocoa↗

U.S. Geological Survey 2002 petroleum resource assessment of the National Petroleum Reserve in Alaska (NPRA): GIS play maps

This report provides digital GIS files of maps for each of the 24 plays evaluated in the U.S. Geological Survey (USGS) 2002 petroleum resource assessment of the NPRA (Bird and Houseknecht, 2002a). These are the same maps released in pdf format by Bird and Houseknecht (2002b). The USGS released in 2002 a summary of the estimated volume of technically recoverable, undiscovered oil and nonassociated gas resources for 24 plays in NPRA (Bird and Houseknecht, 2002b). The NPRA assessment study area includes Federal and Native onshore land and adjacent State offshore areas. A map showing the areal extent of each play was prepared by USGS geologists as a preliminary step in the assessment process. Boundaries were drawn on the basis of a variety of information, including seismic reflection data, results of previous exploration drilling, and regional patterns of rock properties. Play boundary polygons were captured by digitizing the play maps prepared by USGS geologists. Federal, Native, and State areas were later clipped from the play boundary polygons, allowing for acreages to be calculated for entire plays and for various subareas within plays.

Alaska↗

Surficial Geologic Map of the Great Smoky Mountains National Park Region, Tennessee and North Carolina

The Surficial Geology of the Great Smoky Mountains National Park Region, Tennessee and North Carolina was mapped from 1993 to 2003 under a cooperative agreement between the U.S. Geological Survey (USGS) and the National Park Service (NPS). This 1:100,000-scale digital geologic map was compiled from 2002 to 2003 from unpublished field investigations maps at 1:24,000-scale. The preliminary surficial geologic data and map support cooperative investigations with NPS, the U.S. Natural Resource Conservation Service, and the All Taxa Biodiversity Inventory (http://www.dlia.org/) (Southworth, 2001). Although the focus of our work was within the Park, the geology of the surrounding area is provided for regional context. Surficial deposits document the most recent part of the geologic history of this part of the western Blue Ridge and eastern Tennessee Valley of the Valley and Ridge of the Southern Appalachians. Additionally, there is great variety of surficial materials, which directly affect the different types of soil and associated flora and fauna. The surficial deposits accumulated over tens of millions of years under varied climatic conditions during the Cenozoic era and resulted from a composite of geologic processes.

North Carolina, Tennessee↗