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1962 Public use of National Wildlife Refuges.
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Occurrence of viable avian influenza viruses in water and bed sediments from selected water bodies along the Atlantic Flyway, February and May 2006 and January 2007
Water and bed-sediment samples were collected from selected water bodies along the Atlantic Flyway and analyzed for the presence of viable avian influenza viruses. Samples were collected during February and May 2006 and January 2007 at U.S. Fish and Wildlife Service National Wildlife Refuges in Georgia, South Carolina, North Carolina, Virginia, and Maryland. Avian influenza viruses were detected in samples collected from the Savannah National Wildlife Refuge in Georgia during February 2006 and from the Santee National Wildlife Refuge in South Carolina and the Pee Dee National Wildlife Refuge in North Carolina during January 2007. Avian influenza virus was detected in water temperatures ranging from 11.8 to 12.7 degrees Celsius when birds were either present or had departed at least 10 days prior to sampling. Although the literature indicates that avian influenza virus persists in the environment more effectively at colder temperature regimes, these detections were made in a comparatively warmer climate at a time of the year when cooler water temperatures prevail.
Reconnaissance investigation of water quality, bottom sediment, and biota associated with irrigation drainage in the Tulare Lake bed area, southern San Joaquin Valley, California, 1986-87
Concentrations of numerous toxic trace elements and pesticides were measured during 1986 in water, sediment, and biota from three areas near the Tulare Lake Bed, southern San Joaquin Valley, California: Kern National Wildlife Refuge, Pixley National Wildlife Refuge, and Westfarmers evaporation ponds about 5 mi west of Kern National Wildlife Refuge, to determine whether toxic constituents in agricultural-irrigation drainage pose a threat to beneficial uses of water, especially to uses by wildlife. Pesticide residues were found to be low at all three areas. Trace element concentrations were found to be comparatively low at the Kern and Pixley National Wildlife Refuge areas and high at the Westfarmers evaporation ponds. Dissolved selenium concentrations were < 1 micrograms/L (ug/L) in areas on and adjacent to the refuges, but ranged from 110 to 360 ug/L in the saline drainwater impounded in the evaporation ponds. The ratio of mean selenium concentrations in biota from Westfarmers ponds compared to biota from Kesterson National Wildlife Refuge (where adverse effects have been documented) is 5 for waterboatman, 2 for avocet liver, 1 for avocet eggs, and < 1 for widgeongrass. The low concentrations measured at Kern and Pixley National Wildlife Refuges suggest that trace elements and pesticides pose little threat to wildlife there; however, impounded subsurface drainage from agricultural irrigation does pose a threat to wildlife at the nearby Westfarmers ponds. Preliminary results of surveys conducted in 1987 indicated that there are adverse biological effects on shorebirds nesting at the ponds, although interpretation of the magnitude of the effects is premature, pending completion of ongoing studies by the U.S. Fish and Wildlife Service. (Author 's abstract)
Retrospective ecotoxicological data and current information needs for terrestrial vertebrates residing in coastal habitat of the United States
The Contaminant Exposure and Effects—Terrestrial Vertebrates (CEE-TV) database was developed to conduct simple searches for ecotoxicological information, examine exposure trends, and identify significant data gaps. The CEE-TV database contains 16,696 data records on free-ranging amphibians, reptiles, birds, and mammals residing in estuarine and coastal habitats of the Atlantic, Gulf, and Pacific coasts, Alaska, Hawaii, and the Great Lakes. Information in the database was derived from over 1800 source documents, representing 483 unique species (about 252,000 individuals), with sample collection dates spanning from 1884 to 2003. The majority of the records contain exposure data (generally contaminant concentrations) on a limited number ( n = 209) of chlorinated and brominated compounds, cholinesterase-inhibiting pesticides, economic poisons, metals, and petroleum hydrocarbons, whereas only 9.3% of the records contain biomarker or bioindicator effects data. Temporal examination of exposure data provides evidence of declining concentrations of certain organochlorine pesticides in some avian species ( e.g. , ospreys, Pandion haliaetus ), and an apparent increase in the detection and possibly the incidence of avian die-offs related to cholinesterase-inhibiting pesticides. To identify spatial data gaps, 11,360 database records with specific sampling locations were combined with the boundaries of coastal watersheds, and National Wildlife Refuge and National Park units. Terrestrial vertebrate ecotoxicological data were lacking in 41.9% of 464 coastal watersheds in the continental United States. Recent (1990–2003) terrestrial vertebrate contaminant exposure or effects data were available for only about half of the National Wildlife Refuge and National Park units in the geographic area encompassed by the database. When these data gaps were overlaid on watersheds exhibiting serious water quality problems and/or high vulnerability to pollution, 72 coastal watersheds, and 76 National Wildlife Refuge and 59 National Park units in the continental United States were found to lack recent terrestrial vertebrate ecotoxicology data. Delineation of data gaps in watersheds of concern can help prioritize monitoring in areas with impaired water quality and emphasize the need for comprehensive monitoring to gain a more complete understanding of coastal ecosystem health.
Vegetation classification for south Florida natural areas
Introduction A critical component of any ecological restoration program is documenting the temporal changes in the spatial extent, pattern, and proportion of plant communities within the landscape. The Comprehensive Everglades Restoration Plan (CERP - www.evergladesplan.org), authorized as part of the Water Resources and Development Act (WRDA) of 2000 (U.S. Congress, 2000), is an $8 billion hydrologic restoration project for all of south Florida. CERP includes 68 separate projects to be managed over the next 30 years by the South Florida Water Management District (SFWMD), the U. S. Army Corp of Engineers (USACE), and other State and Federal agencies. Restoration Coordination and Verification (RECOVER) is a system-wide program of the CERP, designed to organize, manage, and provide the highest quality scientific and technical support during implementation of the restoration program (RECOVER, in prep.). It is the role of RECOVER to develop and implement a system-wide Monitoring and Assessment Plan (MAP) (RECOVER, 2004) and to document how well the CERP is meeting its objectives for ecosystem restoration. One critical component of the MAP is vegetation mapping to document changes in the spatial extent, pattern, and proportion of plant communities within the Everglades landscape. A major aspect of the vegetation mapping project was determining a classification system for labeling vegetation categories utilizing a grid method. The grid method was created specifically for use in the CERP RECOVER vegetation monitoring and assessment project (Rutchey and others, in prep). The CERP RECOVER vegetation mapping project utilizes aerial photography and photointerpretation techniques (with ground truthing) to identify and label vegetation classes. A classification system that had sufficient flexibility and detail to enable the designation of vegetation classes using various remote sensing platforms and identification techniques needed to be developed. The classification system had to be hierarchical, represent distinct ecological communities, individual species, and physical characteristics such as density and height. In addition, it was desirable to have a classification system that allowed exotic species and cattail to be identified using density classes. The classification system was developed specifically for peninsular south Florida and the Florida Keys, from Lake Okeechobee in the north to Key West in the south (Figure 1). Specific areas of interest include Everglades National Park, Big Cypress National Preserve, Biscayne National Park, Florida Panther National Wildlife Refuge, Loxahatchee National Wildlife Refuge, the State of Florida Water Conservation Areas, Holeyland Wildlife Management Area, Rotenberger Wildlife Management Area, J.W. Corbett Wildlife Management Area, Pal-Mar Wildlife Management Area, the Lake Okeechobee Littoral Zones, and additional coastal wetlands of south eastern Miami-Dade County. In addition to being used for mapping of CERP affected areas, the National Park Service-South Florida/Caribbean Network is using the classification for mapping the remaining areas of Everglades National Park and Big Cypress National Preserve outside the CERP footprint, Florida Panther National Wildlife Refuge, Biscayne National Park, and Dry Tortugas National Park.
Selecting habitat management strategies on refuges
This report is a joint effort of the Biological Resources Division, U.S. Geological Survey and the U.S. Fish and Wildlife Service (FWS) to provide National Wildlife Refuge (NWR) managers guidance on the selection and evaluation of habitat management strategies to meet stated objectives. The FWS recently completed a handbook on writing refuge management goals and objectives (U.S. Fish and Wildlife Service 1996a). the National Wildlife Refuge System Improvement Act of 1997 requires that National Wildlife Refuge System (NWRS) lands be managed according to approved Comprehensive Conservation Plans to guide management decisions and devise strategies for achieving refuge unit purposes and meeting the NWRS mission. It is expected that over the next several years most refuges will develop new or revised refuge goals and objectives for directing their habitat management strategies. This paper outlines the steps we recommend in selecting and evaluating habitat management strategies to meet specific refuge habitat objectives. We selected two examples to illustrate the process. Although each refuge is unique and will require specific information and solutions, these two examples can be used as guidance when selecting and evaluating habitat management strategies for other refuge resources: Example 1. Management of floodplain woods habitat for forest interior birds. The biological recourse of concern is the quality and quantity of floodplain woods habitat for eastern forest interior birds in the Cypress Creek NWR (U.S. Fish and Wildlife Service 1996b). Example 2. Management of habitat for biodiversity: Historical landscape proportions. The biological resource of concern is the change in diversity associated with man-induced changes in the distribution and abundance of habitat types at the Minnesota Valley NWR (U.S. Fish and Wildlife Service 1996c).
Introduction
The Arctic National Wildlife Refuge in northeastern Alaska is one of 16 refuges in Alaska and 539 refuges nationwide within the National Wildlife Refuge System administered by the U.S. Fish and Wildlife Service. First established as the Arctic National Wildlife Range in 1960 by Public Land Order 2214, it initially had a three-fold purpose to preserve unique wildlife, wilderness, and recreation values on 8.9 million acres. In 1980, the Arctic National Wildlife Range was expanded to the southwest and renamed the Arctic National Wildlife Refuge (also called the Arctic Refuge in this report) when the U.S. Congress passed the Alaska National Interest Lands Conservation Act (ANILCA), Public Law 96-487 (94 Stat. 2371). This legislation also designated almost all of the original Arctic National Wildlife Range as wilderness, and it directed the Secretary of the Interior to conduct studies evaluating both the biological resources and the potential petroleum reserves of 1.5 million acres (titled the 1002 Area) on the coastal plain of the Arctic Refuge. In April 1982, the Arctic Refuge staff completed a report summarizing the then current state of knowledge on the fish, wildlife, and their habitats present on the coastal plain of the Arctic Refuge (U.S. Fish and Wildlife Service 1982). From 1982 to 1985, field investigations of biological resources of the 1002 Area were carried out by a number of investigators, and annual reports summarized the results (Garner and Reynolds 1983, 1984, 1985, 1986, 1987). These reports and other resources were used to prepare a Department of the Interior report to Congress: Arctic National Wildlife Refuge, Alaska Coastal Plain Resource Assessment - Report and Recommendation to the Congress of the United States and Final Environmental Impact Satement (Clough et al., 1987).
Biology and conservation of the common murre in California, Oregon, Washington, and British Columbia: Vol. 1, Natural history and population trends
Over the past 30 years, the common murre ( Uria aalge californica ) has been recognized as a prominent indicator of marine conservation issues in California, Oregon, Washington, and British Columbia, especially regarding oil pollution, certain fisheries, and human disturbance. To assist the effective management of the common murre and the marine environments in which they live, this summary of available information on the biology and regional status of the common murre has been sponsored by the U.S. Fish and Wildlife Service (Division of Migratory Bird Management). In Volume 1 (Chapter 1), the natural history of the common murre is summarized, drawing heavily on breeding studies from the South Farallon Islands, California, plus a host of detailed breeding studies from the North Atlantic Ocean. Population trends of the common murre are summarized in Volume 1 (Chapter 2), focusing on changes in whole-colony counts determined from aerial photographs between the late 1970s and 1995 in California, Oregon and Washington. Historical data and human impacts to murre colonies since the early nineteenth century are also summarized. Volume 2 will summarize population threats, conservation, and management. Information presented in Volume 1 has been obtained and recorded by a large number of researchers and natural historians over two centuries. From the 1960s to 1995, most work in California, Oregon, and Washington was sponsored by the U.S. Fish and Wildlife Service, Minerals Management Service, and California Department of Fish and Game. Important breeding biology studies were conducted at the South Farallon Islands (Farallon National Wildlife Refuge) by the Point Reyes Bird Observatory, in coordination with the U.S. Fish and Wildlife Service (San Francisco Bay National Wildlife Refuge). Colony surveys in California were conducted mainly by the U.S. Fish and Wildlife Service (San Francisco Bay National Wildlife Refuge), U.S. Geological Survey (Western Ecological Research Center, Dixon Field Station), Humboldt State University, and University of California (Santa Cruz). Colony surveys in Oregon and Washington were conducted mainly by the U.S. Fish and Wildlife Service (Oregon Coast National Wildlife Refuge and Washington Maritime National Wildlife Refuges). In British Columbia, most work from the 1960s to 1995 was sponsored and conducted by the Canadian Wildlife Service and Royal British Columbia Museum.
Final project memorandum: Southeast Climate Adaptation Science Center Project
Low-lying public lands along the northern Gulf of Mexico coast are vulnerable to sea-level rise. Coastal planners and resource managers in the region have requested customized information that can be used to concisely communicate local sea-level rise scenarios and identify potential impacts to the missions of management agencies. In this project, researchers worked with the Northern Gulf of Mexico Sentinel Site Cooperative to develop information sheets outlining potential sea-level rise scenarios for the region through 2100 including their potential impact on the missions of federally-managed lands. Researchers drew from existing information on regional and global sea-level rise scenarios to develop customized information sheets for 54 federally-managed lands in the region (e.g., National Wildlife Refuges, National Park Service lands, National Estuarine Research Reserves) (Chivoiu et al. 2020). This project was developed in response to a request for customized sea-level rise scenario products from partners at the Northern Gulf of Mexico Sentinel Site Cooperative and the U.S. Fish and Wildlife Service’s Gulf Restoration Program. The results of this project support the conservation stewardship missions of the U.S. Fish and Wildlife Service and National Park Service by providing science to inform management of their lands along the Gulf of Mexico.
Identifying suitable sites for Florida panther reintroduction
A major objective of the 1995 Florida Panther ( Puma concolor cory ) Recovery Plan is the establishment of 2 additional panther populations within the historic range. Our goal was to identify prospective sites for Florida panther reintroduction within the historic range based on quantitative landscape assessments. First, we delineated 86 panther home ranges using telemetry data collected from 1981 to 2001 in south Florida to develop a Mahalanobis distance (D 2 ) habitat model, using 4 anthropogenic variables and 3 landscape variables mapped at a 500-m resolution. From that analysis, we identified 9 potential reintroduction sites of sufficient size to support a panther population. We then developed a similar D 2 model at a higher spatial resolution to quantify the area of favorable panther habitat at each site. To address potential for the population to expand, we calculated the amount of favorable habitat adjacent to each prospective reintroduction site within a range of dispersal distances of female panthers. We then added those totals to the contiguous patches to estimate the total amount of effective panther habitat at each site. Finally, we developed an expert-assisted model to rank and incorporate potentially important habitat variables that were not appropriate for our empirical analysis (e.g., area of public lands, livestock density). Anthropogenic factors heavily influenced both the landscape and the expert-assisted models. Of the 9 areas we identified, the Okefenokee National Wildlife Refuge, Ozark National Forest, and Felsenthal National Wildlife Refuge regions had the highest combination of effective habitat area and expert opinion scores. Sensitivity analyses indicated that variability among key model parameters did not affect the high ranking of those sites. Those sites should be considered as starting points for the field evaluation of potential reintroduction sites.
Reconnaissance investigation of water quality, bottom sediment, and biota associated with irrigation drainage in the American Falls Reservoir area, Idaho, 1988-89
Increased concern about the quality of irrigation drainage and its potential effects on human health, fish, and wildlife prompted the Department of the Interior to begin a program during late 1985 to identify irrigation-induced water-quality problems that might exist in the Western States. During `988, the Task Group on Irrigation Drainage selected the American Falls Reservoir area, Idaho, for study to determine whether potentially toxic concentrations of trace elements or organochlorine compounds existed in water, bottom sediment, and biota. The 91-square mile American Falls Reservoir has a total capacity of 1.7 million acre-feet and is used primarily for irrigation-water supply and power generation. Irrigated land upstream from the reservoir totals about 550,000 acres. Total water inflow to the reservoir is about 5.8 million acre-feet per year, of which about 63 percent is from surface-water runoff, 33 percent is from ground-water discharge, and about 4 percent is from ungaged tributaries, canals, ditches, sloughs, and precipitation. Ground-water discharge to the reservoir originates, in part, from irrigation of land upstream from and adjacent to the reservoir. The 1988 water year was a drought year, and water discharge was about 34 percent less than during 1939-88. Water samples were collected during the post-irrigation (October 1987) and irrigation (July 1988) seasons and were analyzed for major ions and trace elements. Bottom-sediment samples were collected during the irrigation season and were analyzed for trace elements and organochlorine compounds. Biota samples were collected during May, June, July, and August 1988 and were analyzed for trace elements and organochlorine compounds. Dissolved-solids concentrations in water ranged from 216 to 561 milligrams per liter. The similarity of dissolved-solids concentrations between the irrigation and post-irrigation seasons can be attributed to the large volume of ground-water discharge in the study area. Most trace-element concentrations in water were near analytical reporting limits; none exceeded State or Federal water-quality standards or criteria. Trace elements that were present at all sites in analytically detectable concentrations (in micrograms per liter) included arsenic (2 to 7), boron (40 to 130), uranium (0.7 to 3.5), vanadium (1 to 6) and zinc (less than 3 to 42). The ranges of arsenic, cadmium, and mercury concentrations in water analyzed during previous investigations. Selenium concentrations ranged from less than 1 (the reporting limit) to 6 micrograms per liter and did not exceed State of Federal water-quality standards or criteria. Concentrations of most trace elements in bottom sediment were similar to geometric mean concentrations in study area soils and were within the expected 95-percent range of concentrations in soils in the Western United States. Mercury concentrations in 9 of the 18 bottom-sediment samples exceeded the 95th-percentile concentration for mercury in area soils. Selenium concentration for selenium in area soils and, in 1 sample, exceeded the upper limit of the expected 95-percent range for selenium in Western United States soils. Most organochlorine compunds in bottom sediment were lower than analytical reporting limits. Only DDE (0.2 micrograms per kilogram) and DDT (0.3 micrograms per kilogram) were detected in bottom sediment from the Portneuf River. Except for mercury and selenium, concentrations of most trace elements in biota were not considered high enough to be harmful to humans or wildlife. Some mercury concentrations in fish exceeded the U.S. Fish and Wildlife Service National Contaminant Biomonitoring Program 85th-percentile concentration and were at levels that might not be safe for human consumption, especially for pregnant women. Elevated mercury concentrations in fish-eating waterbirds, such as double-crested cormorants, indicates biomagnification in the food chain. Selenium concentrations generally were low except in mallard livers (6.6 to 41.8 micrograms per gram, dry weight). This range is within the range of selenium concentrations (19 to 43 micrograms per gram, dry weight) reported in livers of ducks from Kesterson National Wildlife Refuge, California, where waterbird deformities, moralities, and reproductive impairment were observed. Selenium concentrations in mayfly nymphs were at or near dietary concentrations (5 to 8 micrograms per gram, dry weight) that had adverse reproductive effects on mallards during laboratory toxicity studies. p,p'DDE was detected in all waterbird eggs and juvenile mallared carcasses. Highest concentrations were in cormorant eggs (0.59 to 5.70 micrograms per gram, wet weight). p,p'DDE concentrations in four of five cormorant eggs exceeded the National Academy of Sciences, National Academy of Engineering criterion for protection of aquatic wildlife (1 microgram per gram, wet weight, for p,p'DDT and its metabolites). p,p'DDE was detected in all fish samples except rainbow trout. p,p'DDE was detected in one sample of Utah suckers. No concentrations of p,p'DDE or p,p'DDT in fish exceeded the criterion for protection of aquatic life. Total PCB's were detected in all cormorant eggs and all fish samples. PCB's were not detected in other waterbird eggs. PCB concentrations in cormorant eggs (0.28 to 1.8 micro per gram, wet weight) were lower than concentrations that would be expected to cause adverse effects. Two of the three carp samples contained PCB concntrations higher than the recommended level for protection of fish and wildlife (0.4 micrograms per gram, wet weight). Eggshell thinning was noted in cormorant and mallard eggs but was not considered great enough to cause reporductive problems. Observations of the general health of fish and waterbird populations during the study indicated that the area did not appear to have a serious contaminant problem that could be associated with irrigation grainage. No waterbird or fish die-offs were observed, and nesting waterbird populations were noted to be increasing. Selenium concentrations in mallard livers, however, are of concern, as are p,p'DDE residues in cormorant eggs.
Socioeconomic issues for the Bear River Watershed Conservation Land Area Protection Plan
The Bear River Watershed Conservation Area is located in the Bear River Watershed, a vast basin covering fourteen counties across three states. Located in Wyoming, Utah, and Idaho, the watershed spans roughly 7,500 squares miles: 1,500 squares miles in Wyoming; 2,700 squares miles in Idaho; and 3,300 squares miles in Utah (Utah Division of Water Resources, 2004). Three National Wildlife Refuges are currently contained within the boundary of the BRWCA: the Bear River Migratory Bird Refuge in Utah, the Bear Lake National Wildlife Refuge in Idaho, and the Cokeville Meadows National Wildlife Refuge in Wyoming. In 2010, the U.S. Fish and Wildlife Service conducted a Preliminary Project Proposal and identified the Bear River Watershed Conservation Area as having high-value wildlife habitat. This finding initiated the Land Protection Planning process, which is used by the U.S. Fish and Wildlife Service to study land conservation opportunities including adding lands to the National Wildlife Refuge System. The U.S. Fish and Wildlife Service proposes to include part of the Bear River Watershed Conservation Area in the Refuge System by acquiring up to 920,000 acres of conservation easements from willing landowners to maintain landscape integrity and habitat connectivity in the region. The analysis described in this report provides a profile of the social and economic conditions in the Bear River Watershed Conservation Area and addresses social and economic questions and concerns raised during public involvement in the Land Protection Planning process.
Toward conservation of midcontinental shorebird migrations
Shorebirds represent a highly diverse group of species, many of which experience tremendous energy demands associated with long-distance migratory flights. Transcontinental migrants are dependent upon dynamic freshwater wetlands for stopover resources essential for replenishment of lipid reserves and completion of migration. Patterns of shorebird migration across midcontinental wetlands were detected from migration reports to American Birds and information provided by U.S. Fish and Wildlife Service national wildlife refuges. Patterns in species composition and abundance varied geographically, emphasizing the uniqueness of different regions to migrating shorebirds. Smaller species and neotropical migrants moved primarily across the Great Plains, whereas larger species and North American migrants predominated in assemblages in the intermountain west Shorebirds were broadly dispersed in wetland habitats with dynamic water regimes. Whereas populations of shorebirds in coastal systems appear to concentrate at sites of seasonally predictable and abundant food resources, we propose that transcontinental shorebirds disperse and use wetlands opportunistically. This migration system exemplifies the need for large-scale, coordinated regional management efforts that recognize the dynamic nature of ecosystem processes.
Environmental and human influences on trumpeter swan habitat occupancy in Alaska
Approximately 70-80% of the entire population of the Trumpeter Swan (Cygnus huccinator) depends for reproduction on wetlands in Alaska. This makes the identification of important habitat features and the effects of human interactions important for the species' long-term management. We analyzed the swan's habitat preferences in five areas throughout the state and found that swan broods occupied some wetland types, especially larger closed-basin wetlands such as lakes and ponds, at rates much higher than they occupied other wetland types, such as shrubby or forested wetlands. We also found a negative effect of transportation infrastructure on occupancy by broods in and around the Minto Flats State Game Refuge, Kenai National Wildlife Refuge, and Tetlin National Wildlife Refuge. This finding is of particular interest because much of the Minto Flats refuge has recently been licensed for oil and gas exploration and parts of the Kenai refuge have been developed in the past. We also investigated the potential effects of the shrinkage of closed-basin ponds on habitat occupancy by nesting Trumpeter Swans. We compared nesting swans' use of ponds with changes in the ponds' size and other characteristics from 1982 to 1996 and found no relationships between occupancy and changes in pond size. However, we believe that the recent and rapid growth of Trumpeter Swan populations in Alaska may become limited by available breeding habitat, and anthropogenic and climate-induced changes to the swan's breeding habitats have the potential to limit future production. ?? 2009 by The Cooper Ornithological Society. All rights reserved.
Geologic Map of the Pahranagat Range 30' x 60' Quadrangle, Lincoln and Nye Counties, Nevada
Introduction The Pahranagat Range 30' x 60' quadrangle lies within an arid, sparsely populated part of Lincoln and Nye Counties, southeastern Nevada. Much of the area is public land that includes the Desert National Wildlife Range, the Pahranagat National Wildlife Refuge, and the Nellis Air Force Base. The topography, typical of much of the Basin and Range Province, consists of north-south-trending ranges and intervening broad alluvial valleys. Elevations range from about 1,000 to 2,900 m. At the regional scale, the Pahranagat Range quadrangle lies within the Mesozoic and early Tertiary Sevier Fold-and-Thrust Belt and the Cenozoic Basin and Range Province. The quadrangle is underlain by a Proterozoic to Permian miogeoclinal section, a nonmarine clastic and volcanic section of middle Oligocene or older to late Miocene age, and alluvial deposits of late Cenozoic age. The structural features that are exposed reflect relatively shallow crustal deformation. Mesozoic deformation is dominated by thrust faults and asymmetric or open folds. Cenozoic deformation is dominated by faults that dip more than 45i and dominostyle tilted blocks. At least three major tectonic events have affected the area: Mesozoic (Sevier) folding and thrust faulting, pre-middle Oligocene extensional deformation, and late Cenozoic (mainly late Miocene to Holocene) extensional deformation. Continued tectonic activity is expressed in the Pahranagat Range area by seismicity and faults having scarps that cut alluvial deposits.