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At least 163 records · Page 9Linked to original sources
USGS2008

Preliminary Image Map of the 2007 Ranch Fire Perimeter, Cobblestone Mountain Quadrangle, Los Angeles and Ventura Counties, California

In the fall of 2007, wildfires burned out of control in southern California. The extent of these fires encompassed large geographic areas that included a variety of landscapes from urban to wilderness. The U.S. Geological Survey National Geospatial Technical Operations Center (NGTOC) is currently (2008) developing a quadrangle-based 1:24,000-scale image map product. One of the concepts behind the image map product is to provide an updated map in electronic format to assist with emergency response. This image map is one of 55 preliminary image map quadrangles covering the areas burned by the southern California wildfires. Each map is a layered, geo-registered Portable Document Format (.pdf) file. For more information about the layered geo-registered .pdf, see the readme file (http://pubs.usgs.gov/of/2008/1029/downloads/CA_Agua_Dulce_of2008-1029_README.txt). To view the areas affected and the quadrangles mapped in this preliminary project, see the map index (http://pubs.usgs.gov/of/2008/1029/downloads/CA_of2008_1029-1083_index.pdf) provided with this report.

Open-File Report↗
USGS2017

Geologic field-trip guide to Mount Shasta Volcano, northern California

The southern part of the Cascades Arc formed in two distinct, extended periods of activity: “High Cascades” volcanoes erupted during about the past 6 million years and were built on a wider platform of Tertiary volcanoes and shallow plutons as old as about 30 Ma, generally called the “Western Cascades.” For the most part, the Shasta segment (for example, Hildreth, 2007; segment 4 of Guffanti and Weaver, 1988) of the arc forms a distinct, fairly narrow axis of short-lived small- to moderate-sized High Cascades volcanoes that erupted lavas, mainly of basaltic-andesite or low-silica-andesite compositions. Western Cascades rocks crop out only sparsely in the Shasta segment; almost all of the following descriptions are of High Cascades features except for a few unusual localities where older, Western Cascades rocks are exposed to view along the route of the field trip. The High Cascades arc axis in this segment of the arc is mainly a relatively narrow band of either monogenetic or short-lived shield volcanoes. The belt generally averages about 15 km wide and traverses the length of the Shasta segment, roughly 100 km between about the Klamath River drainage on the north, near the Oregon-California border, and the McCloud River drainage on the south (fig. 1). Superposed across this axis are two major long-lived stratovolcanoes and the large rear-arc Medicine Lake volcano. One of the stratovolcanoes, the Rainbow Mountain volcano of about 1.5–0.8 Ma, straddles the arc near the midpoint of the Shasta segment. The other, Mount Shasta itself, which ranges from about 700 ka to 0 ka, lies distinctly west of the High Cascades axis. It is notable that Mount Shasta and Medicine Lake volcanoes, although volcanologically and petrologically quite different, span about the same range of ages and bracket the High Cascades axis on the west and east, respectively. The field trip begins near the southern end of the Shasta segment, where the Lassen Volcanic Center field trip leaves off, in a field of high-alumina olivine tholeiite lavas (HAOTs, referred to elsewhere in this guide as low-potassium olivine tholeiites, LKOTs). It proceeds around the southern, western, and northern flanks of Mount Shasta and onto a part of the arc axis. The stops feature elements of the Mount Shasta area in an approximately chronological order, from oldest to youngest.

California↗
USGS2003

Phanerozoic strike-slip faulting in the continental interior platform of the United States: examples from the Laramide Orogen, Midcontinent, and Ancestral Rocky Mountains

The continental interior platform of the United States is that part of the North American craton where a thin veneer of Phanerozoic strata covers Precambrian crystalline basement. N- to NE-trending and W- to NW-trending fault zones, formed initially by Proterozoic/Cambrian rifting, break the crust of the platform into rectilinear blocks. These zones were reactivated during the Phanerozoic, most notably in the late Palaeozoic Ancestral Rockies event and the Mesozoic-Cenozoic Laramide orogeny — some remain active today. Dip-slip reactivation can be readily recognized in cross section by offset stratigraphic horizons and monoclinal fault-propagation folds. Strike-slip displacement is hard to document because of poor exposure. Though offset palaeochannels, horizontal slip lineations, and strain at fault bends locally demonstrate strike-slip offset, most reports of strike-slip movements for interior-platform faults are based on occurrence of map-view belts of en echelon faults and anticlines. Each belt overlies a basement-penetrating master fault, which typically splays upwards into a flower structure. In general, both strike-slip and dip-slip components of displacement occur in the same fault zone, so some belts of en echelon structures occur on the flanks of monoclinal folds. Thus, strike-slip displacement represents the lateral component of oblique fault reactivation; dip-slip and strike-slip components are the same order of magnitude (tens of metres to tens of kilometres). Effectively, faults with strike-slip components of displacement act as transfers accommodating jostling of rectilinear crustal blocks. In this context, the sense of slip on an individual strike-slip fault depends on block geometry, not necessarily on the trajectory of regional σ 1 . Strike-slip faulting in the North American interior differs markedly from that of southern and central Eurasia, possibly because of a contrast in lithosphere strength. Weak Eurasia strained significantly during the Alpine-Himalayan collision, forcing crustal blocks to undergo significant lateral escape. The strong North American craton strained relatively little during collisional-convergent orogeny, so crustal blocks underwent relatively small displacements.

Geological Society Special Publication↗
USGS2010

Clockwise rotation and implications for northward drift of the western Transverse Ranges from paleomagnetism of the Piuma Member, Sespe Formation, near Malibu, California

New paleomagnetic results from mid-Tertiary sedimentary beds in the Santa Monica Mountains reinforce the evidence for large-scale rotation of the western Transverse Ranges, and anisotropy measurements indicate that compaction-induced inclination flattening may resolve a long-standing controversy regarding the original paleolatitude of the rotated block. Previously published paleomagnetic data indicate that post-Oligocene rotation amounts to 70°–110° clockwise, affecting the Channel Islands, Santa Monica Mountains, and Santa Ynez Mountains. The Sespe Formation near Malibu consists of a lower member dominated by nonmarine sandstone and conglomerate and an upper section, the Piuma Member, which consists of gray-red sandstone and mudstone interbedded with minor tuff and limestone beds. The Piuma Member has a paleomagnetic pole at 36.6°N, 326.7°E (A 95min = 5.0°, A 95max = 9.6°), obtained by thermal demagnetization of 34 oriented cores from Oligocene and early Miocene beds. After correcting for plunge of the geologic structure, the data are consistent with significant clockwise rotation (77° ± 7°) of the region relative to stable North America. Rotation of the western Transverse Ranges is generally viewed as a consequence of Pacific–North American plate interactions after 28 Ma, when east–west subduction gave way to northwest transform motion in southern California. Inclinations from the Piuma study indicate a paleolatitude anomaly of 11° ± 7° and are consistent with a mean northward drift that exceeds generally accepted San Andreas fault displacement by a factor of 3. However, sedimentary inclination error may accentuate the anomaly. Anisotropy of isothermal remanent magnetization indicates inclination flattening of approximately 8°, and correction for the effect reduces the paleolatitude anomaly to 5.3° ± 5.8°. Compaction may explain the inclination flattening in these sedimentary rocks, but the process does not adequately explain lower-than-expected inclinations found in previous studies of Miocene volcanic rocks of the western Transverse Ranges.

Geochemistry, Geophysics, Geosystems↗
USGS2002

Physical data of soil profiles formed on late Quaternary marine terraces near Santa Cruz, California

The marine terraces in and around Santa Cruz, California, represent a set of well-preserved terraces formed as a product of geology, sea level, and climate. A marine terrace begins as a wave cut platform. Eustatic sea level changes, seacliff erosion, and tectonic uplift work together to generate marine terraces. "When a wave-cut platform is raised (due to tectonic activity) above sea level and cliffed by wave action it becomes a marine terrace" (Bradley, 1957, p. 424). During glacial periods, eustatic sea level is estimated to have dropped by 150 meters (Fairbanks, 1989). Cliff retreat measured from aerial photographs between 1930 and 1980 vary from 0.0 to 0.2 m yr–1 (Best and Griggs, 1991). Estimates of uplift rates along the Santa Cruz coastline vary from 0.10 to 0.48 m kyr–1 (Bradley and Griggs, 1976; Weber and others, 1999). Uplift mechanisms include coseismic uplift associated both with a reverse component of slip on the steeply SW dipping Loma Prieta fault in the restraining bend of the San Andreas Fault and a small component of reverse slip on the steeply SE dipping San Gregorio fault (Anderson and Menking 1994). Previous work studying physical properties on these terraces include Pinney and others (in press) and Aniku (1986) and Bowman and Estrada (1980). Sedimentary deposits of the marine terraces are a mixture of terrestrial and marine sediments but generally consist of a sheet of marine deposits overlying the old platform and a wedge of nonmarine deposits banked against the old sea cliff (Bradley, 1957). Bedrock underlying the terraces in the Santa Cruz area is generally either Santa Margarita Sandstone or Santa Cruz Mudstone. The Santa Margarita Sandstone represents an upper Miocene, transgressive, tidally dominated marine-shelf deposit with crossbedded sets of sand and gravel and horizontally stratified and bioturbated invertebrate-fossils beds (Phillips, 1990). The siliceous Santa Cruz Mudstone, of late Miocene age, conformably overlies the Santa Margarita Sandstone. The Santa Cruz Mudstone is a thin to medium-bedded siliceous mudstone with nonsiliceous mudstone and siltstone and minor amounts of sandstone. The siliceous nature implies organic deposition in a quiescent, deep-water environment. Bedrock is mantled by 1–4 meters of medium to coarse-grained regressive beach sediment and fluvial deposits from the Ben Lomond Mountains. Terrace age increases with elevation above sea level, and weathering of primary minerals increases with age. The suite of soils formed on the terraces is referred to as a soil chronosequence. Soil chronosequences, important tools in characterizing natural weathering rates, are defined as a group of soils that differ in age and therefore in duration of weathering but have similar climatic conditions, vegetation, geomorphic position, and parent material (Jenny, 1941; Birkland, 1999). Soils are frequently useful indicators of geomorphic age (Muhs, 1982; Switzer and others, 1988) and are a function of pedogenic and/or eolian processes. Some aspects of soil development can be episodic but when viewed on large time scales can be perceived as continuous (Switzer and others, 1988). The age of the soil may be constrained by the age of the deposit, since soil formation generally commences when deposition has ceased (Birkland, 1999). Dating of the terraces provides an unprecedented opportunity to study weathering and soil-formation rates (Perg and others, 2001; Hanks and others, 1984; Bradley and Griggs, 1976; Bradley and Addicott, 1968; Bradley, 1956). Ages of the terraces recently dated by cosmogenic radionuclide are, starting with the youngest, 65, 92, 137, 139, and 226 k.y. (Perg and others, 2001). However, these ages are much younger than recent radiometric dates on mollusk shells (Muhs, U.S. Geological Survey, personal communication, 2002; Bradley and Addicott, 1968). For this study, soils were sampled on five terraces. Terrace one in the Lighthouse Field along Westcliff in Santa Cruz was the last site selected, and this report contains minimal data on this terrace. Sites on the second, third, and fourth terraces are located in Wilder Ranch, Santa Cruz, California. Site five is on private property north of Wilder Ranch. Careful consideration was taken in selecting field sites, choosing locations in a topographically flat area to avoid effects of erosion, and trying to keep parent material similar. This report contains physical properties of the soil profiles on four of the five marine terraces near Santa Cruz, California, excluding the youngest terrace in all tables except 6 and 7. Data includes field descriptions, bulk density, grain size analyses, weight percent magnetic fraction, and the soil development index. Soil properties are important when trying to understand the chemistry of a given profile or when comparing profiles. Grain size constrains the movement of water in a profile, thus controlling movement of chemicals and weathering rates. Bulk density is a useful property to calculate chemical inventory. Quantifying the magnetic fraction aids in understanding the Fe inventory for these soils. The soil development index is a semi-quantitative way to define the degree of development of a soil profile. This is a useful way to compare development of profiles for this chronosequence or compare the Santa Cruz terraces to a suit of other terraces or another chronosequence.

California↗
USGS2024

Rayleigh step-selection functions and connections to continuous-time mechanistic movement models

Background The process known as ecological diffusion emerges from a first principles view of animal movement, but ecological diffusion and other partial differential equation models can be difficult to fit to data. Step-selection functions (SSFs), on the other hand, have emerged as powerful practical tools for ecologists studying the movement and habitat selection of animals. Methods SSFs typically involve comparing resources between a set of used and available points at each step in a sequence of observed positions. We use change of variables to show that ecological diffusion implies certain distributions for available steps that are more flexible than others commonly used. We then demonstrate advantages of these distributions with SSF models fit to data collected for a mountain lion in Colorado, USA. Results We show that connections between ecological diffusion and SSFs imply a Rayleigh step-length distribution and uniform turning angle distribution, which can accommodate data collected at irregular time intervals. The results of fitting an SSF model with these distributions compared to a set of commonly used distributions revealed how precision and inference can vary between the two approaches. Conclusions Our new continuous-time step-length distribution can be integrated into various forms of SSFs, making them applicable to data sets with irregular time intervals between successive animal locations.

Movement Ecology↗
USGS2006

Inversion of Gravity Data to Define the Pre-Cenozoic Surface and Regional Structures Possibly Influencing Groundwater Flow in the Rainier Mesa Region, Nye County, Nevada

A three-dimensional inversion of gravity data from the Rainier Mesa area and surrounding regions reveals a topographically complex pre-Cenozoic basement surface. This model of the depth to pre-Cenozoic basement rocks is intended for use in a 3D hydrogeologic model being constructed for the Rainier Mesa area. Prior to this study, our knowledge of the depth to pre-Cenozoic basement rocks was based on a regional model, applicable to general studies of the greater Nevada Test Site area but inappropriate for higher resolution modeling of ground-water flow across the Rainier Mesa area. The new model incorporates several changes that lead to significant improvements over the previous regional view. First, the addition of constraining wells, encountering old volcanic rocks lying above but near pre-Cenozoic basement, prevents modeled basement from being too shallow. Second, an extensive literature and well data search has led to an increased understanding of the change of rock density with depth in the vicinity of Rainier Mesa. The third, and most important change, relates to the application of several depth-density relationships in the study area instead of a single generalized relationship, thereby improving the overall model fit. In general, the pre-Cenozoic basement surface deepens in the western part of the study area, delineating collapses within the Silent Canyon and Timber Mountain caldera complexes, and shallows in the east in the Eleana Range and Yucca Flat regions, where basement crops out. In the Rainier Mesa study area, basement is generally shallow (< 1 km). The new model identifies previously unrecognized structures within the pre-Cenozoic basement that may influence ground-water flow, such as a shallow basement ridge related to an inferred fault extending northward from Rainier Mesa into Kawich Valley.

Open-File Report↗
USGS2014

Geologic and geophysical maps of the eastern three-fourths of the Cambria 30' x 60' quadrangle, central California Coast Ranges

The Cambria 30´ x 60´ quadrangle comprises southwestern Monterey County and northwestern San Luis Obispo County. The land area includes rugged mountains of the Santa Lucia Range extending from the northwest to the southeast part of the map; the southern part of the Big Sur coast in the northwest; broad marine terraces along the southwest coast; and broadvalleys, rolling hills, and modest mountains in the northeast. This report contains geologic, gravity anomaly, and aeromagnetic anomaly maps of the eastern three-fourths of the 1:100,000-scale Cambria quadrangle and the associated geologic and geophysical databases (ArcMap databases), as well as complete descriptions of the geologic map units and the structural relations in the mapped area. A cross section is based on both the geologic map and potential-field geophysical data. The maps are presented as an interactive, multilayer PDF, rather than more traditional pre-formatted map-sheet PDFs. Various geologic, geophysical, paleontological, and base map elements are placed on separate layers, which allows the user to combine elements interactively to create map views beyond the traditional map sheets. Four traditional map sheets (geologic map, gravity map, aeromagnetic map, paleontological locality map) are easily compiled by choosing the associated data layers or by choosing the desired map under Bookmarks.

California↗
USGS2009

The Shawangunk and Martinsburg Formations revisited; sedimentology, stratigraphy, mineralogy, geochemistry, structure and paleontology

In southeastern New York Middle Silurian Shawangunk Formation (Figure 1), containing gray conglomerate, sandstone and shale, lies unconformably above the Ordovician Martinsburg Formation, consisting of shales and graywackes. In southwestern New York, near the Port Jervis area, The Shawangunk Formation is overlain by the Bloomsburg Red Beds, the same stratigraphic sequence that occurs in Pennsylvania and New Jersey to the southwest. The Shawangunk Formation thins gradually from Port Jervis to its pinchout near Hidden Valley and Binnewater, New York. Two tongues of the upper part of the Shawangunk are: the Ellenville Tongue that extends from the Ellenville-Accord area to its feather edge just southwest of the New York-New Jersey border and, the High View Tongue that is restricted to the Wurtsboro area (Epstein and Lyttle, 1987; Epstein, 1993). Early in the Paleozoic carbonate banks lay along the east coast of the ancient North American continent. During the Ordovician plate convergence commenced in the closing of the Iapetus Sea and a deep basin developed into which thick muds and dirty sands were deposited. These were later lithified into the Martinsburg Formation. Eventually, with continued compression, these sediments were folded and faulted during the complex deformation of the Taconic Orogeny. The trend of these folds in southeastern New York is approximately N20E. As one proceeds westward across the Wallkill Valley these structures become less intense. Subsequent to the Taconic Orogeny mountains rose to the east and coarse sediments were transported westward and deposited as the conglomerates and sandstones of the Shawangunk Formation across the beveled folds of the Martinsburg. Deposition occurred on a plain of alluviation and in a marine basin to the northwest. Erosion of the source area was intense, and the climate, based on the mineralogy of the rocks, was warm and at least semiarid. The source was composed predominately of sedimentary and low-grade metamorphic rocks with exceptionally abundant quartz veins and small local areas of gneiss and granite. As the source highlands were eroded, the steep braided streams of the Shawangunk gave way to more gentle-gradient streams of the Bloomsburg Red Beds.

New York, Pennsylvania↗
USGS2015

The Snowmastodon Project: A view of the Last Interglacial Period from high in the Colorado Rockies

In North America, terrestrial records of biodiversity and climate change that span the Last Interglacial Period [or Marine Oxygen Isotope Stage (MIS) 5] are rare. In 2010-11, construction at Ziegler Reservoir near Snowmass Village, Colorado revealed a lacustrine/wetland sedimentary sequence that preserved evidence of past plant communities between ~140 and 55 ka, including all of MIS 5. At an elevation of 2705 m, the Ziegler Reservoir fossil site (ZRFS) also contained thousands of well-preserved bones and teeth of Pleistocene megafauna, including mastodons, mammoths, ground sloths, horses, camels, deer, bison, black bear, coyotes, and bighorn sheep. In addition, the site contained more than 26,000 bones from at least 30 species of small animals, including salamanders, otters, muskrats, minks, rabbits, beavers, frogs, lizards, snakes, fish, and birds. The combination of macro- and micro-vertebrates, invertebrates, terrestrial and aquatic plant macrofossils, a detailed pollen record, and a robust, directly dated stratigraphic framework, shows that high-elevation ecosystems in the Rocky Mountains of Colorado are climatically sensitive and varied dramatically throughout MIS 5.

Conference Paper↗
USGS1994

Guidebook on the geology, history, and surface-water contamination and remediation in the area from Denver to Idaho Springs, Colorado

This guidebook for a 1-day drive in the Front Range west of Denver, Colorado, includes commentary on mountain landscapes, notes on the colorful mining history of the area, and discussions on the geology and some miningrelated environmental hazards in the Idaho Springs area. It was originally prepared as U.S. Geological Survey OpenFile Report 91-426 for a field trip sponsored by Division A-5 (Environmental Quality) of the Soil Science Society of America on October 10, 1991. That original report has been revised and expanded to make this circular more useful as a self-contained guide. A pamphlet entitled "Mountains and Plains: Denver's Geologic Setting" is a complimentary general interest publication that is available free of charge from map sales in building 810 on the Denver Federal Center, Lakewood, Colorado. The pamphlet contains useful background information on the geologic setting of Denver and nearby portions of the Front Range. A few precautions and suggestions are offered to make the trip safe and enjoyable. Idaho Springs is about 7,500 feet above sea level and the lower oxygen content of the air (about 50 percent that of sea level) may adversely affect people with heart or breathing problems. The wetlands are "wet" so use suitable footwear. The daily weather patterns are changeable. Mornings in Denver may be sunny and warm, but afternoons in Idaho Springs may be cloudy, windy, and cool with rain or snow; be prepared for all types of mountain weather. As you travel westward from Denver into the mountains, successively older rocks are crossed. By studying the descriptions at the various mileage points and by taking time at each described STOP, you will get an excellent overview of the geologic events that shaped the Denver Basin and the mountains to the west. After traveling some 18 miles into the mountains, you will reach the old mining town of Idaho Springs. Here, you can learn about the two longest tunnels in the area-the Argo and Big Five Tunnels-and how the mine drainage affects the water of Clear Creek. The Argo Tunnel near the east end of Idaho Springs drains part of the large Central City and Idaho Springs hardrock mining districts and is a source of acid water (which contains arsenic and other heavy metals) that drains into Clear Creek. At the west end ofldaho Springs is the Big Five Tunnel. Near the tunnel entrance an experimental constructed wetland demonstrates technology for the remediation of acid-mine drainage and removal of arsenic and heavy metals. Take an opportunity to view this experimental method for treatment of mine drainage. For access to the wetlands, prior arrangements must be made with the Department of Environmental Sciences and Engineering Ecology or Department of Chemistry and Geochemistry, Colorado School of Mines in Golden, Colorado. Otherwise, the wetlands may be viewed from the road. Permission to enter the Argo Tunnel property may be obtained from Jim Maxwell of Idaho Springs, who owns the hot springs resort. The tunnel may also be viewed from public roads. After you leave Idaho Springs, the road log guides you down Clear Creek canyon, providing an opportunity to get a closer look at the various Precambrian rocks while traveling through one of Colorado's picturesque canyons.

Denver, Idaho Springs↗
USGS2025

SiMPL wildlife magnets: A camera trap tool for detecting all creatures great and small

We created the SiMPL wildlife magnet—a baited camera trap design that allows passive monitoring of wildlife, particularly small- to medium-sized mammals. The SiMPL wildlife magnet is inexpensive and easy to construct. To evaluate its effectiveness, we conducted a two-year case study using 9 camera stations along an elevation gradient in the White Mountains of the northeastern United States. We examined how the detection probability of mammal species changed with the inclusion of a SiMPL wildlife magnet using data from pre-and post-establishment. We found a significant increase in community-level detection probability with the use of SiMPL wildlife magnets and for individual species, including red squirrels ( Tamiasciurus hudsonicus ), American marten ( Martes americana ), and fisher ( Pekania pennanti ). Moreover, we were able to capture more species with SiMPL wildlife magnets than without, including flying squirrels ( Glaucomys spp.), various rodents ( Cricetidae spp.), black bears ( Ursus americanus ), moose ( Alces alces ), owls, and other birds. The SiMPL wildlife magnet is an effective, low-cost method for surveying wildlife communities, especially rodents and mesocarnivores. It addresses the limited field of view presented by other techniques for capturing small mammals on camera traps and enables efficient collection of phenology data, including vegetation and snowpack. This tool has several applications, including monitoring species' responses to management practices and global change.

Ecology and Evolution↗
USGS2003

Reconnaissance-level application of physical habitat simulation in the evaluation of physical habitat limits in the Animas Basin, Colorado

The Animas River is in southwestern Colorado and flows mostly to the south to join the San Juan River at Farmington, New Mexico (Figure 1). The Upper Animas River watershed is in San Juan County, Colorado and is located in the San Juan Mountains. The lower river is in the Colorado Plateau country. The winters are cold with considerable snowfall and little snowmelt in the mountains in the upper part of the basin. The lower basin has less snow but the winters are still cold. The streamflows during the winter are low and reasonably stable. The native trout in the Animas Basin is the cutthroat trout. Few native trout remain and the trout found in the upper watershed are brook trout with rainbow and brown trout in the lower river. There is considerable metal contamination in the upper basin near Silverton but a brook trout fishery does exist in the Animas River from just above Howardsville to where the Animas joins Cement Creek in Silverton. There are two principle objectives of the habitat studies in the Animas Basin: (1) to improve understanding of the fate of sediment from mining operations from the view point of physical habitat impacts, and (2) to determine if reconnaissance level physical habitat studies can be useful in understanding the impacts of mining on the aquatic ecosystem. Part of the project was to apply the Physical Habitat Simulation System (PHABSIM) to selected locations in the Upper Animas River Basin, Colorado in order to demonstrate the importance of physical habitat in evaluating the efficacy of mined land remediation activities. Physical habitat analysis included the use of sedimentation variables in physical habitat simulations. A map of the Upper Animas Basin is presented in Figure 2. The project involves collecting data for the following locations: Animas River above Magee Creek; Animas River above Howardsville; Animas River below Howardsville; Animas River above Silverton at Hillsdale Cemetery; Animas River at Silverton; Cement Creek above Silverton; Cement Creek at Silverton; Mineral Creek at Powerline above Silverton; Mineral Creek at Campground; South Mineral Creek at Overflow Campground; Mineral Creek above Bear Creek; Mineral Creek at Silverton; Animas River below Silverton; and Animas River at Elk Park. Bed material samples were collected at each site. These included samples of the armour, the substrate, and sand and fines deposited on the surface. At selected sites the stream morphology was measured. These measurements included one to three cross sections, stream discharge, and water surface elevations. The data are located in the files of the Fort Collins Science Center.

Colorado, New Mexico↗
USGS2004

Assessing the fit of site-occupancy models

Few species are likely to be so evident that they will always be detected at a site when present. Recently a model has been developed that enables estimation of the proportion of area occupied, when the target species is not detected with certainty. Here we apply this modeling approach to data collected on terrestrial salamanders in the Plethodon glutinosus complex in the Great Smoky Mountains National Park, USA, and wish to address the question 'how accurately does the fitted model represent the data?' The goodness-of-fit of the model needs to be assessed in order to make accurate inferences. This article presents a method where a simple Pearson chi-square statistic is calculated and a parametric bootstrap procedure is used to determine whether the observed statistic is unusually large. We found evidence that the most global model considered provides a poor fit to the data, hence estimated an overdispersion factor to adjust model selection procedures and inflate standard errors. Two hypothetical datasets with known assumption violations are also analyzed, illustrating that the method may be used to guide researchers to making appropriate inferences. The results of a simulation study are presented to provide a broader view of the methods properties.

North Carolina, Tennessee↗
USGS2013

Emulating natural disturbances for declining late-successional species: A case study of the consequences for Cerulean Warblers ( Setophaga cerulea )

Forest cover in the eastern United States has increased over the past century and while some late-successional species have benefited from this process as expected, others have experienced population declines. These declines may be in part related to contemporary reductions in small-scale forest interior disturbances such as fire, windthrow, and treefalls. To mitigate the negative impacts of disturbance alteration and suppression on some late-successional species, strategies that emulate natural disturbance regimes are often advocated, but large-scale evaluations of these practices are rare. Here, we assessed the consequences of experimental disturbance (using partial timber harvest) on a severely declining late-successional species, the cerulean warbler ( Setophaga cerulea ), across the core of its breeding range in the Appalachian Mountains. We measured numerical (density), physiological (body condition), and demographic (age structure and reproduction) responses to three levels of disturbance and explored the potential impacts of disturbance on source-sink dynamics. Breeding densities of warblers increased one to four years after all canopy disturbances (vs. controls) and males occupying territories on treatment plots were in better condition than those on control plots. However, these beneficial effects of disturbance did not correspond to improvements in reproduction; nest success was lower on all treatment plots than on control plots in the southern region and marginally lower on light disturbance plots in the northern region. Our data suggest that only habitats in the southern region acted as sources, and interior disturbances in this region have the potential to create ecological traps at a local scale, but sources when viewed at broader scales. Thus, cerulean warblers would likely benefit from management that strikes a landscape-level balance between emulating natural disturbances in order to attract individuals into areas where current structure is inappropriate, and limiting anthropogenic disturbance in forests that already possess appropriate structural attributes in order to maintain maximum productivity.

PLoS ONE↗
USGS2024

Geologic map of the southern Stillwater Range, Nevada

The southern Stillwater Range in west-central Nevada contains the western part of the Oligocene Stillwater-Clan Alpine caldera complex, which extends about 55 kilometers (km) east from the west side of the Stillwater Range to the northwestern Desatoya Mountains. The complex consists of at least seven nested ignimbrite calderas and subjacent plutonic rocks emplaced into a complex basement composed of Mesozoic metasedimentary and metavolcanic rocks and Cretaceous granitic plutons. The calderas formed during large-volume (100s to greater than (>) 2,500 cubic kilometers [km 3 ]) eruptions of silicic ignimbrites between about 30.4 and 25.1 million years before present (Ma). The Job Canyon and Poco Canyon calderas and the western part of the much larger Elevenmile Canyon caldera, and their plutonic roots, are exposed in the southern Stillwater Range. There, the caldera complex was steeply tilted during large-magnitude crustal extension in the middle Miocene, and further exhumed during the late Miocene to Holocene Basin and Range extension that formed the modern Stillwater Range. This tilted crustal section affords an exceptional opportunity to view structural cross sections of ignimbrite calderas and their plutonic roots to paleodepths as much as 9–10 km.

Nevada↗
USGS2004

Rectified images of selected geologic maps in the Northern Rockies Area, Idaho, Montana, Washington, and Wyoming

Selected geologic maps covering parts of the Northern Rocky Mountains and adjacent areas were converted to raster images and georeferenced (rectified) for use in a geographic information system (GIS). These rectified images were created for the purpose of visually comparing published geologic maps with other geospatial information. However, they cannot be queried or used for spatial analysis thus limiting their use in a GIS. The 42 georeferenced images included in this report range in scale from 1:250,000 to 1:100,000.Tagged Image Format (TIFF) images of the maps were generated by scanning an original paper map or converting previously published Portable Document Format (PDF) images or Encapsulated Post-Script (EPS) files. To reduce file size and minimize image overlap, the TIFF images were cropped, and then rectified using ArcMap? 8 and converted to MrSID? images. Information in the explanation and cross sections can be viewed in un-rectified images of the original publications that are included with this report. In addition, the text in the map unit description along with the unit name, map label, and a citation are organized in a searchable PDF file.

Data Series↗
USGS1999

Characterizing backcountry camping impacts in Great Smoky Mountains National Park

This investigates resource impacts on backcounty campsites in the Great Smoky Mountains National Park, USA. Study objectives were to enhance our understanding of camping impacts and to improve campsite impact assessment procedures by means of multivariate techniques. Three-hundred and eight campsites at designated backcountry campgrounds, and 69 additional unofficial campsites were assessed. Factor analysis of 195 established campsites on eight impact indicator variables revealed three dimensions of campsite impact: area disturbance, soil and groundcover damage, and tree-related damage. Four distinctive backcountry campsite types were identified, three of which were derived from cluster analyses of factor scores. These four backcountry campsite types characterize the intensity and areal extent of resource impacts, and they vary in locational and environmental attributes. At an aggregate level, different campsite types contributed unequally to the cumulative level of impact. The dimensional structure and typology developed in this study demonstrates that campsite impacts can be viewed and examined holistically with the use of multivariate methods. Implications for assessment procedures, management and further research are discussed.

Journal of Environmental Management↗