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Articles 2851 - 2880 of 4541
Full-Text Articles in Earth Sciences
Derivation Of A Tasseled Cap Transformation Based On Landsat 7 At-Satellite Reflectance, C. Huang, Bruce K. Wylie, Limin Yang, Collin Homer, Gregory Zylstra
Derivation Of A Tasseled Cap Transformation Based On Landsat 7 At-Satellite Reflectance, C. Huang, Bruce K. Wylie, Limin Yang, Collin Homer, Gregory Zylstra
United States Geological Survey: Publications
A new tasseled cap transformation based on Landsat 7 at-satellite reflectance was developed. This transformation is most appropriate for regional applications where atmospheric correction is not feasible. The brightness, greenness and wetness of the derived transformation collectively explained over 97% of the spectral variance of the individual scenes used in this study.
Assessment Of Elemental Concentrations In Streams Of The New Lead Belt In Southeastern Missouri, 2002–05, William G. Brumbaugh, Thomas W. May, John M. Besser, Ann L. Allert, Christopher J. Schmitt
Assessment Of Elemental Concentrations In Streams Of The New Lead Belt In Southeastern Missouri, 2002–05, William G. Brumbaugh, Thomas W. May, John M. Besser, Ann L. Allert, Christopher J. Schmitt
United States Geological Survey: Publications
Concerns about possible effects of lead-mining activities on the water quality of federally protected streams located in southeastern Missouri prompted a suite of multidisciplinary studies to be conducted by the U.S. Geological Survey. As part of this investigation, a series of biological studies were initiated in 2001 for streams in the current mining region and the prospecting area. In this report, results are examined for trace elements and other selected chemical measurements in sediment, surface water, and sediment interstitial (pore) water sampled between 2002 and 2005 in association with these biological studies. Compared to reference sites, fine sediments collected downstream …
Evidence For The Timing And Duration Of The Last Interglacial Period From High-Precision Uranium-Series Ages Of Corals On Tectonically Stable Coastlines, Daniel R. Muhs
United States Geological Survey: Staff Publications
The last interglacial period has a timing and duration that can be estimated from U-series dating of emergent, coral-bearing deposits on tectonically stable coastlines. High-precision dating from Bermuda, the Bahamas, Hawaii, and Australia suggests that the last interglacial period had a sea level at least as high as present from ∼128,000 to 116,000 yr B.P. Sea level reached a near-present level more quickly after the close of the penultimate glacial period than at the close of the last glacial period and the duration of high sea level is longer than that implied by the deep-sea record.
Age Of Ground Water At City Of Lincoln's Municipal Well Field Near Ashland, Nebraska, Gregory V. Steele
Age Of Ground Water At City Of Lincoln's Municipal Well Field Near Ashland, Nebraska, Gregory V. Steele
United States Geological Survey: Water Reports and Publications
The Platte River alluvial aquifer, which underlies the Plaue River Valley, is an important source of water for public supply in central and eastern Nebraska. Knowing the age of ground water can help scientists and water managers better understand the dynamics of the groundwater system. In turn, this knowledge will help in calibrating groundwater-flow models and aid in developing a conceptual understanding of how long it takes for recharge water to reach certain areas of the aquifer. Although previous studies (Davis, 1992; Steele and Verstraeten, 1999; Verstraeten et al., 1999) reported the interaction of surface water and ground water at …
Field Trip Guide (For The Nebraska Well Drillers Association) Central Nebraska Geology, James W. Goeke, Robert F. Diffendal Jr., Duane A. Eversoll
Field Trip Guide (For The Nebraska Well Drillers Association) Central Nebraska Geology, James W. Goeke, Robert F. Diffendal Jr., Duane A. Eversoll
Conservation and Survey Division: Faculty and Staff Publications
Field trip guide for the Nebraska Well Drillers Association covering central Nebraska geology from 2002.
Field Trip Guide (For The Nebraska Well Drillers Association) Southwestern Nebraska Geology, D. Eversoll
Field Trip Guide (For The Nebraska Well Drillers Association) Southwestern Nebraska Geology, D. Eversoll
Conservation and Survey Division: Faculty and Staff Publications
No abstract provided.
Scotts Bluff County Test Hole Logs, Vincent H. Dreeszen, Steven S. Sibray, Frank A. Smith
Scotts Bluff County Test Hole Logs, Vincent H. Dreeszen, Steven S. Sibray, Frank A. Smith
Conservation and Survey Division: Faculty and Staff Publications
No abstract provided.
Wildlife Diseases: Crying Wolf Or Crying Shame?, Robert G. Mclean
Wildlife Diseases: Crying Wolf Or Crying Shame?, Robert G. Mclean
United States Geological Survey: Staff Publications
Diseases of North American wildlife are causing serious problems for wildlife, and some wildlife diseases pose health threats to humans and domestic animals. Information will be presented at this wildlife disease session to alert resource managers enough to consider disease as an important issue when managing wildlife populations. It will be a crying shame if appropriate actions are not taken to monitor diseases adequately and to prevent or control them to protect our wildlife resources.
Application Of Classification-Tree Methods To Identify Nitrate Sources In Ground Water, Timothy B. Spruill, William J. Showers, Stephen S. Howe
Application Of Classification-Tree Methods To Identify Nitrate Sources In Ground Water, Timothy B. Spruill, William J. Showers, Stephen S. Howe
United States Geological Survey: Staff Publications
A study was conducted to determine if nitrate sources in ground water (fertilizer on crops, fertilizer on golf courses, irrigation spray from hog (Sus scrofa) wastes, and leachate from poultry litter and septic systems) could be classified with 80% or greater success. Two statistical classification-tree models were devised from 48 water samples containing nitrate from five source categories. Model 1 was con- structed by evaluating 32 variables and selecting four primary predictor variables (δ15N, nitrate to ammonia ratio, sodium to potassium ratio, and zinc) to identify nitrate sources. A δ15N value of nitrate plus …
Relating Net Nitrogen Input In The Mississippi River Basin To Nitrate Flux In The Lower Mississippi River: A Comparison Of Approaches, Gregory F. Mcisaac, Mark B. David, George Z. Gertner, Donald A. Goolsby
Relating Net Nitrogen Input In The Mississippi River Basin To Nitrate Flux In The Lower Mississippi River: A Comparison Of Approaches, Gregory F. Mcisaac, Mark B. David, George Z. Gertner, Donald A. Goolsby
United States Geological Survey: Staff Publications
A quantitative understanding of the relationship between terrestrial N inputs and riverine N flux can help guide conservation, policy, and adaptive management efforts aimed at preserving or restoring water quality. The objective of this study was to compare recently published approaches for relating terrestrial N inputs to the Mississippi River basin (MRB) with measured nitrate flux in the lower Mississippi River. Nitrogen inputs to and outputs from the MRB (1951 to 1996) were estimated from state-level annual agricultural production statistics and NOy (inorganic oxides of N) deposition estimates for 20 states that comprise 90% of the MRB. A model …
Wyoming Toad (Bufo Baxteri), R. Andrew Odum, Paul Stephen Corn
Wyoming Toad (Bufo Baxteri), R. Andrew Odum, Paul Stephen Corn
United States Geological Survey: Staff Publications
Historically, Wyoming toads (Bufo baxteri) were abundant in the vicinity of Laramie, Albany County, Wyoming (Baxter, 1952; Corn, 1991), where they were found in the flood plains of the Big and Little Laramie rivers (Stebbins, 1985), an area of only 2,330 km2 (Lewis et al., 1985). A rapid decline was observed in the mid-1970s (Lewis et al., 1985) when they disappeared from most of their range. Surveys in the early 1980s yielded few animals, and Lewis et al. f 1985) reported their possible extinction in 1983. Wyoming toads were listed as Endangered under the Endangered Species Act …
A 1500-Year Record Of Climatic And Environmental Change In Elk Lake, Clearwater County, Minnesota Ii: Geochemistry, Mineralogy, And Stable Isotopes, Walter E. Dean
United States Geological Survey: Staff Publications
Most of the sediment components that have accumulated in Elk Lake, Clearwater County, northwestern Minnesota, over the past 1500 years are authigenic or biogenic (CaCO3, biogenic SiO2, organic matter, iron and manganese oxyhydroxides, and iron phosphate) and are delivered to the sediment–water interface on a seasonal schedule where they are preserved as distinct annual laminae (varves). The annual biogeochemical cycles of these components are causally linked through the ‘carbon pump’, and are recapitulated in longer-term cycles, most prominently with a periodicity of about 400 years. Organic carbon is fixed in the epilimnion by photosynthetic removal of …
Early Holocene Change In Atmospheric Circulation In The Northern Great Plains: An Upstreamview Of The 8.2 Ka Cold Event, Walter E. Dean, Richard M. Forester, J. Platt Bradbury
Early Holocene Change In Atmospheric Circulation In The Northern Great Plains: An Upstreamview Of The 8.2 Ka Cold Event, Walter E. Dean, Richard M. Forester, J. Platt Bradbury
United States Geological Survey: Staff Publications
Elk Lake, in northwestern Minnesota, contains numerous proxy records of climatic and environmental change contained in varved sediments with annual resolution for the last 10,000 years. These proxies show that about 8200 calendar years ago (8.2 cal. ka; 7300 radiocarbon years) Elk Lake went froma well-stratified lake that was wind-protected in a boreal forest to a well-mixed lake in open prairie savanna receiving northwesterly wind-blown dust, probably from the dry floor of Lake Agassiz. This change in climate marks the initiation of the widely recognized mid-Holocene “altithermal” in central North America. The coincidence of this change with the so-called 8.2 …
Determination Of Melanterite-Rozenite And Chalcanthite-Bonattite Equilibria By Humidity Measurements At 0.1 Mpa, I-Ming Chou, R.R. Seal Ii, B.S. Hemingway
Determination Of Melanterite-Rozenite And Chalcanthite-Bonattite Equilibria By Humidity Measurements At 0.1 Mpa, I-Ming Chou, R.R. Seal Ii, B.S. Hemingway
United States Geological Survey: Staff Publications
Melanterite (FeSO4•7H2O)-rozenite (FeSO4•4H2O) and chalcanthite (CuSO4•5H2O)-bonattite (CuSO4•3H2O) equilibria were determined by humidity measurements at 0.1 MPa. Two methods were used; one is the gas-flow-cell method (between 21 and 98 °C), and the other is the humidity buffer method (between 21 and 70 °C). The first method has a larger temperature uncertainty even though it is more efficient. With the aid of humidity buffers, which correspond to a series of saturated binary salt solutions, the second method yields reliable results as demonstrated by very tight …
Reconstruction Of Hydrological Changes And Response To Effective Moisture Variations From North-Central Usa Lake Sediments, Antje Schwalb, Walter E. Dean
Reconstruction Of Hydrological Changes And Response To Effective Moisture Variations From North-Central Usa Lake Sediments, Antje Schwalb, Walter E. Dean
United States Geological Survey: Staff Publications
Ratios of the stable isotopes of oxygen and carbon in benthic ostracodes and marl from cores taken from two lakes in north-central Minnesota reflect Holocene hydrological and vegetation changes. Oxygen isotopes show that Williams and Shingobee Lakes, located in the same watershed but with different positions along a hydrologic gradient, were connected before 9.8 ka as part of a larger lake, Lake Willobee. From 9.8–7.7 ka, the level of Lake Willobee fell as a result of glacial retreat and increasing evaporation, leaving small separated basins. Further decreases in lake level after 7.7 ka due to increasing aridity triggered the inflow …
Derivation Of A Tasselled Cap Transformation Based On Landsat 7 At-Satellite Reflectance, C. Huang, Wylie L. Yang, Collin Homer, G. Zylstra
Derivation Of A Tasselled Cap Transformation Based On Landsat 7 At-Satellite Reflectance, C. Huang, Wylie L. Yang, Collin Homer, G. Zylstra
United States Geological Survey: Staff Publications
A new tasselled cap transformation based on Landsat 7 at-satellite reflectance was developed. This transformation is most appropriate for regional applications where atmospheric correction is not feasible. The brightness, greenness and wetness of the derived transformation collectively explained over 97% of the spectral variance of the individual scenes used in this study.
Strontium Isotopic Signatures Of The Streams And Lakes Of Taylor Valley, Southern Victoria Land, Antarctica: Chemical Weathering In A Polar Climate, W. B. Lyons, Carmen A. Nezat, Larry V. Benson, Thomas D. Bullen, Elizabeth Y. Graham, Jesicca Kidd, Kathleen A. Welch, James M. Thomas
Strontium Isotopic Signatures Of The Streams And Lakes Of Taylor Valley, Southern Victoria Land, Antarctica: Chemical Weathering In A Polar Climate, W. B. Lyons, Carmen A. Nezat, Larry V. Benson, Thomas D. Bullen, Elizabeth Y. Graham, Jesicca Kidd, Kathleen A. Welch, James M. Thomas
United States Geological Survey: Staff Publications
We have collected and analyzed a series of water samples from three closed-basin lakes (Lakes Bonney, Fryxell, and Hoare) in Taylor Valley, Antarctica, and the streams that flow into them. In all three lakes, the hypolimnetic waters have different 87Sr/86Sr ratios than the surface waters, with the deep water of Lakes Fryxell and Hoare being less radiogenic than the surface waters. The opposite occurs in Lake Bonney. The Lake Fryxell isotopic ratios are lower than modern-day ocean water and most of the whole-rock ratios of the surrounding geologic materials. A conceivable source of Sr to the system …
Organochlorine Chemical Residues In Fish From The Mississippi River Basin, 1995, C.J. Schmitt
Organochlorine Chemical Residues In Fish From The Mississippi River Basin, 1995, C.J. Schmitt
United States Geological Survey: Staff Publications
µ≤≥
Fish were collected in late 1995 from 34 National Contaminant Biomonitoring Program (NCBP) stations and 13 National Water Quality Assessment Program (NAWQA) stations in the Mississippi River basin (MRB) and in late 1996 from a reference site in West Virginia. Four composite samples, each comprising (nominally) 10 adult common carp (Cyprinus carpio) or black bass (Micropterus spp.) of the same sex, were collected from each site and analyzed for organochlorine chemical residues by gas chromatography with electron capture detection. At the NCBP stations, which are located on relatively large rivers, concentrations of organochlorine chemical residues were generally lower than …
Holocene Multidecadal And Multicentennial Droughts Affecting Northern California And Nevada, Larry Benson, Michaele Kashgarian, Robert Rye, Steve Lund, Fred Paillet, Joseph Smoot, Cynthia Kester, Scott Mensing, Dave Meko, Susan Landström
Holocene Multidecadal And Multicentennial Droughts Affecting Northern California And Nevada, Larry Benson, Michaele Kashgarian, Robert Rye, Steve Lund, Fred Paillet, Joseph Smoot, Cynthia Kester, Scott Mensing, Dave Meko, Susan Landström
United States Geological Survey: Staff Publications
Continuous, high-resolution δ18O records from cored sediments of Pyramid Lake, Nevada, indicate that oscillations in the hydrologic balance occurred, on average, about every 150 years (yr) during the past 7630 calendar years (cal yr). The records are not stationary; during the past 2740 yr, drought durations ranged from 20 to 100 yr and intervals between droughts ranged from 80 to 230 yr. Comparison of tree-ring-based reconstructions of climate change for the past 1200 yr from the Sierra Nevada and the El Malpais region of northwest New Mexico indicates that severe droughts associated with Anasazi withdrawal from Chaco Canyon …
Bedform Movement Recorded By Sequential Single-Beam Surveys In Tidal Rivers, R. L. Dinehart
Bedform Movement Recorded By Sequential Single-Beam Surveys In Tidal Rivers, R. L. Dinehart
United States Geological Survey: Staff Publications
A portable system for bedform-mapping was evaluated in the delta of the lower Sacramento and San Joaquin Rivers, California, from 1998 to 2000. Bedform profiles were surveyed with a two-person crew using an array of four single-beam transducers on boats about 6 m in length. Methods for processing the bedform profiles into maps with geographic coordinates were developed for spreadsheet programs and surface-contouring software. Straight reaches were surveyed every few days or weeks to determine locations of sand deposition, net transport directions, flow thresholds for bedform regimes, and bedform transport rates. In one channel of unidirectional flow, the portable system …
Overview Of Hydrocarbon Production, Consumption, Reserves And Potential, At World And Local Scales, Mitchell E. Henry, Debra Higley
Overview Of Hydrocarbon Production, Consumption, Reserves And Potential, At World And Local Scales, Mitchell E. Henry, Debra Higley
United States Geological Survey: Staff Publications
Hydrocarbon (oil and gas) production and consumption, along with remaining resources, are irregularly distributed across the world and within countries. Daily world hydrocarbon production, in 1999, was 72.6 million barrels of oil (mbo) and 232 billion cubic feet of gas (bcfg). Daily average production in 1999, for North America, was 14 mbo and 71.7 bcfg, and, for the United States, it was 8.1 mbo and 50.9 bcfg. North American average daily consumption for 1999 was 23.4 mbo and 71.5 bcfg. The United States produced 42 percent of the oil and 85 percent of the gas it consumed in 1999. Onshore …
West Nile Virus: A Threat To North American Avian Species, Robert G. Mclean
West Nile Virus: A Threat To North American Avian Species, Robert G. Mclean
United States Geological Survey: Staff Publications
West Nile virus (WNV) was introduced into the United States (US), specifically in New York City (NYC), in 1999; this translocation represented a major shift out of its normal geographical distribution of Africa, the Middle East, Europe and the western parts of Asia (Center for Disease Control 1999a). The route or method of entry into the US is still unknown. WNV is in the genus Flavivirus, the family Flaviviridae and is closely related to some other viruses in this family, such as Japanese encephalitis virus in Southeast Asia, Murray Valley encephalitis virus in Australia and St. Louis encephalitis (SLE) …
A Procedural Evaluation Of An Analytic-Deliberative Process: The Columbia River Comprehensive Impact Assessment, Aimee Guglielmo Kinney, Thomas M. Leschine
A Procedural Evaluation Of An Analytic-Deliberative Process: The Columbia River Comprehensive Impact Assessment, Aimee Guglielmo Kinney, Thomas M. Leschine
United States Army Corps of Engineers, Omaha District
The U.S. Department of Energy's Columbia River Comprehensive Impact Assessment (CRCIA) was an ambitious attempt to direct its cleanup of the Hanford Nuclear Reservation toward the most significant risks to the Columbia River resulting from past plutonium production. DOE's approach was uncommonly open, including tribal, regulatory agency, and other Hanford interest group representatives on the board that was to develop the assessment approach. The CRCIA process had attributes of the ``analytic-deliberative'' process for risk assessment recommended by the National Research Council. Nevertheless, differences between the DOE and other participants over what was meant by the term ``comprehensive'' in the group's …
The Last Interglacial Period On The Pacific Coast Of North America: Timing And Paleoclimate, Daniel R. Muhs, Kathleen R. Simmons, George L. Kennedy, Thomas K. Rockwell
The Last Interglacial Period On The Pacific Coast Of North America: Timing And Paleoclimate, Daniel R. Muhs, Kathleen R. Simmons, George L. Kennedy, Thomas K. Rockwell
United States Geological Survey: Staff Publications
New, high-precision U-series ages of solitary corals (Balanophyllia elegans) coupled with molluscan faunal data from marine terraces on the Pacific Coast of North America yield information about the timing and warmth of the last interglacial sea-level highstand. Balanophyllia elegans takes up U in isotopic equilibrium with seawater during growth and shortly after death. Corals from the second terrace on San Clemente Island (offshore southern California), the third terrace on Punta Banda (on the Pacific Coast of northern Baja California), and the Discovery Point Formation on Isla de Guadalupe (in the Pacific Ocean offshore Baja California) date to the …
Last Interglacial Climates, George J. Kukla, Michael L. Bender, Jacques-Louis De Beaulieu, Gerard Bond, Wallace S. Broecker, Piet Cleveringa, Joyce E. Gavin, Timothy D. Herbert, John Imbrie, Jean Jouzel, Lloyd D. Keigwin, Karen-Luise Knudsen, Jerry F. Mcmanus, Josef Merkt, Daniel R. Muhs, Helmut Muller, Richard Z. Poore, Stephen C. Porter, Guy Seret, Nicholas J. Shackleton, Charles Turner, Polychronis C. Tzedakis, Isaac J. Winograd
Last Interglacial Climates, George J. Kukla, Michael L. Bender, Jacques-Louis De Beaulieu, Gerard Bond, Wallace S. Broecker, Piet Cleveringa, Joyce E. Gavin, Timothy D. Herbert, John Imbrie, Jean Jouzel, Lloyd D. Keigwin, Karen-Luise Knudsen, Jerry F. Mcmanus, Josef Merkt, Daniel R. Muhs, Helmut Muller, Richard Z. Poore, Stephen C. Porter, Guy Seret, Nicholas J. Shackleton, Charles Turner, Polychronis C. Tzedakis, Isaac J. Winograd
United States Geological Survey: Staff Publications
The last interglacial, commonly understood as an interval with climate as warm or warmer than today, is represented by marine isotope stage (MIS) 5e, which is a proxy record of low global ice volume and high sea level. It is arbitrarily dated to begin at approximately 130,000 yr B.P. and end at 116,000 yr B.P. with the onset of the early glacial unit MIS 5d. The age of the stage is determined by correlation to uranium–thorium dates of raised coral reefs. The most detailed proxy record of interglacial climate is found in the Vostok ice core where the temperature reached …
Evidence For The Timing And Duration Of The Last Interglacial Period From High-Precision Uranium-Series Ages Of Corals On Tectonically Stable Coastlines, Daniel R. Muhs
United States Geological Survey: Staff Publications
The last interglacial period has a timing and duration that can be estimated from U-series dating of emergent, coral-bearing deposits on tectonically stable coastlines. High-precision dating from Bermuda, the Bahamas, Hawaii, and Australia suggests that the last interglacial period had a sea level at least as high as present from ~128,000 to 116,000 yr B.P. Sea level reached a near-present level more quickly after the close of the penultimate glacial period than at the close of the last glacial period and the duration of high sea level is longer than that implied by the deep-sea record.
Timing And Warmth Of The Last Interglacial Period: New U-Series Evidence From Hawaii And Bermuda And A New Fossil Compilation For North America, Daniel R. Muhs, Kathleen R. Simmons, Bree Steinke
Timing And Warmth Of The Last Interglacial Period: New U-Series Evidence From Hawaii And Bermuda And A New Fossil Compilation For North America, Daniel R. Muhs, Kathleen R. Simmons, Bree Steinke
United States Geological Survey: Staff Publications
The timing and duration of the Last Interglacial period have been controversial, with some studies suggesting a relatively short duration that is orbitally forced and others suggesting a long duration that is at most only partly related to orbital forcing. New, high-precison thermal ionization mass spectrometric (TIMS) U-series ages of Last Interglacial corals from Hawaii and Bermuda test these competing hypotheses. Waimanalo Formation corals from slowly uplifting Oahu, Hawaii range in age from ~ 134 to ~ 113 ka, with most ages between ~ 125 and ~ 115 ka. Combined with published U-series ages from nearby Lanai, the data suggest …
Radiocarbon Dating, Chronologic Framework, And Changes In Accumulation Rates Of Holocene Estuarine Sediments From Chesapeake Bay, Steven M. Colman, Pattie C. Baucom, John F. Bratton, Thomas M. Cronin, John P. Mcgeehin, Debra Willard, Andrew R. Zimmerman, Peter R. Vogt
Radiocarbon Dating, Chronologic Framework, And Changes In Accumulation Rates Of Holocene Estuarine Sediments From Chesapeake Bay, Steven M. Colman, Pattie C. Baucom, John F. Bratton, Thomas M. Cronin, John P. Mcgeehin, Debra Willard, Andrew R. Zimmerman, Peter R. Vogt
United States Geological Survey: Staff Publications
Rapidly accumulating Holocene sediments in estuaries commonly are difficult to sample and date. In Chesapeake Bay, we obtained sediment cores as much as 20min length and used numerous radiocarbon ages measured by accelerator mass spectrometry methods to provide the first detailed chronologies of Holocene sediment accumulation in the bay. Carbon in these sediments is a complex mixture of materials from a variety of sources. Analyses of different components of the sediments show that total organic carbon ages are largely unreliable, because much of the carbon (including coal) has been transported to the bay from upstream sources and is older than …
Probability Of Nitrate Contamination Of Recently Recharged Groundwaters In The Conterminous United States, Bernard Nolan, Kerie Hitt, Barbara Ruddy
Probability Of Nitrate Contamination Of Recently Recharged Groundwaters In The Conterminous United States, Bernard Nolan, Kerie Hitt, Barbara Ruddy
United States Geological Survey: Staff Publications
A new logistic regression (LR) model was used to predict the probability of nitrate contamination exceeding 4 mg/L in predominantly shallow, recently recharged groundwaters of the United States. The new model contains variables representing (1) N fertilizer loading (p < 0.001), (2) percent cropland-pasture (p < 0.001), (3) natural log of human population density (p < 0.001), (4) percent well-drained soils (p < 0.001), (5) depth to the seasonally high water table (p < 0.001), and (6) presence or absence of unconsolidated sand and gravel aquifers (p =0.002). Observed and average predicted probabilities associated with deciles of risk are well correlated (r2 = 0.875), indicating that the LR model fits the data well. The likelihood of nitrate contamination is greater in areas with high N loading and well-drained surficial soils over unconsolidated sand and gravels. The LR model correctly predicted the status of nitrate contamination in 75% of wells in a validation data set. Considering all wells used in both calibration and …
New Amphicyonid Carnivorans (Mammalia, Daphoeninae) From The Early Miocene Of Southeastern Wyoming, Robert M. Hunt Jr.
New Amphicyonid Carnivorans (Mammalia, Daphoeninae) From The Early Miocene Of Southeastern Wyoming, Robert M. Hunt Jr.
Department of Earth and Atmospheric Sciences: Faculty Publications
Latest Arikareean sediments of the upper Arikaree Group in southeastern Wyoming produced rare fossils of large, early Miocene amphicyonid carnivorans for field parties of the Frick Laboratory, American Museum, from 1932 to 1940. Recent geologic field investigations, including mapping, have discovered additional remains of these carnivorans, clarifying their geographic and stratigraphic distribution, and permitting a more informed description of the earlier collections. These carnivorans come from tuffaceous sandstones of the Upper Harrison beds, the terminal formation-rank unit of the Arikaree Group in southeastern Wyoming. A large species of the amphicyonid Daphoenodon (D. falkenbachi, n. sp.) occurs in northern …