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Full-Text Articles in Physical Sciences and Mathematics

New Amphicyonid Carnivorans (Mammalia, Daphoeninae) From The Early Miocene Of Southeastern Wyoming, Robert M. Hunt Jr. Jan 2002

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 …


Intercontinental Migration Of Neogene Amphicyonids (Mammalia, Carnivora): Appearance Of The Eurasian Beardog Ysengrinia In North America, Robert M. Hunt Jr. Jan 2002

Intercontinental Migration Of Neogene Amphicyonids (Mammalia, Carnivora): Appearance Of The Eurasian Beardog Ysengrinia In North America, Robert M. Hunt Jr.

Department of Earth and Atmospheric Sciences: Faculty Publications

At the beginning of the Neogene a remarkable faunal turnover occurred within the North American carnivore community. The dominant larger Oligocene carnivores (creodonts, nimravid cats, the amphicyonid Daphoenus) became extinct during the late Oligocene and were replaced in the early Miocene by amphicyonine amphicyonids and hemicyonine ursids that entered North America from Eurasia. During a five million-year interval from ~23 to 18 Ma, large amphicyonines appear in late Arikareean and early Hemingfordian faunas of the North American midcontinent. Although most fossils are from western Nebraska and southeastern Wyoming, occurrences of amphicyonines at several sites in the eastern United States …


A Procedural Evaluation Of An Analytic-Deliberative Process: The Columbia River Comprehensive Impact Assessment, Aimee Guglielmo Kinney, Thomas M. Leschine Jan 2002

A Procedural Evaluation Of An Analytic-Deliberative Process: The Columbia River Comprehensive Impact Assessment, Aimee Guglielmo Kinney, Thomas M. Leschine

US Army Corps of Engineers

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 …


Reconstruction Of Hydrological Changes And Response To Effective Moisture Variations From North-Central Usa Lake Sediments, Antje Schwalb, Walter E. Dean Jan 2002

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 …


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 Jan 2002

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.


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 Jan 2002

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 …


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 Jan 2002

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 …


West Nile Virus: A Threat To North American Avian Species, Robert G. Mclean Jan 2002

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) …


Vocs, Pesticides, Nitrate, And Their Mixtures In Groundwater Used For Drinking Water In The United States, Paul Squillace, Jonathon Scott, Michael Moran, B. T. Nolan, Dana Kolpin Jan 2002

Vocs, Pesticides, Nitrate, And Their Mixtures In Groundwater Used For Drinking Water In The United States, Paul Squillace, Jonathon Scott, Michael Moran, B. T. Nolan, Dana Kolpin

United States Geological Survey: Staff Publications

Samples of untreated groundwater from 1255 domestic drinking-water wells and 242 public supply wells were analyzed as part of the National Water-Quality Assessment Program of the U.S. Geological Survey between 1992 and 1999. Wells were sampled to define the regional quality of the groundwater resource and, thus, were distributed geographically across large aquifers, primarily in rural areas. For each sample, as many as 60 volatile organic compounds (VOCs), 83 pesticides, and nitrate were analyzed. On the basis of previous studies, nitrate concentrations as nitrogen ≥3 mg/L were considered to have an anthropogenic origin. VOCs were detected more frequently (44%) than …


Wyoming Toad (Bufo Baxteri), R. Andrew Odum, Paul Stephen Corn Jan 2002

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 …


Overview Of Hydrocarbon Production, Consumption, Reserves And Potential, At World And Local Scales, Mitchell E. Henry, Debra Higley Jan 2002

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 …


Scotts Bluff County Test Hole Logs, Vincent H. Dreeszen, Steven S. Sibray, Frank A. Smith Jan 2002

Scotts Bluff County Test Hole Logs, Vincent H. Dreeszen, Steven S. Sibray, Frank A. Smith

Conservation and Survey Division

No abstract provided.


Creep Critters From Nebraska's Past, Roger K. Pabian Jan 2002

Creep Critters From Nebraska's Past, Roger K. Pabian

Conservation and Survey Division

No abstract provided.


Application Of Classification-Tree Methods To Identify Nitrate Sources In Ground Water, Timothy B. Spruill, William J. Showers, Stephen S. Howe Jan 2002

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 …


Probability Of Nitrate Contamination Of Recently Recharged Groundwaters In The Conterminous United States, Bernard Nolan, Kerie Hitt, Barbara Ruddy Jan 2002

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 …


Pharmaceuticals, Hormones, And Other Organic Wastewater Contaminants In U.S. Streams, 1999-2000: A National Reconnaissance, Dana Kolpin, Edward Furlong, Michael Meyer, E. Michael Thurman, Steven Zaugg, Larry Barber, Herbert Buxton Jan 2002

Pharmaceuticals, Hormones, And Other Organic Wastewater Contaminants In U.S. Streams, 1999-2000: A National Reconnaissance, Dana Kolpin, Edward Furlong, Michael Meyer, E. Michael Thurman, Steven Zaugg, Larry Barber, Herbert Buxton

United States Geological Survey: Staff Publications

To provide the first nationwide reconnaissance of the occurrence of pharmaceuticals, hormones, and other organic wastewater contaminants (OWCs) in water resources, the U.S. Geological Survey used five newly developed analytical methods to measure concentrations of 95 OWCs in water samples from a network of 139 streams across 30 states during 1999 and 2000. The selection of sampling sites was biased toward streams susceptible to contamination (i.e. downstream of intense urbanization and livestock production). OWCs were prevalent during this study, being found in 80% of the streams sampled. The compounds detected represent a wide range of residential, industrial, and agricultural origins …


Wildlife Diseases: Crying Wolf Or Crying Shame?, Robert G. Mclean Jan 2002

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.


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 Jan 2002

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 …


Organochlorine Chemical Residues In Fish From The Mississippi River Basin, 1995, C.J. Schmitt Jan 2002

Organochlorine Chemical Residues In Fish From The Mississippi River Basin, 1995, C.J. Schmitt

United States Geological Survey: Staff Publications

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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 …


A 1500-Year Record Of Climatic And Environmental Change In Elk Lake, Clearwater County, Minnesota Ii: Geochemistry, Mineralogy, And Stable Isotopes, Walter E. Dean Jan 2002

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 Jan 2002

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 Jan 2002

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 …


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 Jan 2002

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 Jan 2002

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 …


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 Jan 2002

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 Jan 2002

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 …


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 Jan 2002

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 …


Effects Of Surface Run-Off On The Transport Of Agricultural Chemicals To Ground Water In A Sandplain Setting, Geoffrey N. Delin, Matthew K. Landon Jan 2002

Effects Of Surface Run-Off On The Transport Of Agricultural Chemicals To Ground Water In A Sandplain Setting, Geoffrey N. Delin, Matthew K. Landon

United States Geological Survey: Staff Publications

An experiment was conducted at a depressional (lowland) and an upland site in sandy soils to evaluate the effects of surface run-off on the transport of agricultural chemicals to ground water. Approximately 16.5 cm of water was applied to both sites during the experiment, representing a natural precipitation event with a recurrence interval of approximately 100 years. Run-off was quantified at the lowland site and was not detected at the upland site during the experiment. Run-off of water to the lowland site was the most important factor affecting differences in the concentrations and fluxes of the agricultural chemicals between the …


Progress On Geoenvironmental Models For Selected Mineral Deposit Types, Robert R. Seal Ii, Nora K. Foley Jan 2002

Progress On Geoenvironmental Models For Selected Mineral Deposit Types, Robert R. Seal Ii, Nora K. Foley

United States Geological Survey: Publications

Since the beginning of economic geology as a subdiscipline of the geological sciences, economic geologists have tended to classify mineral deposits on the basis of geological, mineralogical, and geochemical criteria, in efforts to systematize our understanding of mineral deposits as an aid to exploration. These efforts have lead to classifications based on commodity, geologic setting (Cox and Singer, 1986), inferred temperatures and pressures of ore formation (Lindgren, 1933), and genetic setting (Park and MacDiarmid, 1975; Jensen and Bateman, 1979). None of these classification schemes is mutually exclusive; instead, there is considerable overlap among all of these classifications. A natural outcome …


Development Of A Circa 2000 Landcover Database For The United States, Collin Homer, Chengquan Huang, Limin Yang, Bruce K. Wylie Jan 2002

Development Of A Circa 2000 Landcover Database For The United States, Collin Homer, Chengquan Huang, Limin Yang, Bruce K. Wylie

United States Geological Survey: Publications

Multi-Resolution Land Characterization 2000 (MRLC 2000) is a second-generation federal consortium to create an updated pool of nation-wide Landsat 7 imagery, and derive a second-generation National Land Cover Database (NLCD 2000). This multi-layer, multisource database will include a suite of 30-meter resolution data that will serve as standardized ingredients for the production of land cover – both nationally and locally. This database will also provide the framework to allow flexibility in developing and applying suites of independent data layers. These nationally standardized independent data layers or components, will be useful not only within the land-cover classification but as data themes …