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Articles 1 - 30 of 70
Full-Text Articles in Physical Sciences and Mathematics
Seasonal Migration Of Columbia Spotted Frogs (Rana Luteiventris) Among Complementary Resources In A High Mountain Basin, David S. Pilliod, Charles R. Peterson, Peter I. Ritson
Seasonal Migration Of Columbia Spotted Frogs (Rana Luteiventris) Among Complementary Resources In A High Mountain Basin, David S. Pilliod, Charles R. Peterson, Peter I. Ritson
United States Geological Survey: Staff Publications
Information on how animals partition their activities and travel among complementary resources, such as breeding or overwintering habitats, is needed for species conservation. In a mountain basin at 2500 m elevation in central Idaho, we studied the habitat use and movement patterns of 736 marked and 87 radio-tagged Columbia spotted frogs (Rana luteiventris) from 1995 to 1998. The goals of this study were to (i) identify and characterize R. luteiventris breeding, summer foraging, and overwintering habitats, (ii) describe the movement patterns of juvenile, male, and female R. luteiventris among these resources, and (iii …
Effects Of Binary Combinations Of Herbicides On Freshwater Algae, Jill K. Taylor
Effects Of Binary Combinations Of Herbicides On Freshwater Algae, Jill K. Taylor
School of Natural Resources: Dissertations, Theses, and Student Research
No abstract provided.
An Improved Method For Determining Snowmelt Onset Dates Over Arctic Sea Ice Using Scanning Multichannel Microwave Radiometer And Special Sensor Microwave/Imager Data, Sheldon D. Drobot, Mark R. Anderson
An Improved Method For Determining Snowmelt Onset Dates Over Arctic Sea Ice Using Scanning Multichannel Microwave Radiometer And Special Sensor Microwave/Imager Data, Sheldon D. Drobot, Mark R. Anderson
Department of Earth and Atmospheric Sciences: Faculty Publications
Ablation of snow over sea ice is an important physical process affecting the Arctic surface energy balance. An improved understanding of the spatial and temporal variations in snowmelt onset could be utilized to improve climate simulations in the Arctic, as well as monitor the Arctic for signs of climate change. Utilizing an updated approach for monitoring snowmelt onset over Arctic sea ice, spatial variability in passive microwave derived snowmelt onset dates is examined from 1979 through 1998. The improved technique, termed the advanced horizontal range algorithm (AHRA), utilizes temporal variations in 18/19G Hz and 37 GHz passive microwave horizontal brightness …
Orbitally Induced Oscillations In The East Antarctic Ice Sheet At The Oligocene/Miocene Boundary, Tim R. Naish, Ken J. Woolfe, Peter J. Barrett, Gary S. Wilson, Cliff Atkins, Steven M. Bohaty, Christian J. Bücker, Michele Claps, Fred J. Davey, Gavin B. Dunbar, Alistair G. Dunn, Christopher R. Fielding, Fabio Florindo, Michael J. Hannah, David M. Harwood, Stuart A. Henrys, Lawrence A. Krissek, Mark Lavelle, Jaap Van Der Meer, William C. Mcintosh, Frank Niessen, Sandra Passchier, Ross D. Powell, Andrew P. Roberts, Leonardo Sagnotti, Reed P. Scherer, C. Percy Strong, Franco Talarico, Kenneth L. Verosub, Giuliana Villa, David K. Watkins, Peter-N. Webb, Thomas Wonik
Orbitally Induced Oscillations In The East Antarctic Ice Sheet At The Oligocene/Miocene Boundary, Tim R. Naish, Ken J. Woolfe, Peter J. Barrett, Gary S. Wilson, Cliff Atkins, Steven M. Bohaty, Christian J. Bücker, Michele Claps, Fred J. Davey, Gavin B. Dunbar, Alistair G. Dunn, Christopher R. Fielding, Fabio Florindo, Michael J. Hannah, David M. Harwood, Stuart A. Henrys, Lawrence A. Krissek, Mark Lavelle, Jaap Van Der Meer, William C. Mcintosh, Frank Niessen, Sandra Passchier, Ross D. Powell, Andrew P. Roberts, Leonardo Sagnotti, Reed P. Scherer, C. Percy Strong, Franco Talarico, Kenneth L. Verosub, Giuliana Villa, David K. Watkins, Peter-N. Webb, Thomas Wonik
Department of Earth and Atmospheric Sciences: Faculty Publications
Between 34 and 15 million years (Myr) ago, when planetary temperatures were 3-4°C warmer than at present and atmospheric CO2 concentrations were twice as high as today, the Antarctic ice sheets may have been unstable. Oxygen isotope records from deep-sea sediment cores suggest that during this time fluctuations in global temperatures and high-latitude continental ice volumes were influenced by orbital cycles. But it has hitherto not been possible to calibrate the inferred changes in ice volume with direct evidence for oscillations of the Antarctic ice sheets. Here we present sediment data from shallow marine cores in the western Ross …
Island Arcs, Accretionary Terranes And Midcontinent Structure New Understandings Of The Geologic Architecture Of The U.S. Midcontinent, Marvin P. Carlson
Island Arcs, Accretionary Terranes And Midcontinent Structure New Understandings Of The Geologic Architecture Of The U.S. Midcontinent, Marvin P. Carlson
Conservation and Survey Division
A data base collected over the last 100 years, containing both surface and subsurface information, has allowed us to begin to understand the physical framework of Nebraska. We have learned that even in the stable Midcontinent region of North America, there has been an active geologic history. This framework has been deciphered by our programs of surface geologic mapping and by the study of rock samples from both water wells and those deeper test wells for oil and gas. Determining the major structural features across the state (figure 1) has allowed us to better understand both the occurrences of its …
Experimental Diatom Dissolution And The Quantification Of Microfossil Preservation In Sediments, D. B. Ryves, S. Juggins, Sherilyn C. Fritz, R. W. Battarbee
Experimental Diatom Dissolution And The Quantification Of Microfossil Preservation In Sediments, D. B. Ryves, S. Juggins, Sherilyn C. Fritz, R. W. Battarbee
Department of Earth and Atmospheric Sciences: Faculty Publications
Four laboratory experiments on fresh, modern diatoms collected from lakes in the Northern Great Plains of North America were carried out to assess the effects of dissolution on diatom abundance and composition. Marked differences in mean dissolution susceptibility exist between species, despite sometimes significant intra- specific variation between heterovalves. Twenty-four taxa were ranked according to susceptibility to dissolution using an exponential decay model of valve abundance. This dissolution ranking was used to derive two weighted indices of sample preservation. A third index (F) was based on a simple binary classification of valve morphology into dissolved and pristine categories, …
Movement Of Rainbow And Brown Trout In Relation To Water Quality And Food Availability In Lake Ogallala, Nebraska, Corey M. Huxoll
Movement Of Rainbow And Brown Trout In Relation To Water Quality And Food Availability In Lake Ogallala, Nebraska, Corey M. Huxoll
School of Natural Resources: Dissertations, Theses, and Student Research
No abstract provided.
Environmental Change And The Central Great Plains, Carbon Sequestration, Mark A. Mesarch
Environmental Change And The Central Great Plains, Carbon Sequestration, Mark A. Mesarch
Conservation and Survey Division
No abstract provided.
Historical Water-Quality Data For The High Plains Regional Ground-Water Study Area In Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, And Wyoming, 1930–98, David W. Litke
Publications of the US Geological Survey
The High Plains aquifer underlies 174,000 square miles in parts of eight States and includes eight primary hydrogeologic units, including the well-known Ogallala Formation. The High Plains aquifer is an important resource, providing water for 27 percent of the Nation’s irrigated agricul¬tural lands in an otherwise dry landscape. Since the 1980’s there has been concern over the sustainability of the aquifer due to water-level declines caused by substantial pumping. Water quality of the aquifer is a more recent concern. As part of the U.S. Geological Survey’s National Water-Quality Assessment Program, historical water-quality data have been gathered for the High Plains …
Late Quaternary Climate And Hydrology Of Tropical South America Inferred From An Isotopic And Chemical Model Of Lake Titicaca, Bolivia And Peru, Scott L. Cross, Paul A. Baker, Geoffrey O. Seltzer, Sherilyn C. Fritz, Robert B. Dunbar
Late Quaternary Climate And Hydrology Of Tropical South America Inferred From An Isotopic And Chemical Model Of Lake Titicaca, Bolivia And Peru, Scott L. Cross, Paul A. Baker, Geoffrey O. Seltzer, Sherilyn C. Fritz, Robert B. Dunbar
Department of Earth and Atmospheric Sciences: Faculty Publications
A simple mass balance model provides insight into the hydrologic, isotopic, and chemical responses of Lake Titicaca to past climatic changes. Latest Pleistocene climate of the Altiplano is assumed to have been 20% wetter and 5°C colder than today, based on previous modeling. Our simulation of lacustrine change since 15,000 cal yr B.P. is forced by these modeled climate changes. The latest Pleistocene Lake Titicaca was deep, fresh, and overflowing. The latest Pleistocene riverine discharge from the lake was about 8 times greater than the modern average, sufficient to allow the expansion of the great paleolake Tauca on the central …
Ecosystems And Immune Systems: Hierarchical Response Provides Resilience Against Invasions, Craig R. Allen
Ecosystems And Immune Systems: Hierarchical Response Provides Resilience Against Invasions, Craig R. Allen
United States Geological Survey: Staff Publications
Janssen (2001) provides the stimulus for thoughtful comparison and consideration of the ranges of responses exhibited by immune systems and ecological systems in the face of perturbations such as biological invasions. It may indeed be informative to consider the similarities of the responses to invasions exhibited by immune systems and ecological systems. Clearly, both types of systems share a general organizational structure with all other complex hierarchical systems. Their organization provides these systems with resilience. However, when describing the response of ecological-economic systems to invasions, Janssen emphasizes the human-economic response. I would like to expand on his comparison by focusing …
Distributions Of Roosting Sandhill Cranes As Identified By Aerial Thermography, Tierny L. Parrish, Wayne A. Hubert, Stanley H. Anderson, Michael Pucherelli, Warren Mangus
Distributions Of Roosting Sandhill Cranes As Identified By Aerial Thermography, Tierny L. Parrish, Wayne A. Hubert, Stanley H. Anderson, Michael Pucherelli, Warren Mangus
United States Geological Survey: Staff Publications
We used aerial thermography to determine the location of sandhill crane (Grus canadensis) roosting sites during a single night over a 142-km reach of the Platte River, Nebraska. We assessed the influences of human disturbance features, screening of disturbance features by woody vegetation, distance to surrounding cropland of various types and channel width on distribution patterns of sandhill crane roosting sites with the aid of a geographic information system (GIS). We found that roosting sites were farther from bridges and paved roads than random points along the river channel; a visual woody screen mitigated the effect of bridges …
Effects Of Woody Cover In The Landscaping On Riparian Avifauna And A Preliminary Nesting Assessment, Micah W. Perkins
Effects Of Woody Cover In The Landscaping On Riparian Avifauna And A Preliminary Nesting Assessment, Micah W. Perkins
School of Natural Resources: Dissertations, Theses, and Student Research
No abstract provided.
Movements And Habitat Use By Hatchery-Reared Pallid Sturgeon In The Lower Platte River, Nebraska, Vaughn A. Snook
Movements And Habitat Use By Hatchery-Reared Pallid Sturgeon In The Lower Platte River, Nebraska, Vaughn A. Snook
School of Natural Resources: Dissertations, Theses, and Student Research
No abstract provided.
Characteristics Of Nest Sites Of Northern Bobwhites In Western Oklahoma, Darrell E. Townsend Ii, Ronald E. Masters, Robert L. Lochmiller, David M. Leslie Jr., Stephen J. Demaso, Alan D. Peoples
Characteristics Of Nest Sites Of Northern Bobwhites In Western Oklahoma, Darrell E. Townsend Ii, Ronald E. Masters, Robert L. Lochmiller, David M. Leslie Jr., Stephen J. Demaso, Alan D. Peoples
United States Geological Survey: Staff Publications
Previous authors have described nesting habitat of the northern bobwhite (Colinus virginianus) throughout its range, but few have compared structural or compositional differences of vegetation between nest sites and random non-use sites, and successful and non-successful nests. From 1996-1998, we compared cover and structure of 85 plant species from 80 nest sites of northern bobwhite in western Oklahoma. Nest sites were consistently associated with greater structural complexity than what was available at random. Bobwhites selected nest sites with a greater coverage of grass (ca. 50%) and woody (ca. 20-30%) vegetation with a relatively low percentage of bare ground, …
Environmental Change And The Central Great Plains, David Gosselin
Environmental Change And The Central Great Plains, David Gosselin
Conservation and Survey Division
No abstract provided.
Environmental Change And The Central Great Plain, Water Resources, David Gosselin
Environmental Change And The Central Great Plain, Water Resources, David Gosselin
Conservation and Survey Division
No abstract provided.
Agricultural Management Practices And The Groundwater System Of Northern Holt County, Nebraska, With A Focus On The Holt County Groundwater Education Project, Susan Olafsen Lackey, Charles Shapiro, William Kranz
Agricultural Management Practices And The Groundwater System Of Northern Holt County, Nebraska, With A Focus On The Holt County Groundwater Education Project, Susan Olafsen Lackey, Charles Shapiro, William Kranz
Conservation and Survey Division
No abstract provided.
Nebraska's Test-Hole Drilling Program And Records, Duane R. Mohlman, Charles A. Flowerday
Nebraska's Test-Hole Drilling Program And Records, Duane R. Mohlman, Charles A. Flowerday
Conservation and Survey Division
No abstract provided.
Geology Of Pioneers Park, Lancaster County, Nebraska, Roger K. Pabian
Geology Of Pioneers Park, Lancaster County, Nebraska, Roger K. Pabian
Conservation and Survey Division
No abstract provided.
Locating Nests Of Birds In Grasslands From A Mobile Tower Blind, Thomas F. Fondell, Steven T. Hoekman, I. J. Ball
Locating Nests Of Birds In Grasslands From A Mobile Tower Blind, Thomas F. Fondell, Steven T. Hoekman, I. J. Ball
United States Geological Survey: Staff Publications
Locating nests of grassland passerines can be difficult, labor intensive, and disruptive to birds and vegetation. We developed a mobile tower blind for observing adult bird behavior and used it to locate nests in a western Montana grassland. We compared nest-search efficiency of behavioral observations from the tower versus the ground. Nests of savannah sparrow (Passerculus samhvichensis) were found in a higher proportion of territories searched from the tower (13/16 = 82%) than from the ground (4113 = 3 1%). Average search time for each nest found was lower from the tower (44 min) than from the ground …
Tropical Climate Changes At Millennial And Orbital Timescales On The Bolivian Altiplano, Paul A. Baker, Catherine A. Rigsby, Geoffrey O. Seltzer, Sherilyn C. Fritz, Tim K. Lowenstein, Niklas P. Bacher, Carlos Veliz
Tropical Climate Changes At Millennial And Orbital Timescales On The Bolivian Altiplano, Paul A. Baker, Catherine A. Rigsby, Geoffrey O. Seltzer, Sherilyn C. Fritz, Tim K. Lowenstein, Niklas P. Bacher, Carlos Veliz
Department of Earth and Atmospheric Sciences: Faculty Publications
Tropical South America is one of the three main centers of the global, zonal overturning circulation of the equatorial atmosphere (generally termed the “Walker” circulation). Although this area plays a key role in global climate cycles, little is known about South American climate history. Here we describe sediment cores and down-hole logging results of deep drilling in the Salar de Uyuni, on the Bolivian Altiplano, located in the tropical Andes. We demonstrate that during the past 50,000 years the Altiplano underwent important changes in effective moisture at both orbital (20,000-year) and millennial timescales. Long-duration wet periods, such as the Last …
The History Of South American Tropical Precipitation For The Past 25,000 Years, Paul A. Baker, Geoffrey O. Seltzer, Sherilyn C. Fritz, Robert B. Dunbar, Matthew J. Grove, Pedro M. Tapia, Scott L. Cross, Harold D. Rowe, James P. Broda
The History Of South American Tropical Precipitation For The Past 25,000 Years, Paul A. Baker, Geoffrey O. Seltzer, Sherilyn C. Fritz, Robert B. Dunbar, Matthew J. Grove, Pedro M. Tapia, Scott L. Cross, Harold D. Rowe, James P. Broda
Department of Earth and Atmospheric Sciences: Faculty Publications
Long sediment cores recovered from the deep portions of Lake Titicaca are used to reconstruct the precipitation history of tropical South America for the past 25,000 years. Lake Titicaca was a deep, fresh, and continuously overflowing lake during the last glacial stage, from before 25,000 to 15,000 calibrated years before the present (cal yr B.P.), signifying that during the last glacial maximum (LGM), the Altiplano of Bolivia and Peru and much of the Amazon basin were wetter than today. The LGM in this part of the Andes is dated at 21,000 cal yr B.P., approximately coincident with the global LGM. …
Results Of Whole-Rock Organic Geochemical Analyses Of The Crp-3 Drillcore, Victoria Land Basin, Antarctica, Richard M. Kettler
Results Of Whole-Rock Organic Geochemical Analyses Of The Crp-3 Drillcore, Victoria Land Basin, Antarctica, Richard M. Kettler
Department of Earth and Atmospheric Sciences: Faculty Publications
Sediments and rocks recovered in CRP-3 coring operations contain minute amounts of organic matter (average 0.3% TOC). TOC contents and C:N ratios are zoned systematically: those rocks encountered at depths greater than 330 meters below sea floor (mbsf) contain less organic matter and have higher TOC:N ratios (after correcting for inorganic N) than do shallower rocks. The only two samples that have TOC values greater than 1% also contain abundant granule to silt-sized particles of coal. The total sulphur contents of these rocks is very low and indicates either that only small amounts of deposited organic matter were labile, or …
Facies Architecture Of The Crp-3 Drillhole, Victoria Land Basin, Antarctica, Christopher R. Fielding, T. R. Naish, K. J. Woolfe
Facies Architecture Of The Crp-3 Drillhole, Victoria Land Basin, Antarctica, Christopher R. Fielding, T. R. Naish, K. J. Woolfe
Department of Earth and Atmospheric Sciences: Faculty Publications
The Cenozoic Victoria Land Basin (VLB) stratigraphic section penetrated by CRP-3 is mostly of Early Oligocene age. It contains an array of lithofacies comprising fine-grained mudrocks, interlaminated and interbedded mudrocks/sandstones, mud-rich and mud-poor sandstones, conglomerates and diamctites that are together interpreted as the products of shallow marine to possibly non-marine environments of deposition, affected by the periodic advance and retreat of tidewater glaciers. This lithofacies assemblage can be readily rationalised using the facies scheme designed originally for CRP-2/2A, and published previously. The uppermost 330 metres below sea floor (mbsf) shows a cyclical arrangement of lithofacies also similar to that recognised …
Depositional Environments For Strata Cored In Crp-3 (Cape Roberts Project), Victoria Land Basin, Antarctica: Palaeoglaciological And Palaeoclimatological Inferences, R. D. Powell, M. G. Laird, T. R. Naish, Christopher R. Fielding, L. A. Krissek, J.J. M. Van Der Meer
Depositional Environments For Strata Cored In Crp-3 (Cape Roberts Project), Victoria Land Basin, Antarctica: Palaeoglaciological And Palaeoclimatological Inferences, R. D. Powell, M. G. Laird, T. R. Naish, Christopher R. Fielding, L. A. Krissek, J.J. M. Van Der Meer
Department of Earth and Atmospheric Sciences: Faculty Publications
Cape Roberts Project drill core 3 (CRP-3) was obtained from Roberts ridge, a sea-floor high located at 77oS, 12 km offshore from Cape Roberts in western McMurdo Sound, Antarctica. The recovered core is about 939 m long and comprises strata dated as being early Oligocene (possibly latest Eocene) in age, resting unconformably on ~116 m of basement rocks consisting of Palaeozoic Beacon Supergroup sediments. The core includes ten facies commonly occurring in five major associations that are repeated in particular sequences throughout the core and which are interpreted as representing different depositional environments through time. Depositional systems inferred …
Laser-Derived Particle Size Data From Crp-3, Victoria Land Basin, Antarctica: Implications For Sequence And Seismic Stratigraphy, Christopher R. Fielding, G. B. Dunbar, S. M. Bryce
Laser-Derived Particle Size Data From Crp-3, Victoria Land Basin, Antarctica: Implications For Sequence And Seismic Stratigraphy, Christopher R. Fielding, G. B. Dunbar, S. M. Bryce
Department of Earth and Atmospheric Sciences: Faculty Publications
Seven hundred and nineteen samples from throughout the Cainozoic section in CRP-3 were analysed by a Malvern Mastersizer laser particle analyser, in order to derive a stratigraphic distribution of grain-size parameters downhole. Entropy analysis of these data (using the method of Woolfe & Michibayashi, 1995) allowed recognition of four groups of samples, each group characterised by a distinctive grain-size distribution. Group 1, which shows a multi-modal distribution, corresponds to mudrocks, interbedded mudrock/sandstone facies, muddy sandstones and diamictites. Group 2, with a sand-grade mode but showing wide dispersion of particle size, corresponds to muddy sandstones, a few cleaner sandstones and some …
Sedimentary Cyclicity In Crp Drillcore, Victoria Land Basin, Antarctica, T. R. Naish, P. J. Barrett, G. B. Dunbar, K. J. Woolfe, A. G. Dunn, S. A. Henrys, M. Claps, R. D. Powell, Christopher R. Fielding
Sedimentary Cyclicity In Crp Drillcore, Victoria Land Basin, Antarctica, T. R. Naish, P. J. Barrett, G. B. Dunbar, K. J. Woolfe, A. G. Dunn, S. A. Henrys, M. Claps, R. D. Powell, Christopher R. Fielding
Department of Earth and Atmospheric Sciences: Faculty Publications
The upper 1200 m of pre-Pliocene sediment recovered by Cape Roberts Project (CRP) drilling off the Victoria Land coast of Antarctica between 1997-1999 has been subdivided into 54 unconformity-bound stratigraphic sequences, spanning the period c. 32 to 17 Ma. The sequences are recognised on the basis of the cyclical vertical stacking of their constituent lithofacies, which are enclosed by erosion surfaces produced during the grounding of the advancing ice margin onto the sea floor. Each sequence represents deposition in a range of offshore shelf to coastal glacimarine sedimentary environments during oscillations in the ice margin across the Western Ross Sea …
Calcareous Nannofossils From Cape Roberts Project Drillhole Crp-3, Victoria Land Basin, Antarctica, David K. Watkins, S. W. Wise Jr., G. Villa
Calcareous Nannofossils From Cape Roberts Project Drillhole Crp-3, Victoria Land Basin, Antarctica, David K. Watkins, S. W. Wise Jr., G. Villa
Department of Earth and Atmospheric Sciences: Faculty Publications
Fossil specimens of the exclusively oceanic calcareous nannoplankton were found only in the upper 200 m of the Cape Roberts Project 3 (CRP-3) cores. These assemblages are depauperate and sporadic in occurrence. The majority of the assemblages contain fewer than 4 species, indicating a severe palaeoecological restriction. The clear domination of these assemblages by reticulofenestrid species, coupled with the almost total exclusion of Coccolithus pelagicus, indicates cold surface water conditions in the Victoria Land Basin during the lives of these poor algae. These cold surface water conditions, perhaps coupled with abnormal surface water chemistry, excluded almost all of the …
Spatial And Temporal Variability In Snowmelt Onset Over Arctic Sea Ice, Mark R. Anderson, Sheldon D. Drobot
Spatial And Temporal Variability In Snowmelt Onset Over Arctic Sea Ice, Mark R. Anderson, Sheldon D. Drobot
Department of Earth and Atmospheric Sciences: Faculty Publications
Climate models suggest surface warming in the Arctic will be rapid and pronounced, implying substantial changes in snowmelt onset are likely. This research therefore examines spatial and temporal variability in passive-microwave derived snowmelt-onset dates over Arctic sea ice. The objectives are to understand better the regional characteristics of snowmelt and to document whether the snowmelt-onset record shows signs of climate change. Snowmelt-onset dates are derived with Scanning Multichannel Microwave Radiometer and Special Sensor Microwave/Imager brightness-temperature data, and they are subsequently stratified into 13 regions to analyze spatial and temporal variability. Results illustrate significant spatial variability in snowmelt onset, with the …