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Geology

University of Nebraska - Lincoln

2014

Articles 31 - 45 of 45

Full-Text Articles in Physical Sciences and Mathematics

Geologic Setting And Stratigraphy Of The Ziegler Reservoir Fossil Site, Snowmass Village, Colorado, Jeffrey S. Pigati, Ian M. Miller, Kirk R. Johnson, Jeffrey S. Honke, Paul E. Carrara, Daniel R. Muhs, Gary Skipp, Bruce Bryant Jan 2014

Geologic Setting And Stratigraphy Of The Ziegler Reservoir Fossil Site, Snowmass Village, Colorado, Jeffrey S. Pigati, Ian M. Miller, Kirk R. Johnson, Jeffrey S. Honke, Paul E. Carrara, Daniel R. Muhs, Gary Skipp, Bruce Bryant

United States Geological Survey: Staff Publications

The geologic setting of the Ziegler Reservoir fossil site is somewhat unusual—the sediments containing the Pleistocene fossils were deposited in a lake on top of a ridge. The lake basin was formed near Snowmass Village, Colorado (USA) when a glacier flowing down Snowmass Creek Valley became thick enough to overtop a low point in the eastern valley wall and entered the head of Brush Creek Valley. When the glacier retreated at about 155–130 ka, near the end of Marine Oxygen Isotope Stage 6, the Brush Creek Valley lobe left behind a moraine that impounded a small alpine lake. The lake …

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Exposure And Food Web Transfer Of Pharmaceuticals In Ospreys (Pandion Haliaetus): Predictive Model And Empirical Data, Rebecca S. Lazarus, Barnett A. Rattner, Bryan W. Brooks, Bowen Du, Peter C. Mcgowan, Vicki S. Blazer, Mary Ann Ottinger Jan 2014

Exposure And Food Web Transfer Of Pharmaceuticals In Ospreys (Pandion Haliaetus): Predictive Model And Empirical Data, Rebecca S. Lazarus, Barnett A. Rattner, Bryan W. Brooks, Bowen Du, Peter C. Mcgowan, Vicki S. Blazer, Mary Ann Ottinger

United States Geological Survey: Staff Publications

The osprey (Pandion haliaetus) is a well‐known sentinel of environmental contamination, yet no studies have traced pharmaceuticals through the water–fish–osprey food web. A screening‐level exposure assessment was used to evaluate the bioaccumulation potential of 113 pharmaceuticals and metabolites, and an artificial sweetener in this food web. Hypothetical concentrations in water reflecting “wastewater effluent dominated” or “dilution dominated” scenarios were combined with pH‐specific bioconcentration factors (BCFs) to predict uptake in fish. Residues in fish and osprey food intake rate were used to calculate the daily intake (DI) of compounds by an adult female osprey. Fourteen pharmaceuticals and a drug …

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Identifying Sources Of Aeolian Mineral Dust: Present And Past, Daniel R. Muhs, Joseph M. Prospero, Matthew C. Baddock, Thomas E. Gill Jan 2014

Identifying Sources Of Aeolian Mineral Dust: Present And Past, Daniel R. Muhs, Joseph M. Prospero, Matthew C. Baddock, Thomas E. Gill

United States Geological Survey: Publications

Aeolian mineral dust is an important component of the Earth’s environmental systems, playing roles in the planetary radiation balance, as a source of fertilizer for biota in both terrestrial and marine realms and as an archive for understanding atmospheric circulation and paleoclimate in the geologic past. Crucial to understanding all of these roles of dust is the identification of dust sources. Here we review the methods used to identify dust sources active at present and in the past. Contemporary dust sources, produced by both glaciogenic and non-glaciogenic processes, can be readily identified by the use of Earth-orbiting satellites. These data …

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Interpreting The Paleozoogeography And Sea Level History Of Thermally Anomalous Marine Terrace Faunas: A Case Study From The Last Interglacial Complex Of San Clemente Island, California, Daniel R. Muhs, Lindsey T. Groves, R. Randall Schumann Jan 2014

Interpreting The Paleozoogeography And Sea Level History Of Thermally Anomalous Marine Terrace Faunas: A Case Study From The Last Interglacial Complex Of San Clemente Island, California, Daniel R. Muhs, Lindsey T. Groves, R. Randall Schumann

United States Geological Survey: Publications

Marine invertebrate faunas with mixtures of extralimital southern and extralimital northern faunal elements, called thermally anomalous faunas, have been recognized for more than a century in the Quaternary marine terrace record of the Pacific Coast of North America. Although many mechanisms have been proposed to explain this phenomenon, no single explanation seems to be applicable to all localities where thermally anomalous faunas have been observed. Here, we describe one such thermally anomalous fossil fauna that was studied on the second emergent marine terrace at Eel Point on San Clemente Island. The Eel Point terrace complex is a composite feature, consisting …

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Structural Equation Models Of Vmt Growth In Us Urbanised Areas, Reid Ewing, Shima Hamidi, Frank Gallivan, Arthur C. Nelson, James B. Grace Jan 2014

Structural Equation Models Of Vmt Growth In Us Urbanised Areas, Reid Ewing, Shima Hamidi, Frank Gallivan, Arthur C. Nelson, James B. Grace

United States Geological Survey: Staff Publications

Vehicle miles travelled (VMT) is a primary performance indicator for land use and transportation, bringing with it both positive and negative externalities. This study updates and refines previous work on VMT in urbanised areas, using recent data, additional metrics and structural equation modelling (SEM). In a cross-sectional model for 2010, population, income and freeway capacity are positively related to VMT, while gasoline prices, development density and transit service levels are negatively related. Findings of the cross-sectional model are generally confirmed in a more tightly controlled longitudinal study of changes in VMT between 2000 and 2010, the first model of its …

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Summary Of The Snowmastodon Project Special Volume: A High-Elevation, Multi-Proxy Biotic And Environmental Record Of Mis 6–4 From The Ziegler Reservoir Fossil Site, Snowmass Village, Colorado, Usa, Ian M. Miller, Jeffrey S. Pigati, R. Scott Anderson, Kirk R. Johnson, Shannon A. Mahan, Thomas A. Ager, Richard G. Baker, Maarten Blaauw, Jordon Bright, Peter M. Brown, Bruce Bryant, Zachary T. Calamari, Paul E. Carrara, Michael D. Cherney, John R. Demboski, Scott A. Elias, Daniel C. Fisher, Harrison J. Gray, Danielle R. Haskett, Jeffrey S. Honke, Stephen T. Jackson, Gonzalo Jiménez- Moreno, Douglas Kline, Eric M. Leonard, Nathaniel A. Lifton, Carol Lucking, H. Gregory Mcdonald, Dane M. Miller, Daniel R. Muhs, Stephen E. Nash, Cody Newton, James B. Paces, Lesley Petrie, Mitchell A. Plummer, David F. Porinchu, Adam N. Rountrey, Eric Scott, Joseph J.W. Sertich, Saxon E. Sharpe, Gary L. Skipp, Laura E. Strickland, Richard K. Stucky, Robert S. Thompson, Jim Wilson Jan 2014

Summary Of The Snowmastodon Project Special Volume: A High-Elevation, Multi-Proxy Biotic And Environmental Record Of Mis 6–4 From The Ziegler Reservoir Fossil Site, Snowmass Village, Colorado, Usa, Ian M. Miller, Jeffrey S. Pigati, R. Scott Anderson, Kirk R. Johnson, Shannon A. Mahan, Thomas A. Ager, Richard G. Baker, Maarten Blaauw, Jordon Bright, Peter M. Brown, Bruce Bryant, Zachary T. Calamari, Paul E. Carrara, Michael D. Cherney, John R. Demboski, Scott A. Elias, Daniel C. Fisher, Harrison J. Gray, Danielle R. Haskett, Jeffrey S. Honke, Stephen T. Jackson, Gonzalo Jiménez- Moreno, Douglas Kline, Eric M. Leonard, Nathaniel A. Lifton, Carol Lucking, H. Gregory Mcdonald, Dane M. Miller, Daniel R. Muhs, Stephen E. Nash, Cody Newton, James B. Paces, Lesley Petrie, Mitchell A. Plummer, David F. Porinchu, Adam N. Rountrey, Eric Scott, Joseph J.W. Sertich, Saxon E. Sharpe, Gary L. Skipp, Laura E. Strickland, Richard K. Stucky, Robert S. Thompson, Jim Wilson

United States Geological Survey: Staff Publications

In North America, terrestrial records of biodiversity and climate change that span Marine Oxygen Isotope Stage (MIS) 5 are rare. Where found, they provide insight into how the coupling of the ocean–atmosphere system is manifested in biotic and environmental records and how the biosphere responds to climate change. In 2010–2011, construction at Ziegler Reservoir near Snowmass Village, Colorado (USA) revealed a nearly continuous, 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 also contained thousands of well-preserved bones …

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The Inky Story Of The Dinky Oak Gall, Ken Sulak Jan 2014

The Inky Story Of The Dinky Oak Gall, Ken Sulak

United States Geological Survey: Staff Publications

Maybe you have noticed these little spheres before – but did not give them much thought. Or maybe, you puzzled: What are these wooden pearls? How did they get there? Well, a tiny wasp, called the pea galler wasp or gallfly, Belonocnema treatae, is the culprit. The diminutive female gallfly (one of nearly a thousand species in the gall wasp family Cynipidae), about the size of a fire ant, lays eggs on a freshly budded live oak leaf in spring. When the larva hatches, it produces a chemical that induces the oak to enclose it in a protective and …

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Probit Models For Capture-Recapture Data Subject To Imperfect Detection, Individual Heterogeneity And Misidentification, Brett T. Mcclinktock, Larissa L. Bailey, Brian P. Dreher, William A. Link Jan 2014

Probit Models For Capture-Recapture Data Subject To Imperfect Detection, Individual Heterogeneity And Misidentification, Brett T. Mcclinktock, Larissa L. Bailey, Brian P. Dreher, William A. Link

United States Geological Survey: Staff Publications

As noninvasive sampling techniques for animal populations have become more popular, there has been increasing interest in the development of capture-recapture models that can accommodate both imperfect detection and misidentification of individuals (e.g., due to genotyping error). However, current methods do not allow for individual variation in parameters, such as detection or survival probability. Here we develop misidentification models for capture-recapture data that can simultaneously account for temporal variation, behavioral effects and individual heterogeneity in parameters. To facilitate Bayesian inference using our approach, we extend standard probit regression techniques to latent multinomial models where the dimension and zeros of the …

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Evidence Of Repeated Wildfires Prior To Human Occupation On San Nicolas Island, California, Jeffrey S. Pigati, John P. Mcgeehin, Gary L. Skipp, Daniel R. Muhs Jan 2014

Evidence Of Repeated Wildfires Prior To Human Occupation On San Nicolas Island, California, Jeffrey S. Pigati, John P. Mcgeehin, Gary L. Skipp, Daniel R. Muhs

United States Geological Survey: Staff Publications

Understanding how early humans on the California Channel Islands might have changed local fire regimes requires a baseline knowledge of the frequency of natural wildfires on the islands prior to human occupation. A sedimentary sequence that was recently discovered in a small canyon on San Nicolas Island contains evidence of at least 24 burn events that date to between ~37 and 25 ka (thousands of calibrated 14C years before present), well before humans entered North America. The evidence includes abundant macroscopic charcoal, blackened sediments, and discrete packages of oxidized, reddish-brown sediments that are similar in appearance to sedimentary features …

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Integrating Land Cover Modeling And Adaptive Management To Conserve Endangered Species And Reduce Catastrophic Fire Risk, David Breininger, Brean Duncan, Mitchell J. Eaton, Fred Johnson, James Nichols Jan 2014

Integrating Land Cover Modeling And Adaptive Management To Conserve Endangered Species And Reduce Catastrophic Fire Risk, David Breininger, Brean Duncan, Mitchell J. Eaton, Fred Johnson, James Nichols

United States Geological Survey: Staff Publications

Land cover modeling is used to inform land management, but most often via a two-step process, where science informs how management alternatives can influence resources, and then, decision makers can use this information to make decisions. A more efficient process is to directly integrate science and decision-making, where science allows us to learn in order to better accomplish management objectives and is developed to address specific decisions. Co-development of management and science is especially productive when decisions are complicated by multiple objectives and impeded by uncertainty. Multiple objectives can be met by the specification of tradeoffs, and relevant uncertainty can …

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Some Reflections On Our Experiences At Sun Yat-Sen University Since 1985, Robert F. Diffendal Jr., Anne P. Diffendal Jan 2014

Some Reflections On Our Experiences At Sun Yat-Sen University Since 1985, Robert F. Diffendal Jr., Anne P. Diffendal

Robert F. Diffendal, Jr., Publications

Professor Zhang Ke, Chairman of the Department of Earth Sciences at Sun Yat-sen University, has asked us to write about some of our memories from our several visits to Sun Yat-sen University, as part of the 2014 celebration of the 90th anniversary of the founding of the university and the creation of the department. We are very pleased to do so and to include with our written comments copies of some photographs that we have taken during these visits. We have gone back through our notes, books, tourist maps, photo files, and other information that we have kept as souvenirs …

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Ashfall Tephra In The Ogallala Group Of The Great Plains: Characteristics And Significance, Michael E. Perkins, Robert F. Diffendal Jr., Michael R. Voorhies, Barbara P. Nash, Bruce E. Bailey Jan 2014

Ashfall Tephra In The Ogallala Group Of The Great Plains: Characteristics And Significance, Michael E. Perkins, Robert F. Diffendal Jr., Michael R. Voorhies, Barbara P. Nash, Bruce E. Bailey

Robert F. Diffendal, Jr., Publications

The Miocene Ogallala Group blankets the Great Plains east of the Rocky Mountains. This sheet of largely fluvial deposits, lying downwind of major silicic volcanic fields to the west, was ideally located to receive and preserve tephra from these fields. This investigation brings modern methods of tephrochronlogy to bear on the age and identity of Ogallala tephra. Results indicate that ~40 separate tephra layers, ranging in age from ~16.5–5.0 Ma, in the Ogallala. Most tephra came from Yellowstone hotspot sources. The relative frequency of hotspot tephra in the Ogallala matches that in more proximal regions to the west with peak …

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The Groundwater Atlas Of Lancaster County, Dana Divine Jan 2014

The Groundwater Atlas Of Lancaster County, Dana Divine

Conservation and Survey Division

No abstract provided.

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Analysis Of Vesicular Porosity In Soils Using High-Resolution X-Ray Computed Tomograpy, Judith K. Turk, Robert C. Graham Jan 2014

Analysis Of Vesicular Porosity In Soils Using High-Resolution X-Ray Computed Tomograpy, Judith K. Turk, Robert C. Graham

Conservation and Survey Division

Vesicular horizons are common at the surface of arid and semiarid soils and play a critical role in regulating infiltration. Most methods for examining pore morphology in the vesicular horizon involve physical sectioning of the sample and individual measurement of pores, which is time-consuming and provides an incomplete view of the pores. The objectives of this study were to (i) develop methods for the classification and characterization of pores in the vesicular horizon using high resolution X-ray computed tomography (HRXCT) and (ii) use these methods to examine the distribution of pores within vesic-ular peds. Three intact peds were scanned by …

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Nebraska Statewide Groundwater-Level Monitoring Report 2014, A. R. Young, M. E. Burbach, L. M. Howard Jan 2014

Nebraska Statewide Groundwater-Level Monitoring Report 2014, A. R. Young, M. E. Burbach, L. M. Howard

Conservation and Survey Division

No abstract provided.

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