Physical Sciences and Mathematics Commons^™

Does Gender Bias Influence Awards Given By Societies?, Mary Anne Holmes, Pranoti Asher, John Farrington, Rana Fine, Margaret S. Leinen, Phoebe Leboy

Department of Earth and Atmospheric Sciences: Faculty Publications

AGU is a participant in a U.S. National Science Foundation (NSF)–funded project called Advancing Ways of Awarding Recognition in Disciplinary Societies (AWARDS), which seeks to examine whether gender bias affects selection of recipients of society awards. AGU is interested in learning why there is a higher proportion of female recipients of service and education awards over the past 2 decades. Combined with a lower rate of receipt of research awards, these results suggest that implicit (subconscious) bias in favor of male candidates still influences awardee selection.

Six other professional societies (American Chemical Society, American Mathematical Society, American Society of Anesthesiologists, …

The Pennsylvanian–Permian Transition In The Low-Latitude Carbonate Record And The Onset Of Major Gondwanan Glaciation, Jesse Koch, Tracy D. Frank

Department of Earth and Atmospheric Sciences: Faculty Publications

Recent studies suggest a marked expansion of glacial ice across much of Gondwana beginning in the earliest Permian. Because expansion of glacial ice results in a lowering of sea level, the imprint of ice expansion should be evident worldwide as significant exposure event, hiatuses, or other evidence for sea level drop at or near the Pennsylvanian–Permian boundary. This literature review investigates the signature of an Early Permian expansion of Gondwanan ice through examination of stratigraphic records from eight carbonate-dominated, palaeotropical regions across Pangaea. Tropical carbonate environments are used because most form in tectonically quiescent regions and are sensitive indicators of …

The Collaborative Colorado– Nebraska Unmanned Aircraft System Experiment, Adam L. Houston, Brian Argrow, Jack Elston, Jamie Lahowetz, Eric W. Frew, Patrick C. Kennedy

Department of Earth and Atmospheric Sciences: Faculty Publications

Unmanned aircraft (UA) can provide observations of atmospheric phenomena that are either difficult or impossible to obtain with existing platforms. It is for this reason that facilitating the maturation of this relatively new technology has become a high priority in the atmospheric sciences. This position is reflected in the 2007 National Research Council Decadal Survey, which states that unmanned aircraft technology “should be increasingly factored into the nation’s strategic plan for Earth science” (National Research Council 2007, p. 14). Moreover, the fiscal year 2008 budget for the National Oceanic and Atmospheric Administration (NOAA) featured an increased investment in unmanned aircraft …

Environmental History Of A Closed-Basin Lake In The Us Great Plains: Diatom Response To Variations In Groundwater Flow Regimes Over The Last 8500 Cal. Yr Bp, William O. Hobbs, Sherilyn C. Fritz, Jeffery R. Stone, Joseph J. Donovan, Eric C. Grimm, James E. Almendinger

Department of Earth and Atmospheric Sciences: Faculty Publications

Sediment records from closed-basin lakes in the Northern Great Plains (NGP) of North America have contributed significantly to our understanding of regional paleoclimatology. A high-resolution (near decadal) fossil diatom record from Kettle Lake, ND, USA that spans the last 8500 cal. yr BP is interpreted in concert with percent abundance of aragonite in the sediment as an independent proxy of groundwater flow to the lake (and thus lake water level). Kettle Lake has been relatively fresh for the majority of the Holocene, likely because of the coarse substrata and a strong connection to the underlying aquifer. Interpretation of diatom assemblages …

Abrupt Holocene Climate Change As An Important Factor For Human Migration In West Greenland, William J. D'Andrea, Yongsong Huang, Sherilyn C. Fritz, N. John Anderson

Department of Earth and Atmospheric Sciences: Faculty Publications

West Greenland has had multiple episodes of human colonization and cultural transitions over the past 4,500 y. However, the explanations for these large-scale human migrations are varied, including climatic factors, resistance to adaptation, economic marginalization, mercantile exploration, and hostile neighborhood interactions. Evaluating the potential role of climate change is complicated by the lack of quantitative paleoclimate reconstructions near settlement areas and by the relative stability of Holocene temperature derived from ice cores atop the Greenland ice sheet. Here we present high-resolution records of temperature over the past 5,600 y based on alkenone unsaturation in sediments of two lakes in West …

Taxonomic Composition, Paleoecology And Biostratigraphy Of Late Cretaceous Diatoms From Devon Island, Nunavut, Canadian High Arctic, Jakub Witkowski, David M. Harwood, Karen Chin

Department of Earth and Atmospheric Sciences: Faculty Publications

Upper Cretaceous sediments of the Kanguk Formation exposed in Eidsbotn and Viks Fiord grabens on Devon Island, Nunavut, Canadian High Arctic, yielded 91 fossil marine diatom species and varieties (including indeterminate taxa), representing 41 genera. Excellent preservation of the assemblages was aided by shallow burial, protection in down­faulted linear grabens, and the presence of abundant volcanic material. Planktonic species and resting spores com­prise nearly 70% of the diatom assemblage, and provided abundant food resources for the Late Cretaceous Arctic eco­system. Deposition of the approximately 225 m-thick stratigraphic sequence was predominantly in a shallow marine neritic setting, with an upward progression …

Late Pleistocene Paleohydrography And Diatom Paleoecology Of The Central Basin Of Lake Malawi, Africa, Jeffery R. Stone, Karlyn S. Westover, Andrew S. Cohen

Department of Earth and Atmospheric Sciences: Faculty Publications

Analysis of sedimentary diatom assemblages (10 to 144 ka) form the basis for a detailed reconstruction of the paleohy­drography and diatom paleoecology of Lake Malawi. Lake-level fluctuations on the order of hundreds of meters were in­ferred from dramatic changes in the fossil and sedimentary archives. Many of the fossil diatom assemblages we observed have no analog in modern Lake Malawi. Cyclotelloid diatom species are a major component of fossil assemblages prior to 35 ka, but are not found in significant abundances in the modern diatom communities in Lake Malawi. Salinity- and alkalin­ity-tolerant plankton has not been reported in the modern …

Aragonite Loss In A Cold-Water Coral Mound: Mechanisms And Implications, Tracy D. Frank, Jürgen Titschack, Mieke Thierens

Department of Earth and Atmospheric Sciences: Faculty Publications

Selective dissolution of aragonitic grains is emerging as a volumetrically significant process that affects a broad range of modern carbonate settings. This study explores mechanisms and implications of aragonite loss in Challenger Mound, a giant cold-water coral (Lophelia pertusa) mound of Pleistocene age, which lies on the continental slope off southwest Ireland. A comprehensive sampling scheme allowed the integration of petrographic data with geochemical analyses of sediment and pore water. The mound remains virtually unlithified and consists of stacked, fining-upward cycles of silty coral floatstone–rudstone and bafflestone grading into wackestone. Whereas calcitic grains appear unaltered, aragonitic grains are …

Late Cretaceous To Recent Deformation Related To Inherited Structures And Subsequent Compression Within The Persian Gulf: A 2d Seismic Case Study, Caroline M. Burberry, C. A.-L. Jackson, J. W. Cosgrove

Department of Earth and Atmospheric Sciences: Faculty Publications

The Persian Gulf is part of an asymmetric foreland basin related to the Zagros Orogen. Few published studies of this basin and associated onshore areas include seismic reflection data. We present a seismic-stratigraphic interpretation based on marine 2D seismic data, which reveals the presence of two types of compressional structures within the basin: (1) faulted domes related to salt movement and the offshore trace of a NNE–SSW-trending dextral basement fault (the Kazerun Fault); (2) long-wavelength (16 km), low-amplitude (60 ms two-way travel time) folds relating to the advancing deformation front associated with the orogen. Thinning of age-constrained stratal units across …

Estimating Hydraulic Conductivity For The Martian Subsurface Based On Drainage Patterns — A Case Study In The Mare Tyrrhenum Quadrangle, Wei Luo, Bartosz Grudzinski, Darryll T. Pederson

Department of Earth and Atmospheric Sciences: Faculty Publications

Hydraulic conductivity K, as the coefficient of proportionality in Darcy’s Law, is critical in understanding the past Martian hydrologic cycle, climate, and landform evolution. However, K and its spatial variability on Mars are thus far poorly constrained due to lack of accessibility. Using an innovative method based on surface drainage dissection patterns, which has been successfully tested in the Oregon Cascades on Earth, we estimated K in the Mare Tyrrhenum Quadrangle on Mars. The basic assumption is that under long-term dynamic equilibrium conditions, the overall dissection pattern in a watershed as reflected in drainage density is controlled by the …

Late Pleistocene Dune Activity In The Central Great Plains, Usa, Joseph A. Mason, James B. Swinehart, Paul R. Hanson, David Loope, Ronald J. Goble, Xiaodong Miao, Rebecca L Schmeisser

Department of Earth and Atmospheric Sciences: Faculty Publications

Stabilized dunes of the central Great Plains, especially the megabarchans and large barchanoid ridges of the Nebraska Sand Hills, provide dramatic evidence of late Quaternary environmental change. Episodic Holocene dune activity in this region is now well-documented, but Late Pleistocene dune mobility has remained poorly documented, despite early interpretations of the Sand Hills dunes as Pleistocene relicts. New optically stimulated luminescence (OSL) ages from drill cores and outcrops provide evidence of Late Pleistocene dune activity at sites distributed across the central Great Plains. In addition, Late Pleistocene eolian sands deposited at 20–25 ka are interbedded with loess south of the …

A Regional-Scale Climate Reconstruction Of The Last 4000 Years From Lakes In The Nebraska Sand Hills, Usa, Jens Schmieder, Sherilyn C. Fritz, James B. Swinehart, Avery L. C. Shinneman, Alexander P. Wolfe, Gifford Miller, N. Daniels, K. C. Jacobs, Eric C. Grimm

Department of Earth and Atmospheric Sciences: Faculty Publications

High-resolution paleohydrological reconstructions were carried out in five shallow lakes in the Nebraska Sand Hills across an east–west transect in order to 1) determine whether long-term droughts of the past 4000 years were spatially and temporally coherent across the region, 2) distinguish local variation in climate or hydrology from regional patterns of change, and 3) compare the paleolimnological results with the existing dune-inferred drought records. Diatom- inferred lake-level was reconstructed for all sites and compared with other regional records. Alterations between high and low lake-levels were frequent during the past 4000 years, which suggests that shifts between dry and wet …

Evolution Of Large Carnivores During The Mid-Cenozoic Of North America: The Temnocyonine Radiation (Mammalia, Amphicyonidae) Robert M., Robert M. Hunt Jr.

Department of Earth and Atmospheric Sciences: Faculty Publications

This study describes and summarizes the Temnocyoninae (Mammalia, Carnivora), a subfamily of amphicyonid carnivores of considerable diversity and singular ecomorphology within Cenozoic faunas of North America. In temnocyonines, we see the first carnivorans to occupy an ecological niche as large cursorial predators. The subfamily is confined to the Arikareean NALMA, ranging in age from the latest early Oligocene to the early Miocene. Distributed from the Pacific Northwest to the Great Plains and Florida, there are four genera (Temnocyon, Mammacyon, Delotrochanter n. gen., Rudiocyon n. gen.) and 12 species, of which eight are newly described (Temnocyon subferox …

Mass Wasting As A Geologic Hazard In The Province Of Salta, Argentina, William J. Wayne

Department of Earth and Atmospheric Sciences: Faculty Publications

The north-south orient ation ofthe mo unta inous part ofthe Province ofSalta form s a massive barrier to easy communication between the more populate d region in the central pan of the provin ce and the communities to the west. Routes follow deeply entrenched valleys th at are frequ entl y th e sites ofdebris flows that cause disruptions in th e flow of traffic during the months of December through March , wh en most of the precipitation of the region is recorded . The steep topography and the tecton ic settings have resulted in nearly 150 large landslides …

Dissolved Organic Matter Composition And Photoreactivity In Prairie Lakes Of The U.S. Great Plains, Christopher L. Osburn, Courtney R. Wigdahl, Sherilyn C. Fritz, Jasmine E. Saros

Department of Earth and Atmospheric Sciences: Faculty Publications

Dissolved organic matter (DOM) of 27 prairie saline lake ecosystems was investigated in the Northern and Central Great Plains of the United States using absorbance, fluorescence, lignin concentration, and stable C isotope values. The majority of variation in DOM fluorescence among lakes was due to humic (peak C) and microbially formed (peak M) fluorescent components, which appear to be derived from autochthonous primary production. Strong correlations between peak M and nutrients allow us to model total phosphorus (TP) concentration using peak M fluorescence and chromophoric dissolved organic matter (CDOM) absorption. The rate of primary production (PP) was positively correlated with …