Earth Sciences Commons^™

Century-Scale Paleoclimatic Reconstruction From Moon Lake, A Closed-Basin Lake In The Northern Great Plains, Kathleen R. Laird, Sherilyn C. Fritz, Eric C. Grimm, Pietra G. Mueller

Department of Earth and Atmospheric Sciences: Faculty Publications

Estimates of past lake-water salinity from fossil diatom assemblages were used to infer past climatic conditions at Moon Lake, a climatically sensitive site in the northern Great Plains. A good correspondence between diatom-inferred salinity and historical records of mean annual precipitation minus evapotranspiration (P - ET) strongly suggests that the sedimentary record from Moon Lake can be used to reconstruct past climatic conditions. Century-scale analysis of the Holocene diatom record indicates four major hydrological periods: an early Holocene transition from an open freshwater system to a closed saline system by 7300 B.P., which corresponds with a transition from spruce forest …

Linking Planktonic Diatoms And Climate Change In The Large Lakes Of The Yellowstone Ecosystem Using Resource Theory, Susan S. Kilham, Edward C. Theriot, Sherilyn C. Fritz

Department of Earth and Atmospheric Sciences: Faculty Publications

Resource-based physiology of the eight important planktonic diatom species in the large lakes of the Yellowstone region can be used to explain their relative abundances and seasonal changes. The diatoms are ranked along resource ratio gradients according to their relative abilities to grow under limitation by Si, N, P, and light. Hypotheses based on resource physiology can be integrated with observations on seasonal changes in diatom assemblages to explain the present distributions of diatoms and to test the causal factors proposed to explain diatom distributions over the Holocene. Knowledge of the limnology of these lakes and process-oriented physiology provide the …

Geology Beneath The Primary Management Systems Evaluation Area (Msea) Site Southwest Of Shelton, Buffalo County, Nebraska, Robert F. Diffendal Jr., Frank A. Smith

Department of Earth and Atmospheric Sciences: Faculty Publications

In 1990, as part of a national presidential initiative on water quality, researchers from the University of Nebraska-Lincoln (UNL) Institute of Agriculture and Natural Resources (IANR) received a multi-year grant from the United States Department of Agriculture, Cooperative State Research Service, to study management of irrigated com and soybeans to minimize groundwater contamination. D.G. Watts, R.F. Spalding, and J.S. Schepers, of the IANR led a study at one of the Management Systems Evaluation Areas (MSEA). This area was made up of two sites, a primary site on a terrace of the Platte River near Shelton and a secondary site nearer …

Regional Analysis Of Rural Domestic Well-Water Quality -- Southeastern Glacial Drift Area, D. C. Gosselin, J. Headrick, X- H. Chen, S. E. Summerside

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Regional Analysis Of Rural Domestic Well-Water Quality In The Northeast Glacial Drift Area, D. C. Gosselin, J. Headrick, X- H. Chen, S. E. Summerside

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Pesticides In Streams Draining Agricultural And Urban Areas In Colorado, Robert Kimbrough, David Litke

United States Geological Survey: Staff Publications

A study was conducted from April 1993 through April 1994 to describe and compare the occurrence and distribution of pesticides in streams in a small agricultural and a small urban area in Colorado. Twenty-five water samples collected at least monthly at the mouths of two tributary streams of the South Platte River were analyzed for 47 pesticides. The results indicate that both agricultural and urban areas are probable sources for pesticides in streams. In the agricultural area, 30 pesticides were detected, and in the urban area, 22 pesticides were detected in one or more samples. Most often, the more frequently …

Sea-Level Records At ~80 Ka From Tectonically Stable Platforms: Florida And Bermuda, K. R. Ludwig, D. R. Muhs, K. R. Simmons, R. B. Halley, E. A. Shinn

United States Geological Survey: Staff Publications

Studies from tectonically active coasts on New Guinea and Barbados have suggested that sea level at ~80 ka was significantly lower than present, whereas data from the Atlantic and Pacific coasts of North America indicate an ~80 ka sea level close to that of the present. We determined ages of corals from a shallow submerged reef off the Florida Keys and an emergent marine deposit on Bermuda. Both localities are on tectonically stable platforms distant from plate boundaries. Uranium-series ages show that corals at both localities grew during the ~80 ka sea-level highstand, and geologic data show that sea level …

New Palaeothentid Marsupials (Caenolestoidea) From The Early Miocene Of Patagonian Argentina, Todd C. Rae, Thomas M. Bown, John G. Fleagle

United States Geological Survey: Staff Publications

Recent fieldwork in Argentina has resulted in the recovery of numerous new specimens of palaeothentid marsupials, an important component of the Deseadan-Santacrucian (Oligocene-middle Miocene) mammalian fauna of Patagonia. The 1994 collections include a new genus and species from the early Miocene Pinturas Formation at Estancia La Cafnada and the first complete lower dentition of Acdestis oweni from a locality in the Santa Cruz Formation along the Rio Chalia.

Stress Perturbation Associated With The Amazonas And Other Ancient Continental Rifts, Mary Lou Zoback, Randall M. Richardson

United States Geological Survey: Staff Publications

The state of stress in the vicinity of old continental rifts is examined to
investigate the possibility that crustal structure associated with ancient rifts (specifically a dense rift pillow in the lower crust) may modify substantially the regional stress field. Both shallow (2.0-2.6 km depth) breakout data and deep (20-45 km depth) crustal earthquake focal mechanisms indicate a N to NNE maximum horizontal compression in the vicinity of the Paleozoic Amazonas rift in central Brazil. This compressive stress direction is nearly perpendicular to the rift structure and represents a ~75 ° rotation relative to a regional E-W compressive stress direction …

Burt County Test Hole Logs, Raymond R. Burchett, Frank A. Smith

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Annual Departures From Average Annual Precipitation In Nebraska, 1876-1995/ Annual Installation Of Irrigation Wells (1937-1995), Conservation Survey Division

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Regional Hydrogeologic Summaries From Domestic Water-Well Quality In Nebraska -- North Central Tablelands, D. C. Gosselin, J. Headrick, X- H. Chen, S. E. Summerside

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Regional Analysis Of Rural Domestic Well-Water Quality -- East Central Dissected Plains, D. C. Gosselin, X- H. Chen, S. E. Summerside

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Origin Of Bermuda's Clay-Rich Quaternary Paleosols And Their Paleoclimatic Significance, Stanley R. Herwitz, Daniel R. Muhs, Joseph M. Prospero, Shannon Mahan, Bruce Vaughn

United States Geological Survey: Staff Publications

Saharan dust deposition on Bermuda during successive Quaternary glacial periods is consistent with patterns of general circulation models, which indicate that during glacial maxima the northeast summer trade winds were stronger than at present and reached latitudes higher than 30°N despite lower-than-present sea surface temperatures in the North Atlantic.

Resource News-Summer 1996

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Registered Irrigation Wells In Nebraska-Summer 1995, Mack Ann, Jim Weir, Jennifer Sharpe

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Polk County Test Hole Logs, Raymond R. Burchett, Frank A. Smith

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Resource News-Spring 1996

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

North Central Tablelands Hydrogeologic Summary From Domestic Well-Water Quality In Rural Nebraska, D C. Gosselin

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Regional Analysis Of Rural Domestic Well-Water Quality -- Southern Panhandle Tablelands, D. C. Gosselin, J. Headrick, X- H. Chen, S. E. Summerside

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Geology Along Selected Lincoln Bike Trails, R. K. Pabian

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Regional Hydrogeologic Summaries From Domestic Well-Water Quality In Rural Nebraska -- Sand Hills, D. C. Gosselin, J. Headrick, X- H. Chen, S. E. Summerside

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Regional Hydrogeologic Summaries From Domestic Well-Water Quality In Rural Nebraska -- Missouri River Lowlands, D. C. Gosselin, J. Headrick, X- H. Chen, S. E. Summerside

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Regional Hydrogeologic Summaries From Domestic Well-Water Quality In Rural Nebraska -- Southeastern Glacial Drift Area, D. C. Gosselin

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Factors Affecting Attwater's Prairie-Chicken Decline On The Attwater Prairie Chicken, Michael E. Morrow, Robert S. Adamcik, Jenny D. Friday, Lloyd B. Mckinney

United States Geological Survey: Staff Publications

We examined the association between changes in the number of Attwater's prairie-chicken (Tympanuchus cupido attwateri) on the Attwater Prairie Chicken National Wildlife Refuge from 1972 to 1993 and changes in refuge management practices (burning and grazing). We also examined the relationship of prairie-chicken population increases and decreases on the refuge to rainfall and off-refuge prairie-chicken populations. Burning within the prairie-chicken's core habitat on the refuge and variability in grassland structure were directly correlated (P < 0.05) with increases and declines in prairie-chicken populations. Refuge population increases and declines were inversely correlated (P < 0.1) with average April rainfall/event, May absolute departure from long-term average rainfall, May number of rainfall events, annual absolute departure of rainfall from the long-term average, and the annual number of rainfall events. Refuge population increases and declines were directly correlated (P < 0.1) with off-refuge populations, although the off- refuge population decline began 4 years earlier than on-refuge.

Occurrence Of Selected Pesticides And Their Metabolites In Near-Surface Aquifers Of The Midwestern United States, Dana Kolpin, E. Michael Thurman, Donald Goolsby

United States Geological Survey: Staff Publications

The occurrence and distribution of selected pesticides and their metabolites were investigated through the collection of 837 water-quality samples from 303 wells across the Midwest. Results of this study showed that five of the six most frequently detected compounds were pesticide metabolites. Thus, it was common for a metabolite to be found more frequently in groundwater than its parent compound. The metabolite alachlor ethanesulfonic acid (alachlor- ESA; 2-[(2,6-diethylphenyl)(methoxymethyl)amino]-2- oxoethanesulfonic acid) was detected almost 10 times as frequently and at much higher concentrations than its parent compound alachlor (2-chloro-2',6'- diethyl-N-(methoxymethyl)acetamide). The median detectable atrazine (2-chloro-4-ethylamino-6- isopropylamino-s-triazine) concentration was almost half that …

Acetochlor In The Hydrologic System In The Midwestern United States, 1994, Dana Kolpin, Brenda Nations, Donald Goolsby, E. Michael Thurman

United States Geological Survey: Staff Publications

The herbicide acetochlor [2-chloro-N-(ethoxymethyl)- N-(2-ethyl-6-methylphenyl)acetamide] was given conditional registration in the United States by the U.S. Environmental Protection Agency in March 1994. This registration provided a rare opportunity to investigate the occurrence of a pesticide during its first season of extensive use in the midwestern United States. Water samples collected and analyzed by the U.S. Geological Survey during 1994 documented the distribution of acetochlor in the hydrologic system; it was detected in 29% of the rain samples from four sites in Iowa, 17% of the stream samples from 51 sites across nine states, and 0% of the groundwater samples from …

Late Pliocene Diatoms In A Diatomite From Prydz Bay, East Antarctica, Albert D. Mahood, John A. Barron

United States Geological Survey: Staff Publications

Very well-preserved Pliocene diatoms from a diatomite unit interbedded within glacial sediments at Ocean Drilling Program Site 742 in Prydz Bay, Antarctica are documented and illustrated. The presence of Thalassiosira kolbei, T torokina, Actinocyclus actinochilus, A karstenii and the absence of Nitzschia interfrigidaria, T. insigna and T. vulnifica in Sample 119-742A-15R-4, 44-46 cm constrain its age to ca. 2.2-1.8 Ma (late Pliocene). Diatoms associated with sea ice constitute 35% of the Pliocene diatom assemblage, compared with 71% of the modern sediment assemblage at the site, suggesting that sea ice was present during the late Pliocene period of deposition of the …

Climatic And Hydrologic Oscillations In The Owens Lake Basin And Adjacent Sierra Nevada, California, Larry Benson, James W. Burdett, Michaele Kashgarian, Steve Lund, Fred Phillips, Robert O. Rye

United States Geological Survey: Staff Publications

Oxygen isotope and total inorganic carbon values of cored sediments from the Owens Lake basin, California, indicate that Owens Lake overflowed most of the time between 52,500 and 12,500 carbon-14 (¹⁴C) years before present (B.P.). Owens Lake desicated during or after Heinrich event H1 and was hydrologically closed during Heinrich event H2. The magnetic susceptibility and organiz carbon content of cored sediments indicate that about 19 Sierra Nevada glaciations occurred between 52,500 and 23,500 ¹⁴C years B.P.

Origin Of The Late Quaternary Dune Fields Of Northeastern Colorado, Daniel R. Muhs, Thomas W. Stafford, Scott D. Cowherd, Shannon A. Mahan, Rolf Kihl, Paula B. Maat, Charles A. Bush, Jennifer Nehring

United States Geological Survey: Staff Publications

Stabilized eolian deposits, mostly parabolic dunes and sand sheets, cover much of the landscape of northeastern Colorado and adjacent parts of southwestern Nebraska in four geographically distinct dune fields. Stratigraphic and soil-geomorphic relations and accelerator radiocarbon dating indicate that at least three episodes of eolian sand movement occurred between 27 ka and 11 ka. possibly between 11 ka and 4 ka. and within the past 1.5 ka. Thus, eolian sand deposition took place under both glacial and interglacial climatic conditions. In the youngest episodes of eolian sand movement. Holocene parabolic dunes partially buried Pleistocene sand sheet deposits.

Late Holocene sands …