Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Earth Sciences

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 50341 - 50370 of 59432

Full-Text Articles in Entire DC Network

A Reinterpretation Of The Small Captorhinid Reptile Captorhinikos Parvus Olson As A New Genus, Reanalysis Of Its Cranial Anatomy, And A Phylogenetic Analysis Of The Basal Reptilian Family Captorhinidae, Gavan Mcbride Albright Jan 2003

A Reinterpretation Of The Small Captorhinid Reptile Captorhinikos Parvus Olson As A New Genus, Reanalysis Of Its Cranial Anatomy, And A Phylogenetic Analysis Of The Basal Reptilian Family Captorhinidae, Gavan Mcbride Albright

Theses Digitization Project

The cranial anatomy of the basal captorhinid reptile Captorhinikos parvus (Reptilia, Captorhinidae), is reinterpreted here based on analysis of a group of new specimens recovered subsequent to its original diagnosis as well as further analysis of the original specimens utilized in E.C. Olson's original characterization of the species. Structural features inconsistent with the generic description suggest the redefinition of C. parvus as a new genus, Rhodotheratus parvus. Analyses of basal members and selected derived members support the characterization of Rhodotheratus as a distinct taxon.

Go to article

Could Mammoth Cave Be Reduced To A Single Equation?, Chris Groves, Joe Meiman Jan 2003

Could Mammoth Cave Be Reduced To A Single Equation?, Chris Groves, Joe Meiman

Earth, Environmental, and Atmospheric Sciences Faculty Publications

Since the evolution of any cave system is largely deterministic, in theory the processes responsible for this development could be described mathematically. In a practical sense, we will never have such a model to realistically describe the evolution of the Mammoth Cave System in detail. However, the search itself can provide a framework within which to understand what processes areimportant. This can guide the design of rate process studies that would eventually be coupled to provide a comprehensive understanding of the cave's evolution. Data gaps, as well, are identified during this process. The geometry of a cave system depends on …

Go to article

Entropy And Generalized Least Square Methods In Assessment Of The Regional Value Of Streamgages, Momcilo Markus, H. Vernon Knapp, Gary D. Tasker Jan 2003

Entropy And Generalized Least Square Methods In Assessment Of The Regional Value Of Streamgages, Momcilo Markus, H. Vernon Knapp, Gary D. Tasker

United States Geological Survey: Staff Publications

The Illinois State Water Survey performed a study to assess the streamgaging network in the State of Illinois. One of the important aspects of the study was to assess the regional value of each station through an assessment of the information transfer among gaging records for low, average, and high flow conditions. This analysis was performed for the main hydrologic regions in the State, and the stations were initially evaluated using a new approach based on entropy analysis. To determine the regional value of each station within a region, several information parameters, including total net information, were defined based on …

Go to article

Changes In The Timing Of High River Flows In New England Over The 20th Century, G. A. Hodgkins, R. W. Dudley, T. G. Huntington Jan 2003

Changes In The Timing Of High River Flows In New England Over The 20th Century, G. A. Hodgkins, R. W. Dudley, T. G. Huntington

United States Geological Survey: Staff Publications

The annual timing of river flows is a good indicator of climate-related changes, or lack of changes, for rivers with long-term data that drain unregulated basins with stable land use. Changes in the timing of annual winter/spring (January 1 to May 31) and fall (October 1 to December 31) center of volume dates were analyzed for 27 rural, unregulated river gaging stations in New England, USA with an average of 68 years of record. The center of volume date is the date by which half of the total volume of water for a given period of time flows past a …

Go to article

Selectivities Of Potassium-Calcium And Potassium-Lead Exchange In Two Tropical Soils, Chip Appel, Lena Q. Ma, R. Dean Rhue, William Reve Jan 2003

Selectivities Of Potassium-Calcium And Potassium-Lead Exchange In Two Tropical Soils, Chip Appel, Lena Q. Ma, R. Dean Rhue, William Reve

Earth and Soil Sciences

Measurement of cation selectivity in soils provides important information about the affinity and binding strength of a particular cation on soil surfaces. Gaines-Thomas (KGT) selectivity coefficients were determined for a variety of K/Ca and K/Pb ratios on an Oxisol and Ultisol soil from Puerto Rico. The calculated KGT values indicated a preference for K+ over Ca2+ or Pb2+. The selectivity for Pb2+ was significantly greater than that for Ca2+ due to Pb2+'s larger hydrated charge density relative to that of Ca2+. The patterns of selectivity were independent …

Go to article

Soil Survey Of Grand Staircase- Escalante National Monument Area, Parts Of Kane And Garfield Counties, Utah, United States Department Of Agriculture, Natural Resources Conservation Service Jan 2003

Soil Survey Of Grand Staircase- Escalante National Monument Area, Parts Of Kane And Garfield Counties, Utah, United States Department Of Agriculture, Natural Resources Conservation Service

All U.S. Government Documents (Utah Regional Depository)

This soil survey contains information that affects land use planning in this survey area. It contains predictions of soil behavior for selected land uses. The survey also highlights soil limitations, improvements needed to overcome the limitations and the impact of selected land uses on the environment. This soil survey is designed for many different users. Farmers, ranchers, foresters and agronomists can use it to evaluate the potential of the soil and the management needed for maximum food and fiber production. Planners, community officials, engineers, developers, builders and home buyers can use the survey to plan land use, select sites for …

Go to article

Lower Gascoyne Land Resources Survey, Peter J. Tille, Henry J. Smolinski, M R. Wells, J A. Bessell-Browne, C D M Keating, Veronica P M Oma, A Mcr Holm Jan 2003

Lower Gascoyne Land Resources Survey, Peter J. Tille, Henry J. Smolinski, M R. Wells, J A. Bessell-Browne, C D M Keating, Veronica P M Oma, A Mcr Holm

Land resources series

No abstract provided.

Go to article

Nyabing-Kukerin Area Land Resources Survey, H M. Percy, Dennis Van Gool, Geoff Allan Moore, Noel R. Schoknecht, National Landcare Program (Australia), Natural Heritage Trust (Australia) Jan 2003

Nyabing-Kukerin Area Land Resources Survey, H M. Percy, Dennis Van Gool, Geoff Allan Moore, Noel R. Schoknecht, National Landcare Program (Australia), Natural Heritage Trust (Australia)

Land resources series

This report presents the results from soil and landform mapping at a scale of 1:500,000 in the Kukerin, Lake Grace and Nyabing areas of Western Australia. This land resource information has been collected to help improve the decisions made by planners, researchers and land managers. The information can be used at the regional scale, catchment scale and farm level. By improving knowledge of our land resources, more sustainable land uses can be developed within the region. The soil-landscape map of the area covers approximately 515,000 hectares and is included on the accompanying interactive CD-ROM. The map extends from Lake Grace …

Go to article

Pliocene Summer Sea Surface Temperature Reconstruction Using Silicoflagellates From Southern Ocean Odp Site 1165, Jason M. Whitehead, Steven M. Bohaty Jan 2003

Pliocene Summer Sea Surface Temperature Reconstruction Using Silicoflagellates From Southern Ocean Odp Site 1165, Jason M. Whitehead, Steven M. Bohaty

Department of Earth and Atmospheric Sciences: Faculty Publications

In the modern marine environment the silicoflagellate genus Dictyocha is rare, or absent, south of the Antarctic polar front (APF); the genus Distephanus, in contrast, is dominant. In sediments recovered from ODP Site 1165, 1600 km south of the front, however, three intervals where Dictyocha is abundant are interpreted to represent Pliocene warm events. Comparison of our data with Ciesielski and Weaver’s [1974] modern core top silicoflagellate relationship with sea surface temperature (SST) indicates that at Site 1165 mean annual SST was approximately 5C at 3.7 Ma (event I), and approximately 4C at 4.3–4.4 Ma (event II) and 4.55–4.8 …

Go to article

Red Willow County Test Hole Logs, Duane A. Eversoll Jan 2003

Red Willow County Test Hole Logs, Duane A. Eversoll

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Go to article

Mid-Holocene Climates Of The Americas: A Dynamical Response To Changed Seasonality, S. P. Harrison, J. E. Kutzbach, Z. Liu, P. J. Bartlein, B. Otto-Bliesner, Daniel R. Muhs, I. C. Prentice, R. S. Thompson Jan 2003

Mid-Holocene Climates Of The Americas: A Dynamical Response To Changed Seasonality, S. P. Harrison, J. E. Kutzbach, Z. Liu, P. J. Bartlein, B. Otto-Bliesner, Daniel R. Muhs, I. C. Prentice, R. S. Thompson

United States Geological Survey: Staff Publications

Abstract Simulations of the climatic response to mid- Holocene (6 ka BP) orbital forcing with two coupled ocean–atmosphere models (FOAM and CSM) show enhancement of monsoonal precipitation in parts of the American Southwest, Central America and northernmost South America during Northern Hemisphere summer. The enhanced onshore flow that brings precipitation into Central America is caused by a northward displacement of the inter-tropical convergence zone, driven by cooling of the equatorial and warming of the northern subtropical and mid-latitude ocean. Ocean feedbacks also enhance precipitation over the American Southwest, although the increase in monsoon precipitation there is largely driven by increases …

Go to article

Monitoring Trends In Bat Populations Of The United States And Territories: Problems And Prospects, T.J. O'Shea, M. A. Bogan Jan 2003

Monitoring Trends In Bat Populations Of The United States And Territories: Problems And Prospects, T.J. O'Shea, M. A. Bogan

United States Geological Survey: Publications

Bats are ecologically and economically important mammals. The life histories of bats (particularly their low reproductive rates and the need for some species to gather in large aggregations at limited numbers of roosting sites) make their populations vulnerable to declines. Many of the species of bats in the United States (U.S.) and territories are categorized as endangered or threatened, have been candidates for such categories, or are considered species of concern. The importance and vulnerability of bat populations makes monitoring trends in their populations a goal for their future management. However, scientifically rigorous monitoring of bat populations requires well-planned, statistically …

Go to article

Geologic Studies Of Mercury By The U.S. Geological Survey Jan 2003

Geologic Studies Of Mercury By The U.S. Geological Survey

United States Geological Survey: Publications

A liquid at room temperature, mercury is a unique metal with unusual properties. Elemental mercury has long been used in thermometers because it responds to changes in temperature. In fact, mercury’s many diverse properties have made it useful for many products. Mercury is a good metallic conductor with a low electrical resistivity; it has been used in electrical products including electrical wiring and switches, fluorescent lamps, mercury batteries, and thermostats (Eisler, 1987). Mercury also is used in navigational instruments to measure changes in temperature and pressure. In the medical field, mercury is used as a component in dental fillings and …

Go to article

Review Of Population Viability Analysis, Mark W. Miller Jan 2003

Review Of Population Viability Analysis, Mark W. Miller

United States Geological Survey: Staff Publications

Population viability analysis (PVA) historically has been used to estimate the probability that a population will become extinct within a given time period. More recently, PVA has been used to evaluate alternative management strategies. Some might even say PVA gave rise to conservation biology. Nevertheless, PVA has been heavily criticized. This is the second book to present a synthesis and address those concerns. It does so extremely well.

Go to article

Genetic Variation In Black Bears In Arkansas And Louisiana Using Microsatellite Dna Markers, Ildiki Csiki, Cynthia Lam, Audie Key, Erica Coulter, Joseph D. Clark, Richard M. Pace Iii, Kimberley G. Smith, Douglas D. Rhoads Jan 2003

Genetic Variation In Black Bears In Arkansas And Louisiana Using Microsatellite Dna Markers, Ildiki Csiki, Cynthia Lam, Audie Key, Erica Coulter, Joseph D. Clark, Richard M. Pace Iii, Kimberley G. Smith, Douglas D. Rhoads

United States Geological Survey: Staff Publications

In the 1950s and 1960s, translocation projects reintroduced black bears (Ursus americanus) from Minnesota and Manitoba to Arkansas and Louisiana. Today, several geographically disconnected populations exist in Arkansas and Louisiana, but their origins are unclear. Some populations may represent a separate subspecies, U. a. luteolus, which is federally protected. We characterized 5 microsatellite loci in 5 isolated populations in Arkansas and Louisiana and compared them with genotypes from Minnesota. Our data indicate that bears of the Ozark and Ouachita mountains of Arkansas, an inland area of Louisiana, and those of Minnesota are similar in overall genetic diversity …

Go to article

Evidence For Disease-Related Amphibian Decline In Colorado, Erin Muths, Paul Stephen Corn, Allan P. Pessier, D. Earl Green Jan 2003

Evidence For Disease-Related Amphibian Decline In Colorado, Erin Muths, Paul Stephen Corn, Allan P. Pessier, D. Earl Green

United States Geological Survey: Staff Publications

The recent discovery of a pathogenic fungus (Batrachochytrium dendrobatidis) associated with declines of frogs in the American and Australian tropics, suggests that at least the proximate cause, may be known for many previously unexplained amphibian declines. We have monitored boreal toads in Colorado since 1991 at four sites using capture–recapture of adults and counts of egg masses to examine the dynamics of this metapopulation. Numbers of male toads declined in 1996 and 1999 with annual survival rate averaging 78% from 1991 to 1994, 45% in 1995 and 3% between 1998 and 1999. Numbers of egg masses also declined. …

Go to article

Unprecedented Last-Glacial Mass Accumulation Rates Determined By Luminescence Dating Of Loess From Western Nebraska, Helen M. Roberts, Daniel R. Muhs, Ann G. Wintle, Geoff A. T. Duller, E. Arthur Bettis Iii Jan 2003

Unprecedented Last-Glacial Mass Accumulation Rates Determined By Luminescence Dating Of Loess From Western Nebraska, Helen M. Roberts, Daniel R. Muhs, Ann G. Wintle, Geoff A. T. Duller, E. Arthur Bettis Iii

United States Geological Survey: Staff Publications

A high-resolution chronology for Peoria (last glacial period) Loess from three sites in Nebraska, midcontinental North America, is determined by applying optically stimulated luminescence (OSL) dating to 35–50 µm quartz. At Bignell Hill, Nebraska, an OSL age of 25,000 yr near the contact of Peoria Loess with the underlying Gilman Canyon Formation shows that dust accumulation occurred early during the last glacial maximum (LGM), whereas at Devil’s Den and Eustis, Nebraska, basal OSL ages are significantly younger (18,000 and 21,000 yr, respectively). At all three localities, dust accumulation ended at some time after 14,000 yr ago. Mass accumulation rates …

Go to article

Stratigraphy And Palaeoclimatic Significance Of Late Quaternary Loess–Palaeosol Sequences Of The Last Interglacial–Glacial Cycle In Central Alaska, Daniel R. Muhs, Thomas A. Ager, E. Arthur Bettis Iii, John Mcgeehin, Josh M. Been, James E. Begét, Milan J. Pavich, Thomas W. Stafford Jr., De Anne S. P. Stevens Jan 2003

Stratigraphy And Palaeoclimatic Significance Of Late Quaternary Loess–Palaeosol Sequences Of The Last Interglacial–Glacial Cycle In Central Alaska, Daniel R. Muhs, Thomas A. Ager, E. Arthur Bettis Iii, John Mcgeehin, Josh M. Been, James E. Begét, Milan J. Pavich, Thomas W. Stafford Jr., De Anne S. P. Stevens

United States Geological Survey: Staff Publications

Loess is one of the most widespread subaerialdeposits in Alaska and adjacent Yukon Territory and may have a history that goes back 3 Ma. Based on mineralogy and major and trace element chemistry, central Alaskan loess has a composition that is distinctive from other loess bodies of the world, although it is quartz-dominated. Central Alaskan loess was probably derived from a variety of rock types, including granites, metabasalts and schists. Detailed stratigraphic data and pedologic criteria indicate that, contrary to early studies, many palaeosols are present in central Alaskan loess sections. The buried soils indicate that loess sedimentation was episodic, …

Go to article

High Precision Earthquake Locations Reveal Seismogenic Structure Beneath Mammoth Mountain, California, Stephanie Prejean, Anna Stork, William Ellsworth, David Hill, Bruce Julian Jan 2003

High Precision Earthquake Locations Reveal Seismogenic Structure Beneath Mammoth Mountain, California, Stephanie Prejean, Anna Stork, William Ellsworth, David Hill, Bruce Julian

United States Geological Survey: Staff Publications

In 1989, an unusual earthquake swarm occurred beneath Mammoth Mountain that was probably associated with magmatic intrusion. To improve our understanding of this swarm, we relocated Mammoth Mountain earthquakes using a double difference algorithm. Relocated hypocenters reveal that most earthquakes occurred on two structures, a near-vertical plane at 7–9 km depth that has been interpreted as an intruding dike, and a circular ring-like structure at ~5.5 km depth, above the northern end of the inferred dike. Earthquakes on this newly discovered ring structure form a conical section that dips outward away from the aseismic interior. Fault-plane solutions indicate that in …

Go to article

Imaging The Complexity Of An Active Normal Fault System: The 1997 Colfiorito (Central Italy) Case Study, L. Chiaraluce, W. L. Ellseworth, C. Chiarabba, M. Cocco Jan 2003

Imaging The Complexity Of An Active Normal Fault System: The 1997 Colfiorito (Central Italy) Case Study, L. Chiaraluce, W. L. Ellseworth, C. Chiarabba, M. Cocco

United States Geological Survey: Staff Publications

Six moderate magnitude earthquakes (5 < Mw < 6) ruptured normal fault segments of the southern sector of the North Apennine belt (central Italy) in the 1997 Colfiorito earthquake sequence. We study the progressive activation of adjacent and nearby parallel faults of this complex normal fault system using ~1650 earthquake locations obtained by applying a double-difference location method, using travel time picks and waveform cross-correlation measurements. The lateral extent of the fault segments range from 5 to 10 km and make up a broad, ~45 km long, NW trending fault system. The geometry of each segment is quite simple and consists of planar faults gently dipping toward SW with an average dip of 40 °–45 °. The fault planes are not listric but maintain a constant dip through the entire seismogenic volume, down to 8 km depth. We observe the activation of faults on the hanging wall and the absence of seismicity in the footwall of the structure. The observed fault segmentation appears to be due to the lateral heterogeneity of the upper crust: preexisting thrusts inherited from Neogene’s compressional tectonic intersect the active normal faults and control their maximum length. The stress tensor obtained by inverting the six main shock focal mechanisms of the sequence is in agreement with the tectonic stress active in the inner chain of the Apennine, revealing a clear NE trending extension direction. Aftershock focal mechanisms show a consistent extensional kinematics, 70% of which are mechanically consistent with the main shock stress field.

Go to article

Mapping Vegetation In Yellowstone National Park Using Spectral Feature Analysis Of Aviris Data, Raymond F. Kokaly, Don G. Despain, Roger N. Clark, K. Eric Livo Jan 2003

Mapping Vegetation In Yellowstone National Park Using Spectral Feature Analysis Of Aviris Data, Raymond F. Kokaly, Don G. Despain, Roger N. Clark, K. Eric Livo

United States Geological Survey: Staff Publications

Knowledge of the distribution of vegetation on the landscape can be used to investigate ecosystem functioning. The sizes and movements of animal populations can be linked to resources provided by different plant species. This paper demonstrates the application of imaging spectroscopy to the study of vegetation in Yellowstone National Park (Yellowstone) using spectral feature analysis of data from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). AVIRIS data, acquired on August 7, 1996, were calibrated to surface reflectance using a radiative transfer model and field reflectance measurements of a ground calibration site. A spectral library of canopy reflectance signatures was created by …

Go to article

Interplay Of Late Cenozoic Siliciclastic Supply And Carbonate Response On The Southeast Florida Platform, Kevin J. Cunningham, Stanley D. Locker, Albert C. Hine, David Bukry, Laura A. Guertin, John A. Barron Jan 2003

Interplay Of Late Cenozoic Siliciclastic Supply And Carbonate Response On The Southeast Florida Platform, Kevin J. Cunningham, Stanley D. Locker, Albert C. Hine, David Bukry, Laura A. Guertin, John A. Barron

United States Geological Survey: Staff Publications

High-resolution seismic-reflection data collected along the length of the Caloosahatchee River in southwestern Florida have been correlated to nannofossil biostratigraphy and strontium-isotope chemostratigraphy at six continuously cored boreholes. These data are interpreted to show a major Late Miocene(?) to Early Pliocene fluvial– deltaic depositional system that prograded southward across the carbonate Florida Platform, interrupting nearly continuous carbonate deposition since early in the Cretaceous. Connection of the platform top to a continental source of siliciclastics and significant paleotopography combined to focus accumulation of an immense supply of siliciclastics on the southeastern part of the Florida Platform. The remarkably thick (> 100 …

Go to article

Paleolimnology Of Lake Tanganyika, East Africa, Over The Past 100 K Yr, Christopher A. Scholz, John W. King, Geoffrey S. Ellis, Peter K. Swart, J. Curt Stager, Steven M. Colman Jan 2003

Paleolimnology Of Lake Tanganyika, East Africa, Over The Past 100 K Yr, Christopher A. Scholz, John W. King, Geoffrey S. Ellis, Peter K. Swart, J. Curt Stager, Steven M. Colman

United States Geological Survey: Staff Publications

New sediment core data from a unique slow-sedimentation rate site in Lake Tanganyika contain a much longer and continuous record of limnological response to climate change than have been previously observed in equatorial regions of central Africa. The new core site was first located through an extensive seismic reflection survey over the Kavala Island Ridge (KIR), a sedimented basement high that separates the Kigoma and Kalemie Basins in Lake Tanganyika.

Proxy analyses of paleoclimate response carried out on core T97-52V include paleomagnetic and index properties, TOC and isotopic analyses of organic carbon, and diatom and biogenic silica analyses. A robust …

Go to article

Groundwater Study Of The Nyabing Townsite, Louise Hopgood Jan 2003

Groundwater Study Of The Nyabing Townsite, Louise Hopgood

Resource management technical reports

A groundwater study was carried out in the townsite of Nyabing, Western Australia. The study presents a model of the hydrogeology below the town and defines management options to help limit damage to infrastructure from surface water and groundwater rise. A drilling program and expansion of the network of monitoring bores were also part of the study.

Go to article

Mississippi River Blufflands And Bird Conservation, Eileen M. Kirsch Jan 2003

Mississippi River Blufflands And Bird Conservation, Eileen M. Kirsch

United States Geological Survey: Staff Publications

The "rubber hits the road" in conservation when the landowning public involved. Researchers and amateur birders know that populations of many species of neotropical migrant birds are declining because of habitat loss and many natural- and human-caused dangers. However, the landowners may not know what neotropical migrants are or that they are in peril. This excellent booklet and enclosed pamphlet are intended to educate landowners along the Mississippi River blufflands in Iowa, Illinois, Wisconsin, and Minnesota about neotropical migrant birds and their plight. Furthermore, it tactfully attempts to inspire concern about neotropical migrants and explains how management can help. While …

Go to article

Holocene Paleoflood Hydrology Of The Lower Deschutes River, Oregon, Kurt J. Hosman, Lisa L. Ely, Jim E. O'Connor Jan 2003

Holocene Paleoflood Hydrology Of The Lower Deschutes River, Oregon, Kurt J. Hosman, Lisa L. Ely, Jim E. O'Connor

Student Published Works

Flood deposits at four sites along the lower Deschutes River, Oregon, were analyzed to determine magnitude and frequency of late Holocene flooding. Deposit stratigraphy was combined with hydraulic modeling at two sites to determine ranges of likely discharges for individual deposits. Combining these results with gaged flood data provides improved flood frequency estimates at the Axford site. The completeness and age spans of preserved flood chronologies differed among the four sites, but results were consistent for the largest floods of the last 5000 years. Single floods exceeded 2860-3800 mVs -4600 cal yr BP, 1060-1810 mVs -1300 cal yr BP, and …

Go to article

Trace Elements In Lesser Scaup (Aythya Affinis) From The Mississippi Flyway, Christine Custer, Thomas Custer, Michael J. Anteau, Alan D. Afton, David Wooten Jan 2003

Trace Elements In Lesser Scaup (Aythya Affinis) From The Mississippi Flyway, Christine Custer, Thomas Custer, Michael J. Anteau, Alan D. Afton, David Wooten

United States Geological Survey: Staff Publications

Previous research reported that concentrations of selenium in the livers of 88-95% of lesser scaup from locations in Lake Erie, Lake St. Clair, and Lake Michigan, USA were either elevated (10-33 μg/g dry weight [dw]) or in the potentially harmful range (>33 μg/g dw). In order to determine the geographic extent of these high selenium concentrations, we collected lesser scaup in Louisiana, Arkansas, Illinois, Minnesota, Wisconsin, and Manitoba and analyzed the livers for 19 trace elements. We found that all trace element concentrations, except for selenium, generally were low. Arsenic, which usually is not detected in liver samples, was …

Go to article

Strontium Isotope Geochemistry In The Central Part Of The Great Plains (Dakota) Aquifer, U.S.A.. Applied Geochemistry, D. C. Gosselin, F. E. Harvey, C. Frost, R. Stotler, P. A. Macfarlane Jan 2003

Strontium Isotope Geochemistry In The Central Part Of The Great Plains (Dakota) Aquifer, U.S.A.. Applied Geochemistry, D. C. Gosselin, F. E. Harvey, C. Frost, R. Stotler, P. A. Macfarlane

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Go to article

Late Albian Adaptive Radiation In The Calcareous Nannofossil Genus Eiffellithus, David K. Watkins, James A. Bergen Jan 2003

Late Albian Adaptive Radiation In The Calcareous Nannofossil Genus Eiffellithus, David K. Watkins, James A. Bergen

Department of Earth and Atmospheric Sciences: Faculty Publications

Well preserved nannofossil assemblages in upper Albian and lower Cenomanian hemipelagic sections from Ocean Drilling Program (ODP) Leg 171B preserve a record of the early history and adaptive radiation of the genus Eiffellithus. Seven distinct taxa are recognized and differentiated, with one previously named taxon (E. monechiae) emended and four new species described: E. praestigium, E. vonsalisiae, E. equibiramus, and E. parvus. Sample census data indicate that most species evolved, rose to dominance, and then rapidly declined to extinction, to be replaced by other members of the genus. Newly evolved species tended to remain at low …

Go to article

Lake Sediments Record Large-Scale Shifts In Moisture Regimes Across The Northern Prairies Of North America During The Past Two Millennia, Kathleen R. Laird, Brian F. Cumming, Sybille Wunsam, James A. Rusak, Robert J. Oglesby, Sherilyn C. Fritz, Peter R. Leavitt Jan 2003

Lake Sediments Record Large-Scale Shifts In Moisture Regimes Across The Northern Prairies Of North America During The Past Two Millennia, Kathleen R. Laird, Brian F. Cumming, Sybille Wunsam, James A. Rusak, Robert J. Oglesby, Sherilyn C. Fritz, Peter R. Leavitt

Department of Earth and Atmospheric Sciences: Faculty Publications

Six high-resolution climatic reconstructions, based on diatom analyses from lake sediment cores from the northern prairies of North America, show that shifts in drought conditions on decadal through multicentennial scales have prevailed in this region for at least the last two millennia. The predominant broad-scale pattern seen at all sites is a major shift in moisture regimes from wet to dry, or vice versa (depending on location), that occurred after a period of relative stability. These large-scale shifts at the different sites exhibit spatial coherence at regional scales. The three Canadian sites record this abrupt shift between anno Domini 500 …

Go to article

First Prev Next Last