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Articles 3391 - 3420 of 4541

Full-Text Articles in Earth Sciences

Flat Water: A History Of Nebraska And Its Water, Robert D. Kuzelka, Charles A. Flowerday, Robert N. Manley, Bradley C. Rundquist, Sally J. Herrin Mar 1993

Flat Water: A History Of Nebraska And Its Water, Robert D. Kuzelka, Charles A. Flowerday, Robert N. Manley, Bradley C. Rundquist, Sally J. Herrin

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Geological Field Guide To The Cedar Point Biological Station, Keith County, Nebraska, Robert F. Diffendal Jr., Roger K. Pabian Feb 1993

Geological Field Guide To The Cedar Point Biological Station, Keith County, Nebraska, Robert F. Diffendal Jr., Roger K. Pabian

School of Natural Resources: Faculty Publications

This field guide was produced by staff members of the Conservation and Survey Division of the University of Nebraska originally in 1979 at the request of Dr. Brent Nickol, former Director of the Cedar Point Biological Station. It is an introduction to the geologic history and paleoecology of the Cedar Point area intended for students, staff, and other persons using the camp. This revision has been made some 15 years after the first version to reflect changes in ideas resulting from new data collected during that time.

Users of this guide should take care when studying the rock exposures described …


Application Of Sealevel Stratigraphy To Neogene Great Plains Stratigraphy, Robert F. Diffendal Jr., A. Lowrie Jan 1993

Application Of Sealevel Stratigraphy To Neogene Great Plains Stratigraphy, Robert F. Diffendal Jr., A. Lowrie

Robert F. Diffendal, Jr., Publications

Absolute-dated high frequency (Milankovitch cycles) marine climate/sealevel oscillatory stratigraphy can be correlated generally with continental stratigraphies. Improvements in absolute dating of Neogene formations across the North American Great Plains make this a candidate area in which to correlate marine and continental stratigraphies. Mid-latitude continental areas respond directly to climate variations. During glaciated/ cold climates, sealevel lowering results in steepened river gradients, increased erosion all along the river channel, and larger stress-bed loads. This, combined with glacial catastrophic flooding, produces greater cut-and-fill sequences along river systems than crevasse splays along the emergent coastal plain, deltas along the shelf, and submarine fans …


G93-1191 Glossary Of Water-Related Terms, William L. Kranz, Delynn Hay, James W. Goeke, David Gosselin Jan 1993

G93-1191 Glossary Of Water-Related Terms, William L. Kranz, Delynn Hay, James W. Goeke, David Gosselin

University of Nebraska-Lincoln Extension: Historical Materials

This NebGuide is a glossary of water quantity, quality and human health related terms involving water. Terms are defined in contexts that could affect Nebraskans. We depend upon water for our very existence. The impact of water quality and quantity issues has never been greater. Yet the terminology used to describe the water we drink, the water we provide to plants and animals, the water stored underground, in lakes, rivers, and oceans, is not well understood by many Nebraskans. This listing of water-related terms is intended to reduce the potential for misunderstanding presentations made by elected officials, environmental agencies and …


G93-1128 Understanding Groundwater, William L. Kranz, Delynn Hay, James W. Goeke Jan 1993

G93-1128 Understanding Groundwater, William L. Kranz, Delynn Hay, James W. Goeke

University of Nebraska-Lincoln Extension: Historical Materials

This NebGuide provides information on how groundwater exists, where it exists, and how it moves. Key definitions are highlighted. Water is the life blood of every living creature on earth. Approximately 70 percent of the earth's surface is covered with water. Through the wonders of nature, water can take on many different forms, from the water we drink, to the ice we use to chill a glass of lemonade, to the water vapor used to steam clean equipment. It is easy to understand the significance water plays in our lives, but it may be much more difficult to understand the …


Uranium Deposits In Nebraska, R. R. Burchett Jan 1993

Uranium Deposits In Nebraska, R. R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Exceptionally Well-Preserved Early Oligocene Diatoms From Glacial Sediments Of Prydz Bay, East Antarctica, John A. Barron, Albert D. Mahood Jan 1993

Exceptionally Well-Preserved Early Oligocene Diatoms From Glacial Sediments Of Prydz Bay, East Antarctica, John A. Barron, Albert D. Mahood

United States Geological Survey: Staff Publications

An exceptionally well-preserved early Oligocene diatom assemblage is documented and illustrated from the internal sediment of a gastropod shell, which was collected from glacial sediments recovered at Ocean Drilling Program Site 739 on the continental shelf in Prydx Bay, Antarctica. The diatoms were deposited between 35.9 and 34.8 Ma according to diatom and calcareous nannofossil stratigraphy, apparently soon after a period of major ice sheet advance across the Prydz Bay continental shelf. The diatom assemblage is neritic in character. but it can readily be correlated with open ocean assemblages from the Southern Ocean as well as with similar material recovered …


Short-Term Sediment Accumulation Rates Determined From Eocene Alluvial Paleosols, Mary J. Kraus, Thomas M. Bown Jan 1993

Short-Term Sediment Accumulation Rates Determined From Eocene Alluvial Paleosols, Mary J. Kraus, Thomas M. Bown

United States Geological Survey: Staff Publications

A new method uses alluvial paleosols to calculate sediment accumulation rates for thin (25 m) stratigraphic intervals and allows the reliable interpolation of ages for stratigraphic levels within a thick stratigraphic interval bounded by established dates. Sediment accumulation rates calculated for a 650 m composite section in the Eocene Willwood Formation of Wyoming span time intervals ranging from only 0.05 to 0.25 may. Important sedimentologic changes coincide with changes in accumulation rate and indicate close and direct relations between the history of basin subsidence and depositional patterns.


Systematics, Biostratigraphy, And Dental Evolution Of The Palaeothentidae, Later Oligocene To Early-Middle Miocene (Deseadan-Santacrucian) Caenolestoid Marsupials Of South America, Thomas M. Bown, John G. Fleagle Jan 1993

Systematics, Biostratigraphy, And Dental Evolution Of The Palaeothentidae, Later Oligocene To Early-Middle Miocene (Deseadan-Santacrucian) Caenolestoid Marsupials Of South America, Thomas M. Bown, John G. Fleagle

United States Geological Survey: Staff Publications

The family Palaeothentidae contains some of the dentally more specialized of the small-bodied marsupials of South America and was a clade almost equivalent with the Abderitidae in having been the most abundant caenolestoids. They were unquestionably the most diverse, containing two subfamilies, nine genera, and 19 species, with a distribution ranging from Colombia to Tierra del Fuego. The best and most continuous record of the Palaeothentidae is from Patagonian Argentina where eight genera and 17 species are recognized. There, the Palaeothentidae ranged in age from the Deseadan (later Oligocene) through the late Santacrucian (middle Miocene-the Santacrucian record lasting from about …


Water-Quality Assessment Of The Central Nebraska Basins: Summary Of Data For Recent Conditions Through 1990, Ronald B. Zelt, P. R. Jordan Jan 1993

Water-Quality Assessment Of The Central Nebraska Basins: Summary Of Data For Recent Conditions Through 1990, Ronald B. Zelt, P. R. Jordan

United States Geological Survey: Publications

Among the first activities undertaken in each National Water-Quality Assessment (NAWQA) investigation are the compilation, screening, and statistical summary of available data concerning recent water-quality conditions in the study unit. The water-quality conditions of interest in addressing the objectives of the NAWQA program are those that are representative of the general water quality of a given stream reach or area of an aquifer. This report (1) identifies which existing water-quality data are suitable for characterizing general conditions in a nationally consistent manner and (2) describes, to the extent possible, recent, general water-quality conditions in the Central Nebraska Basins. The study …


Seismotectonics Of The San Andreas Fault System Between Point Arena And Cape Mendocino In Northern California' Implications For The Development And Evolution Of A Young Transform, David A. Castillo, William L. Ellsworth Jan 1993

Seismotectonics Of The San Andreas Fault System Between Point Arena And Cape Mendocino In Northern California' Implications For The Development And Evolution Of A Young Transform, David A. Castillo, William L. Ellsworth

United States Geological Survey: Staff Publications

The northernmost and relatively youthful segment of the San Andreas fault system is situated within a 100+ km wide zone of northwest trending strike-slip faults that includes, from west to east, the San Andreas, Maacama, and Bartlett Springs faults. Although the San Andreas fault is the principal strike-slip fault in this system, it has been virtually aseismic since the 1906 earthquake. Moderate levels of seismicity locate to the east along the Maacama fault and, to a lesser extent, the Bartlett Springs fault at focal depths typical of other strike-slip faults within the San Andreas fault system in central California. North …


The Potential Effects Of Climate Change On Summer Season Dairy Cattle Milk Production And Reproduction, Peggy L. Klinedinst, Donald A. Wilhite, G. Leroy Hahn, Kenneth G. Hubbard Jan 1993

The Potential Effects Of Climate Change On Summer Season Dairy Cattle Milk Production And Reproduction, Peggy L. Klinedinst, Donald A. Wilhite, G. Leroy Hahn, Kenneth G. Hubbard

National Drought Mitigation Center: Faculty Publications

The potential direct effects of possible global warming on summer season dairy production and re-production were evaluated for the United States and Europe. Algorithms used for milk production and conception rate were previously developed and validated. Three widely known global circulation models (GISS, GFDL, and UKMO) were used to represent possible scenarios of future climate. Milk production and conception rate declines were highest under the UKMO model scenario and lowest under the GISS model scenario. Predicted declines for the GCM scenarios are generally higher than either “l year in 10” probability-based declines or declines based on the abnormally hot summer …


G93-1128 Understanding Groundwater, William L. Kranz, Delynn R. Hay, James W. Goeke Jan 1993

G93-1128 Understanding Groundwater, William L. Kranz, Delynn R. Hay, James W. Goeke

University of Nebraska-Lincoln Extension: Historical Materials

This NebGuide provides information on how groundwater exists, where it exists, and how it moves. Key definitions are highlighted. Water is the life blood of every living creature on earth. Approximately 70 percent of the earth's surface is covered with water. Through the wonders of nature, water can take on many different forms, from the water we drink, to the ice we use to chill a glass of lemonade, to the water vapor used to steam clean equipment. It is easy to understand the significance water plays in our lives, but it may be much more difficult to understand the …


Geology Of Arbor Day Farm Nebraska City, Nebraska, R. R. Burchett Jan 1993

Geology Of Arbor Day Farm Nebraska City, Nebraska, R. R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Reconnaissance Data For Selected Herbicides, Two Atrazine Metabolites, And Nitrate In Surface Water Of The Midwestern United States, 1989-90, Elisabeth A. Scribner, E. Michael Thurman, Donald A. Goolsby, Michael T. Meyer, Margaret S. Mills, Michael L. Pomes Jan 1993

Reconnaissance Data For Selected Herbicides, Two Atrazine Metabolites, And Nitrate In Surface Water Of The Midwestern United States, 1989-90, Elisabeth A. Scribner, E. Michael Thurman, Donald A. Goolsby, Michael T. Meyer, Margaret S. Mills, Michael L. Pomes

United States Geological Survey: Publications

Water-quality data were collected from 147 rivers and streams during 1989-90 to determine the temporal and geographic distribution of selected preemergent herbicides, two atrazine metabolites, and nitrate in 10 Midwestern States. This report includes a description of the sampling design, data-collection techniques, laboratory and analytical methods, and a compilation of constituent concentrations and quality-assurance data. All water samples were collected by depth-integrating techniques at three to five locations across the wetted perimeter of each stream. Sites were sampled three times in 1989~before application of herbicides, during the first major runoff after application of herbicides, and in the fall during a …


Resource News-March/April 1993 Jan 1993

Resource News-March/April 1993

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Cedar County Test Hole Logs, Raymond R. Burchett Jan 1993

Cedar County Test Hole Logs, Raymond R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Time-Stratigraphic Reconstruction And Integration Of Paleopedologic, Sedimentologic, And Biotic Events (Willwood Formation, Lower Eocene, Northwest Wyoming, U.S.A.), Thomas M. Bown, Mary J. Kraus Jan 1993

Time-Stratigraphic Reconstruction And Integration Of Paleopedologic, Sedimentologic, And Biotic Events (Willwood Formation, Lower Eocene, Northwest Wyoming, U.S.A.), Thomas M. Bown, Mary J. Kraus

United States Geological Survey: Staff Publications

Relative paleosol maturities are inversely proportional to the accumulation rates of the sediment upon which they formed, and are therefore excellent relative indicators of how much geologic time elapsed between any two horizons. An empirically-based model is advanced using paleosol maturities to estimate the relative geologic time separating any stratigraphic levels within the lower Eocene Willwood Formation. The revised Willwood time stratigraphy from this analysis helps evaluate the nature, tempo, and possible causes of three major episodes of mammalian appearance and disappearance. These faunal events are directly correlated with certain aspects of paleosol evolution in the Willwood Formation. That evolution …


Nebraska Mineral Operations Review, 1992, R. R. Burchett, Duane A. Eversoll Jan 1993

Nebraska Mineral Operations Review, 1992, R. R. Burchett, Duane A. Eversoll

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Geology And Mineral Resources Of Boone, Greeley, Nance, And Wheeler Counties, Nebraska, Raymond R. Burchett Jan 1993

Geology And Mineral Resources Of Boone, Greeley, Nance, And Wheeler Counties, Nebraska, Raymond R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Resource Notes-Academic Year 1992-93 Jan 1993

Resource Notes-Academic Year 1992-93

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Resource News-July/August 1993 Jan 1993

Resource News-July/August 1993

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Niobrara River Basin Geological References, Including Parts Of South Dakota Both In And Outside Of The Basin, Robert F. Diffendal Jr. Jan 1993

Niobrara River Basin Geological References, Including Parts Of South Dakota Both In And Outside Of The Basin, Robert F. Diffendal Jr.

Conservation and Survey Division: Faculty and Staff Publications

Includes Niobrara River Basin geological references, including parts of South Dakota both in and outside of the basin.


Cuming County Test Hole Logs, Raymond R. Burchett, Frank A. Smith Jan 1993

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

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


The Influence Of Alfalfa Root Structure On Plains Pocket Gopher Damage And Behavior, Bruce A. Jasch Dec 1992

The Influence Of Alfalfa Root Structure On Plains Pocket Gopher Damage And Behavior, Bruce A. Jasch

School of Natural Resources: Dissertations, Theses, and Student Research

No abstract provided.


Groundwater-Level Changes In Nebraska, 1991, Gregory V. Steele, Perry B. Wigley Oct 1992

Groundwater-Level Changes In Nebraska, 1991, Gregory V. Steele, Perry B. Wigley

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Groundwater Flow In A Compressible Unconfined Aquifer With Uniform Circular Recharge, Vitaly A. Zlotnik, Glenn Ledder Jun 1992

Groundwater Flow In A Compressible Unconfined Aquifer With Uniform Circular Recharge, Vitaly A. Zlotnik, Glenn Ledder

Department of Earth and Atmospheric Sciences: Faculty Publications

The distributions of the hydraulic head and velocity components of the transient groundwater flow in an unconfined compressible aquifer of finite thickness under constant uniform circular recharge are obtained from the linearized mathematical model by the use of integral transforms. The result generalizes Dagan’s (1967) solution which was derived by neglecting the compressibility. By treating the compressibility parameter as a small value, the formula for the hydraulic head is analyzed by asymptotic methods, resulting in approximations to the exact solutions for the head and velocities on small and large time scales. The hydraulic head and flow velocities can be accurately …


Stable Isotope Composition Of Calcareous Paleosols And Ground-Water Cements From The Ogallala Group (Neogene), Western Nebraska, Leonard Robert Gardner, Robert F. Diffendal Jr., Douglas F. Williams May 1992

Stable Isotope Composition Of Calcareous Paleosols And Ground-Water Cements From The Ogallala Group (Neogene), Western Nebraska, Leonard Robert Gardner, Robert F. Diffendal Jr., Douglas F. Williams

Robert F. Diffendal, Jr., Publications

A preliminary survey has been made of the stable isotope composition of secondary carbonates in the Ogallala Group of western Nebraska. The purpose of the study was to ascertain whether the isotopic signatures of calcareous paleosols in the fine grained facies of the Ogallala and groundwater cements in gravel facies might provide a basis for stratigraphic correlation and/or paleoclimatic interpretation.

The groundwater cemented channel gravels are modestly depicted in IRO (δ18O = –10‰) as compared to calcareous paleo'sols (δ18O = –8.0 to –9.0‰). Gravels of different age, however, have essentially identical isotopic signatures. The isotopic variability …


Logistic Regression Models Of Habitat Use By Three Cyprinids In The Platte River, Nebraska, Shyi-Liang Yu May 1992

Logistic Regression Models Of Habitat Use By Three Cyprinids In The Platte River, Nebraska, Shyi-Liang Yu

School of Natural Resources: Dissertations, Theses, and Student Research

No abstract provided.


Hydrogeology Of Parts Of The Twin Platte And Middle Republican Natural Resources Districts, Southwestern Nebraska, J. W. Goeke, J. M. Peckenpaugh, R. E. Cady, J. T. Dugan, R. A. Engberg Apr 1992

Hydrogeology Of Parts Of The Twin Platte And Middle Republican Natural Resources Districts, Southwestern Nebraska, J. W. Goeke, J. M. Peckenpaugh, R. E. Cady, J. T. Dugan, R. A. Engberg

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.