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1999

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Articles 61 - 90 of 94

Full-Text Articles in Geology

Description And Taphonomy Of A Turtle Assemblage (Chelonia: Trionychidae) In The Sentinel Butte Formation (Paleocene), Billings County, North Dakota, Glenn B. Kays Jan 1999

Description And Taphonomy Of A Turtle Assemblage (Chelonia: Trionychidae) In The Sentinel Butte Formation (Paleocene), Billings County, North Dakota, Glenn B. Kays

Theses and Dissertations

Soft-shelled turtle fossils (Family: Trionychidae) are common in Late Mesozoic and Early Cenozoic freshwater terrestrial deposits throughout western North America. Taxonomy of the Trionychidae is confusing for two reasons: 1) there are differences of opinion as to which characters are important in defining the lower systematic groups; 2) trionychid fossil material is often incomplete and fragmentary and has been used as the basis for numerous taxonomic descriptions.

The Ash Coulee Quarry is a fossil turtle assemblage located within the lower portion of the Sentinel Butte Formation (Paleocene) in Billings County, North Dakota. This quarry has produced at least 40 individual …


In-Situ Measurement Of Denitrification In The Elk Valley Aquifer, Allen Schlag Jan 1999

In-Situ Measurement Of Denitrification In The Elk Valley Aquifer, Allen Schlag

Theses and Dissertations

Groundwater serves more than half of North Dakota's population as a drinking water source. Nitrate (NO₃¯) is a common groundwater contaminant associated with fertilizers, septic systems and livestock waste in shallow unconfined aquifers. As a suspected carcinogen and cause of potentially lethal methemoglobinemia in infants, the natural attenuation of NO₃¯ by denitrification can be an important process in keeping groundwater as a reliable source of clean drinking water for North Dakota. Organic carbon is often considered the most important electron donor for the chemical reduction of NO₃¯ into harmless nitrogen gas. However, several studies have shown that inorganic electron donors …


Bridger Formation Sandstones Used As An Indication Of Tectonics In The Green River Basin And Western Wyoming, Lisa S. Novins Jan 1999

Bridger Formation Sandstones Used As An Indication Of Tectonics In The Green River Basin And Western Wyoming, Lisa S. Novins

Honors Papers

Sandstone from the Eocene Bridger Formation of southwestern Wyoming can be used as a tool to constrain the timing and order of controversial tectonic events in the region. The key tectonic element in this region is the Wind River Range. Sandstones in the Bridger were derived from two source areas to the north, one being the basement rocks from the Wind River Range and the other volcanic rocks from the Absaroka Volcanic field (AVF). The abundance of volcanic grains increases upsection in the Bridger indicating that more volcanic material was carried through the Wind River Range. This evidence supports the …


Olivine Petrofabric Analysis From The Leka Ophiolite Complex, Sarah J. Titus Jan 1999

Olivine Petrofabric Analysis From The Leka Ophiolite Complex, Sarah J. Titus

Honors Papers

Peridotites, gabbros and basaltic volcanic rocks on the island of Leka, Norway in the western Scandinavian Caledonides compose a nearly complete ophiolite sequence. I examined samples from the harzburgite to dunite transition within the ultramafic tectonites of the Leka Ophiolite Complex. This rock sequence probably corresponds to the petrologic Moho, which is the true base of the oceanic crust and lies below the seismic Moho. I used universal stage techniques to determine the crystallographic preferred orientations (CPO) of olivine grains in both dunites from the base of the oceanic crust and residual harzburgites in the uppermost upper mantle. Olivine CPOs …


Evolution Of Quaternary Intraplate Mafic Lavas Detailed Using Helium-3 Surface Exposure And Argon-40/Argon-39 Dating, And Elemental And Helium, Strontium, Neodymium And Lead Isotopic Signatures: Potrillo Volcanic Field, New Mexico, United States Of America And San Quintin Volcanic Field, Baja California Norte, Mexico, Wendi Joan Whitehead Williams Jan 1999

Evolution Of Quaternary Intraplate Mafic Lavas Detailed Using Helium-3 Surface Exposure And Argon-40/Argon-39 Dating, And Elemental And Helium, Strontium, Neodymium And Lead Isotopic Signatures: Potrillo Volcanic Field, New Mexico, United States Of America And San Quintin Volcanic Field, Baja California Norte, Mexico, Wendi Joan Whitehead Williams

Open Access Theses & Dissertations

The Pleistocene Potrillo volcanic field (PVF) resides within the southern axis of the Rio Grande Rift, New Mexico, U.S.A., near the eastern extent of the Basin and Range Province. Its alkalic mafic volcanism has resulted in several hundred cones, flows and maars distributed over approximately 4,600 km2. Alignments are segregated into two halves relative to the East Robledo fault system that dissects this field. Three of the five maars have brought peridotitic and lower to upper crustal xenoliths to the surface; several older, non maar-related flows from the west half of the field host ultramafic clots. Stratigraphic relationships, 3He surface …


Glacial Deposits, Vol. 27, 1998-1999, Department Of Geography-Geology Jan 1999

Glacial Deposits, Vol. 27, 1998-1999, Department Of Geography-Geology

Glacial Deposits

Newsletter of the Department of Geography-Geology


Avon And Upper Hotham Region Natural Resource Atlas, Sarah Weaving, Jason Batory Jan 1999

Avon And Upper Hotham Region Natural Resource Atlas, Sarah Weaving, Jason Batory

All other publications

The Avon and Upper Hotham Region Atlas is one of a series of Natural Resource Atlases covering the agricultural region of Western Australia. The purpose of the Atlas is to provide data for local people who manage or have an interest in natural resources. This includes the members of Land Conservation District Committees (LCDC), catchment groups, local government, non-government organisations, conservation groups, schools and libraries.

The aim of this publication is to bring together land and natural resource information from a number of sources and present it in a clear and accessible way. The data covers a number of topics …


Hydrologic Setting Of Two Interdunal Valleys In The Central Sand Hills Nebraska, D. C. Gosselin, S. Drda, F. E. Harvey, J. Goeke Jan 1999

Hydrologic Setting Of Two Interdunal Valleys In The Central Sand Hills Nebraska, D. C. Gosselin, S. Drda, F. E. Harvey, J. Goeke

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Surface Features Of The Salt Basin Of Lancaster County, Nebraska, R. M. Joeckel, B. A. Clement Jan 1999

Surface Features Of The Salt Basin Of Lancaster County, Nebraska, R. M. Joeckel, B. A. Clement

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Reconnaissance Water Quality Study Of The Dakota Aquifer In Lancaster County, Nebraska, J. Anderson, D. D. Gosselin Jan 1999

Reconnaissance Water Quality Study Of The Dakota Aquifer In Lancaster County, Nebraska, J. Anderson, D. D. Gosselin

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Groundwater-Level Changes In Nebraska, Predevelopment To Spring 1997/Registered Irrigation Wells In Nebraska-Spring 1997, Conservation Survey Division, Jennifer Stanton, Ann Mack, Jim Weir Jan 1999

Groundwater-Level Changes In Nebraska, Predevelopment To Spring 1997/Registered Irrigation Wells In Nebraska-Spring 1997, Conservation Survey Division, Jennifer Stanton, Ann Mack, Jim Weir

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Acres Irrigated In Nebraska - Past, Present, And Future, Bryce B. Pease Jan 1999

Acres Irrigated In Nebraska - Past, Present, And Future, Bryce B. Pease

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Groundwater-Level Changes In Nebraska, 1996, Abraham H. Chen, Mohan J. Khisty Jan 1999

Groundwater-Level Changes In Nebraska, 1996, Abraham H. Chen, Mohan J. Khisty

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Stanton County Test Hole Logs, Sue Olafsen Lackey, Frank A. Smith, Raymond R. Burchett Jan 1999

Stanton County Test Hole Logs, Sue Olafsen Lackey, Frank A. Smith, Raymond R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Resource Notes-Academic Year 1998-99 Jan 1999

Resource Notes-Academic Year 1998-99

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Resource News-Spring 1999 Jan 1999

Resource News-Spring 1999

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Comparison Of An Enzyme-Linked Immunosorbent Assay (Elisa) To Gas Chromatography (Gc) - Measurement Of Polychlorinated Biphenyls (Pcbs) In Selected Us Fish Extracts, James L. Zajicek, Donald E. Tillitt, Ted R. Schwartz, Christopher J. Schmitt, Robert O. Harrison Jan 1999

Comparison Of An Enzyme-Linked Immunosorbent Assay (Elisa) To Gas Chromatography (Gc) - Measurement Of Polychlorinated Biphenyls (Pcbs) In Selected Us Fish Extracts, James L. Zajicek, Donald E. Tillitt, Ted R. Schwartz, Christopher J. Schmitt, Robert O. Harrison

United States Geological Survey: Staff Publications

The analysis of PCBs in fish tissues by immunoassay methods was evaluated using fish collected from a US monitoring program, the National Contaminant Biomonitoring Program of the US Department of Interior, Fish and Wildlife Service. Selected composite whole fish samples, which represented widely varying concentrations and sources of PCBs, were extracted and subjected to congener PCB analysis by gas chromatography (GC) and total PCB analysis using an ELISA (ePCBs) calibrated against technical Aroclor 1248. PCB congener patterns in these fishes were different from the patterns found in commercial Aroclors or their combinations as demonstrated by principal component analysis of normalized …


200,000 Years Of Climate Change Recorded In Eolian Sediments Of The High Plains Of Eastern Colorado And Western Nebraska, Daniel R. Muhs, James Swinehart, David Loope, John N. Aleinikoff, Josh Been Jan 1999

200,000 Years Of Climate Change Recorded In Eolian Sediments Of The High Plains Of Eastern Colorado And Western Nebraska, Daniel R. Muhs, James Swinehart, David Loope, John N. Aleinikoff, Josh Been

United States Geological Survey: Staff Publications

Loess and eolian sand cover vast areas of the western Great Plains of Nebraska, Kansas and Colorado (Fig. 1). In recent studies of Quaternary climate change, there has been a renewed interest in loess and eolian sand. Much of the attention now given to loess stems from new studies of long loess sequences that contain detailed records of Quaternary glacial-interglacial cycles, thought to be a terrestrial equivalent to the foraminiferal oxygen isotope record in deep-sea sediments (Fig. 2). Loess is also a direct record of atmospheric circulation, and identification of loess paleowinds in the geologic record can test atmospheric general …


Stratigraphy And Tectonics Of Tertiary Strata Of Southern Cache Valley, North-Central Utah, R. Q. Oaks Jr., K. A. Smith, Susanne U. Janecke, M. E. Perkins, W. P. Nash Jan 1999

Stratigraphy And Tectonics Of Tertiary Strata Of Southern Cache Valley, North-Central Utah, R. Q. Oaks Jr., K. A. Smith, Susanne U. Janecke, M. E. Perkins, W. P. Nash

Geosciences Faculty Publications

Southern Cache Valley occupies one of several large north-trending valleys in the northeastern part of the Basin and Range Province. It lies between the Wellsville Mountains in the west and the Bear River Range in the east. Paleozoic rocks exposed in the two mountain ranges dip easterly adjacent to the north part of the study area and in a narrow horst along the valley center in the south, but curve to a northerly dip in the southwest. A complex depositional and tectonic evolution of Tertiary strata in southern Cache Valley was determined in this study. Detailed photogeologic and field mapping, …


Folded And Faulted Salt Lake Formation Above The Miocene To Pliocene New Canyon And Clifton Detachment Faults, Malad And Bannock Ranges, Idaho: Field Trip Guide To The Deep Creek Half Graben And Environs, Susanne U. Janecke, J. C. Evans Jan 1999

Folded And Faulted Salt Lake Formation Above The Miocene To Pliocene New Canyon And Clifton Detachment Faults, Malad And Bannock Ranges, Idaho: Field Trip Guide To The Deep Creek Half Graben And Environs, Susanne U. Janecke, J. C. Evans

Geosciences Faculty Publications

Previous studies identified a major detachment terrane in southeast Idaho in the Oxford Ridge area of the Bannock Range. This study shows that these top-to-the-WSW detachment faults are late Cenozoic in age, not Mesozoic to early Tertiary as previously inferred. Provenance and facies patterns in the Miocene-Pliocene Salt Lake Formation in the Deep Creek supradetachment basin show that deposition was syntectonic to slip on the detachment faults. The highly extended Bannock detachment terrane likely persists north to the Snake River Plain and south into Utah. The breakaway for this system lies in the Portneuf Range to the east. At least …


Stability Of Paleosinks And Karstic Carbonates In The Southern Fire Clay Mining District Of Missouri, Robert Weiser Dillon Jan 1999

Stability Of Paleosinks And Karstic Carbonates In The Southern Fire Clay Mining District Of Missouri, Robert Weiser Dillon

Doctoral Dissertations

"The Southern Fire Clay District of Missouri was intensely mined during the late-1800’s to mid-1900’s for its valuable resource of high refractory clays deposited within Pennsylvanian sinkholes “paleosinks”. Mining operations have produced modifications in the Ozark aquifer, which in effect has possibly increased the instability of this paleokarst terrain and the potential of further environmental impacts to the land. Evidence supporting this hypothesis are: (1) A southerly shift in the regional groundwater divide relative to the topographic divide. This possibly is caused by the distribution of leaking clay pits, which suggests that the bedrock permeability or hydraulic conductivity has been …


Land Use And Human Impact In The Dinaric Karst, Ivan Gams, Matej Gabrovec Jan 1999

Land Use And Human Impact In The Dinaric Karst, Ivan Gams, Matej Gabrovec

International Journal of Speleology

The article presents Dinaric karst, human impacts in the area, and its long history of deforestation, transformation into stony semi-desert, and a century long reforestation, where plans to restore the primary thick soil were just hoping against hope.


Impact Of Agricultural Land Use On Some Hungarian Karst Regions, Ilona Bárány-Kevei Jan 1999

Impact Of Agricultural Land Use On Some Hungarian Karst Regions, Ilona Bárány-Kevei

International Journal of Speleology

The karst regions are found in the medium altitude mountains of Hungary. Their land use types are natural and sustainable forestry, grazing and vineyards. In international comparison, Hungary belongs to those countries of Europe where arable land is abundant, therefore, in the future its extension has to be reduced. That means agricultural activity has to be restricted on the sensitive karst surfaces. This paper presents ways of sustainable forestry and other land use types for three karst regions of Hungary.


Agriculture, Grazing And Land Changes At The Serra De Tramuntana Karstic Mountains, Ángel Ginés Jan 1999

Agriculture, Grazing And Land Changes At The Serra De Tramuntana Karstic Mountains, Ángel Ginés

International Journal of Speleology

Karst landforms are one of the most outstanding characteristics of the Serra de Tramuntana range on the island of Mallorca, especially regarding traditional farming and the landscape wilderness. Good examples of polje-like depressions, dolines, karstic gorges and karrenfields are widely distributed over the mountain range. Owing to karrenfields occupying a large surface area in the Serra to the exclusion of arable land, the traditional activity based on the repetitive burning of the Ampelodesmos mauritanica brushwoods for cattle-raising promotes hastening deforestation and soil removal.


Land Use In The Karstic Lands In The Mediterranean Region, Ibrahim Atalay Jan 1999

Land Use In The Karstic Lands In The Mediterranean Region, Ibrahim Atalay

International Journal of Speleology

Karstic lands have special importance in terms of soil formation and land-use. Soil appears only on the flat and slightly undulating karstic lands, while soils are found along the cracks and bedding surfaces between the layers on the hilly karst areas although these lands are rocky in appearance. Karstic lands in the hilly area are not conducive to cultivation. But rocky areas create a favourable habitat for the growth of forests except in an arid climate. Because the tree roots easily follow and develop along the cracks in the limestone. As a general rule soil erosion does not occur on …


Sustainable Development Of Agriculture In Karst Areas, South China, Linhua Song Jan 1999

Sustainable Development Of Agriculture In Karst Areas, South China, Linhua Song

International Journal of Speleology

The exposed carbonate rocks aged from Sinian to Mid-Triassic Periods cover an area of 500,000 km2 in south-west China. In karst areas with spectacular landscapes characterized by magnificent tower karst and conical karst, rare surface drainage systems and prevalent subsurface drainage systems, the environment is ecologically very fragile. The rapid increase of population, over deforested and cultivated lands, worsted the ecological system, causing a higher frequency of draught, flood and various disasters, backward economic development, low living standard of the people. In order to improve the sustainability of the agriculture the experience shows that the following operations should be …


Agriculture, Landscape And Human Impact In Some Karst Areas Of Italy, Ezio Burri, Benedetta Castiglioni, Ugo Sauro Jan 1999

Agriculture, Landscape And Human Impact In Some Karst Areas Of Italy, Ezio Burri, Benedetta Castiglioni, Ugo Sauro

International Journal of Speleology

Italy is made up for about 1/5 of its surface by soluble rocks, which represent the arena of karst environments. The karst morpho-units, some hundreds, are mainly distributed inside the alpine structure of the Mediterranean mountains. A very large number of rock formations are present, different in facies, lithology, age, etc. Among these, carbonate rocks prevail, followed by gypsum and salt. Most of the carbonate rocks are limestones sedimented in a platform environment and they show a wide range of porosity, frequency of fractures and bedding planes. The climatic processes, the expression of some different sub-types of Mediterranean climate (from …


Agriculture And Nature Conservation In The Moravian Karst (Czech Republic), Ivan Balák, Jozef Janèo, Leos Stefka, Pavel Bosák Jan 1999

Agriculture And Nature Conservation In The Moravian Karst (Czech Republic), Ivan Balák, Jozef Janèo, Leos Stefka, Pavel Bosák

International Journal of Speleology

Moravian karst is a narrow strip of limestone with long history of settlement, agricultural use and man impact to karst. It is naturally divided into smaller units - karst plateaus - separated by deep valleys (glens). Each plateau has different proportion of land use, i.e. the percentage of agricultural land, forests, etc. The agricultural land constitutes now up to 70% in the north and max. 30% in the centre and south of the total area of plateaus. Intensive agricultural use of the arable land since 60ties of this Century caused great impact to quality of soils and groundwater by overdoses …


Interaction Between Karst, Water And Agriculture Over The Climatic Gradient Of Israel, Amos Frumkin Jan 1999

Interaction Between Karst, Water And Agriculture Over The Climatic Gradient Of Israel, Amos Frumkin

International Journal of Speleology

The dry climate of Israel and the karstic nature of its rocks have always imposed human innovation for utilisation of water resources and agriculture. Large perennial karst springs are available only in the lowlands, but sophisticated water supply systems were built both in the lowland and highland regions. Marl layers interbedded within carbonates give rise to local perched springs and allow terrace construction. Deforestation has taken place for some 4000 years, causing intense soil erosion, but terraces have reduced this impact.


Land Use In The Tropical Karst - The Case Of Peruaçu, Januária And Jaiba; Se Brazil, Heinz Charles Kohler, Sergio Dos Anjos Ferreira Pinto, João Francisco De Abreu Jan 1999

Land Use In The Tropical Karst - The Case Of Peruaçu, Januária And Jaiba; Se Brazil, Heinz Charles Kohler, Sergio Dos Anjos Ferreira Pinto, João Francisco De Abreu

International Journal of Speleology

The karstic regions of the municipalities of Peruaçu, Januária and Jaiba present a variety of soil uses which are a function of the organization of the karstic relief. This relief system forms a rift, which received fluvial sediments deposition from the São Francisco River. The horst of the Peruaçu plateau is developed on limestone rocks of Late Proterozoic age with a high concentration of calcium carbonate. The South American Surface was formed on this and is today occupied by cattle ranching. In the graben, due to easy irrigation from underground karst waters and because of the nearby drainage system of …