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Articles 26581 - 26610 of 29957

Full-Text Articles in Geology

A Methodology For Studying Denitrification By Recently Formed Sulfides, Bethany A. Bolles Jan 1998

A Methodology For Studying Denitrification By Recently Formed Sulfides, Bethany A. Bolles

Theses and Dissertations

Nitrate (N03) contamination due to anthropogenic sources is a serious and widespread health problem. In many groundwater systems, N03-can be reduced to a harmless gas, N2, through the bacterially mediated process of denitrification. During this process, bacteria gain energy by transferring electrons from an "electron donor" to nitrate, the "electron acceptor". It is typically believed that organic carbon is the most important electron donor in the denitrification process; however, increasing amounts of research suggest the importance of inorganic electron donors. The most extensive studies involving the reduction ofN03- by inorganic species have focused on pyrite (FeS2) and Fe(II). Few studies …


Identification Of Past Climate Variability Of The Eastern Pacific Ocean Using Both D13c And D18o Records In Corals From Clipperton Atoll (1994-1906), Lei Ren Jan 1998

Identification Of Past Climate Variability Of The Eastern Pacific Ocean Using Both D13c And D18o Records In Corals From Clipperton Atoll (1994-1906), Lei Ren

Geology Theses and Dissertations

The ENSO (El Nino and the Southern Oscillation) is a fundamental ocean-atmosphere phenomenon that dominates interannual global climate variability. Reconstructing past ENSO events is therefore important for documenting and understanding the past behavior of the global climate system and enabling us to predict future climate change. However, the present understanding of ENSO events has been mainly based on the instrumental record of Pacific climate which provides detailed data only for the past few decades. Recent studies have shown that the stable isotope record in coral skeletons can be used as a valuable indicator of paleoclimatic changes in tropical regions, and …


Oil And Gas Map Of The Evansville 30 X 60 Minute Quadrangle, Kentucky, Brandon C. Nuttall Jan 1998

Oil And Gas Map Of The Evansville 30 X 60 Minute Quadrangle, Kentucky, Brandon C. Nuttall

Map and Chart--KGS

No abstract provided.


Mineral And Fuel Resources Map Of Kentucky, Warren H. Anderson, Garland R. Dever Jr. Jan 1998

Mineral And Fuel Resources Map Of Kentucky, Warren H. Anderson, Garland R. Dever Jr.

Map and Chart--KGS

The production of minerals and fuels in Kentucky is a multibillion dollar industry. Historically, coal, oil, natural gas, limestone, sand and gravel, clay, fluorite, barite, lead, iron, phosphate, zinc, and brines have been produced in the State. These resources have greatly influenced the development of Kentucky by providing raw materials for the early settlers who settled the State and for current industrial and economic development. Electrical power for homes, businesses, and factories; materials for constructing houses, buildings, automobiles, and roads; and products we consume in everyday life come from the earth's mineral and fuel resources.


Impact Of Topographic And Data Resolution On Hydrologic And Nonpoint-Source Pollution Modeling In A Karst Terrane, Alex W. Fogle Jan 1998

Impact Of Topographic And Data Resolution On Hydrologic And Nonpoint-Source Pollution Modeling In A Karst Terrane, Alex W. Fogle

Report of Investigations--KGS

To prevent or reduce the contamination of ground water from agricultural sources, Best Management Practices (BMP’s) such as land-use changes, modifications to control surface runoff, various tillage methods, variations in rates and kinds of chemical applications, and handling procedures for chemicals are being employed and analyzed for effectiveness. The effectiveness of a BMP is often estimated before implementation by evaluating the BMP through the use of computer simulation models. The interactions between surface water and ground water that are unique to karst terranes are not incorporated into the frequently used predictive models. The purpose of this study was to document …


Volcanic Caves Of East Africa - An Overview, Jim W. Simons Jan 1998

Volcanic Caves Of East Africa - An Overview, Jim W. Simons

International Journal of Speleology

Numerous Tertiary to recent volcanoes are located in East Africa. Thus, much of the region is made up volcanic rock, which hosts the largest and greatest variety of East Africas caves. Exploration of volcanic caves has preoccupied members of Cave Exploration Group of East Africa (CEGEA) for the past 30 years. The various publications edited by CEGEA are in this respect a treasure troves of speleological information. In the present paper an overview on the most important volcanic caves and areas are shortly reported.


Guano Mining In Kenyan Lava Tunnel Caves, Jim W. Simons Jan 1998

Guano Mining In Kenyan Lava Tunnel Caves, Jim W. Simons

International Journal of Speleology

Commercial mining of bat guano for agricultural fertilizer only became possible in Kenya through discovery of major deposits in the lava tunnel caves of Mt. Suswa and the North Chyulu Hills in the early 1960’s. This paper provides historical information leading up to the guano mining, describes the cave deposits, outlines the mining under-takings, and provides information on the guano producing bats and insect faunas. The results of guano analyses, details of the tonnages extracted and sold to recipients between 1966 to 1984, and some benefits which resulted from its use on crops are given. A brief outline of attempts …


"Hades" - A Remarkable Cave On Oldoinyo Lengai In The East African Rift Valley, Gordon J. Davies Jan 1998

"Hades" - A Remarkable Cave On Oldoinyo Lengai In The East African Rift Valley, Gordon J. Davies

International Journal of Speleology

Oldoinyo Lengai is the world’s only active carbonatite volcano, situated in northern Tanzania within the Eastern Rift Valley, al 2.751 degrees S, 35.902 degrees E. It forms an isolated symmetrical cone at the southern end of Lake Natron, with a summit elevation of 2,890 m (9,480 ft). Periodic eruptions of ash and lava have been recorded since about 1880, and with increasing precision during this century since 1904. In 1990 a routine expedition to monitor activity levels at the summit led to the discovery of a remarkable cave located in the crater floor, filled with numerous long delicate pale yellow …


Tectonic Caves Of Solai In The Kenyan Rift Valley, Robert A. Davis Jan 1998

Tectonic Caves Of Solai In The Kenyan Rift Valley, Robert A. Davis

International Journal of Speleology

Tectonic caves at Solai, Kenya, were explored in 1970. These lie in a complex geological area of the Great Rift Valley in columnar-faulted ignimbrite. Fissures are presumed to have been widened by later tectonic activity -e.g. the major earthquake of January, 1928. The caves and exploration are briefly described. Questions of formation, drainage and possibilities of steam reservoirs are discussed.


Lava Caves Of Grande Comore, Indian Ocean: An Initial Reconnaissance, September 1997, Gregory J. Middleton Jan 1998

Lava Caves Of Grande Comore, Indian Ocean: An Initial Reconnaissance, September 1997, Gregory J. Middleton

International Journal of Speleology

What are believed to have been the first speleological investigations in the Comoros Islands were carried out on Grande Comore island between 7 and 13 September 1997. A number of caves were located with the help of local informants and the more significant ones surveyed. Exploration of some caves was not able to be completed. The potential for further significant discoveries is believed to be high.


Lava Caves Of The Republic Of Mauritius, Indian Ocean, Gregory J. Middleton Jan 1998

Lava Caves Of The Republic Of Mauritius, Indian Ocean, Gregory J. Middleton

International Journal of Speleology

In their Underground Atlas, MIDDLETON & WALTHAM (1986) dismissed Mauritius as: “very old volcanic islands with no speleological interest”. Recent investigations indicate this judgement is inaccurate; there are over 50 significant caves, including lava tube caves up to 687 m long (one 665 m long was surveyed as early as 1769) and 35 m wide. Plaine des Roches contains the most extensive system of lava tube caves with underground drainage rising at the seashore. Notable fauna includes an insectivorous bat and a cave swiftlet (Collocalia francica), the nests of which are unfortunately prized for ‘soup”. The caves …


Hollow Volcanic Tumulus Caves Of Kilauea Caldera, Hawaii County, Hawaii, William R. Halliday Jan 1998

Hollow Volcanic Tumulus Caves Of Kilauea Caldera, Hawaii County, Hawaii, William R. Halliday

International Journal of Speleology

In addition to lava tube caves with commonly noted features, sizable subcrustal spaces of several types exist on the floor of Kilauea Caldera. Most of these are formed by drainage of partially stabilized volcanic structures enlarged or formed by injection of very fluid lava beneath a plastic crust. Most conspicuous are hollow tumuli, possibly first described by Walker in 1991. Walker mapped and described the outer chamber of Tumulus E-1 Cave. Further exploration has revealed that it has a hyperthermic inner room beneath an adjoining tumulus with no connection evident on the surface. Two lengthy, sinuous hollow tumuli also are …


Sheet Flow Caves Of Kilauea Caldera, Hawaii County, Hawaii, William R. Halliday Jan 1998

Sheet Flow Caves Of Kilauea Caldera, Hawaii County, Hawaii, William R. Halliday

International Journal of Speleology

Terminal lobes of sheet flows of pahoehoe lava sometimes form three-dimensional nests, initially separated by partitions consisting of accreted "skins” of each lobe. Melting breaks down these partitions, forming a uniform flow unit. In Kilauea Caldera we have found and mapped sizable drained cavities in low-slope sheet flows. Their general pattern includes three-dimensional nests, with partially melted septa evident in some examples. Christmas Cave is the most extensive found to date, with 632 meters surveyed on two levels. It is located at the lower end of an inflated sheet flow tongue which underwent local deflation as a result of drainage …


"Pit Craters", Lava Tubes, And Open Vertical Volcanic Conduits In Hawaii: A Problem In Terminology, William R. Halliday Jan 1998

"Pit Craters", Lava Tubes, And Open Vertical Volcanic Conduits In Hawaii: A Problem In Terminology, William R. Halliday

International Journal of Speleology

Almost from the 1849 publication of the term pit crater, volcanologists have disagreed about the parameters differentiating these features from other vertical volcanic structures. Kaluaiki is a jameo giving entry to Thurston Lava Tube in Hawaii Volcanoes National Park. Long-standing misidentification of it as a pit crater is an example of misunderstandings arising from the lack of a clear definition of pit crater. In general, pit craters are unrelated to lava tube caves genetically, but two special cases are discussed. One probably is genetically related to a rift tube deep below the surface; the other is a complex of a …


The 1981 Eruptive Fissure On Mt. Etna: Considerations On Its Exploration And Genesis, Angelo Leotta, Marco Liuzzo Jan 1998

The 1981 Eruptive Fissure On Mt. Etna: Considerations On Its Exploration And Genesis, Angelo Leotta, Marco Liuzzo

International Journal of Speleology

This paper is targeted to an analysis of features common to various fissure caves on Mt. Etna, Sicily. The Authors report the preliminary results of the exploration carried out in the 1981 eruptive fissure, the technical problems met during the exploration, the flow trends and the different courses of the molten material inside the fissure, the particular morphologies. A genetic model is proposed, different from those characterising the lava tube cave genesis, and links are suggested between the various fissures and the main tectonic stress systems operating on Mt. Etna, as well as the morpho-structural conditions of the volcanic edifice …


Chemical Deposits In Volcanic Caves Of Argentina, Carlos Benedetto, Paolo Forti, Ermanno Galli, Antonio Rossi Jan 1998

Chemical Deposits In Volcanic Caves Of Argentina, Carlos Benedetto, Paolo Forti, Ermanno Galli, Antonio Rossi

International Journal of Speleology

During the last Conference of the FEALC (Speleological Federation of Latin America and Caribbean Islands) which was held in the town of Malargue, Mendoza, in February 1997, two volcanic caves not far from that town were visited and sampled for cave mineral studies. The first cave (Cueva del Tigre) opens close to the Llancanelo lake, some 40 kms far from Malargue and it is a classical lava tube. Part of the walls and of the fallen lava blocks are covered by white translucent fibres and grains. The second visited cave is a small tectonic cavity opened on a lava bed …


Lava Tube Remelt By Radiant Heat And Burning Gasses, Kevin Allred Jan 1998

Lava Tube Remelt By Radiant Heat And Burning Gasses, Kevin Allred

International Journal of Speleology

Some volcanologists assume that interior surfaces of hot lava tubes can commonly be remelted by burning gases and radiant heat. Pending further data, this appears to be unlikely.


Overview Of The 8th International Symposium On Vulcanospeleology, William R. Halliday Jan 1998

Overview Of The 8th International Symposium On Vulcanospeleology, William R. Halliday

International Journal of Speleology

In February 1998 the 8h International Symposium on Vulcanospeleology was hosted by CEGEA (Cave Exploration Group of East Africa) in Nairobi, Kenya: it was attended by 16 scientists coming from 4 continents. Pre- and Post- Symposium excursions allowed the participants to have an overview on the most important and famous volcanic cave of that area.


Lave Caves Of Kilimanjaro. Mawenzi Lava Tubes, Clive Ward Jan 1998

Lave Caves Of Kilimanjaro. Mawenzi Lava Tubes, Clive Ward

International Journal of Speleology

This is the first short report on the exploration of lava tubes in the upper part of Kilimanjaro. The area seems to be extremely interesting from vulcanospeleological point of view.


The Origin Of Tubular Lava Stalactites And Other Related Forms, Kevin Allred, Carlene Allred Jan 1998

The Origin Of Tubular Lava Stalactites And Other Related Forms, Kevin Allred, Carlene Allred

International Journal of Speleology

Tubular lava stalactites are often found in lava tubes. Field observations, sample analysis, and comparative studies indicate that these are segregations extruded during cooling from partially crystallized lava al about 1,070 - 1,000 °C. Retrograde boiling (gas pressure) within the lava provides a mechanism to expel the interstitial liquid. In addition to tubular lava stalactites, a variety of other lava features can also result, such as lava helictites, lava coralloids, barnacle-like stretched lava, runners, runner channels, and some lava blisters and squeeze-ups.


South Central Nebraska Geology Field Trip Conservation And Survey Division-Ianr-Unl & Nebraska Well Drillers Association, Conservation Survey Division Jan 1998

South Central Nebraska Geology Field Trip Conservation And Survey Division-Ianr-Unl & Nebraska Well Drillers Association, Conservation Survey Division

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Estimation Of Suspended Sediment Concentration In Water Using Integrated Surface Reflectance, Mahtab A. Lodhi, Donald C. Rundquist, Luoheng Han, Mark S. Kuzila Jan 1998

Estimation Of Suspended Sediment Concentration In Water Using Integrated Surface Reflectance, Mahtab A. Lodhi, Donald C. Rundquist, Luoheng Han, Mark S. Kuzila

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Nebraska Oil And Gas Production And Value For 1996 And 1997, R. R. Burchett, W. H. Sydow Jan 1998

Nebraska Oil And Gas Production And Value For 1996 And 1997, R. R. Burchett, W. H. Sydow

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Oil And Gas Facts For Nebraska, R. R. Burchett Jan 1998

Oil And Gas Facts For Nebraska, R. R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Dodge County Test Hole Logs, Frank A. Smith, Raymond R. Burchett Jan 1998

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

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Harlan County Test Hole Logs, Raymond R. Burchett Jan 1998

Harlan County Test Hole Logs, Raymond R. Burchett

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Twin Platte Natural Resources District Groundwater Quality Study, D. C. Gosselin, L. Howard, J. Goeke Jan 1998

Twin Platte Natural Resources District Groundwater Quality Study, D. C. Gosselin, L. Howard, J. Goeke

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Paleosols As Holocene Proxy Climate Indicators, Mclean County, North Dakota, Deborah L. Beck Jan 1998

Paleosols As Holocene Proxy Climate Indicators, Mclean County, North Dakota, Deborah L. Beck

Theses and Dissertations

An exposure with 15 buried A-horizons near Douglas Creek, Lake Sakakawea, central North Dakota, has provided an excellent opportunity for paleoclimate reconstruction. Analyses included texture, stable carbon, radiocarbon, pollen, and phytoliths. The variations in these properties between individual soil horizons served to reconstruct the former environments of each soil horizon.

The paleosols were developed in a sequence of deposits in a mile-long tributary to the Missouri River. The soils are in a shallow valley fill exposed by wave action along the north shore of Lake Sakakawea. The 1996 exposure was up to 4m high and 51.5m wide. There were up …


Quartzite Fabric Transition In A Cordilleran Metamorphic Core Complex, Allen J. Mcgrew, Martin Casey Jan 1998

Quartzite Fabric Transition In A Cordilleran Metamorphic Core Complex, Allen J. Mcgrew, Martin Casey

Department of Earth, Environment and Sustainability Faculty Publications

Photomicrographs 143A-143F record fabric variations in quartzite with increasing structural depth in a > 1 km thick, amphibolite-facies, normal-sense shear zone in the East Humboldt metamorphic core complex, Nevada (Figure 143.1). This shear zone and the overlying detachment system unroofed an infrastructure of high-grade, migmatitic gneiss during Oligocene to early Miocene extension (Dallmeyer and others, 1986; Wright and Snoke, 1993; McGrew and Snee, 1994). Thermobarometric constraints from near the base of the mylonitic zone record deformation conditions of 550°- 620°C and 300-400 MPa (Hurlow and others, 1991). Sample WBC6 (l43A and 143B) characterizes the mylonitic zone, whereas sample 8706-1 (143C and …


Comparison Of Median Indicator Kriging With Full Indicator Kriging In The Analysis Of Spatial Data, Donna Hill Jan 1998

Comparison Of Median Indicator Kriging With Full Indicator Kriging In The Analysis Of Spatial Data, Donna Hill

Theses : Honours

In the earth sciences, and particularly in the mining of precious metals, data distributions are often strongly positively skewed. When making decisions on the potential profitability of a gold mine, for example, the high values of the distribution are of particular importance. Indicator kriging provides estimates of cumulative distribution functions from which grade tonnage curves may be calculated. Multiple or full indicator kriging requires a semivariogram to be modelled and a kriging system of equations to be solved for each cut off. This can be time consuming and modelling indicator semivariograms at high cut-offs may be difficult because of the …