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Articles 841 - 861 of 861

Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology

A Pleistocene Sand Sea On The Alaskan Arctic Coastal Plain, L. David Carter Jan 1981

A Pleistocene Sand Sea On The Alaskan Arctic Coastal Plain, L. David Carter

United States Geological Survey: Staff Publications

A ridge and thermokarst-basin landscape that is strikingly portrayed in Landsat winter imagery consists of large Pleistocene dunes that have been modified by younger eolian activity and thermokarst processes. This is the most extensive area of large stabilized dunes yet reported in the North American Arctic; the landscape is ofparticular interest because it has been proposed as a$rst-order analog for martian fretted terrain. Recognition of the large dunes permits a new interpretation for linear and curvilinear trends visible in Landsat summer imagery.


Emission Rates Of Co2 From Plume Measurements., D. M. Harris, M. Sato, T. J. Casadevall, William I. Rose, T. J. Bornhorst Jan 1981

Emission Rates Of Co2 From Plume Measurements., D. M. Harris, M. Sato, T. J. Casadevall, William I. Rose, T. J. Bornhorst

Michigan Tech Publications, Part 1

Most of the CO2 that emanated from Mount St. Helens became part of the gas plume as it moved away from the volcano. An airborne technique was developed for continuous sampling and infrared analysis for CO2 in the plume. The CO2-emission rates were determined by measuring the area, the horizontal velocity, and the CO2 concentration anomaly in vertical cross sections of the plume The emission rate varied from 2100 t/day to about 22 000 t/day.-from Author


Radar Observations Of Ash Eruptions, D. M. Harris, William I. Rose, R. Roe, M. R. Thompson Jan 1981

Radar Observations Of Ash Eruptions, D. M. Harris, William I. Rose, R. Roe, M. R. Thompson

Michigan Tech Publications, Part 1

Radar systems located at Portland, Oreg., Seattle, Wash., and near Spokane, Wash., have been used extensively for observations of ash clouds from explosive volcanic eruptions at Mount St. Helens during 1980. Eruption clouds are composed of silicate particles and are therefore detectable by radar. Radar observations can be made at night and in overcast weather when conventional observations of eruptions are difficult.-from Authors


Effects Of Changes In Surface Water Regime And/Or Land Use On The Vertical Distribution Of Water Available For Wetland Vegetation: Dynamic Model Of The Zone Of Aeration (Part 1 Of Completion Report For Project A-023-Ark), Robert N. Maccallum, R. A. Sims Jun 1980

Effects Of Changes In Surface Water Regime And/Or Land Use On The Vertical Distribution Of Water Available For Wetland Vegetation: Dynamic Model Of The Zone Of Aeration (Part 1 Of Completion Report For Project A-023-Ark), Robert N. Maccallum, R. A. Sims

Arkansas Water Resources Center Technical Reports

A mathematical model by Green, simulating one-dimensional vertical ground-water movement in unsaturated soils of the prairie region of Kansas, has been adapted for use in a wetlands environment typified by the wetlands forest of Eastern Arkansas. The model consists of two second-order, non-linear, partial differential equations and an algorithm for their numerical solution. The original model was extended to include functions for seasonal changes in transpiration and for drainage of excess precipitation. Before the addition of the two functions, the model reliability was limited to one growth season.


Chemistry Of The Spring Waters Of The Ouachita Mountains Excluding Hot Springs, Arkansas, George H. Wagner, Kenneth F. Steele Mar 1980

Chemistry Of The Spring Waters Of The Ouachita Mountains Excluding Hot Springs, Arkansas, George H. Wagner, Kenneth F. Steele

Arkansas Water Resources Center Technical Reports

This report is based on the chemical analysis of the waters from 93 springs and 9 wells. Springs, when free from metal plumbing, provide an uncontaminated source of the ground water and it was desired to obtain water uncontaminated with metals. A few wells were added to the list, usually because of their unique location in the sampling grid.


The Effect Of Dissolution Of Volcanic Glass On The Water Chemistry In A Tuffaceous Aquifer, Rainier Mesa, Nevada, Art F. White, Hans C. Claassen, Larry Benson Jan 1980

The Effect Of Dissolution Of Volcanic Glass On The Water Chemistry In A Tuffaceous Aquifer, Rainier Mesa, Nevada, Art F. White, Hans C. Claassen, Larry Benson

United States Geological Survey: Staff Publications

Geochemistry of ground water associated with the Tertiary tuffs within Rainier Mesa, southern Nevada, was investigated to determine the relative importance of glass dissolution in controlling water chemistry. Water samples were obtained both from interstitial pores in core sections and from free-flowing fractures. Cation compositions showed that calcium and magnesium decreased as a function of depth in the mesa, as sodium increased. The maximum effect occurs within alteration zones containing clinoptilolite and montmorillonite, suggesting these minerals effectively remove bivalent cations from the system.

Comparisons are made between compositions of ground waters found within Rainier Mesa that apparently have not reacted …


The Origin Of Fine Scale Acoustic Stratigraphy In Deep-Sea Carbonates, Larry A. Mayer Oct 1979

The Origin Of Fine Scale Acoustic Stratigraphy In Deep-Sea Carbonates, Larry A. Mayer

Affiliate Scholarship

In this paper we investigate the origin and geologic significance of the closely spaced high-frequency subbottom acoustic reflectors characteristic of pelagic carbonates. A detailed survey was conducted of a small area in the equatorial Pacific with the Marine Physical Laboratory's Deep-Tow instrument package, providing high-resolution 4-kHz profiles and precise positioning of core samples. The cores were sampled at closely spaced intervals for sound velocity and saturated bulk density. Acoustic impedances were calculated, and a reflection coefficient log determined for the upper 10 m of the sediment column. The reflection coefficient log revealed no interfaces with large reflection coefficients that correlated …


Uranium Transport In The Walker River Basin, California And Nevada, Larry Benson, D. L. Leach Jan 1979

Uranium Transport In The Walker River Basin, California And Nevada, Larry Benson, D. L. Leach

United States Geological Survey: Staff Publications

During the summer of 1976 waters from tributaries, rivers, springs and wells were sampled in the Walker River Basin. Snow and sediments from selected sites were also sampled. All samples were analyzed for uranium and other elements. The resulting data provide an understanding of the transport of uranium within a closed hydrologic basin as well as providing a basis for the design of geochemical reconnaissance studies for the Basin and Range Province of the Western United States. Spring and tributary data are useful in locating areas containing anomalous concentrations of uranium. However, agricultural practices obscure the presence of known uranium …


Geology Of The Mafic/Ultramafic Transition, Table Mountain, Western Newfoundland, Suzanne O'Connell Jan 1979

Geology Of The Mafic/Ultramafic Transition, Table Mountain, Western Newfoundland, Suzanne O'Connell

Geology Theses and Dissertations

A thin (<200 m.) mafic suite and well developed mafic/ultramafic transition zone are exposed above a flat lying peridotite contact on northwestern Table Mountain. The igneous layering and sedimentary features indicate mineral deposition under conditions which promoted adcumulate growth, were capable of minor transport, and were subjected to at least minor tectonic activity during consolidation. Feldspathic,. mafic, and ultramafic dikes and veins cross-cut the layering. Microscopic futures indicate deformation at elevated temperature and/or low strain rates. Deformation is best developed within the transition zone, but cataclastic zones are most common in the hornblende gabbros. Orientations of layering, foliation, and lineation indicate a variable mafic/ultramafic transition and macroscopic folding. Geometric analysis indicates three distinct fold axis orientations: an east-west horizontal fold axis, a northeast trending modestly plunging axis, and a vertical though poorly defined axis. Such features demonstrate that an apparently simple contact relationship may be extremely complex. This has important implications for ocean floor accretion. The relatively simple ocean floor seismic stratigraphy masks very complex petrological and structural processes. Such processes may involve deposition in an actively convecting magma chamber with a differentially subsiding wedge (Dewey and Kidd, 1977), in which folding occurs in response to the steepening angle between the cumulate banding and the base of the magma chamber. The instability is enhanced by the different accumulation rates and densities of the minerals involved. The lineation may originally be a sedimentary feature indicative of transport direction from the convection cell, and perpendicular to the compressive stress which produced. the folding. The different orientations of lineations and fold axes could be produced by rotation of the ocean crustal blocks during lateral transport along the ocean floor and/or obduction. Further detailed study of ophiolite complexes will continue to shed light upon the nature and development of oceanic crust.


Paleoclimatic Implications Of Oxygen Isotope And Sedimentological Study Of Late Miocene And Early Pliocene Sediments From The South Atlantic, Western Indian Ocean, And The Gulf Of Aden, Kathryn M. Scanlon Jan 1979

Paleoclimatic Implications Of Oxygen Isotope And Sedimentological Study Of Late Miocene And Early Pliocene Sediments From The South Atlantic, Western Indian Ocean, And The Gulf Of Aden, Kathryn M. Scanlon

Geology Theses and Dissertations

Previous work by many authors has implied that the Antarctic ice sheet underwent a major expansion in the latest Miocene. It was intended in the present study to use the oxygen isotope event, which could be expected to accompany this glacial expansion, as a stratigraphic marker to aid in the correlation of several DSDP Sites. Samples were taken at approximately 100,000 year intervals throughout the latest Miocene and early Pliocene sections at Sites 237 and 249 in the western Indian Ocean, Site 360 in the South Atlantic and Site 231 in the Gulf of Aden. Oxygen isotope analyses were done …


Final Report - Lake Mead Monitoring Program, James E. Deacon Jul 1976

Final Report - Lake Mead Monitoring Program, James E. Deacon

Publications (WR)

The Lake Mead monitoring program has developed a substantial body of information on the physical, chemical and biological limnology of Lake Mead since 1972. This report summarizes pertinent aspects of that data, with emphasis on studies completed in 1975 -76. It is our continuing hope that the data developed by us will be useful to an ever broader group of users of the water resource represented by Lake Mead. We have been privileged to see our data have a significant influence in some very important water resource decisions over the past four years. There is every reason to expect that …


Petrology Of The Oceanographer Fracture Zone (35ºn35ºw), Tsugio Shibata Jan 1976

Petrology Of The Oceanographer Fracture Zone (35ºn35ºw), Tsugio Shibata

Geology Theses and Dissertations

During a geological and geophysical survey of the Oceanographer Fracture Zone (35°N, 35°W), seventeen dredge hauls containing a variety of rocks were obtained. Petrographic study shows that these rock samples can be classified into six main rock types: fresh basalt, weathered basalt, metabasalt, gabbro, metagabbro, and serpentinite. Most of the dredge hauls were positioned on the steep, southern wall of the fracture zone, and an inference from the dredging results suggests that basalt is the most abundant rock type which outcrops at the junction between the rift valley and the fracture zone; however, as we move away from the junction, …


Regional Hydrothermal Alteration Of The Leadville Limestone (Mississippian) Of Central Colorado, L. V. Benson Jan 1973

Regional Hydrothermal Alteration Of The Leadville Limestone (Mississippian) Of Central Colorado, L. V. Benson

United States Geological Survey: Staff Publications

Massive metallic-sulfide deposits were implaced in the Leadville Limestone {Mississippian) of Central Colorado less than 70 million years ago. The thermal fluids which precipitated ore at Gilman, Colorado have regionally altered the Leadville Limestone. The sequence of alteration began with the recrystallization of limestone to a dark medium~grained dolomite containing a homogeneous distribution of Fe. This Was followed by partial recrystallization of the medium-grained dolomite to coarse-clear dolomite which contains an inhomogeneous distribution of Fe. The resulting banded rock is known as "zebra rock" . Precipitation of Si0 2 (jasperoid) occurred next. The jaspe=oid formed prior to the deposition of …


History Of Sedimentation In Montsweag Bay, Detmar Schnitker Jan 1972

History Of Sedimentation In Montsweag Bay, Detmar Schnitker

Maine Collection

History of Sedimentation In Montsweag Bay

by Setmar Schnitker

Bulletin #25, Department of Forestry, Augusta, Maine, 1972.

Contents: Abstract / Introduction / Geographic Setting / Seismic Profiling / Pleistocene Sediments / Holocene Sediments / Actual Sedimentation /. Suspended Sediments / Recent Changes / Outlook / Acknowledgements / References


A Preliminary Survey Of The Damariscotta River Estuary, Lincoln County, Maine, Maine Department Of Economic Development Jun 1970

A Preliminary Survey Of The Damariscotta River Estuary, Lincoln County, Maine, Maine Department Of Economic Development

Maine Collection

A Preliminary Survey of the Damariscotta River Estuary, Lincoln County, Maine

Part I - Hydrology; Part II - Sediments

"Prepared Under a Grant From the Maine Marine Stipend Program".

Maine Department of Economic Development - Division of Science, Technology & Mineral Resources, Augusta, Maine (July 1969 - June 1970).



A Fluorescent Tracer Study At A Tidal Inlet (Rudee Inlet, Virginia), James W. Bunch Jan 1969

A Fluorescent Tracer Study At A Tidal Inlet (Rudee Inlet, Virginia), James W. Bunch

OES Theses and Dissertations

Patterns and approximate rates of littoral transport south of Rudee Inlet. Virginia were investigated with fluorescent tracers. Sand movement was traced under a variety of longshore current and wave conditions. Patterns of tracer dispersal reflected the importance of wave height, breaker angle, and longshore current velocity on modes of littoral transport. A direct relationship between angle of breaker incidence. generated longshore current. and direction of tracer sand movement was found. Onshore offshore paths were taken by tracer material during periods of weak longshore currents and small breaker angles while alongshore paths were followed by tracer material during strong longshore currents …


Beach Erosion Control Study On Duval County, Fla, U.S. Army Engineer District, Jacksonville Corps Of Engineers Nov 1964

Beach Erosion Control Study On Duval County, Fla, U.S. Army Engineer District, Jacksonville Corps Of Engineers

Waterways and wildlife

The purpose of this study was to define the beach erosion and the hurricane-induced flooding problems in Duval County, to determine the most economical methods of alleviating those problems, and to determine the division of costs between the Federal Government and local interests .


Interbasin Movement Of Ground Water At The Nevada Test Site, Isaac J. Winograd Mar 1962

Interbasin Movement Of Ground Water At The Nevada Test Site, Isaac J. Winograd

Publications (WR)

The present paper presents hydraulic evidence for the interbasin circulation of ground water through carbonate rocks of Paleozoic age at the Nevada Test Site. An integral part of this evidence is the discovery that aquifers in alluvium and tuff, formerly thought to be the principal aquifers at the Test Site, are semiperched above a thick tuffaceous aquiclude that separates them from the carbonate rocks.

This paper is based on one of the studies being made by the Geological
/="/">Survey for the Atomic Energy Commission. These studies seek to evaluate
/="/">the risk that may arise if ground water should …


Progress Report On The Ground-Water Resources Of The Las Vegas Artesian Basin, Nevada, George B. Maxey, C. Harry Jameson Mar 1945

Progress Report On The Ground-Water Resources Of The Las Vegas Artesian Basin, Nevada, George B. Maxey, C. Harry Jameson

Publications (WR)

Whether the tremendously increased population acquired by Las Vegas in the years 1940 to 1942 will be retained cannot at present be foretold. However, the valley will undoubtedly be expected to support a considerably larger population than it did at any time prior to 1940, and continually increasing demands on the water supply for innumerable pcacetimc activities must be anticipated. Therefore, a sound evaluation of tho ground water resources of Las Vegas Valley is directly in line with the other wisely progressive planning programs which are now operating or are taking shape in the valley as well as in the …


Ua94/6/2/7 Physiography Notebook, Carl Ellis Jan 1911

Ua94/6/2/7 Physiography Notebook, Carl Ellis

Student/Alumni Personal Papers

Atlas Science Table for Laboratory Notes and Drawings in Physiography notebook used by Carl Ellis for Robert Green's class.


The Aerosphere As A Network Connector Of Organisms And Their Diseases, Jeremy D. Ross, Eli S. Bridge, Diann J. Prosser, John Y. Takekawa Dec 200

The Aerosphere As A Network Connector Of Organisms And Their Diseases, Jeremy D. Ross, Eli S. Bridge, Diann J. Prosser, John Y. Takekawa

United States Geological Survey: Staff Publications

Aeroecological processes, especially powered flight of animals, can rapidly connect biological communities across the globe. This can have profound consequences for evolutionary diversification, energy and nutrient transfers, and the spread of infectious diseases. The latter is of particular consequence for human populations, since migratory birds are known to host diseases which have a history of transmission into domestic poultry or even jumping to human hosts. In this chapter, we present a scenario under which a highly pathogenic avian influenza (HPAI) strain enters North America from East Asia via postmolting waterfowl migration. We use an agent-based model (ABM) to simulate the …