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Page 1524, results 38076 - 38100

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Storm-controlled oblique dunes of the Oregon coast
R. E. Hunter, B. M. Richmond, T. R. Alpha
1983, Geological Society of America Bulletin (94) 1450-1465
The large (mean height 25 m, spacing 300 m), relatively straight-crested dunes of the central Oregon coast migrate an average of 3.8 m/yr toward an azimuth of 26°. The dunes are transverse to the strong, south-southwesterly winter storm winds that are responsible for...
A mechanism to explain the generation of earthquake lights
D.A. Lockner, M.J.S. Johnston, J.D. Byerlee
1983, Nature (302) 28-33
Explanations of how earthquake lights might arise have failed to show how large charge densities can be concentrated and sustained in a conductive Earth. A physical model is proposed, based on frictional heating of the fault, that solves this and related problems. ?? 1983 Nature Publishing Group....
Simulation of solute transport in a mountain pool-and-riffle stream with a kinetic mass transfer model for sorption
Kenneth E. Bencala
1983, Water Resources Research (19) 732-738
In natural channels there are often long periods of low flow during which solutes have repeated opportunity for contact with relatively immobile bed materials. Such conditions can exist in very small pool-and-riffle mountain streams. If a solute can sorb onto bed materials, then both hydrodynamic and chemical processes control solute...
Process and rate of dedolomitization: Mass transfer and C14 dating in a regional carbonate aquifer
W. Back, B.B. Hanshaw, Niel Plummer, P.H. Rahn, C.T. Rightmire, M. Rubin
1983, Geological Society of America Bulletin (94) 1415-1429
Regional dedolomitization is the major process that controls the chemical character of water in the Mississippian Pahasapa Limestone (Madison equivalent) surrounding the Black Hills, South Dakota and Wyoming. The process of dedolomitization consists of dolomite dissolution and concurrent precipitation of calcite; it is...
The 1979 Homestead Valley earthquake sequence, California: Control of aftershocks and postseismic deformation
R.S. Stein, M. Lisowski
1983, Journal of Geophysical Research Solid Earth (88) 6477-6490
The coseismic slip and geometry of the March 15, 1979, Homestead Valley, California, earthquake sequence are well constrained by precise horizontal and vertical geodetic observations and by data from a dense local seismic network. These observations indicate 0.52±0.10 m of right-lateral slip and 0.17±0.04 m of reverse slip on a...
Land-use planning: One geologist's viewpoint
E-An Zen
1983, Environmental Conservation (10) 97-104
Planning for the best use of land and its resources should take fully into consideration the long-term consequences of each type of use in order to stretch out most beneficially the well-being of society in the future, and to protect the integrity of the land and its...
A short-pulse electromagnetic transponder for hole-to-hole use
David L. Wright, Raymond D. Watts, Erik Bramsoe
1983, IEEE Transactions on Geoscience and Remote Sensing (GE-22) 720-725
We have made hole-to-hole observations through nearly 20 m of granite using an electromagnetic transponder (an active reflector) in one borehole and a single-hole short-pulse radar in another. We found that the transponder is inexpensive, operationally simple, and effective in extending the capability of a short-pulse borehole radar system to...
Calculation of amorphous silica solubilities at 25° to 300°C and apparent cation hydration numbers in aqueous salt solutions using the concept of effective density of water
Robert O. Fournier, Marshall L. Williams
1983, Geochimica et Cosmochimica Acta (47) 587-596
The solubility of amorphous silica in aqueous salt solutions at 25° to 300°C can be calculated using information on its solubility in pure water and a model in which the activity of water in the salt solution is defined to equal the effective density. pe, of “free” water in that solution....
Thermal decarboxylation of acetic acid: Implications for origin of natural gas
Y.K. Kharaka, W.W. Carothers, R.J. Rosenbauer
1983, Geochimica et Cosmochimica Acta (47) 397-402
Laboratory experiments on the thermal decarboxylation of solutions of acetic acid at 200°C and 300°C were carried out in hydrothermal equipment allowing for on-line sampling of both the gas and liquid phases for chemical and stable-carbon-isotope analyses. The solutions had ambient pH values between 2.5 and 7.1; pH values and...
HIGH-TEMPERATURE GEOTHERMAL RESOURCES IN HYDROTHERMAL CONVECTION SYSTEMS IN THE UNITED STATES.
Manuel Nathenson
1983, Conference Paper, Electric Power Research Institute, Advanced Power Systems Division, (Report) EPRI AP
The calculation of high-temperature geothermal resources ( greater than 150 degree C) in the United States has been done by estimating the temperature, area, and thickness of each identified system. These data, along with a general model for recoverability of geothermal energy and a calculation that takes account of the...
Snow and ice in a changing hydrological world
M. F. Meier
1983, Hydrological Sciences Journal (28) 3-22
On the occasion of the 60th anniversary of the International Association of Hydrological Sciences, the 100th and 50th anniversaries of the First and Second International Polar Years, and the 25th anniversary of the International Geophysical Year, it seems appropriate to re-examine the world's water balance and the role of snow...
GEOLOGIC FRAMEWORK FOR GEOTHERMAL ENERGY IN THE CASCADE RANGE.
W. A. Duffield
1983, Conference Paper, Transactions - Geothermal Resources Council
Quaternary volcanoes of the Cascade Range form a 1200-km-long belt from northern California to southwest British Columbia and lie above the subduction zone formed as the Juan de Fuca plate is consumed beneath North America. Volcanoes throughout this belt may have been active during Quaternary time, and many have erupted...
Nonequilibrium models for predicting forms of precipitated manganese oxides
J.D. Hem, Carol J. Lind
1983, Geochimica et Cosmochimica Acta (47) 2037-2046
Manganese oxides precipitated by bubbling air through 0.01 molar solutions of MnCl2, Mn(NO3)2, MnSO4, or Mn(ClO4)2 at a constantly maintained pH of 8.5 to 9.5 at temperatures of 25°C or higher consisted mainly of hausmannite, Mn3O4. At temperatures near 0°C, but with other conditions the same, the product is feitknechtite, βMnOOH,...
Characteristics of resuspended sediment from Georges Bank collected with a sediment trap
C.M. Parmenter, Michael H. Bothner, B. Butman
1983, Estuarine, Coastal and Shelf Science (17) 521-533
A sediment trap was deployed 3 m from the bottom at a water depth of 62 m on the southern flank of Georges Bank (41°02·2′N, 67°33·5′W) from 30 September 1978 to 10 March 1979 to qualitatively determine the size of sediments resuspended from the bottom by winter storms and to...
Euler-Lagrangian computation for estuarine hydrodynamics
Ralph T. Cheng
1983, Conference Paper, Numerical Methods in Laminar and Turbulent Flow, Proceedings of the International Conference
The transport of conservative and suspended matter in fluid flows is a phenomenon of Lagrangian nature because the process is usually convection dominant. Nearly all numerical investigations of such problems use an Eulerian formulation for the convenience that the computational grids are fixed in space and because the vast majority...
Hole-to-surface resistivity measurements
J.J. Daniels
1983, Geophysics (48) 87-97
Hole-to-surface resistivity measurements over a layered volcanic tuff sequence illustrate procedures for gathering, reducing, and interpreting hole-to-surface resistivity data. The magnitude and direction of the total surface electric field resulting from a buried current source is calculated from orthogonal potential difference measurements for a grid of closely spaced stations. A...
Crustal and upper mantle structure of the northern and central Sierra Nevada
B.B. Mavko, G. A. Thompson
1983, Journal of Geophysical Research Solid Earth (88) 5874-5892
Teleseismic data were recorded within the Sierra Nevada to look for lateral variations in the upper mantle. The data were collected at both temporary and permanent stations, and P wave residuals were computed. After correcting the P residual data for crustal and topographic effects, there is still a variation of as much as 0.5-0.6...
Reinterpretation of the exposed record of the last two cycles of Lake Bonneville, Western United States
W. E. Scott, W.D. McCoy, R. R. Shroba, M. Rubin
1983, Quaternary Research (20) 261-285
A substantially modified history of the last two cycles of Lake Bonneville is proposed. The Bonneville lake cycle began prior to 26,000 yr B.P.; the lake reached the Bonneville shoreline about 16,000 yr B.P. Poor dating control limits our knowledge of the timing of subsequent events. Lake level was maintained...
Taeniolite, an uncommon lithium-mica from Coyote Peak, Humboldt County, California.
Richard C. Erd, G.K. Czamanske, C.E. Meyer
1983, Mineralogical Record (14) 39-40
Taeniolite has been found in a late pegmatitic clot in a mafic alkalic diatreme at Coyote Peak; associated species are natrolite, pectolite, aegirine, barytolamprophyllite, rasvumite and sphalerite. The taeniolite is green-brown with sp. gr. (meas.) 2.85(1) and H. 31/2. Optically it is biaxial (-) with alpha 1.541(2), beta = gamma...
Isotopic and chemical composition of Parbati Valley geothermal discharges, north-west Himalaya, India
W.F. Giggenbach, R. Gonfiantini, B.L. Jangi, A.H. Truesdell
1983, Geothermics (12) 199-222
The isotopic compositions of the waters discharged from Parbati Valley geothermal areas indicate a higher altitude meteoric origin, with discharge temperatures reflecting variations in the depth of penetration of the waters to levels heated by the existence of a ‘normal’ geothermal gradient. On the basis of mixing models involving silica,...
Objective procedures for lineament enhancement and extraction
G. K. Moore, F. A. Waltz
1983, Photogrammetric Engineering and Remote Sensing (49) 641-647
A longterm research goal at EROS Data Center is to develop automated, objective procedures for lineament mapping. In support of this goal, a five-step digital convolution procedure has been used to produce directionally enhanced images, which contain few artifacts and little noise. The main limitation of this procedure is that...
Dual extraction of R-mode and Q-mode factor solutions
D. Zhou, T. Chang, J.C. Davis
1983, Journal of the International Association for Mathematical Geology (15) 581-606
It is mathematically possible to extract both R-mode and Q-mode factors simultaneously (RQ-mode factor analysis)by invoking the Eckhart-Young theorem. The resulting factors will be expressed in measures determined by the form of the scalings that have been applied to the original data matrix. Unless the measures for both solutions are...
Requirements for modeling trace metal partitioning in oxidized estuarine sediments
Samuel N. Luoma, J.A. Davis
1983, Marine Chemistry (12) 159-181
The fate of particulate-bound metals is of particular importance in estuaries because major biological energy flows involve consumption of detrital particles. The biological impact of particulate-bound metals is strongly influenced by the partitioning of metals among sediment components at the oxidized sediment-water interface. Adequate methods for directly measuring this partitioning...