Debris-flow mobilization from landslides
Richard M. Iverson, Mark E. Reid, Richard G. Lahusen
1997, Annual Review of Earth and Planetary Sciences (25) 85-138
Field observations, laboratory experiments, and theoretical analyses indicate that landslides mobilize to form debris flows by three processes: (a) widespread Coulomb failure within a sloping soil, rock, or sediment mass, (b) partial or complete liquefaction of the mass by high pore-fluid pressures, and (c) conversion of landslide translational energy to...
Use of chemical and isotopic tracers to characterize the interactions between ground water and surface water in mantled karst
B. G. Katz, T.B. Coplen, T.D. Bullen, J. Hal Davis
1997, Ground Water (35) 1014-1028
In the mantled karst terrane of northern Florida, the water quality of the Upper Floridan aquifer is influenced by the degree of connectivity between the aquifer and the surface. Chemical and isotopic analyses [18O/16O (δ18O), 2H/1H (δD), 13C/12C (δ13C), tritium (3H), and strontium‐87/strontium‐86 (87Sr/86Sr)] along with geochemical mass‐balance modeling were used to...
Ordovidan K-bentonites in the Precordillera of San Juan and its tectomasmatic significance
C.A. Cingolani, W. Huff, S. Bergstrom, D. Kolata
1997, Revista de la Asociacion Geologica Argentina (52) 47-55
A succession of approximately 35 early Middle Ordovician K-bentonite beds are exposed in the Precordillera region near the town of Jachal, in San Juan Province (at Cerro Viejo and La Chilca sections). They occur in argillaceous limestone in the upper part of the San Juan Limestone and in the interbedded...
Factors controlling sulfur concentrations in volcanic apatite
G. Peng, J.F. Luhr, J. J. McGee
1997, American Mineralogist (82) 1210-1224
Apatite crystals from two types of samples were analyzed by electron microprobe for 15 major and trace elements: (1) apatite in H2O- and S-saturated experimental charges of the 1982 El Chicho??n trachyandesite and (2) apatite in volcanic rocks erupted from 20 volcanoes. The SO3 contents of the experimental apatite increase...
The effect of diet on dorsal fin erosion in steelhead trout (Oncorhynchus mykiss)
W.A. Lellis, F.T. Barrows
1997, Aquaculture (156) 229-240
A 2 X 2 factorial experiment of diet type (krill vs. fish meal) and steroid supplementation (0 vs. 30 ??g 17??-methyltestosterone kg-1) was conducted to determine the effects on dorsal fin erosion in steelhead trout. Triplicate tanks of 250 fry were fed one of the four diets at a rate...
The 1936, 1945-1947, and 1950 earthquake sequences near Lassen Peak, California
R.D. Norris, K.L. Meagher, C.S. Weaver
1997, Journal of Geophysical Research B: Solid Earth (102) 449-457
Three vigorous earthquake sequences occurred near Lassen Peak in 1936, between 1945 and 1947, and in 1950; the latter two sequences included mainshocks of magnitude 5.0 and 5.5, respectively, and thousands of smaller events. No comparable earthquake sequences have occurred near Lassen Peak since 1950. The epicentral area lies within...
Plagioclase zonation styles in hornblende gabbro inclusions from Little Glass Mountain, Medicine Lake volcano, California: Implications for fractionation mechanisms and the formation of composition gaps
J. G. Brophy, M. J. Dorais, J. Donnelly-Nolan, B. S. Singer
1997, Contributions to Mineralogy and Petrology (126) 121-136
The rhyolite of Little Glass Mountain (73–74% SiO2) is a single eruptive unit that contains inclusions of quenched andesite liquid (54–61% SiO2) and partially crystalline cumulate hornblende gabbro (53–55% SiO2). Based on previous studies, the quenched andesite inclusions and host rhyolite lava are related to one another through fractional crystallization...
Recovery strategies for the California clapper rail (Rallus longirostris obsoletus) in the heavily-urbanized San Francisco estuarine ecosystem
Theodore C. Foin, E. Jacqueline Garcia, Robert E. Gill Jr., Steven D. Culberson, Joshua N. Collins
1997, Landscape and Urban Planning (38) 229-243
The California clapper rail (Rallus longirostris obsoletus), a Federal- and State-listed endangered marsh bird, has a geographic range restricted to one of the most heavily-urbanized estuaries in the world. The rail population has long been in a state of decline, although the exact contribution of each of the many contributing...
Bulk-friction modeling of afterslip and the modified Omori law
Leif Wennerberg, Robert V. Sharp
1997, Tectonophysics (277) 109-136
Afterslip data from the Superstition Hills fault in southern California, a creep event on the same fault, the modified Omori law, and cumulative moments from aftershocks of the 1957 Aleutian Islands earthquake all indicate that the original formulation by Dieterich (1981) [Constitutive properties of faults with simulated gouge. AGU, Geophys....
The genus Krithe (Ostracoda) from the Campanian and Maastrichtian (Upper Cretaceous) of the northern US Gulf Coastal Plain
T.M. Puckett
1997, Journal of Micropalaeontology (16) 145-157
The ostracode genus Krithe is one of the most common genera in the Upper Cretaceous (late Santonian to Maastrichtian) deposits of the northern Gulf Coastal Plain of North America. Although it is never abundant, the genus occurs in sediments that were deposited under a wide range of palaeoenvironments, including nearshore...
Large-scale variability of wind erosion mass flux rates at Owens Lake 1. Vertical profiles of horizontal mass fluxes of wind-eroded particles with diameter greater than 50 μm
Dale A. Gillette, D.W. Fryrear, Jing Bing Xiao, Paul Stockton, Duane Ono, Paula J. Helm, Thomas E Gill, Trevor Ley
1997, Journal of Geophysical Research D: Atmospheres (102) 25977-25987
A field experiment at Owens (dry) Lake, California, tested whether and how the relative profiles of airborne horizontal mass fluxes for >50-μm wind-eroded particles changed with friction velocity. The horizontal mass flux at almost all measured heights increased proportionally to the cube of friction velocity above an apparent threshold friction...
Experiments on the role of water in petroleum formation
M. D. Lewan
1997, Geochimica et Cosmochimica Acta (61) 3691-3723
Pyrolysis experiments were conducted on immature petroleum source rocks under various conditions to evaluate the role of water in petroleum formation. At temperatures less than 330°C for 72 h, the thermal decomposition of kerogen to bitumen was not significantly affected by the presence or absence of liquid water in contact...
A study of the temporal variability of atrazine in private well water. Part I: Study design, implementation, and database development
M. Lorber, Kevin Johnson, B. Kross, P. Pinsky, L. Burmeister, M. Thurman, A. Wilkins, G. Hallberg
1997, Environmental Monitoring and Assessment (47) 175-195
In 1988, the Iowa Department of Natural Resources, along with the University of Iowa conducted the Statewide Rural Well Water Survey, commonly known as SWRL. A total of 686 private rural drinking water wells was selected by use of a probability sample and tested for pesticides and nitrates. Sixty-eight of...
A numerical model of sediment transport applied to San Francisco Bay, California
E.T. Mcdonald, R. T. Cheng
1997, Journal of Marine Environmental Engineering (4) 1-41
A two dimensional depth-averaged sediment transport model is used to simulate field measurements of suspended sediment concentrations in northern San Francisco Bay. The model uses a semi-implicit finite difference method to solve the shallow water equations and incorporates standard empirical expressions for erosion and deposition of sediments into the transport...
Geologic hazards in the region of the Hurricane fault
W.R. Lund
1997, Brigham Young University Geology Studies (42) 235-277
Complex geology and variable topography along the 250-kilometer-long Hurricane fault in northwestern Arizona and southwestern Utah combine to create natural conditions that can present a potential danger to life and property. Geologic hazards are of particular concern in southwestern Utah, where the St. George Basin and Interstate-15 corridor north to...
Bedrock geology of snyderville basin: Structural geology techniques applied to understanding the hydrogeology of a rapidly developing region, Summit County, Utah
K.E. Keighley, W.A. Yonkee, F.X. Ashland, J.P. Evans
1997, Brigham Young University Geology Studies (42) 325-343
The availability of ground water is a problem for many communities throughout the west. As these communities continue to experience growth, the initial allocation of ground water supplies proves inadequate and may force restrictions on existing, and future, development plans. Much of this new growth relies on ground water supplies...
Depth dependence of earthquake frequency-magnitude distributions in California: Implications for rupture initiation
J. Mori, R.E. Abercrombie
1997, Journal of Geophysical Research B: Solid Earth (102) 15081-15090
Statistics of earthquakes in California show linear frequency-magnitude relationships in the range of M2.0 to M5.5 for various data sets. Assuming Gutenberg-Richter distributions, there is a systematic decrease in b value with increasing depth of earthquakes. We find consistent results for various data sets from northern and southern California that both include and exclude...
Wrinkle-like slip pulse on a fault between different materials
D.J. Andrews, Y. Ben-Zion
1997, Journal of Geophysical Research B: Solid Earth (102) 553-571
Pulses of slip velocity can propagate on a planar interface governed by a constant coefficient of friction, where the interface separates different elastic materials. Such pulses have been found in two-dimensional plane strain finite difference calculations of slip on a fault between elastic media with wave speeds differing by 20%....
Bimodal magmatism, basaltic volcanic styles, tectonics, and geomorphic processes of the eastern Snake River Plain, Idaho
S.S. Hughes, R.P. Smith, W. R. Hackett, M. McCurry, S. R. Anderson, G.C. Ferdock
1997, Brigham Young University Geology Studies (42) 423-458
Geology presented in this field guide covers a wide spectrum of internal and surficial processes of the eastern Snake River Plain, one of the largest components of the combined late Cenozoic igneous provinces of the western United States. Focus is on widespread Quaternary basaltic plains volcanism that produced coalescent shields...
Mississippian coral latitudinal diversity gradients (western interior United States): Testing the limits of high resolution diversity data
G.E. Webb, W.J. Sando, A. Raymond
1997, Journal of Paleontology (71) 780-791
Analysis of high resolution diversity data for Mississippian corals in the western interior United States yielded mild latitudinal diversity gradients despite the small geographic area covered by samples and a large influence on diversity patterns by geographic sampling intensity (sample bias). Three competing plate tectonic reconstructions were...
The inverse problem of argon diffusion from minerals: Determination of kinetic parameters from stepwise-heating experiments
Stephen B. Brandt, S.V. Rasskazov, I.S. Brandt, A.V. Ivanov, Michael J. Kunk
1997, Isotopes in Environmental and Health Studies (33) 399-409
Results of two routine 40Ar/39Ar stepwise heating experiments on a biotite and a basanite are interpreted in terms of Fick's and Arrhenius' laws. Both patterns represent a saddle-shaped 39Ar release. Argon isotope spectra are suggested to be controlled by the activation energy of diffusion E and the frequency factor Do . The activation energy of 39Ar is...
Water level and strain changes preceding and following the August 4, 1985 Kettleman Hills, California, earthquake
E. Roeloffs, E. Quilty
1997, Pure and Applied Geophysics (149) 21-60
Two of the four wells monitored near Parkfield, California, during 1985 showed water level rises beginning three days before the M4 6.1 Kettleman Hills earthquake. In one of these wells, the 3.0 cm rise was nearly unique in five years of water level data. However, in the other well, which...
Accretion of a New England (U.S.A.) salt marsh in response to inlet migration, storms, and sea-level rise
C. T. Roman, J.A. Peck, J.R. Allen, J.W. King, P.G. Appleby
1997, Estuarine, Coastal and Shelf Science (45) 717-727
Sediment accumulation rates were determined at several sites throughout Nauset Marsh (Massachusetts, U.S.A.), a back-barrier lagoonal system, using feldspar marker horizons to evaluate short-term rates (1 to 2 year scales) and radiometric techniques to estimate rates over longer time scales (137Cs,210Pb,14C). The barrier spit fronting theSpartina-dominated study site has a...
Regional landslide-hazard evaluation using landslide slopes, Western Wasatch County, Utah
M.D. Hylland, Mark Lowe
1997, Environmental & Engineering Geoscience (3) 31-43
Landsliding has historically been one of the most damaging geologic hazards in western Wasatch County, Utah. Accordingly, we mapped and analyzed landslides (slumps and debris slides) in the area to provide an empirical basis for regional landslide-hazard evaluation. The 336 landslides in the...
Probabilistic and statistical relationships between number of vehicles and number of visitors at a geologic site in a National Park
R. A. Crovelli
1997, Mathematical Geology (29) 173-182
The National Park Service needs to establish in all of the national parks how large the parking lots should be in order to enjoy and presence our natural resources, for example, in the Delicate Arch in the Arches National Park. Probabilistic and statistical relationships were developed between the number of...
