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Two simple strategies are presented that use random delay times for repeatedly summing the record of a relatively small earthquake to simulate the effects of a larger earthquake. The simulations do not assume any fault plane geometry or rupture dynamics, but realy only on the ω−2 spectral model of an...

Precipitation causes several short- and long-term effects on wind-induced surface erodibility and subsequent dust emission. Among the principal effects considered by this paper are soil moisture, soil crusts, and vegetation. A quantitative method is developed to assess these effects using differences between the potential and the actual amounts of dust...

A series of hydrothermal experiments was performed to determine the effect of fluid abundance on the reaction of smectite to illite. Experiments were conducted on K-saturated montmorillonite (<0.1-µm fraction) in a closed system at 250° to 400°C using run times of 1, 7, 14, 30, and 60 days at 100...

The use of direct current resistivity soundings to explore the geothermal potential of the Medicine Lake area in northern California proved to be challenging because of high contact resistances and winding roads. Deep Schlumberger soundings were made by expanding current electrode spacings along the winding roads. Measured apparent resistivities were...

At least 180 small spore species assignable to 62 miospore genera have been identified from the Middle Pennsylvanian Hernshaw coal bed in southern West Virginia, and its stratigraphic equivalent, the Fire Clay coal bed, in eastern Kentucky. The established natural affinities of a majority of these miospore taxa indicate that...

The Mississippi River and its tributaries drain extensive agricultural regions of the midcontinental United States, where large amounts of herbicides are applied as weed control agents on crops such as corn and soybeans. Studies being conducted by the U.S. Geological Survey along the lower Mississippi River and its major tributaries,...

Quaternary (2–0 Ma) extrusion rates change significantly along the Cascade Range volcanic arc. The extrusion rate north of Mount Rainier is about 0.21 km3 km−1 m.y.−1; the rate in southern Washington and northern Oregon south to Mount Hood is about 1.6 km3 km−1 m.y.−1; in central Oregon the rate is 3–6 km3 km−1 m.y.−1; and in...

Abundant gabbroic xenoliths in porphyritic pillow basalt were dredged from the northern Gorda Ridge. The host lava is a moderately fractionated, normal mid-ocean ridge basalt with a heterogeneous glass rind (Mg numbers 56-60). Other lavas in the vicinity range from near primary (Mg number 69) to fractionated (Mg number 56)....

Lignites occur in the Cretaceous McNairy Formation and the Eocene Claiborne Formation in the Jackson Purchase region of western Kentucky. The lone Cretaceous lignite sample has over 18 percent inertodetrinite and 32 percent humodetrinite which, along with the abundant mineral matter,...

Changing light availability may be responsible for the discontinuous distribution of submersed aquatic macrophytes in the freshwater tidal Potomac River. During the 1985-1986 growing seasons, light attenuation and chlorophyll a and suspended particulate material concentrations were measured in an unvegetated reach (B) and in two adjacent vegetated reaches (A and...

By using a very stable voltage reference and a high precision digital-to-analog converter to set bias in digital increments, the inherently high stability and accuracy of a ring core magnetometer can be significantly enhanced. In this case it becomes possible to measure not only variations about the bias level, but...

The plate tectonic setting, regional geology and certain aspects of the economic geology of the iron-rare-earth-niobium ore bodies at Bayan Obo, Inner Mongolia, China, were studied by a team of geologists from the Tianjin Geologic Research Academy and the U.S. Geological Survey between 1987 and 1989. These ore bodies were...

Organic and inorganic affinities were determined by comparing the elemental concentrations in the vitrinite concentrates to the concentrations in the companion whole coals. The ratios of these concentrations for 33 selected elements are shown in Figure 1. Ratios greater than 1...

Many Tertiary coals contain abundant fossilized remains of angiosperms, which commonly dominated the ancient peat-swamp environments; modern analogs of such swamps can be found in tropical and subtropical regions of the world. Comparisons of angiospermous wood from Australian brown coal with...

A Lagrangian strategy for sampling large rivers, which was developed and tested in the Orinoco and Amazon Rivers of South America during the early 1980s, is now being applied to the study of toxic chemicals in the Mississippi River. A series of 15-20 cross-sections of the Mississippi mainstem and its...

Erosion of the nation's shoreline and loss and deterioration of our coastal wetlands are widespread and serious problems that affect all regions of the US. As a result of natural and human-induced factors, the coastal plain of Louisiana, which contains 40% of the tidal wetlands in the conterminous 48 States,...

A preliminary geologic map at 1:50,000 of the Lassen region encompasses 1400 km2. The map displays many small, monogenetic volcanoes of basalt to andesite as well as three major late Pliocene and Quaternary volcanic centers that have erupted products ranging from basaltic andesite to rhyolite. The youngest of these volcanic...

Colloidal materials, dispersed phases with dimensions between 0.001 and 1 μm, are potential transport media for a variety of contaminants in surface and ground water. Characterization of these colloids, and identification of the parameters that control their movement, are necessary before transport simulations can be attempted. Two techniques that can...

In the early 1980's, renewed interest in the geothermal potential of the Long Valley caldera, California, highlighted the need to balance the benefits of energy development with the established recreational activities of the area. The Long Valley Hydrologic Advisory Committee, formed in 1987, instituted a monitoring program to collect data...

Discusses the components of the National Digital Cartographic Data Base of the USA, to be completed by the year 2000. Key tasks are; expand the digitising programme; modify data structures; develop digital revision capabilities; develop and adopt standards and implement quality control; support advanced analysis. -after Authors...

A 145-km-long seismic refraction line recorded parallel to the eastern coastline of Maine within the Avalon terrane provides information about the crustal velocity structure within the Avalon block and its relation to other Appalachian terranes. A crustal velocity model for the upper 8...

Well-constrained hypocenters (latitude, longitude, depth, and origin time) are required for nearly all studies that use earthquake data. We have examined the theoretical basis behind some of the widely accepted “rules of thumb” for obtaining accurate hypocenter estimates that pertain to the use of S phases and illustrate, in a...

Vapor pressures for nonpolar and moderately polar organochlorine, pyrethroid, and organophosphate insecticides, phthalate esters, and organophosphate flame retardants were determined by capillary gas chromatography (GC). Organochlorines and polycyclic aromatic hydrocarbons with known liquid-phase vapor pressures (P??L) (standard compounds) were chromatographed along with two reference compounds n-C20 (elcosane) and p,p???-DDT on...

The crystal chemistry of the natural vanadium bronze minerals is reviewed on the basis of published information and new studies (mainly by X-ray powder-diffraction methods) using type material wherever possible. The known V bronze minerals are divided into three categories: 1) the hewettite group, 2) the straczekite group, 3) other...

We examined short-period P waves to investigate if waveform data could be used to determine which of two nodal planes was the actual fault plane for a small (ML 4.6) earthquake near Upland, California. We removed path and site complications by choosing a small aftershock (ML 2.7) as an empirical...