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No abstract available....

A portable apparatus was used to filter large quantities of water from streams in California's Sierra Nevada. Samples were processed and examined for Giardia spp. Cysts of Giardia were detected in 22 of 49 (44.9 percent) samples collected at sites downstream from areas of high recreational use and in 5...

The influence of thermal disturbance and site characteristics on distribution of herbs was studied in portions of a 3020 ha wetland in the southeastern USA. Presence-absence of 52 species in 130 0.25 m2 plots was determined from four sites with different disturbance histories and from an undisturbed site. Data from...

Major and trace element and Sr, Nd and O isotopic data are presented for ferrobasalts, icelandites, rhyolites, mixed pumices and silicic xenoliths of the 1875 eruption of Askja. Trace element modelling and Sr and Nd data largely confirm previous major element calculations that fractional crystallization was dominant in the generation...

No abstract available....

No abstract available....

Rates of aqueous, abiotic pyrite oxidation were measured in oxygen-saturated and anaerobic Fe(III)-saturated solutions with initial pH from 2 to 9. These studies included analyses of sulfite, thiosulfate, polythionates and sulfate and procedures for cleaning oxidation products from pyrite surfaces were evaluated. Pyrite oxidation in oxygen-saturated solutions produced (1) rates...

The objectives of this study were to evaluate survival of striped bass (Morone saxatilis) prolarvae and yearlings in the Potomac River by using in situ test chambers; correlate survival of both striped bass life stages with the presence of water quality conditions, inorganic contaminants, and organic contaminants and conduct histological...

A coring device has been developed to obtain long and minimally disturbed samples of saturated cohesionless sand and gravel. The coring device, which includes a wireline and piston, was developed specifically for use during hollow-stem auger drilling but it also offers possibilities for cable tool and rotary drilling. The core...

Residents of a West Seattle neighborhood must have been puzzled one Saturday morning in December 1986. Two men were leaning against the wall of a house and rhythmically pushing against it, and were being urged on by the shouts of another man standing on the roof. A horizontal seismometer was...

No abstract available....

Intertidal mud has buried extensive, well-vegetated lowlands in westernmost Washington at least six times in the past 7000 years. Each burial was probably occasioned by rapid tectonic subsidence in the range of 0.5 to 2.0 meters. Anomalous sheets of sand atop at least three ofthe buried lowlands suggest that tsunamis...

The southern hemisphere of Ariel, a satellite of Uranus, can be divided into several terrain types. Data on the size-frequency distribution of craters for those different terrain types indicate that these terrains formed over a relatively short period of time. Much information on Ariel's geological history can be gained from...

Seismic‐reflection profiles over the sediment‐filled Escanaba Trough at the southern Gorda Ridge reveal a series of volcanic centers that pierce the sediment. The volcanic edifices are 3 to 6 km in diameter and are spaced at 15 to 20 km intervals along the axis of the trough. The volcanic intrusions...

The 25-km-long section of the San Andreas fault near Parkfield, California ruptured in similar magnitude-6 earthquakes in 1881, 1901, 1922, 1934 and 1966. On the basis of a number of lines of seismological evidence, a section of the San Andreas fault, now termed the Parkfield preparation zone, has been identified...

No abstract available....

Clasts of an unusual type of lunar highlands igneous rock, alkali gabbronorite, have been found in Apollo 16 breccia 67975. The alkali gabbronorites form two distinct subgroups, magnesian and ferroan. Modes and bulk compositions are highly varied. The magnesian alkali gabbronorites are composed of bytownitic plagioclase (OrAn), hypersthene (WoEn), augite...

Field studies in the Colorado Plateau occupy an honored place in the development of geomorphic theory. The purpose of this chapter is to briefly review the foundational, regional, and process-oriented studies in the region, and to provide a review of promising threads of inquiry set in a context of more...

Alluvium deposited in a reservoir from 1937 to 1976 records the sediment-yield history of a small (2.8 km2), high-relief basin in semiarid southern Utah. Stratification in the alluvium shows that sediment was deposited in the reservoir only 21 times in 38 yr, a runoff recurrence interval of 1.8 yr. Thus,...

Vertical-incidence reflection profiling has identified several characteristic features of the continental lithosphere including a generally transparent upper crust, a reflective lower crust, reflections from the crust-mantle boundary, and a commonly transparent upper mantle. The underlying physical causes of these characteristic features remain poorly understood. This review summarizes additional information...

In 1981, the U.S. Geological Survey conducted a seismic-refraction experiment in northeastern California designed to study the Klamath Mountains, Cascade Range, Modoc Plateau, and Basin and Range provinces. Key profiles include 135-km-long, north-south lines in the Klamath Mountains and Modoc Plateau provinces and a 260-km-long, east-west line crossing all of...

A gravity and aeromagnetic study was conducted in and adjacent to the Goat Rocks Wilderness area, Washington. This work was done in conjunction with geologic and geochemical studies which were critically important to our interpretation. The Bouguer gravity anomaly map displays a large central positive gravity anomaly and three superimposed...

At two locations in the Atlantic Ocean (DSDP Sites 367 and 530) early to middle Cretaceous organic-carbon-rich beds (“black shales”) were found to have significantly lower δ15N values (lower15N/14N ratios) than adjacent organic-carbon-poor beds (white limestones or green claystones). While these lithologies are of marine origin, the black strata in...