Conference Papers

The population of Perris Valley, California, has increased from about 20,000 in 1970 to more than 130,000 in 1992. Increased urbanization in Perris Valley since 1970 has produced appreciable changes in storm-runoff characteristics. Additional impervious area has resulted in increased storm-runoff volumes and peak discharges. Few studies have documented the effect of urbanization on...

Black-legged Kittiwakes (Rissa tridactyla) are widely distributed in the subarctic North Pacific and adjacent seas, with a total breeding population of about 2.6 million individuals. Red-legged Kittiwakes (R. brevirostris) breed in four locations, and at least 95% of their estimated world population of 230,000 birds nest on one island (St. George, Pribilof Islands). Compared to Black...

The Cody Shale and the Mesaverde, Meeteetse, and Lance Formations of Late Cretaceous age and the Fort Union Formation of Paleocene age within the Wind River Reservation contain strata that were deposited during the final major regression of the Cretaceous epicontinental sea eastward across central Wyoming and the ensuing initial stages of mountain-building and basin subsidence of the...

At Yucca Mountain, calcite occurs as open-space fillings and coatings on fractures within much of the host volcanic rocks in both the saturated and unsaturated zones. Strontium isotope analyses of these calcites divide the samples into two groups corresponding to their location in either the saturated or unsaturated zones. The group of samples from the unsaturated zone corresponds very...

Detailed structural mapping of an area that straddles the southern part of the Ghost Dance Fault has revealed the presence of several additional subparallel to anastomosing faults. These faults, mapped at a scale of 1:240, are: 1) dominantly north trending, 2) present on both the upthrown and downthrown sides of the surface trace of the Ghost Dance fault, 3) near-vertical features that...

Existing gravity data in the vicinity of Yucca Mountain and Crater Flat have been examined to determine if these data support only the caldera model or if they support other geologic models such as for a high-angle graben or detachment fault. The west to east isostatic gravity profile reduced for a density of 2.0 g/cm3 shows a gravity low of about 20 mGal centered only 2 km from the...

No abstract available

The revised map for the potentiometric surface of the uppermost saturated zone in Tertiary volcanic rocks at Yucca Mountain, Nevada, is based mainly on 1988 water levels. Refinement of the water-level corrections has increased understanding of the area immediately east-southeast and hydrologically downgradient of Yucca Mountain. This small-gradient area is a nearly horizontal surface...

The amount of large woody debris that potentially could be transported to bridge sites was assessed in the basin of the West Harpeth River in Tennessee in the fall of 1992. The assessment was based on inspections of study sites at 12 bridges and examination of channel reaches between bridges. It involved estimating the amount of woody material at least 1.5 meters long, stored in the...

In November 1992 the valve at the top of a U.S. Geological Survey drill hole in Yellowstone National Park parted from the casting as a result of corrosion. This allowed uncontrolled venting of boiling water and steam from the well at an estimated liquid flow rate of about 25-50 gallons per minute. A flow diverter assembly was designed, fabricated and installed on the well within 16 days...

Tectonic characterization of a potential high-level nuclear waste repository at Yucca Mountain, Nevada, is needed to assess seismic and possible volcanic hazards that could affect the site during the preclosure (next 100 years) and the behavior of the hydrologic system during the postclosure (the following 10,000 years) periods. Tectonic characterization is based on assembling mapped...

No abstract available