Conference Papers

Shallow-land burial in arid areas is considered the best method for isolating low-level radioactive waste from the environment (Nichols and Goode, this report; Mercer and others, 1983). A major threat to waste isolation in shallow trenches is ground-water percolation. Repository sites in arid areas are believed to minimize the risk of ground-water contamination because such sites receive minimal p

More than 60 Quaternary vents make up the basalt-to-rhyodacite Mount Adams volcanic field and have erupted scoriae and lavas with a total volume of >370 km3. The Mount Adams andesite-dacite stratocone itself is a compound edifice that includes the high cone above 2300 m (20-10 ka), remnants of at least two earlier andesite-dacite cones as old as 0.5 Ma, and 7 Holocene flank vents. Four other Holoc

Crater Lake caldera collapsed about 6,850 yr B.P. during the climactic eruption of Mount Mazama, a High Cascade basaltic andesitic to dacitic volcanic center that was constructed during a period of about 400,000 yr. The caldera and the products of the climactic eruption are clear evidence for the presence of a shallow magma body that must have supported a hydrothermal system in the recent past. Th

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 centers is the Lassen volcanic center, active from 600,000 years B.P. to t

Medicine Lake volcano (MLV) is located in an E-W extensional environment on the Modoc Plateau just east of the main arc of the Cascades. It consists mainly of mafic lavas, although drillhole data indicate that a larger volume of rhyolite is present than is indicated by surface mapping. The most recent eruption was rhyolitic and occurred about 900 years ago. At least seventeen eruptions have occurr

As members of multidisciplinary teams, geotechnical engineers apply quantitative knowledge about the behavior of earth materials toward designing systems for disposing of wastes in the oceans and monitoring waste disposal sites. In dredge material disposal, geotechnical engineers assist in selecting disposal equipment, predict stable characteristics of dredge mounds, design mound caps, and predict

Characteristics of the crustal thermal regime of the Quaternary Cascades vary systematically along the range. Spatially congruent changes in volcanic vent distribution, volcanic extrusion rate, hydrothermal discharge rate, and regional conductive heat flow define 5 geothermal segments. These segments are, from north to south: (1) the Washington Cascades north of Mount Rainier, (2) the Cascades fro

A study of potential impacts of geothermal development in the Corwin Springs KGRA north of Yellowstone Park on thermal springs within the Park is being conducted by the U.S. Geological Survey. Thermal waters in the KGRA and at Mammoth Hot Springs, located 13 km inside the Park boundary, are high in bicarbonate and sulfate and are actively depositing travertine. These similarities and the existence

A two-dimensional, depth-integrated, hydrodynamic/transport model of the Potomac Estuary between Indian Head and Morgantown, Md., has been extended to include treatment of baroclinic forcing due to horizontal density gradients. The finite-difference model numerically integrates equations of mass and momentum conservation in conjunction with a transport equation for heat, salt, and constituent flux

Ground water in Ogden Valley occurs in perched, confined, and unconfined aquifers in the valley fill to depths of 600 feet and more. The confined aquifer, which underlies only the western portion of the valley, is overlain by cleyey silt lacustrine sediments probably deposited during the Bonneville Basin's Little Valley lake cycle sometime between 90,000 and 150,000 years ago. The top of this cley

During implantation of radiotelemetry devices in sea otters (Enhydra lutris) at the Seward Otter Rehabilitation Center, surgical team members noted ulcers in the oral cavity of each of five animals examined. Oral lesions were identified in 25 of 27 otters examined at the center. Histological evaluation of the lesions revealed focal areas of mucosal epithelial necrosis with associated intranuclear

Cerro Prieto geothermal reservoirs tend to exhibit good hydraulic communication with adjacent cool groundwater aquifers. Under natural state conditions the hot fluids mix with the surrounding colder waters along the margins of the geothermal system, or discharge to shallow levels by flowing up fault L. In response to exploitation reservoir pressures decrease, leading to changes in the fluid flow p