Search Results

Recognition of differences in the habitats, apparatuses, and ranges of Late Devonian Icriodus and Pelekysgnathus permits refinement of their biofacies interpretations and construction of an alternate icriodontid zonation. Icriodus is a euphotic genus that predominated in most environments during the early Late Devonian (Frasnian) but died out during the early Famennian. Its apparatus consists of platform...

Large volumes of water have been pumped from the Central Valley aquifer system since the early 1900's. Water levels in the most heavily pumped areas had declined as much as 120 m by 1970. These large water-level declines resulted in approximately 21,000 hm3 of water released by inelastic compaction...

By a proper treatment of the known boundary conditions of a boundary value problem, a complex variable boundary element method (CVBEM) can be used to exactly satisfy the known nodal point boundary values. In this fashion, a numerical model can be developed which generates relative error information along the problem...

No abstract available....

A groundwater hydraulic management model is used to identify the optimal strategy for allocating limited fresh-water supplies and containing wastes in a hypothetical aquifer affected by brine contamination from surface disposal ponds. The present cost of pumping from a network of potential supply and interception wells is minimized over a...

Bald eagle (Haliaeetus leucocephalus) eggs were collected in 14 States in 1969–79 and analyzed for organochlorine pesticides, polychlorobiphenyls, and mercury. Moderate shell thinning occurred in eggs from several areas. Eggs from the Chesapeake Bay area contained the highest residue levels of most organochlorines. DDE was detected in all eggs; other...

The addition of random variation in survival to a single prereproductive age class in a Leslie matrix population model can alter population growth in the modeled system. Methods are presented to characterize the stochastic variation in survival and to determine a correction factor that, when included in the model, will...

Classic descriptive models of barrier sedimentation have been developed with data from the Atlantic and Gulf coasts of the United States. These models are dominated by low to moderate rates of relative sea level (RSL) rise and wave energy. Barriers respond by landward recycling of sediment through the mechanism of...

A study of the East Frisian Islands has shown that the plan form of these islands can be explained by processes of inlet sediment bypassing. This island chain is located on a high wave energy, high tide range shoreline where the average deep-water significant wave height exceeds 1.0 m and...

The U.S. Geological Survey has begun a research project to improve understanding of the mobilization, transport, and fate of petroleum contaminants in the shallow subsurface and to use this understanding to develop predictive models of contaminant behavior. The project site is near Bemidji in northern Minnesota where an accidental spill...

Indonesia faces a perpetual volcanic-hazards problem of enormous proportions, exemplified by the 1982-83 eruption of Galunggung in West Java. Though moderate in size, this caused widespread destruction and a marked socio-economic impact on more than half a million people. The prolonged activity provided and opportunity for the Volcanological Survey of...

A thin claystone layer found in nonmarine rocks at the palynological Cretaceous-Tertiary boundary in eastern Montana contains an anomalously high value of iridium. The nonclay fraction is mostly quartz with minor feldspar, and some of these grains display planar features. These planar features are related to specific crystallographic directions in...

Comparison of several aspects of surface and underground methods of mining for large-scale oil shale extraction in the Piceance Creek Basin suggests that surface mining techniques may have several advantages over underground methods. For a production level of one million barrels of shale oil per day,...

A 275‐km‐long reversed refraction profile in the Oregon Cascades, two shallow earthquakes of magnitude 5 in southern Washington, a shallow earthquake of magnitude 4.6 in northern California, and a previously published analysis of the Bouguer gravity field are used to develop a crustal P wave velocity model for the...

Muir Inlet in Glacier Bay, Alaska, is a glacial fjord receiving a tremendous volume of sediment annually. The rate of sediment accumulation is greatest proximal to Muir Glacier (about 9 m yr−1) and decreases away from the glacier. The primary sediment sources are meltwater streams discharging at subglacial and ice-marginal...

No abstract available....

Carbon-14 contents as low as 3.3 ± 0.2 percent modern (apparent age, 27,000 years) measured from the shells of snails Melanoides tuberculatus living in artesian springs in southern Nevada are attributed to fixation of dissolved HCO3- with which the shells are in carbon isotope equilibrium. Recognition of the existence of such extreme deficiencies...

The nesting behavior of a concentration of nesting mallards (Anas platyrhynchos) and gadwalls (A. strepera) was studied on a 4.5-ha island in Miller Lake, North Dakota, in 1977. A single 0.59-ha clump of thick shrub contained 225 simultaneously active mallard nests on 10 May. During the peak nesting period, mallard...

Breeding populations of 28 species of wetland-dwelling birds other than waterfowl (Anatidae) were censused on 1,321 wetlands lying within the prairie pothole region of North Dakota. Ecological distribution and two crude measures of relative density were calculated for the 22 commonest species using eight wetland classes. Semipermanent wetlands supported nearly...

Feeding trials were used to compare the ability of northern pintails (Anas acuta), gadwalls (A. strepera), and northern shovelers (A. clypeata) to metabolize energy from a turkey starter ration, alfalfa pellets, and common barnyardgrass (Echinochloa crusgalli) seeds. No differences (P > 0.05) were detected among the three species for any...

A refined northeast Pacific plate-motion model provides a framework for analysis of the Tertiary volcanic and tectonic history of western Oregon and Washington. We examine three possible models for the origin of the allochthonous Paleocene and Eocene oceanic basalt basement of the Coast Range: (1) accretion to the continent of...

Management programs for waterfowl populations include rationale for, and establishment of, hunting regulations. These programs rest partially on the results of scientific studies on the effect of harvest rates on annual survival rates. The evidence of this relationship has changed markedly since the mid-1970's, and it is not...

Fossil worm tubes of Cretaceous age preserved in the Bayda massive sulfide deposit of the Samail ophiolite, Oman, are apparently the first documented examples of fossils embedded in massive sulfide deposits from the geologic record. The geologic setting of the Bayda deposit and the distinctive mineralogic and textural features of...

A Zn- and Y-group-bearing senaite, formulated as AM21O38 (Pb0.63Na0.46Ba0.11)Σ1.20(Ti14.64Zn1.74Y‒group REE0.70Mn0.38Nb0.20Sn0.03Zr0.03Th0.02)Σ20.9O38, a member of the crichtonite group, is a newly characterized phase associated with murataite at the St Peters Dome...

Eocene to Pliocene silicoflagellates from the Rockall Plateau are sparse to moderately abundant and include assem blages at the upper and lower boundaries of the Miocene Series. Relative paleotemperature values for silicoflagellates from the upper Miocene and lower Pliocene at DSDP Hole 552A based on quantitative data are cooler than...