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Along 50 km of the complex, southwest-dipping, Laramide Grand Hogback monocline, which wraps around the southwest flank of the White River uplift in westcentral Colorado, detailed mapping provides evidence of late Cenozoic collapse that resulted from subsurface flow, diapirism, and dissolution of Pennsylvanian Eagle Valley Evaporite. Numerous discontinuous, small-amplitude, strike-parallel...

A network of 74 randomly distributed domestic water-supply wells completed in the central High Plains aquifer was sampled and analyzed from April to August 1999 as part of the High Plains Regional Ground-Water Study conducted by the U. S. Geological Survey National Water-Quality Assessment Program to provide a broad-scale assessment...

Three different KNO3 salts with δ18O values ranging from about −31 to +54‰ relative to VSMOW were used to compare three off-line, sealed glass tube combustion methods (widely used for isotope studies) with a more recently developed on-line carbon combustion technique. All methods yielded roughly similar...

This paper describes the design and performance of a two-dimensional moored array for sampling horizontal variability in the upper ocean. The mooring was deployed in Massachusetts Bay in a water depth of 84 m for the purpose of measuring the horizontal structure of internal waves. The mooring was instrumented with...

Magma intrusions and eruptions commonly produce abrupt changes in seismicity far from magma conduits1,2,3,4 that cannot be associated with the diffusion of pore fluids or heat5. Such ‘swarm’ seismicity also migrates with time, and often exhibits a ‘dog-bone’-shaped distribution3,4,6,7,8,9. The largest earthquakes in swarms produce aftershocks that obey an Omori-type (exponential)...

AimNative American burning impacts on California shrubland dominated landscapes are evaluated relative to the natural lightning fire potential for affecting landscape patterns.LocationFocus was on the coastal ranges of central and southern California.MethodsPotential patterns of Indian burning were evaluated based upon historical documents, ethnographic accounts, archaeological records and consideration of contemporary...

To investigate possible long-range flow paths through the interbedded basalts and sediments of a 200-m-thick unsaturated zone, we applied a chemical tracer to seasonally filled infiltration ponds on the Snake River Plain in Idaho. This site is near the Subsurface Disposal Area for radioactive and other hazardous waste at the...

The U.S. Geological Survey, in cooperation with the Los Angeles County Department of Public Works and the Antelope Valley-East Kern Water Agency, conducted three cycles of injection, storage, and recovery tests to evaluate the feasibility of artificially recharging ground water in the Lancaster area of Antelope Valley, California. During the...

Coevolved mutualisms, such as those between senita cacti, yuccas, and their respective obligate pollinators, benefit both species involved in the interaction. However, in these pollination mutualisms the pollinator's larvae impose a cost on plants through consumption of developing seeds and fruit. The effects of pollinators on benefits and costs are...

High incidences of Ichthyophonus hoferi, a parasite primarily of marine and estuarine fishes, have recently been reported in rockfishes and Pacific herring from the eastern North Pacific (Kent et al 2001, Hershberger et al 2002). Taxonomic position of I. hoferi remains unresolved, but recent phylogenetic studies have grouped the organism...

One of the current controversies in Cordilleran tectonics concerns the position of Baja California prior to ∼300 km of opening of the Gulf of California. Geologic arguments, together with paleomagnetic results from Lower Cretaceous volcanic rocks, suggest that the rocks of the Baja Peninsula formed and evolved along the coast...

The paper aims at exploring the viability of the Florida snail kite population under various drought regimes in its wetland habitat. The population dynamics of snail kites are strongly linked with the hydrology of the system due to the dependence of this bird species on one exclusive prey species, the...

This report, a product of the National Water- Quality Assessment Program, is a compilation of physical data and biological data for algae, aquatic invertebrates, and fish collected in the Carson and Truckee River Basins, Nevada and California. Most of the data were collected between 1993 and 1996 at selected reaches on the Carson and Truckee Rivers. Algae...

We examined phylogeographic relationships of moose (Alces alces) worldwide to test the proposed existence of two geographic races and to infer the timing and extent of demographic processes underpinning the expansion of this species across the Northern Hemisphere in the late Pleistocene. Sequence variation within the left hypervariable domain of...

We subjected juvenile fall chinook salmon from the Hanford Reach of the Columbia River to acute thermal stressors in the laboratory that were derived from field data. We assessed the effects of thermal stress on: (1) the extent of direct mortality; (2) the vulnerability of fish to predation by smallmouth...

It is very unusual that nine large earthquakes of similar magnitudes (M = 6.1-6.8) occured within a very small area and a very short period of time (1997-1998) in Jiashi of Xinjiang Province, Northwest China. This paper analyzes the observed data of the aftershocks in the Jiashi earthquake region for...

In 2001, the National Water-QualityAssessment (NAWQA) Program of the U.S. Geological Survey (USGS) began its second decade of studies. A total of 42 study units (major river basins and aquifers across the nation) will be reassessed in three groups of 14 on a rotating schedule. Each...

Major-, minor-, and trace-element abundance data on 220, late Cenozoic, basaltic rocks in and around the Carbondale and Eagle collapse centers in west-central Colorado are combined with isotopic, age, and petrographic data to correlate lava flows and establish the timing and minimum areal extent of collapse events associated with removal...

Delta smelt abundance in San Francisco Estuary has been declining since 1983. The exposure of delta smelt to toxic pesticides during larval and juvenile life stages may be one possible factor of this decline (Bennett and Moyle 1996; Moyle and others 1996). Although pesticides have been detected in the Delta...

Beginning in the 1970s, the promise of a new method for separatingstormflow hydrographs...

A decision support system for the management of the Rocky Mountain Population of Trumpeter Swans (Cygnus buccinators) is being developed. As part of this, three expert systems are also in development: one for assessing the quality of Trumpeter Swan breeding habitat; one for making water level recommendations in montane, palustrine...

For public land management in Idaho and western Montana, the U.S. Forest Service (USFS) has requested that the U.S. Geological Survey (USGS) predict where mineral-related activity will occur in the next decade. Cellular automata provide an approach to simulation of this human activity. Cellular automata (CA) are defined by an...

Classification methods used in machine learning (e.g., artificial neural networks, decision trees, and k-nearest neighbor clustering) are rarely used with population genetic data. We compare different nonparametric machine learning techniques with parametric likelihood estimations commonly employed in population genetics for purposes of assigning individuals to their population...

Double-crested cormorants (Phalacrocorax auritus) and boats of 2 length classes (≤ 8 m and > 8 m) were counted from a boat along 31 established strip transects in western Lake Erie from 24 April to 1 September 2000. Each transect included only one of the following habitats:...

The Cretaceous Iles and Williams Fork Formations of the Mesaverde Group contain important reservoir and source rocks for basin-centered gas accumulations in the Piceance Basin of northwestern Colorado. The sandstones in these formations have very low permeability, so low that successful production of gas requires the presence of fractures. To...