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United States Geological Survey: Staff Publications

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Articles 631 - 660 of 1026

Full-Text Articles in Earth Sciences

A Multilocus Population Genetic Survey Of The Greater Sage-Grouse Across Their Range, S. J. Oyler-Mccance, S.E. Taylor, T. W. Quinn Jan 2005

A Multilocus Population Genetic Survey Of The Greater Sage-Grouse Across Their Range, S. J. Oyler-Mccance, S.E. Taylor, T. W. Quinn

United States Geological Survey: Staff Publications

The distribution and abundance of the greater sage-grouse (Centrocercus urophasianus) have declined dramatically, and as a result the species has become the focus of conservation efforts. We conducted a range-wide genetic survey of the species which included 46 populations and over 1000 individuals using both mitochondria1 sequence data and data from seven nuclear microsatellites. Nested clade and STRUCTURE analyses revealed that, in general, the greater sage-grouse populations follow an isolation-by-distance model of restricted gene flow. This suggests that movements of the greater sage-grouse are typically among neighboring populations and not across the species, range. This may have important …

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Participant Observations On Environmental And Social Eff Ect S Of The Conservation Reserve Program: Results Of A National Survey, Arthur W. Alen Jan 2005

Participant Observations On Environmental And Social Eff Ect S Of The Conservation Reserve Program: Results Of A National Survey, Arthur W. Alen

United States Geological Survey: Staff Publications

A national survey of Conservation Reserve Program (CRP) contractees was completed to obtain information about environmental and social effects of the program on participants, farms, and communities. Over 75% of respondents believed CRP benefits to wildlife were important. Seventy-three percent of respondents observed increased numbers of wildlife associated with CRP lands. A majority of respondents (82%) believed the amount of assistance furnished by the U.S. Department of Agriculture related to planning and maintaining wildlife habitat associated with CRP lands was appropriate. The majority of respondents reported CRP benefits, including increased quality of surface and ground waters, improved air quality, control …

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Transport Of Chemical And Microbial Compounds From Known Wastewater Discharges: Potential For Use As Indicators Of Human Fecal Contamination, Susan Glassmeyer, Edward Furlong, Dana Kolpin, Jeffrey Cahill, Steven Zaugg, Stephen Werner, Michael Meyer, David Kryak Jan 2005

Transport Of Chemical And Microbial Compounds From Known Wastewater Discharges: Potential For Use As Indicators Of Human Fecal Contamination, Susan Glassmeyer, Edward Furlong, Dana Kolpin, Jeffrey Cahill, Steven Zaugg, Stephen Werner, Michael Meyer, David Kryak

United States Geological Survey: Staff Publications

The quality of drinking and recreational water is currently (2005) determined using indicator bacteria. However, the culture tests used to analyze for these bacteria require a long time to complete and do not discriminate between human and animal fecal material sources. One complementary approach is to use chemicals found in human wastewater, which would have the advantages of (1) potentially shorter analysis times than the bacterial culture tests and (2) being selected for human-source specificity. At 10 locations, water samples were collected upstream and at two successive points downstream from a waste-waster treatment plant (WWTP); a treated effluent sample was …

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Characterization Of Waste Rock Associated With Acid Drainage At The Penn Mine, California, By Ground-Based Visible To Short-Wave Infrared Reflectance Spectroscopy Assisted By Digital Mapping, Irene C. Montero S., George H. Brimhall, Charles N. Alpers, Gregg A. Swayze Jan 2005

Characterization Of Waste Rock Associated With Acid Drainage At The Penn Mine, California, By Ground-Based Visible To Short-Wave Infrared Reflectance Spectroscopy Assisted By Digital Mapping, Irene C. Montero S., George H. Brimhall, Charles N. Alpers, Gregg A. Swayze

United States Geological Survey: Staff Publications

Prior to remediation at the abandoned Cu–Zn Penn Mine in the Foothills massive sulfide belt of the Sierra Nevada, CA, acid mine drainage (AMD) was created, in part, by the subaerial oxidation of sulfides exposed on several waste piles. To support remediation efforts, a mineralogical study of the waste piles was undertaken by acquiring reflectance spectra (measured in the visible to short-wave infrared range of light (0.35–2.5 Am) using a portable, digitally integrated pen tablet PC mapping system with differential global positioning system and laser rangefinder support. Analysis of the spectral data made use of a continuum removal and band-shape …

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High Dispersal In A Frog Species Suggests That It Is Vulnerable To Habitat Fragmentation, W. Chris Funk, Allison E. Greene, Paul Stephen Corn, Fred W. Allendorf Oct 2004

High Dispersal In A Frog Species Suggests That It Is Vulnerable To Habitat Fragmentation, W. Chris Funk, Allison E. Greene, Paul Stephen Corn, Fred W. Allendorf

United States Geological Survey: Staff Publications

Global losses of amphibian populations are a major conservation concern and their causes have generated substantial debate. Habitat fragmentation is considered one important cause of amphibian decline. However, if fragmentation is to be invoked as a mechanism of amphibian decline, it must first be established that dispersal is prevalent among contiguous amphibian populations using formal movement estimators. In contrast, if dispersal is naturally low in amphibians, fragmentation can be disregarded as a cause of amphibian declines and conservation efforts can be focused elsewhere. We examined dispersal rates in Columbia spotted frogs (Rana luteiventris) using capture–recapture analysis of over …

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Enhanced Marine Productivity Off Western North America During Warm Climate Intervals Of The Past 52 K.Y., J.D. Ortiz, S.B. O’Connell, J. Delviscio, W. Dean, J.D. Carriquiry, T. Marchitto, Y. Zheng, A. Van Geen Jun 2004

Enhanced Marine Productivity Off Western North America During Warm Climate Intervals Of The Past 52 K.Y., J.D. Ortiz, S.B. O’Connell, J. Delviscio, W. Dean, J.D. Carriquiry, T. Marchitto, Y. Zheng, A. Van Geen

United States Geological Survey: Staff Publications

Studies of the Santa Barbara Basin off the coast of California have linked changes in its bottom-water oxygen content to millennial-scale climate changes as recorded by the oxygen isotope composition of Greenland ice. Through the use of detailed records from a sediment core collected off the Magdalena Margin of Baja California, Mexico, we demonstrate that this teleconnection predominantly arose from changes in marine productivity, rather than changes in ventilation of the North Pacific, as was originally proposed. One possible interpretation is that the modern balance of El Nino–La Nina conditions that favors a shallow nutricline and high productivity today and …

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Stable Hydrogen Isotope Analysis Of Bat Hair As Evidence For Seasonal Molt And Long-Distance Migration, Paul M. Cryan, Michael A. Bogan, Robert O. Rye, Gary P. Landis, Cynthia L. Kester Jan 2004

Stable Hydrogen Isotope Analysis Of Bat Hair As Evidence For Seasonal Molt And Long-Distance Migration, Paul M. Cryan, Michael A. Bogan, Robert O. Rye, Gary P. Landis, Cynthia L. Kester

United States Geological Survey: Staff Publications

Although hoary bats (Lasiurus cinereus) are presumed to be migratory and capable of long-distance dispersal, traditional marking techniques have failed to provide direct evidence of migratory movements by individuals. We measured the stable hydrogen isotope ratios of bat hair (∂Dh) and determined how these values relate to stable hydrogen isotope ratios of precipitation (∂Dp). Our results indicate that the major assumptions of stable isotope migration studies hold true for hoary bats and that the methodology provides a viable means of determining their migratory movements. We present evidence that a single annual molt occurs in L. cinereus …

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Genetic Structure Of Cougar Populations Across The Wyoming Basin: Metapopulation Or Megapopulation, Charles R. Anderson Jr., Federick G. Lindzey, David B. Mcdonald Jan 2004

Genetic Structure Of Cougar Populations Across The Wyoming Basin: Metapopulation Or Megapopulation, Charles R. Anderson Jr., Federick G. Lindzey, David B. Mcdonald

United States Geological Survey: Staff Publications

We examined the genetic structure of 5 Wyoming cougar (Puma concolor) populations surrounding the Wyoming Basin, as well as a population from southwestern Colorado. When using 9 microsatellite DNA loci, observed heterozygosity was similar among populations (HO = 0.49–0.59) and intermediate to that of other large carnivores. Estimates of genetic structure (FST = 0.028, RST = 0.029) and number of migrants per generation (Nm) suggested high gene flow. Nm was lowest between distant populations and highest among adjacent populations. Examination of these data, plus Mantel test results of genetic versus geographic distance (P ≤ 0.01), suggested both isolation …

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New Distributional Record Of The Nothern Redbelly Dace In The Northern Great Plains, Nathan M. Morey, Charles R. Berry Jr. Jan 2004

New Distributional Record Of The Nothern Redbelly Dace In The Northern Great Plains, Nathan M. Morey, Charles R. Berry Jr.

United States Geological Survey: Staff Publications

The range of the northern redbelly dace (Phoxinus eos) is grouped into two regions in central North America (Stasiak 1980). In the northern Great Plains, the species is distributed throughout the upper Missouri River drainage in Montana and Canada (Brown 1971, Scott and Crossman 1973). In the Central Lowlands, the northern redbelly dace is distributed through northern Minnesota, Wisconsin, Canada, and the Great Lakes region (Hubbs and Cooper 1936, Eddy and Underhill 1976, Becker 1983). The present distribution of northern redbelly dace has shifted northward from a more southerly distribution during Pleistocene glaciation (Cross et al. 1986). Relict …

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Mineralogical Maturity In Dunefields Of North America, Africa And Australia, Daniel R. Muhs Jan 2004

Mineralogical Maturity In Dunefields Of North America, Africa And Australia, Daniel R. Muhs

United States Geological Survey: Staff Publications

Studies of dunefields in central and western North America show that mineralogical maturity can provide new insights into the origin and evolution of aeolian sand bodies. Many of the world’s great sand seas in Africa, Asia and Australia are quartz-dominated and thus can be considered to be mineralogically mature. The Algodones (California) and Parker (Arizona) dunes in the southwestern United States are also mature, but have inherited a high degree of mineralogical maturity from quartz-rich sedimentary rocks drained by the Colorado River. In Libya, sediments of the Zallaf sand sea, which are almost pure quartz, may have originated in a …

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Reproduction And Seasonal Activity Of Silver-Haired Bats In Western Nebraska, Keith Geluso, Jeffrey J. Huebschman, Jeremy A. White, Michael A. Bogan Jan 2004

Reproduction And Seasonal Activity Of Silver-Haired Bats In Western Nebraska, Keith Geluso, Jeffrey J. Huebschman, Jeremy A. White, Michael A. Bogan

United States Geological Survey: Staff Publications

Silver-haired bats (Lasionycteris noctivagans) were thought only to migrate through Nebraska; however, recent surveys in eastern Nebraska report summer records of females and their young. Our study in western Nebraska also shows that silver-haired bats are summer residents. We discovered the 1st reproductively active L. noctivagans in this part of the state. We caught lactating females and volant young in riparian forests along the North Platte River and in forested areas of the Pine Ridge. Previously, adult males were not known from Nebraska in summer, and only 4 records of L. noctivagans were known from western Nebraska during …

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Corrigendum To ‘‘Radiocarbon Dating, Chronologic Framework, And Changes In Accumulation Rates Of Holocene Estuarine Sediments From Chesapeake Bay’’ [Quaternary Research 57 (2002) 58–70], Steven M. Colman, Pattie C. Baucom, John F. Bratton, Thomas M. Cronin, John P. Mcgeehin, Debra Willard, Andrew R. Zimmerman, Peter R. Vogt Jan 2004

Corrigendum To ‘‘Radiocarbon Dating, Chronologic Framework, And Changes In Accumulation Rates Of Holocene Estuarine Sediments From Chesapeake Bay’’ [Quaternary Research 57 (2002) 58–70], Steven M. Colman, Pattie C. Baucom, John F. Bratton, Thomas M. Cronin, John P. Mcgeehin, Debra Willard, Andrew R. Zimmerman, Peter R. Vogt

United States Geological Survey: Staff Publications

Because of an error in the calculation of bulk densities from water contents, the cumulative masses in Fig. 8 are too high by a factor of about 2. The actual correction depends to small degree on water content and ranges from 1.8 for a water content of 50% to 2.2 for a water content of 75%. The values for mass accumulation rates in the left two columns of Table 5 are also affected, but the ratios between pre- and post-settlement times are not. A revised version of that table is given below. None of the major conclusions of the paper …

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Record Of Late Pleistocene Glaciation And Deglaciation In The Southern Cascade Range. I. Petrological Evidence From Lacustrine Sediment In Upper Klamath Lake, Southern Oregon, Richard L. Reynolds, Joseph G. Rosenbaum, Josh Rapp, Michael W. Kerwin, J. Platt Bradbury, David Adam, Steven Colman Jan 2004

Record Of Late Pleistocene Glaciation And Deglaciation In The Southern Cascade Range. I. Petrological Evidence From Lacustrine Sediment In Upper Klamath Lake, Southern Oregon, Richard L. Reynolds, Joseph G. Rosenbaum, Josh Rapp, Michael W. Kerwin, J. Platt Bradbury, David Adam, Steven Colman

United States Geological Survey: Staff Publications

Petrological and textural properties of lacustrine sediments from Upper Klamath Lake, Oregon, reflect changing input volumes of glacial flour and thus reveal a detailed glacial history for the southern Cascade Range between about 37 and 15 ka. Magnetic properties vary as a result of mixing different amounts of the highly magnetic, glacially generated detritus with less magnetic, more weathered detritus derived from unglaciated parts of the large catchment. Evidence that the magnetic properties record glacial flour input is based mainly on the strong correlation between bulk sediment particle size and parameters that measure the magnetite content and magnetic mineral freshness. …

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Estimating Accumulation Rates And Physical Properties Of Sediment Behind A Dam: Englebright Lake, Yuba River, Northern California, Noah P. Snyder, David M. Rubin, Charles N. Alpers, Jonathan R. Childs, Jennifer A. Curtis, Lorraine E. Flint, Scott A. Wright Jan 2004

Estimating Accumulation Rates And Physical Properties Of Sediment Behind A Dam: Englebright Lake, Yuba River, Northern California, Noah P. Snyder, David M. Rubin, Charles N. Alpers, Jonathan R. Childs, Jennifer A. Curtis, Lorraine E. Flint, Scott A. Wright

United States Geological Survey: Staff Publications

Studies of reservoir sedimentation are vital to understanding scientific and management issues related to watershed sediment budgets, depositional processes, reservoir operations, and dam decommissioning. Here we quantify the mass, organic content, and grain-size distribution of a reservoir deposit in northern California by two methods of extrapolating measurements of sediment physical properties from cores to the entire volume of impounded material. Englebright Dam, completed in 1940, is located on the Yuba River in the Sierra Nevada foothills. A research program is underway to assess the feasibility of introducing wild anadromous fish species to the river upstream of the dam. Possible management …

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Mercury And Methylmercury Concentrations And Loads In The Cache Creek Watershed, California, Joseph L. Domagalski, Charles N. Alpers, Darell G. Slotton, Thomas H. Suchanek, Shaun M. Ayers Jan 2004

Mercury And Methylmercury Concentrations And Loads In The Cache Creek Watershed, California, Joseph L. Domagalski, Charles N. Alpers, Darell G. Slotton, Thomas H. Suchanek, Shaun M. Ayers

United States Geological Survey: Staff Publications

Concentrations and loads of total mercury and methylmercury were measured in streams draining abandoned mercury mines and in the proximity of geothermal discharge in the Cache Creek watershed of California during a 17-month period from January 2000 through May 2001. Rainfall and runoff were lower than long-term averages during the study period. The greatest loading of mercury and methylmercury from upstream sources to downstream receiving waters, such as San Francisco Bay, generally occurred during or after winter rainfall events. During the study period, loads of mercury and methylmercury from geothermal sources tended to be greater than those from abandoned mining …

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Chronology Of Sediment Deposition In Upper Klamath Lake, Oregon, Steven M. Colman, J. Platt Bradbury, John P. Mcgeehin, Charles W. Holmes, David Edginton, Andrei M. Sarna-Wojcicki Jan 2004

Chronology Of Sediment Deposition In Upper Klamath Lake, Oregon, Steven M. Colman, J. Platt Bradbury, John P. Mcgeehin, Charles W. Holmes, David Edginton, Andrei M. Sarna-Wojcicki

United States Geological Survey: Staff Publications

A combination of tephrochronology and 14C, 210Pb, and 137Cs measurements provides a robust chronology for sedimentation in Upper Klamath Lake during the last 45 000 years. Mixing of surficial sediments and possible mobility of the radio-isotopes limit the usefulness of the 137Cs and 210Pb data, but 210Pb profiles provide reasonable average sediment accumulation rates for the last 100–150 years. Radiocarbon ages near the top of the core are somewhat erratic and are too old, probably as a result of detrital organic carbon, which may have become a more common component in recent times as …

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Limnological And Climatic Environments At Upper Klamath Lake, Oregon During The Past 45 000 Years, J. Platt Bradbury, Steven M. Colman, Walter E. Dean Jan 2004

Limnological And Climatic Environments At Upper Klamath Lake, Oregon During The Past 45 000 Years, J. Platt Bradbury, Steven M. Colman, Walter E. Dean

United States Geological Survey: Staff Publications

Upper Klamath Lake, in south-central Oregon, contains long sediment records with well-preserved diatoms and lithological variations that reflect climate-induced limnological changes. These sediment archives complement and extend high resolution terrestrial records along a north–south transect that includes areas influenced by the Aleutian Low and Subtropical High, which control both marine and continental climates in the western United States. The longest and oldest core collected in this study came from the southwest margin of the lake at Caledonia Marsh, and was dated by radiocarbon and tephrochronology to an age of about 45 ka. Paleolimnological interpretations of this core, based upon geochemical …

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Grassland Vegetation And Bird Communities In The Southern Great Plains Of North America, Robert N. Chapman, David M. Engle, Ronald E. Masters, David M. Leslie Jr. Jan 2004

Grassland Vegetation And Bird Communities In The Southern Great Plains Of North America, Robert N. Chapman, David M. Engle, Ronald E. Masters, David M. Leslie Jr.

United States Geological Survey: Staff Publications

Structure and composition of vegetation and abundance of breeding birds in grasslands seeded to Old World bluestem (Bothriochloa ischmaeum) were compared to native mixed prairie in the southern Great Plains of North America. Abundance of birds was determined using fixed-radius point counts. Detrended correspondence analysis was used to compare plant community composition and canonical correspondence analysis was used to examine the relationships between plant species composition and vegetation structure with the bird community. Plant species composition differed distinctly between seeded grassland and native mixed prairie, but the differences were not reflected in habitat structure, bird community composition, or …

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Mudfish On The Menu? Rise Of The Much-Maligned Bowfin, Ken Sulak Jan 2004

Mudfish On The Menu? Rise Of The Much-Maligned Bowfin, Ken Sulak

United States Geological Survey: Staff Publications

Cajuns call it “choupique” (say “shoe-pick”), from its Choctaw name. Elsewhere, it’s the dogfish, blackfish, grindle, cottonfish, or cypress trout. Its official common name is “Bowfin” (Amia calva)1. But to most anglers, this is the “mudfish,” a strange, unusual, and much-maligned fish, most everywhere considered a useless trash fish. One look and the words relict, prehistoric, primitive, and living fossil come to mind. Indeed, the bowfin is the last of its line, the sole-surviving species of a very ancient group of fishes. Its predecessors flourished in the Jurassic and Cretaceous periods during the Mesozoic (= Middle-Animal) Era, a …

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Earthquake Source Parameters Determined By The Safod Pilot Hole Seismic Array, Kazutoshi Imanishi, William L. Ellsworth, Stephanie G. Prejean Jan 2004

Earthquake Source Parameters Determined By The Safod Pilot Hole Seismic Array, Kazutoshi Imanishi, William L. Ellsworth, Stephanie G. Prejean

United States Geological Survey: Staff Publications

We estimate the source parameters of #3 microearthquakes by jointly analyzing seismograms recorded by the 32-level, 3-component seismic array installed in the SAFOD Pilot Hole. We applied an inversion procedure to estimate spectral parameters for the omega-square model (spectral level and corner frequency) and Q to displacement amplitude spectra. Because we expect spectral parameters and Q to vary slowly with depth in the well, we impose a smoothness constraint on those parameters as a function of depth using a linear first-difference operator. This method correctly resolves corner frequency and Q, which leads to a more accurate estimation of source …

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Sources Of Ancient Maize Found In Chacoan Great Houses, Larry Benson Jan 2004

Sources Of Ancient Maize Found In Chacoan Great Houses, Larry Benson

United States Geological Survey: Staff Publications

Between the 9th and 12th centuries A.D., Chaco Canyon, located near the middle of the high-desert San Juan Basin of north-central New Mexico (fig. 1), was the focus of an unprecedented construction effort by pre-Columbian Native Americans. It has been estimated that from 2,000 to 6,000 people occupied Chaco Canyon during its heyday (Windes, 1984; Drager, 1976). One indication of Chaco’s regional importance is a network of roads that linked Chaco Canyon with other great houses and communities spread throughout a region covering at least 60,000 km2 (fig. 2). At the height of its cultural florescence in the 11th century, …

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Stress Field Variations In The Swiss Alps And The Northern Alpine Foreland Derived From Inversion Of Fault Plane Solutions, Ulrike Kastrup, Mary Lou Zoback, Nicholas Deichmann, Keith Evans, Domenico Giardini, Andrew J. Michael Jan 2004

Stress Field Variations In The Swiss Alps And The Northern Alpine Foreland Derived From Inversion Of Fault Plane Solutions, Ulrike Kastrup, Mary Lou Zoback, Nicholas Deichmann, Keith Evans, Domenico Giardini, Andrew J. Michael

United States Geological Survey: Staff Publications

This study is devoted to a systematic analysis of the state of stress of the central European Alps and northern Alpine foreland in Switzerland based on focal mechanisms of 138 earthquakes with magnitudes between 1 and 5. The most robust feature of the results is that the azimuth of the minimum compressive stress, S3, is generally well constrained for all data subsets and always lies in the NE quadrant. However, within this quadrant, the orientation of S3 changes systematically both along the structural strike of the Alpine chain and across it. The variation in stress along the mountain …

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Federal Listing Of Prairie Grouse: Lessons From The Attwater’S Prairie Chicken, Michael Morrow, Terry A. Rossignol, Nova J. Silvy Jan 2004

Federal Listing Of Prairie Grouse: Lessons From The Attwater’S Prairie Chicken, Michael Morrow, Terry A. Rossignol, Nova J. Silvy

United States Geological Survey: Staff Publications

Considerable controversy has often surrounded proposals to confer official status (i.e., list) species under the authority of the Endangered Species Act (ESA) of 1973 as amended or its precursors. Recent proposals to list the lesser prairie-chicken (Tympanuchus pallidicinctus), the western sage grouse (Centrocercus urophasianus phaios), and the Gunnison sage grouse (C. minimus) were met with strong opposition by those concerned with prospects of an increased regulatory environment associated with such an action. The Attwater's prairie-chicken (T. cupido attwateri) was one of the first species listed under The Endangered Species Conservation Act of …

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History Of Greater Sage-Grouse In The Dakotas: Distribution And Population Trends, Joe T. Smith, Lester D. Flake, Kenneth F. Higgins, Gerald D. Kobriger Jan 2004

History Of Greater Sage-Grouse In The Dakotas: Distribution And Population Trends, Joe T. Smith, Lester D. Flake, Kenneth F. Higgins, Gerald D. Kobriger

United States Geological Survey: Staff Publications

The greater sage-grouse (Centrocercus urophasianus) has declined throughout its range and its status is of major concern to federal, state, and provincial wildlife agencies. We collected information on current and historical greater sage-grouse distribution and lek activity in western North and South Dakota. A steady decline in lek attendance by males occurred over the entire recorded period in North Dakota (1951-2002) and South Dakota (1972-2002). There was no apparent change in numbers of known active leks due to discovery of new leks, but there was an abandonment of regions once occupied by active leks.

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The History Of Recent Limnological Changes And Human Impact On Upper Klamath Lake, Oregon, J. Platt Bradbury, Steven M. Colman, Richard L. Reynolds Jan 2004

The History Of Recent Limnological Changes And Human Impact On Upper Klamath Lake, Oregon, J. Platt Bradbury, Steven M. Colman, Richard L. Reynolds

United States Geological Survey: Staff Publications

Hypereutrophic Upper Klamath Lake has been studied for almost 50 years to evaluate the nature, cause, and effects of its very productive waters. Mitigation of undesirable effects of massive cyanobacterial blooms requires understanding their modern causes as well as their history. Knowledge of the pre-settlement natural limnology of this system can provide guidelines for lake restoration and management of land and water use strategies to maximize the benefits of this aquatic resource. This investigation uses a paleolimnological approach to document the nature and chronology of limnological and biological changes in Upper Klamath Lake for the past 200 years, covering the …

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Geochemical Cycles In Sediments Deposited On The Slopes Of The Guaymas And Carmen Basins Of The Gulf Of California Over The Last 180 Years, Walter E. Dean, Carol Prideb, Robert Thunell Jan 2004

Geochemical Cycles In Sediments Deposited On The Slopes Of The Guaymas And Carmen Basins Of The Gulf Of California Over The Last 180 Years, Walter E. Dean, Carol Prideb, Robert Thunell

United States Geological Survey: Staff Publications

Sediments deposited on the slopes of the Guaymas and Carmen Basins in the central Gulf of California were recovered in two box cores. Q-mode factor analyses identified detrital-clastic, carbonate, and redox associations in the elemental composition of these sediments. The detrital-clastic fraction appears to contain two source components, a more mafic component presumably derived from the Sierra Madre Occidental along the west coast of Mexico, and a more felsic component most likely derived from sedimentary rocks (mostly sandstones) of the Colorado Plateau and delivered by the Colorado River. The sediments also contain significant siliceous biogenic components and minor calcareous biogenic …

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A Mechanical Model Of The San Andreas Fault And Safod Pilot Hole Stress Measurements, Jean Chéry, Mark D. Zoback, Stephen Hickman Jan 2004

A Mechanical Model Of The San Andreas Fault And Safod Pilot Hole Stress Measurements, Jean Chéry, Mark D. Zoback, Stephen Hickman

United States Geological Survey: Staff Publications

Stress measurements made in the SAFOD pilot hole provide an opportunity to study the relation between crustal stress outside the fault zone and the stress state within it using an integrated mechanical model of a transform fault loaded in transpression. The results of this modeling indicate that only a fault model in which the effective friction is very low (<0.1) through the seismogenic thickness of the crust is capable of matching stress measurements made in both the far field and in the SAFOD pilot hole. The stress rotation measured with depth in the SAFOD pilot hole (~28 ° ) appears to be a typical feature of a weak fault embedded in a strong crust and a weak upper mantle with laterally variable heat flow, although our best model predicts less rotation (15 ° ) than observed. Stress magnitudes predicted by our model within the fault zone indicate low shear stress on planes parallel to the fault but a very anomalous mean stress, approximately twice the lithostatic stress.

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A Holocene Pollen Record Of Persistent Droughts From Pyramid Lake, Nevada, Usa, Scott A. Mensing, Larry Benson, Michaele Kashgarian, Steve Lund Jan 2004

A Holocene Pollen Record Of Persistent Droughts From Pyramid Lake, Nevada, Usa, Scott A. Mensing, Larry Benson, Michaele Kashgarian, Steve Lund

United States Geological Survey: Staff Publications

Pollen and algae microfossils preserved in sediments from Pyramid Lake, Nevada, provide evidence for periods of persistent drought during the Holocene age. We analyzed one hundred nineteen 1-cm-thick samples for pollen and algae from a set of cores that span the past 7630 years. The early middle Holocene, 7600 to 6300 cal yr B.P., was found to be the driest period, although it included one short but intense wet phase. We suggest that Lake Tahoe was below its rim for most of this period, greatly reducing the volume and depth of Pyramid Lake. Middle Holocene aridity eased between 5000 and …

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Mortality Of An Adult Cougar Due To A Forest Fire, Dorothy M. Fecske, Jonathan A. Jenks, Frederick D. Lindzey Jan 2004

Mortality Of An Adult Cougar Due To A Forest Fire, Dorothy M. Fecske, Jonathan A. Jenks, Frederick D. Lindzey

United States Geological Survey: Staff Publications

Mortality from natural causes has been documented throughout the range of the cougar (Puma concolor), including California (Beier and Barrett 1993), Canada (Ross et al. 1995), Florida (Taylor et al. 2002), Idaho (Hornocker 1970), Nevada (Ashman et al. 1983), New Mexico (Logan and Sweanor 2001), and Utah (Gashwiler and Robinette 1957, Lindzey et al. 1988). Intraspecific killing by adult males is the most common cause of death in unhunted populations; adult males have killed kittens, subadults, and adults of both sexes (Beier and Barrett 1993, Maehr 1997, Logan and Sweanor 2001, Taylor et al. 2002). Other mortality factors …

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High Resolution Paleoceanography Of The Guaymas Basin, Gulf Of California, During The Past 15 000 Years, John A. Barron, David Bukry, James L. Bischoff Jan 2004

High Resolution Paleoceanography Of The Guaymas Basin, Gulf Of California, During The Past 15 000 Years, John A. Barron, David Bukry, James L. Bischoff

United States Geological Survey: Staff Publications

Deep Sea Drilling Project Site 480 (27°54.10’N, 111°39.34’W; 655 m water depth) contains a high resolution record of paleoceanographic change of the past 15 000 years for the Guaymas Basin, a region of very high diatom productivity within the central Gulf of California. Analyses of diatoms and silicoflagellates were completed on samples spaced every 40-50 yr, whereas ICP-AES geochemical analyses were completed on alternate samples (sample spacing 80-100 yr). The Bolling-Allerod interval (14.6-12.9 ka) (note, ka refers to 1000 calendar years BP throughout this report) is characterized by an increase in biogenic silica and a decline in calcium carbonate relative …

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