Trace element geochemistry and surface water chemistry of the Bon Air coal, Franklin County, Cumberland Plateau, southeast Tennessee
S.A. Shaver, J.C. Hower, C.F. Eble, E.D. McLamb, K. Kuers
2006, International Journal of Coal Geology (67) 47-78
Mean contents of trace elements and ash in channel, bench-column, and dump samples of the abandoned Bon Air coal (Lower Pennsylvanian) in Franklin County, Tennessee are similar to Appalachian COALQUAL mean values, but are slightly lower for As, Fe, Hg, Mn, Na, Th, and U, and slightly higher for ash,...
Constraints on the mechanism of long-term, steady subsidence at Medicine Lake volcano, northern California, from GPS, leveling, and InSAR
Michael P. Poland, Roland Burgmann, Daniel Dzurisin, Michael Lisowski, Timothy Masterlark, Susan Owen, Jonathan Fink
2006, Journal of Volcanology and Geothermal Research (150) 55-78
Leveling surveys across Medicine Lake volcano (MLV) have documented subsidence that is centered on the summit caldera and decays symmetrically on the flanks of the edifice. Possible mechanisms for this deformation include fluid withdrawal from a subsurface reservoir, cooling/crystallization of subsurface magma, loading by the...
An evaluation of factors influencing pore pressure in accretionary complexes: Implications for taper angle and wedge mechanics
D.M. Saffer, B.A. Bekins
2006, Journal of Geophysical Research B: Solid Earth (111)
At many subduction zones, accretionary complexes form as sediment is off-scraped from the subducting plate. Mechanical models that treat accretionary complexes as critically tapered wedges of sediment demonstrate that pore pressure controls their taper angle by modifying basal and internal shear strength. Here, we combine a numerical model of groundwater...
Altitude and configuration of the potentiometric surface in East Nottingham and West Nottingham Townships, Chester County, Pennsylvania, April through June 2004
Lindsay B. Hale
2006, Scientific Investigations Map 2911
Since 1984, the U.S. Geological Survey (USGS) has been mapping the altitude and configuration of the potentiometric surface in Chester County as part of an ongoing cooperative program to measure and describe the water resources of the county. Areas where the potentiometric surface has been mapped are shown on figure...
Ecological values of shallow-water habitats: Implications for the restoration of disturbed ecosystems
C.B. Lopez, J. E. Cloern, T.S. Schraga, A.J. Little, L.V. Lucas, J.K. Thompson, J.R. Burau
2006, Ecosystems (9) 422-440
A presumed value of shallow-habitat enhanced pelagic productivity derives from the principle that in nutrient-rich aquatic systems phytoplankton growth rate is controlled by light availability, which varies inversely with habitat depth. We measured a set of biological indicators across the gradient of habitat depth within the Sacramento–San Joaquin River...
Altitude and configuration of the potentiometric surface in the Lower White Clay Creek and Upper Christina River Basins including portions of Franklin, London Britain, New Garden, and New London Townships, Chester County, Pennsylvania, June through September 2005
Lindsay B. Hale
2006, Scientific Investigations Map 2939
Since 1984, the U.S. Geological Survey (USGS) has been mapping the altitude and configuration of the potentiometric surface in Chester County as part of an ongoing cooperative program to measure and describe the water resources of the county. Areas where the potentiometric surface has been mapped are shown on figure...
Estimating hydraulic properties using a moving-model approach and multiple aquifer tests
K. J. Halford, D. Yobbi
2006, Ground Water (44) 284-291
A new method was developed for characterizing geohydrologic columns that extended >600 m deep at sites with as many as six discrete aquifers. This method was applied at 12 sites within the Southwest Florida Water Management District. Sites typically were equipped with multiple production wells, one for each aquifer and...
Timing of magmatism following initial convergence at a passive margin, southwestern U.S. Cordillera, and ages of lower crustal magma sources
A. P. Barth, J. L. Wooden
2006, Journal of Geology (114) 231-245
Initiation of the Cordilleran magmatic arc in the southwestern United States is marked by intrusion of granitic plutons, predominantly composed of alkali-calcic Fe- and Sr-enriched quartz monzodiorite and monzonite, that intruded Paleoproterozoic basement and its Paleozoic cratonal-miogeoclinal cover. Three intrusive suites, recognized on the basis of differences in high field...
Estimating thermal diffusivity and specific heat from needle probe thermal conductivity data
W.F. Waite, L.Y. Gilbert, W.J. Winters, D.H. Mason
2006, Review of Scientific Instruments (77)
Thermal diffusivity and specific heat can be estimated from thermal conductivity measurements made using a standard needle probe and a suitably high data acquisition rate. Thermal properties are calculated from the measured temperature change in a sample subjected to heating by a needle probe. Accurate thermal conductivity measurements are obtained...
Sulfate deposition in subsurface regolith in Gusev crater, Mars
A. Wang, L.A. Haskin, S. W. Squyres, B.L. Jolliff, L. Crumpler, Ralf Gellert, C. Schroder, Kenneth E. Herkenhoff, J. Hurowitz, N.J. Tosca, W. H. Farrand, R. Anderson, A.T. Knudson
2006, Journal of Geophysical Research E: Planets (111)
Excavating into the shallow Martian subsurface has the potential to expose stratigraphic layers and mature regolith, which may hold a record of more ancient aqueous interactions than those expected under current Martian surface conditions. During the Spirit rover's exploration of Gusev crater, rover wheels were used to dig three trenches...
An introduced predator alters Aleutian Island plant communities by thwarting nutrient subsidies
J.L. Maron, J. A. Estes, D.A. Croll, E.M. Danner, S.C. Elmendorf, S.L. Buckelew
2006, Ecological Monographs (76) 3-24
The ramifying effects of top predators on food webs traditionally have been studied within the framework of trophic cascades. Trophic cascades are compelling because they embody powerful indirect effects of predators on primary production. Although less studied, indirect effects of predators may occur via routes that are not exclusively trophic....
Distribution of foraminifera in Pamlico Sound, North Carolina, over the past century
I.J. Abbene, S.J. Culver, D.R. Corbett, M.A. Buzas, L.S. Tully
2006, Journal of Foraminiferal Research (36) 135-151
Foraminiferal and radionuclide data have been used to investigate environmental change that has occurred within Pamlico Sound, North Carolina, over the last century. Environmental conditions were evaluated for three time slices; (1) the modern environment as determined by surficial (0-1 cm) sediments, (2) short-core intervals representing approximately 40 years BP,...
Regional and local species richness in an insular environment: Serpentine plants in California
S. Harrison, H.D. Safford, J.B. Grace, J.H. Viers, K.F. Davies
2006, Ecological Monographs (76) 41-56
We asked how the richness of the specialized (endemic) flora of serpentine rock outcrops in California varies at both the regional and local scales. Our study had two goals: first, to test whether endemic richness is affected by spatial habitat structure (e.g., regional serpentine area, local serpentine outcrop area, regional...
Correlates of biological soil crust abundance across a continuum of spatial scales: Support for a hierarchical conceptual model
M. A. Bowker, J. Belnap, D. W. Davidson, H. Goldstein
2006, Journal of Applied Ecology (43) 152-163
1. Desertification negatively impacts a large proportion of the global human population and > 30% of the terrestrial land surface. Better methods are needed to detect areas that are at risk of desertification and to ameliorate desertified areas. Biological soil crusts are an important soil lichen-moss-microbial community that can be...
Common clay and shale
R.L. Virta
2006, Mining Engineering (58) 25-26
At present, 150 companies produce common clay and shale in 41 US states. According to the United States Geological Survey (USGS), domestic production in 2005 reached 24.8 Mt valued at $176 million. In decreasing order by tonnage, the leading producer states include North Carolina, Texas, Alabama, Georgia and Ohio. For...
Yucca Mountain, Nevada - A proposed geologic repository for high-level radioactive waste
R.A. Levich, J. S. Stuckless
2006, Memoir of the Geological Society of America (199) 1-7
Yucca Mountain in Nevada represents the proposed solution to what has been a lengthy national effort to dispose of high-level radioactive waste, waste which must be isolated from the biosphere for tens of thousands of years. This chapter reviews the background of that national effort and includes some discussion of...
Stress changes along the Sunda trench following the 26 December 2004 Sumatra-Andaman and 28 March 2005 Nias earthquakes
F. F. Pollitz, P. Banerjee, R. Burgmann, M. Hashimoto, N. Choosakul
2006, Geophysical Research Letters (33)
The 26 December 2004 Mw = 9.2 and 28 March 2005 Mw = 8.7 earthquakes on the Sumatra megathrust altered the state of stress over a large region surrounding the earthquakes. We evaluate the stress changes associated with coseismic and postseismic deformation following these two large events, focusing on postseismic...
Estimating recharge rates with analytic element models and parameter estimation
W. R. Dripps, R. J. Hunt, Marilyn P. Anderson
2006, Ground Water (44) 47-55
Quantifying the spatial and temporal distribution of recharge is usually a prerequisite for effective ground water flow modeling. In this study, an analytic element (AE) code (GFLOW) was used with a nonlinear parameter estimation code (UCODE) to quantify the spatial and temporal distribution of recharge using measured base flows as...
Influence of landscape-scale factors in limiting brook trout populations in Pennsylvania streams
P.M. Kocovsky, R.F. Carline
2006, Transactions of the American Fisheries Society (135) 76-88
Landscapes influence the capacity of streams to produce trout through their effect on water chemistry and other factors at the reach scale. Trout abundance also fluctuates over time; thus, to thoroughly understand how spatial factors at landscape scales affect trout populations, one must assess the changes in populations over time...
Development of partial rock veneers by root throw in a subalpine setting
W. R. Osterkamp, T.J. Toy, M.T. Lenart
2006, Earth Surface Processes and Landforms (31) 1-14
Rock veneers stabilize hillslope surfaces, occur especially in areas of immature soil, and form through a variety of process sets that includes root throw. Near Westcliffe, Colorado, USA, data were collected from a 20 ?? 500 m transect on the east slope of the Sangre de Cristo Mountains. Ages of...
Response of Tridens flavus (L.) A. S. Hitchc. to soil nutrients and disturbance in an early successional old field
Y. A. K. Honu, D.J. Gibson, B.A. Middleton
2006, Journal of the Torrey Botanical Society (133) 421-428
Soil nutrients and disturbance are two of the main abiotic factors that influence plant dominance (canopy cover), density, and fecundity in early successional old field plant communities. The manner in which the dominant species in old field successional systems respond to the interaction of nutrients and disturbance is poorly known....
Grenvillian magmatism in the northern Virginia Blue Ridge: Petrologic implications of episodic granitic magma production and the significance of postorogenic A-type charnockite
R.P. Tollo, J. N. Aleinikoff, E.A. Borduas, A.P. Dickin, R.H. McNutt, C.M. Fanning
2006, Precambrian Research (151) 224-264
Grenvillian (1.2 to 1.0 Ga) plutonic rocks in northern Virginia preserve evidence of episodic, mostly granitic magmatism that spanned more than 150 million years (m.y.) of crustal reworking. Crystallization ages determined by sensitive high resolution ion microprobe (SHRIMP) U-Pb isotopic analyses of zircon and monazite, combined with results from previous...
Evaluating dominance as a component of non-native species invasions
A.W. Crall, G.J. Newman, T.J. Stohlgren, C. S. Jarnevich, P. Evangelista, D. Guenther
2006, Diversity and Distributions (12) 195-204
Many studies have quantified plant invasions by determining patterns of non-native species establishment (i.e. richness and absolute cover). Until recently, dominance has been largely overlooked as a significant component of invasion. Therefore, we re-examined a 6-year data set of 323 0.1 ha plots within 18 vegetation types collected in the Grand...
Hindcasting nitrogen deposition to determine an ecological critical load
Jill Baron
2006, Ecological Applications (16) 433-439
Using an estimated background nitrogen (N) deposition value of 0.5 kg N·ha−1·yr−1 in 1900, and a 19-year record of measured values from Loch Vale (Colorado, USA; NADP site CO98), I reconstructed an N-deposition history using exponential equations that correlated well with EPA-reported NOx emissions from Colorado and from the sum...
Novel ecosystems: Theoretical and management aspects of the new ecological world order
R.J. Hobbs, S. Arico, J. Aronson, Jill Baron, P. Bridgewater, V.A. Cramer, P.R. Epstein, J.J. Ewel, C.A. Klink, A.E. Lugo, D. Norton, D. Ojima, D.M. Richardson, E.W. Sanderson, F. Valladares, M. Vila, R. Zamora, M. Zobel
2006, Global Ecology and Biogeography (15) 1-7
We explore the issues relevant to those types of ecosystems containing new combinations of species that arise through human action, environmental change, and the impacts of the deliberate and inadvertent introduction of species from other regions. Novel ecosystems (also termed ‘emerging ecosystems’) result when species occur in combinations and relative...
