Developing a bubble number-density paleoclimatic indicator for glacier ice
M. K. Spencer, R. B. Alley, J. J. Fitzpatrick
2006, Journal of Glaciology (52) 358-364
Past accumulation rate can be estimated from the measured number-density of bubbles in an ice core and the reconstructed paleotemperature, using a new technique. Density increase and grain growth in polar firn are both controlled by temperature and accumulation rate, and the integrated effects are recorded in the number-density of...
Size dimorphism, molt status, and body mass variation of Prairie Falcons nesting in the Snake River Birds of Prey National Conservation Area
Karen Steenhof, James O. McKinley
2006, Journal of Raptor Research (40) 71-75
Birds face challenges in how they allocate energy during the reproductive season. Most temperate zone species do not breed and molt at the same time, presumably because of the high energy demands of these two activities (Espie et al. 1996 and citations therein). However, representatives of at least four raptor...
Active dust devils in Gusev crater, Mars: Observations from the Mars Exploration Rover Spirit
R. Greeley, P.L. Whelley, R. E. Arvidson, N.A. Cabrol, D.J. Foley, B.J. Franklin, P.G. Geissler, M.P. Golombek, R.O. Kuzmin, G. A. Landis, M.T. Lemmon, L.D.V. Neakrase, S. W. Squyres, S.D. Thompson
2006, Journal of Geophysical Research E: Planets (111)
A full dust devil "season" was observed from Spirit from 10 March 2005 (sol 421, first active dust devil observed) to 12 December 2005 (sol 691, last dust devil seen); this corresponds to the period Ls 173.2?? to 339.5??, or the southern spring and summer on Mars. Thermal Emission Spectrometer...
Reversing storm hotspots on sandy beaches: Spatial and temporal characteristics
J. H. List, A.S. Farris, C. Sullivan
2006, Marine Geology (226) 261-279
Coastal erosion hotspots are defined as sections of coast that exhibit significantly higher rates of erosion than adjacent areas. This paper describes the spatial and temporal characteristics of a recently identified type of coastal erosion hotspot, which forms in response to storms on uninterrupted sandy coasts largely free from human...
Regulation of an unexploited brown trout population in Spruce Creek, Pennsylvania
R.F. Carline
2006, Transactions of the American Fisheries Society (135) 943-954
The purpose of this paper is to describe the annual variations in the density of an unexploited population of lotic brown trout Salmo trutta that has been censused annually for 19 years and to explore the importance of density-independent and density-dependent processes in regulating population size. Brown trout density and...
Fire severity and plant age in postfire resprouting of woody plants in sage scrub and chaparral
Jon E. Keeley
2006, Madroño (53) 373-379
Postfire resprouting by woody plants confers a marked advantage in rate of recovery over species that regenerate entirely from seed. However, the predictability of this advantage varies markedly between species, with some showing nearly 100% rootcrown survival and others often much lower. This study examined patterns of fire-caused mortality and...
Migration depths of juvenile Chinook salmon and steelhead relative to total dissolved gas supersaturation in a Columbia River reservoir
J.W. Beeman, A.G. Maule
2006, Transactions of the American Fisheries Society (135) 584-594
The in situ depths of juvenile salmonids Oncorhynchus spp. were studied to determine whether hydrostatic compensation was sufficient to protect them from gas bubble disease (GBD) during exposure to total dissolved gas (TDG) supersaturation from a regional program of spill at dams meant to improve salmonid passage survival. Yearling Chinook...
Shelf stratigraphy and the influence of antecedent substrate on Holocene reef development, south Oahu, Hawaii
E. E. Grossman, W. A. Barnhardt, P. Hart, B. M. Richmond, M.E. Field
2006, Marine Geology (226) 97-114
Paired analyses of drill cores and high-resolution seismic reflection data show that development of Holocene framework reefs on the Oahu (Hawaii) shelf is limited to settings of low wave energy and to the period 8000 to 3000 yr BP. A prominent bounding surface that is mapped across much of the...
Tree mortality from fire and bark beetles following early and late season prescribed fires in a Sierra Nevada mixed-conifer forest
Dylan W. Schwilk, Eric E. Knapp, Scott Ferrenberg, Jon E. Keeley, Anthony C. Caprio
2006, Forest Ecology and Management (232) 36-45
Over the last century, fire exclusion in the forests of the Sierra Nevada has allowed surface fuels to accumulate and has led to increased tree density. Stand composition has also been altered as shade tolerant tree species crowd out shade intolerant species. To restore forest structure and reduce the risk...
Form drag in rivers due to small-scale natural topographic features: 2. Irregular sequences
J. W. Kean, J.D. Smith
2006, Journal of Geophysical Research F: Earth Surface (111)
The size, shape, and spacing of small-scale topographic features found on the boundaries of natural streams, rivers, and floodplains can be quite variable. Consequently, a procedure for determining the form drag on irregular sequences of different-sized topographic features is essential for calculating near-boundary flows and sediment transport. A method for...
Erosion rates at the Mars Exploration Rover landing sites and long-term climate change on Mars
M.P. Golombek, J. A. Grant, L.S. Crumpler, R. Greeley, R. E. Arvidson, J.F. Bell III, C.M. Weitz, R.J. Sullivan, P. R. Christensen, L.A. Soderblom, S. W. Squyres
2006, Journal of Geophysical Research E: Planets (111)
Erosion rates derived from the Gusev cratered plains and the erosion of weak sulfates by saltating sand at Meridiani Planum are so slow that they argue that the present dry and desiccating environment has persisted since the Early Hesperian. In contrast, sedimentary rocks at Meridiani formed in the presence of...
Unrest in Long Valley Caldera, California, 1978-2004
David P. Hill
Troise C.De Natale G.Kilburn C.R.J., editor(s)
2006, Geological Society Special Publication 1-24
Long Valley Caldera and the Mono-Inyo Domes volcanic field in eastern California lie in a left-stepping offset along the eastern escarpment of the Sierra Nevada, at the northern end of the Owens Valley and the western margin of the Basin and Range Province. Over the last 4 Ma, this volcanic...
Leg 197 synthesis: Southward motion and geochemical variability of the Hawaiian hotspot
Robert A. Duncan, John A. Tarduno, David W. Scholl
Robert A. Duncan, John A. Tarduno, Thomas A. Davies, David W. Scholl, editor(s)
2006, Proceedings of the Ocean Drilling Program: Scientific Results (197)
The bend in the Hawaiian-Emperor volcanic chain is an often-cited example of a change in plate motion with respect to a stationary hotspot. Growing evidence, however, suggests that the bend might instead record variable drift of the Hawaiian hotspot within a convecting mantle. Paleomagnetic and radiometric age data from samples...
Regional patterns in the isotopic composition of natural and anthropogenic nitrate in groundwater, High Plains, U.S.A.
P.B. McMahon, J.K. Böhlke
2006, Environmental Science & Technology (40) 2965-2970
Mobilization of natural nitrate (NO3-) deposits in the subsoil by irrigation water in arid and semiarid regions has the potential to produce large groundwater NO3- concentrations. The use of isotopes to distinguish between natural and anthropogenic NO3- sources in these settings could be complicated by the wide range in δ15N...
Simulation of solute transport across low-permeability barrier walls
P. T. Harte, Leonard F. Konikow, G.Z. Hornberger
2006, Journal of Contaminant Hydrology (85) 247-270
Low-permeability, non-reactive barrier walls are often used to contain contaminants in an aquifer. Rates of solute transport through such barriers are typically many orders of magnitude slower than rates through the aquifer. Nevertheless, the success of remedial actions may be sensitive to these low rates of transport. Two numerical simulation...
State summaries: California
S. G. Kohl
2006, Mining Engineering (58) 70-74
According to the United States Geological Survey (USGS), California ranked second behind Arizona among the states in nonfuel mineral production during 2005. It accounted for 7% of the US's total. The market value of mineral production for California amounted to $3.7 billion. During the year, California produced 30 varieties of...
Vascular flora of Izembek National Wildlife Refuge, westernmost Alaska Peninsula, Alaska
Stephen S. Talbot, Sandra Looman Talbot, Wilfred B. Schofield
2006, Rhodora (108) 249-293
The vascular flora of Izembek National Wildlife Refuge (NWR), where few previous collections had been reported, was collected and recorded at sites selected to represent the totality of environmental variation. A total of 349 species (339 native and 10 introduced) was identified. To provide a comparative phytogeographic framework, we analyzed...
Youngest volcanism about 1 million years ago at Kahoolawe Island, Hawaii
H. Sano, D. R. Sherrod, Takahiro Tagami
2006, Journal of Volcanology and Geothermal Research (152) 91-96
Young volcanic deposits in Kahoolawe Island, cutting up through the caldera-filling lava, colluvium and talus in the west wall of Kanapou Bay, had long been stratigraphically considered the rejuvenated-stage products. New K-Ar ages, combined with magnetic polarity data, show that young volcanism was at about 0.98-1.04 Ma and indicate no...
Petrography and geochemistry of the Middle Devonian coal from Luquan, Yunnan Province, China
S. Dai, D. Han, C. L. Chou
2006, Fuel (85) 456-464
Coals from Luquan, Yunnan Province, China, have high contents of cutinite and microsporinite, with an average of 55 and 33.5 vol%, respectively, (on a mineral-free basis). The coals are classified as cutinitic liptobiolith, sporinite-rich durain, cutinite-rich durain, and sporinitic liptobiolith. These four liptinite-rich coals are often interlayered within the coal...
Sexual dimorphism of the internal mandibular chamber in Fayum Pliohyracidae (Mammalia)
de Blieux, M.R. Baumrind, E.L. Simons, P.S. Chatrath, G.E. Meyer, Y.S. Attia
2006, Journal of Vertebrate Paleontology (26) 160-169
An internal mandibular fenestra and chamber are found in many fossil hyracoids. The internal mandibular fenestra is located on the lingual surface of the mandibular corpus and opens into a chamber within the mandible. The mandibular chamber is maximally developed in late Eocene Thyrohyrax meyeri and early Oligocene Thyrohyrax domorictus...
Spatial and temporal dynamics of microcystin in a Missouri reservoir
J.L. Graham, J.R. Jones, S.B. Jones, T.E. Clevenger
2006, Lake and Reservoir Management (22) 59-68
Environmental factors associated with spatiotemporal variation of microcystin (MC) in Mozingo Lake, a Missouri reservoir, were studied during summer 2001, and annual MC trends were characterized from May 2001-May 2002. MC increased during summer, ranging from 20 to 1220 ng/L. Seasonal patterns in MC corresponded with chlorophyll>35 ??m (Net Chl)...
Uplift, thermal unrest and magma intrusion at Yellowstone caldera
Charles W. Wicks, Wayne Thatcher, Daniel Dzurisin, Jerry Svarc
2006, Nature (440) 72-75
The Yellowstone caldera, in the western United States, formed 640,000 years ago when an explosive eruption ejected 1,000 km3 of material1. It is the youngest of a series of large calderas that formed during sequential cataclysmic eruptions that began 16 million...
Seasonal effects of the zebra mussel (Dreissena polymorpha) on sediment denitrification rates in Pool 8 of the Upper Mississippi River
Denise A. Bruesewitz, Jennifer L. Tank, Melody J. Bernot, William B. Richardson, Eric A. Strauss
2006, Canadian Journal of Fisheries and Aquatic Sciences (63) 957-969
Zebra mussels (Dreissena polymorpha) have altered the structure of invaded ecosystems and exhibit characteristics that suggest they may influence ecosystem processes such as nitrogen (N) cycling. We measured denitrification rates seasonally on sediments underlying zebra mussel beds collected from the impounded zone of Navigation Pool 8 of the Upper Mississippi...
Differentiation of commercial fuels based on polar components using negative electrospray ionization/mass spectrometry
C.E. Rostad
2006, Environmental Forensics (7) 5-14
Polar components in fuels may enable differentiation between fuel types or commercial fuel sources. A range of commercial fuels from numerous sources were analyzed by flow injection analysis/electrospray ionization/mass spectrometry without extensive sample preparation, separation, or chromatography. This technique enabled screening for unique polar components at...
Scattered surface wave energy in the seismic coda
Y. Zeng
2006, Pure and Applied Geophysics (163) 533-548
One of the many important contributions that Aki has made to seismology pertains to the origin of coda waves (Aki, 1969; Aki and Chouet, 1975). In this paper, I revisit Aki's original idea of the role of scattered surface waves in the seismic coda. Based on the radiative transfer theory,...
