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Articles 721 - 750 of 861
Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology
Introduction To The Legal Foundation Of Federal Land Management, University Of Colorado Boulder. Natural Resources Law Center
Introduction To The Legal Foundation Of Federal Land Management, University Of Colorado Boulder. Natural Resources Law Center
Introduction to the Legal Foundation of Federal Land Management (December 1-3)
1 v. (various pagings) : ill., maps ; 28 cm
Materials prepared for the course held at the National Center for Atmospheric Research in Boulder, Colorado on December 1-3, 2004
Course instructors: Charles Wilkinson; Sarah Krakoff; Kathryn Mutz; Ann Morgan; Maggie Fox
Contents:
Introduction -- Agenda -- Summaries of laws -- Case studies. Travel management; Oil and gas development; Timber/fuels reduction -- How to influence agency decision makers -- Natural resource related legal and policy resources for the non-legal professional
Light & Dark: The Hidden Wonders Of Buck Creek, Lee J. Florea
Light & Dark: The Hidden Wonders Of Buck Creek, Lee J. Florea
Earth, Environmental, and Atmospheric Sciences Faculty Publications
As early morning mists rise from the banks of its supple waters, beams of light penetrate the Buck Creek valley illuminating its beauty. While light illuminates most of the land, there are secret places, nestled within the forest where darkness reigns supreme. Places beyond the touch of the sun, beyond the influence of seasons. Here time is measured not in cycles of light but by the flow of water and fall of rock. These are the caves, conduits for water past and present. Nestled in the hills of south-central Kentucky the caves along Buck Creek provide the lifeblood for a …
An Association Of Benthic Foraminifera And Gypsum In Holocene Sediments Of Estuarine Chesapeake Bay, Usa, John Cann, Thomas Cronin
An Association Of Benthic Foraminifera And Gypsum In Holocene Sediments Of Estuarine Chesapeake Bay, Usa, John Cann, Thomas Cronin
United States Geological Survey: Staff Publications
Two cores of Holocene sediments recovered from the Cape Charles Channel of Chesapeake Bay yielded radiocarbon ages of about 6.8 to 5.8 ka for the lower intervals. Fossil foraminifera preserved in these lower sediments are dominated by species of Elphidium, which make up about 90% of the assemblage throughout, and probably signify deposition in hypersaline waters. Buccella frigida and Ammonia beccarii are the only other species commonly present. Hypersalinity of bottom waters seems to have been maintained by water-density stratification in a basin-like section of the channel. In core PTXT -4-P-I transition to modem Chesapeake conditions, in which numbers …
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.
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 …
Mudfish On The Menu? Rise Of The Much-Maligned Bowfin, Ken Sulak
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 …
A Holocene Record Of Changing Arctic Ocean Ice Drift Analogous To The Effects Of The Arctic Oscillation, Dennis A. Darby, Jens F. Bischof
A Holocene Record Of Changing Arctic Ocean Ice Drift Analogous To The Effects Of The Arctic Oscillation, Dennis A. Darby, Jens F. Bischof
OES Faculty Publications
The Arctic Oscillation (AO) controls the configuration of the Transpolar Drift (TPD). If thicker ice from the Beaufort Gyre were exported, the volume of fresh water/sea ice in the Nordic seas would significantly increase, decreasing the formation of North Atlantic deep water. This would cool large parts of the Northern Hemisphere and affect global climate. Therefore, in order to understand how the global climate system functions, it is imperative to know how the TPD changed over the last millennium or more. The provenance of grains in a sediment core located near the confluence of the TPD and the Beaufort Gyre …
Stable Isotopic And Trace Metal Analyses Of Two Porites Lobata Colonies - Oahu, Hawaii: Implications For Past Seasonal Variation And Sea Surface Temperatures And Anthropogenic Effects On The Reef Environment, Jonathan Macdonald
Geology Theses and Dissertations
Corals from the western and equatorial Pacific Ocean have been extensively studied for the purposes of generating paleoclimate reconstructions spanning the last several hundred years. However, in the central subtropical North Pacific, there are currently few published coral records extending beyond 10 to 20 years. The hermatypic coral species Porites lobata and Porites lutea have proven to be useful indicators of paleoclimate and past sea surface conditions at other locations. Here I have analyzed two Porites lobata coral cores collected from colonies from opposite sides of Oahu, Hawaii to assess their utility for developing multi-decadal length climatic reconstructions in this …
Sources Of Ancient Maize Found In Chacoan Great Houses, Larry Benson
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, …
Genetic Identification Of Spotted Owls, Barred Owls, And Their Hybrids: Legal Implications Of Hybrid Identity, Susan M. Haig, Thomas D. Mullins, Eric D. Forsman, Pepper W. Trail, Liv Wennerberg
Genetic Identification Of Spotted Owls, Barred Owls, And Their Hybrids: Legal Implications Of Hybrid Identity, Susan M. Haig, Thomas D. Mullins, Eric D. Forsman, Pepper W. Trail, Liv Wennerberg
United States Geological Survey: Staff Publications
Recent population expansion of Barred Owls (Strix varia) into western North America has led to concern that they may compete with and further harm the Northern Spotted Owl (S. occidentalis caurina), which is already listed as threatened under the U.S. Endangered Species Act (ESA). Because they hybridize, there is a legal need under the ESA for forensic identification of both species and their hybrids. We used mitochondrial control-region DNA and amplified fragment-length polymorphism (AFLP) analyses to assess maternal and biparental gene flow in this hybridization process. Mitochondrial DNA sequences (524 base pairs) indicated large divergence between …
Subspecific Relationships And Genetic Structure In The Spotted Owl, Susan M. Haig, Thomas D. Mullins, Eric D. Forsman
Subspecific Relationships And Genetic Structure In The Spotted Owl, Susan M. Haig, Thomas D. Mullins, Eric D. Forsman
United States Geological Survey: Staff Publications
Hierarchical genetic structure was examined in the three geographically-defined subspecies of spotted owl (Strix occidentalis) to define relationships among subspecies and quantify variation within and among regional and local populations. Sequences (522 bp) from domains I and II of the mitochondrial control region were analyzed for 213 individuals from 30 local breeding areas. Results confirmed significant differences between northern spotted owls and the other traditional geographically defined subspecies but did not provide support for subspecific level differences between California and Mexican spotted owls. Divergence times among subspecies estimated with a 936 bp portion of the cytochrome b gene …
A Holocene Pollen Record Of Persistent Droughts From Pyramid Lake, Nevada, Usa, Scott A. Mensing, Larry Benson, Michaele Kashgarian, Steve Lund
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 …
Quaternary Sea-Level History Of The United States, Daniel R. Muhs, John F. Wehmiller, Kathleen R. Simmons, Linda L. York
Quaternary Sea-Level History Of The United States, Daniel R. Muhs, John F. Wehmiller, Kathleen R. Simmons, Linda L. York
United States Geological Survey: Staff Publications
In the past 30 years, there have been tremendous advances in our understanding of Quaternary sea-level history, due directly to developments in Quaternary dating methods, particularly uranium-series disequilibrium and amino acid racemization. Another reason for this progress is that coastline history can now be tied to the oxygen-isotope record of foraminifera in deep-sea cores. Furthermore, both records have been linked to climate change on the scale of glacial-interglacial cycles that are thought to be forced by changes in Earth-Sun geometry, or “orbital forcing” (Milankovitch, 1941).
Ancient Maize From Chacoan Great Houses: Where Was It Grown?, Larry Benson, Linda Cordell, Kirk Vincent, Howard E. Taylor, John Stein, G. Lang Farmer, U.S. Geological Survey
Ancient Maize From Chacoan Great Houses: Where Was It Grown?, Larry Benson, Linda Cordell, Kirk Vincent, Howard E. Taylor, John Stein, G. Lang Farmer, U.S. Geological Survey
United States Geological Survey: Staff Publications
In this article, we compare chemical (87Sr/86Sr and elemental) analyses of archaeological maize from dated contexts within Pueblo Bonito, Chaco Canyon, New Mexico, to potential agricultural sites on the periphery of the San Juan Basin. The oldest maize analyzed from Pueblo Bonito probably was grown in an area located 80 km to the west at the base of the Chuska Mountains. The youngest maize came from the San Juan or Animas river floodplains 90 km to the north. This article demonstrates that maize, a dietary staple of southwestern Native Americans, was transported over considerable distances in …
Day 3. Wednesday, August 13, 2003: Coalbed Methane Development, University Of Colorado Boulder. Natural Resources Law Center
Day 3. Wednesday, August 13, 2003: Coalbed Methane Development, University Of Colorado Boulder. Natural Resources Law Center
Energy Field Tour 2003 (August 11-16)
10 pages (includes color illustrations and maps).
Agenda: Energy Field Tour 2003, University Of Colorado Boulder. Natural Resources Law Center
Agenda: Energy Field Tour 2003, University Of Colorado Boulder. Natural Resources Law Center
Energy Field Tour 2003 (August 11-16)
Congressional staff tour held August 11-16, 2003
Summary: Binder of assorted articles, maps, brochures and other materials prepared for participants of the tour
Contents:
MONDAY, AUGUST 11, 2003: BLUE SPRUCE PEAKER PLANT: University of Colorado Natural Resources Law Center : congressional staff tour of Blue Spruce Energy Center / Peggy Duxbury -- 'Power Struggle', National Journal, June 27, 2003 / Margaret Kritz -- 'Calpine's Blue Spruce Energy Center begins commercial operation', Calpine press release, April 17, 2003 -- NATIONAL RENEWABLE ENERGY LAB: NREL at a glance -- NREL technologies -- SHOSHONE HYDROELECTRIC PLANT: 'River District Board supports spring Shoshone call …
Mid-Holocene Climates Of The Americas: A Dynamical Response To Changed Seasonality, S. P. Harrison, J. E. Kutzbach, Z. Liu, P. J. Bartlein, B. Otto-Bliesner, Daniel R. Muhs, I. C. Prentice, R. S. Thompson
Mid-Holocene Climates Of The Americas: A Dynamical Response To Changed Seasonality, S. P. Harrison, J. E. Kutzbach, Z. Liu, P. J. Bartlein, B. Otto-Bliesner, Daniel R. Muhs, I. C. Prentice, R. S. Thompson
United States Geological Survey: Staff Publications
Abstract Simulations of the climatic response to mid- Holocene (6 ka BP) orbital forcing with two coupled ocean–atmosphere models (FOAM and CSM) show enhancement of monsoonal precipitation in parts of the American Southwest, Central America and northernmost South America during Northern Hemisphere summer. The enhanced onshore flow that brings precipitation into Central America is caused by a northward displacement of the inter-tropical convergence zone, driven by cooling of the equatorial and warming of the northern subtropical and mid-latitude ocean. Ocean feedbacks also enhance precipitation over the American Southwest, although the increase in monsoon precipitation there is largely driven by increases …
New Evidence For Enhanced Ocean Primary Production Triggered By Tropical Cyclone, I. Lin, W. Timothy Liu, Chun-Chieh Wu, George T. F. Wong, Chuanmin Hu, Zhiqiang Chen, Wen-Der Liang, Yih Yang, Kon-Kee Liu
New Evidence For Enhanced Ocean Primary Production Triggered By Tropical Cyclone, I. Lin, W. Timothy Liu, Chun-Chieh Wu, George T. F. Wong, Chuanmin Hu, Zhiqiang Chen, Wen-Der Liang, Yih Yang, Kon-Kee Liu
OES Faculty Publications
[1] New evidence based on recent satellite data is presented to provide a rare opportunity in quantifying the long-speculated contribution of tropical cyclones to enhance ocean primary production. In July 2000, moderate cyclone Kai-Tak passed over the South China Sea (SCS). During its short 3-day stay, Kai-Tak triggered an average 30-fold increase in surface chlorophyll-a concentration. The estimated carbon fixation resulting from this event alone is 0.8 Mt, or 2-4% of SCS's annual new production. Given an average of 14 cyclones passing over the SCS annually, we suggest the long-neglected contribution of tropical cyclones to SCS's annual new production may …
Methods And Models For Estimating Advective Pore Water Exchange In Tidal Flats, Timothy J. Shaw
Methods And Models For Estimating Advective Pore Water Exchange In Tidal Flats, Timothy J. Shaw
Faculty Publications
No abstract provided.
Late-Holocene Climate And Ecosystem History From Chesapeake Bay Sediment Cores, Usa, Debra A. Willard, Thomas M. Cronin, Stacey Verardo
Late-Holocene Climate And Ecosystem History From Chesapeake Bay Sediment Cores, Usa, Debra A. Willard, Thomas M. Cronin, Stacey Verardo
United States Geological Survey: Staff Publications
Palaeoclimate records from late-Holocene sediments in Chesapeake Bay, the largest estuary in the USA, provide evidence that both decadal to centennial climate variability and European colonization had severe impacts on the watershed and estuary. Using pollen and dinoflagellate cysts as proxies for mid-Atlantic regional precipitation, estuarine salinity and dissolved oxygen (DO) during the last 2300 years, we identified four dry intervals, centred on ad 50 (P1/D1), ad 1000 (P2/D2), ad 1400 (P3) and ad 1600 (P4). Two centennial-scale events, P1/D1 and P2/D2, altered forest composition and led to increased salinity and DO levels in the estuary. Intervals P3 and P4 …
Calibration Of Remotely Sensed, Coarse Resolution Ndvi To Co2 Fluxes In A Sagebrush–Steppe Ecosystem, Bruce K. Wylie, Douglas A. Johnson, Emilio Laca, Nicanor Z. Saliendra, Tagir G. Gilmanov, Bradley C. Reed, Larry L. Tieszen, Bruce B. Worstell
Calibration Of Remotely Sensed, Coarse Resolution Ndvi To Co2 Fluxes In A Sagebrush–Steppe Ecosystem, Bruce K. Wylie, Douglas A. Johnson, Emilio Laca, Nicanor Z. Saliendra, Tagir G. Gilmanov, Bradley C. Reed, Larry L. Tieszen, Bruce B. Worstell
United States Geological Survey: Staff Publications
The net ecosystem exchange (NEE) of carbon flux can be partitioned into gross primary productivity (GPP) and respiration (R). The contribution of remote sensing and modeling holds the potential to predict these components and map them spatially and temporally. This has obvious utility to quantify carbon sink and source relationships and to identify improved land management strategies for optimizing carbon sequestration. The objective of our study was to evaluate prediction of 14-day average daytime CO2 fluxes ( Fday) and nighttime CO2 fluxes (Rn) using remote sensing and other data. Fday …
An Approach For Mapping Large-Area Impervious Surfaces: Synergistic Use Of Landsat-7 Etm+ And High Spatial Resolution Imagery, Limin Yang, Chengquan Huang, Bruce K. Wylie, Michael J. Coan
An Approach For Mapping Large-Area Impervious Surfaces: Synergistic Use Of Landsat-7 Etm+ And High Spatial Resolution Imagery, Limin Yang, Chengquan Huang, Bruce K. Wylie, Michael J. Coan
United States Geological Survey: Staff Publications
A wide range of urban ecosystem studies, including urban climate, land use planning, and resource management, require current and accurate geospatial data of urban impervious surfaces. We developed an approach to quantify urban impervious surfaces as a continuous variable by using multisensor datasets. Subpixel percent impervious surfaces at 30-m resolution were mapped using a regression tree model. The utility, practicality, and affordability of the proposed method for large-area imperviousness mapping were tested over three spatial scales (Sioux Falls, South Dakota, Richmond, Virginia, and the Chesapeake Bay areas of the United States). Average error of predicted versus actual percent impervious surface …
Influence Of The Pacific Decadal Oscillation On The Climate Of The Sierra Nevada, California And Nevada, Larry Benson, Braddock Linsley, Joe Smoot, Scott Mensing, Steve Lund, Scott Stine, Andre Sarna-Wojcicki
Influence Of The Pacific Decadal Oscillation On The Climate Of The Sierra Nevada, California And Nevada, Larry Benson, Braddock Linsley, Joe Smoot, Scott Mensing, Steve Lund, Scott Stine, Andre Sarna-Wojcicki
United States Geological Survey: Staff Publications
Mono Lake sediments have recorded five major oscillations in the hydrologic balance between A.D. 1700 and 1941. These oscillations can be correlated with tree-ring-based oscillations in Sierra Nevada snowpack. Comparison of a tree-ring-based reconstruction of the Pacific Decadal Oscillation (PDO) index (D’Arrigo et al., 2001) with a coral-based reconstruction of Subtropical South Pacific sea-surface temperature (Linsley et al., 2000) indicates a high degree of correlation between the two records during the past 300 yr. This suggests that the PDO has been a pan-Pacific phenomena for at least the past few hundred years. Major oscillations in the hydrologic balance of the …
Age Of The Mono Lake Excursion And Associated Tephra, Larry Benson, Joseph Liddicoat, Joseph Smoot, Andrei Sarna-Wojcicki, Robert M. Negrini, Steve Lund
Age Of The Mono Lake Excursion And Associated Tephra, Larry Benson, Joseph Liddicoat, Joseph Smoot, Andrei Sarna-Wojcicki, Robert M. Negrini, Steve Lund
United States Geological Survey: Staff Publications
The Mono Lake excursion (MLE) is an important time marker that has been found in lake and marine sediments across much of the Northern Hemisphere. Dating of this event at its type locality, the Mono Basin of California, has yielded controversial results with the most recent effort concluding that the MLE may actually be the Laschamp excursion (Earth Planet. Sci. Lett. 197 (2002) 151). We show that a volcanic tephra (Ash #15) that occurs near the midpoint of the MLE has a date (not corrected for reservoir effect) of 28,620 ± 300 14C yr BP (~32,400 GISP2 yr BP) …
Rare-Earth Elements And Nd And Pb Isotopes As Source Indicators For Labrador Sea Clay-Size Sediments During Heinrich Event 2, Larry V. Benson, Don Barber, John T. Andrews, Howard E. Taylor, Paul Lamothe
Rare-Earth Elements And Nd And Pb Isotopes As Source Indicators For Labrador Sea Clay-Size Sediments During Heinrich Event 2, Larry V. Benson, Don Barber, John T. Andrews, Howard E. Taylor, Paul Lamothe
United States Geological Survey: Staff Publications
Elemental abundances and Nd and Pb isotope ratios were determined on samples from the carbonate-free, clay-size fractions of sediments from intervals above, within, and below Heinrich event 2 (H-2) in core HU87-9 from the Northwest Labrador Sea slope. In HU87-9, rare-earth element (REE) distributions and elemental concentrations within the H-2 event are distinct from those outside this event. ɛNd(0) and 206Pb/204Pb data also indicate different values for sediments deposited within and outside the H-2 event. Comparisons of REE patterns from the H-2 interval with those from bedrock units in Baffin Island, northern Quebec, and Labrador …
Response Of North American Great Basin Lakes To Dansgaard–Oeschger Oscillations, Larry Benson, Steve Lund, Robert M. Negrini, Braddock Linsley, Mladen Zic
Response Of North American Great Basin Lakes To Dansgaard–Oeschger Oscillations, Larry Benson, Steve Lund, Robert M. Negrini, Braddock Linsley, Mladen Zic
United States Geological Survey: Staff Publications
We correlate oscillations in the hydrologic and/or cryologic balances of four Great Basin surface-water systems with Dansgaard– Oeschger (D–O) events 2–12. This correlation is relatively strong at the location of the magnetic signature used to link the lake records, but becomes less well constrained with distance/time from the signature. Comparison of proxy glacial and hydrologic records from Owens and Pyramid lakes indicates that Sierran glacial advances occurred during times of relative dryness. If our hypothesized correlation between the lake-based records and the GISP2 δ18O record is correct, it suggests that North Atlantic D–O stades …
Aeolian Cliff-Top Deposits And Buried Soils In The White River Badlands, South Dakota, Usa, J. Elmo Rawling Iii, Glen G. Fredlund, Shannon Mahan
Aeolian Cliff-Top Deposits And Buried Soils In The White River Badlands, South Dakota, Usa, J. Elmo Rawling Iii, Glen G. Fredlund, Shannon Mahan
United States Geological Survey: Staff Publications
Aeolian deposits in the North American Great Plains are important sources of Holocene palaeoenvironmental records. Although there are extensive studies on loess and dune records in the region, little is known about records in aeolian cliff-top deposits. These are common on table (mesa) edges in the White River Badlands. These sediments typically have loam and sandy-loam textures with dominantly very fine sand, 0.5–1% organic carbon and 0.5–5% CaCO3. Some of these aeolian deposits are atypically coarse and contain granules and fine pebbles. Buried soils within these deposits are weakly developed with A-C and A-AC-C profiles. Beneath these are …
New Record Of The Rare Emballonurid Bat Centronycteris Centralis Thomas, 1912 In Costa Rica, With Notes On Feeding Habits, Neal Woodman
New Record Of The Rare Emballonurid Bat Centronycteris Centralis Thomas, 1912 In Costa Rica, With Notes On Feeding Habits, Neal Woodman
United States Geological Survey: Staff Publications
The shaggy sac-winged bat, Centronycteris centralis (Chiroptera: Emballonuridae), occurs mainly in lowland forests from Veracruz, Mexico, to Peru, although it has been reported from elevations as high at 1450 m in Panama (Simmons and Handley 1998; Hice and Solari 2002). Most captures of the species are of single individuals, and throughout its distribution, this bat is rare and poorly-known (Emmons 1997; Reid 1997; Simmons and Handley 1998). Centronycteris centralis generally has been assumed to be an aerial insectivore, capturing flying insects on the wing (Starrett and Casebeer 1968; Wilson 1973; Timm et al. 1989; LaVal and Rodrı´guez 2002). However, direct …
Quaternary Loess-Paleosol Sequences As Examples Of Climate-Driven Sedimentary Extremes, Daniel R. Muhs, E. Arthur Bettis Iii
Quaternary Loess-Paleosol Sequences As Examples Of Climate-Driven Sedimentary Extremes, Daniel R. Muhs, E. Arthur Bettis Iii
United States Geological Survey: Staff Publications
Loess is a widespread, wind-transported, silt-dominated deposit that contains geologic archives of atmospheric circulation and paleoclimate on continents. Loess may cover as much as 10% of the Earth’s land surface. It is composed mainly of quartz, feldspars, and clay minerals, with varying amounts of carbonate minerals. The geochemistry of loess differs from region to region, depending on source materials, but all loess is very high in SiO2 with lesser amounts of other major elements. Trends in loess downwind from source areas include systematic decreases in thickness and amounts of sand and coarse silt, and increases in amounts of fine silt …
Arctic Ice Export Events And Their Potential Impact On Global Climate During The Late Pleistocene, Dennis A. Darby, Jens F. Bischof, Robert F. Spielhagen, Steven A. Marshall, Stephen W. Herman
Arctic Ice Export Events And Their Potential Impact On Global Climate During The Late Pleistocene, Dennis A. Darby, Jens F. Bischof, Robert F. Spielhagen, Steven A. Marshall, Stephen W. Herman
OES Faculty Publications
Ice sheets in the North American Arctic and, to a lesser extent, those in northern Eurasia calved large quantities of icebergs that drifted through Fram Strait into the Greenland Sea several times during the late Pleistocene. These icebergs deposited Fe oxide grains (45-250 mum) and coarse lithic clasts >250 mum matched to specific circum-Arctic sources. Four massive Arctic iceberg export events are identified from the Laurentide and the Innuitian ice sheets, between 14 and 34 ka (calendar years) in a sediment core from Fram Strait. These relatively short duration (<1-4 kyr) events contain 3-5 times the background levels of Fe oxide grains. They began suddenly, as indicated by a steep rise in the number of grains matched to an ice sheet source, suggesting rapid purges of ice through Fram Strait, due perhaps to collapse of ice sheets. The larger events from the northwestern Laurentide ice sheet are preceded by events from the Innuitian ice sheet. Despite the chronological uncertainties, the Arctic export events appear to occur prior to Heinrich events.
Organochlorine Chemical Residues In Fish From The Mississippi River Basin, 1995, C.J. Schmitt
Organochlorine Chemical Residues In Fish From The Mississippi River Basin, 1995, C.J. Schmitt
United States Geological Survey: Staff Publications
µ≤≥
Fish were collected in late 1995 from 34 National Contaminant Biomonitoring Program (NCBP) stations and 13 National Water Quality Assessment Program (NAWQA) stations in the Mississippi River basin (MRB) and in late 1996 from a reference site in West Virginia. Four composite samples, each comprising (nominally) 10 adult common carp (Cyprinus carpio) or black bass (Micropterus spp.) of the same sex, were collected from each site and analyzed for organochlorine chemical residues by gas chromatography with electron capture detection. At the NCBP stations, which are located on relatively large rivers, concentrations of organochlorine chemical residues were generally lower than …