Physical Sciences and Mathematics | Open Access Articles

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 …

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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 …

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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 …

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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 ( F_day) and nighttime CO₂ fluxes (R_n) using remote sensing and other data. F_{day …}

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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 …

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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 …

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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 …

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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 …

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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 …

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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) …

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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 …

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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. ɛ_Nd(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 …

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Full-Text Articles in Physical Sciences and Mathematics

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

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

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

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

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

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

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

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

Quaternary Loess-Paleosol Sequences As Examples Of Climate-Driven Sedimentary Extremes, Daniel R. Muhs, E. Arthur Bettis Iii

United States Geological Survey: Staff Publications

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

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

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