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Articles 2911 - 2940 of 4541

Full-Text Articles in Earth Sciences

Citizen Knowledge And Perception Of Black-Tailed Prairie Dog Management, Natalie R. Sexton, Ayeisha Brinson, Phadrea D. Ponds, Kurt Cline, Berton L. Lamb Jan 2001

Citizen Knowledge And Perception Of Black-Tailed Prairie Dog Management, Natalie R. Sexton, Ayeisha Brinson, Phadrea D. Ponds, Kurt Cline, Berton L. Lamb

United States Geological Survey: Publications

What do citizens know about black-tailed prairie dogs, and where do they get their information? When management decisions need to be made regarding an animal such as the black-tailed prairie dog, an understanding of the species and its relationship to humans is necessary. This includes knowing the biology of the animal, where it lives, and how it interacts with other animals. But it is equally important for those making decisions about the species to understand citizens’ knowledge and perceptions so managers can effectively communicate with the public and help the public participate in planning and decision making activities. Unfortunately, what …


Occurrence And Potential Adverse Effects Of Semivolatile Organic Compounds In Streambed Sediment, United States, 1992–1995, Thomas J. Lopes, Edward T. Furlong Jan 2001

Occurrence And Potential Adverse Effects Of Semivolatile Organic Compounds In Streambed Sediment, United States, 1992–1995, Thomas J. Lopes, Edward T. Furlong

United States Geological Survey: Staff Publications

The occurrence and potential adverse effects of select semivolatile organic compounds (SVOCs) in streambed sediment were assessed at 536 sites in 20 major river basins across the United States from 1992 to 1995. Fifty-six SVOCs were detected at one or more sites, and one or more SVOCs were detected at 71% of sites. The northeastern and Great Lakes regions and large metropolitan areas have the highest SVOC concentrations. Polycyclic aromatic hydrocarbons (PAHs) were detected most frequently and at the highest concentrations. Concentrations of PAHs and phthalates were about 10 times higher at sites influenced by urban activities than at sites …


Calcareous Nannofossils From Cape Roberts Project Drillhole Crp-3, Victoria Land Basin, Antarctica, David K. Watkins, S. W. Wise Jr., G. Villa Jan 2001

Calcareous Nannofossils From Cape Roberts Project Drillhole Crp-3, Victoria Land Basin, Antarctica, David K. Watkins, S. W. Wise Jr., G. Villa

Department of Earth and Atmospheric Sciences: Faculty Publications

Fossil specimens of the exclusively oceanic calcareous nannoplankton were found only in the upper 200 m of the Cape Roberts Project 3 (CRP-3) cores. These assemblages are depauperate and sporadic in occurrence. The majority of the assemblages contain fewer than 4 species, indicating a severe palaeoecological restriction. The clear domination of these assemblages by reticulofenestrid species, coupled with the almost total exclusion of Coccolithus pelagicus, indicates cold surface water conditions in the Victoria Land Basin during the lives of these poor algae. These cold surface water conditions, perhaps coupled with abnormal surface water chemistry, excluded almost all of the …


Vertical Profiles Of Streambed Hydraulic Conductivity Determined Using Slug Tests In Central And Western Nebraska, David L. Rus, Virginia L. Mcguire, Brian R. Zurbuchen, Vitaly A. Zlotnik Jan 2001

Vertical Profiles Of Streambed Hydraulic Conductivity Determined Using Slug Tests In Central And Western Nebraska, David L. Rus, Virginia L. Mcguire, Brian R. Zurbuchen, Vitaly A. Zlotnik

Department of Earth and Atmospheric Sciences: Faculty Publications

Many issues of water-resources management rely on modeling of ground-water/surface-water interactions, and streambed hydraulic conductivity is a key parameter controlling the water fluxes across the stream/aquifer interface. However, in central and western Nebraska, this parameter is generally undefined. The U.S. Geological Survey, in cooperation with the Nebraska Platte River Cooperative Hydrology Study Group, performed slug tests at 15 steam sites in the Platte, Republican, and Little Blue River watersheds to determine the hydraulic conductivity of streambeds in central and western Nebraska. Slug tests were completed at several discrete depth intevals using pneumatic or mechanical methods, and the water-level response was …


Small Oligocene Amphicyonids From North America (Paradaphoenus, Mammalia, Carnivora), Robert M. Hunt Jr. Jan 2001

Small Oligocene Amphicyonids From North America (Paradaphoenus, Mammalia, Carnivora), Robert M. Hunt Jr.

Department of Earth and Atmospheric Sciences: Faculty Publications

North American amphicyonid camivorans are important members of the mid-Cenozoic terrestrial carnivore community during the late Eocene to late Miocene (Duchesnean to Clarendonian). Species range in size from < 5 kg to > 200 kg. Among the smallest and rarest amphicyonids are Oligocene species of Paradaphoenus Wortman and Matthew, found at a few localities in the Great Plains and the Pacific Northwest. Paradaphoenus is known from only 10 individuals placed in 3 species (P. minimus; P. tooheyi. n. sp.; P. cuspigerus). representing a single lineage ranging from the Orellan to Arikareean. The existence of three skulls, one with associated mandibles, allows …


Variations Of Teleconnection Of Enso And Interannual Variation In Summer Rainfall In The Central United States, Q. Steven Hu, Yongjun Zheng Jan 2001

Variations Of Teleconnection Of Enso And Interannual Variation In Summer Rainfall In The Central United States, Q. Steven Hu, Yongjun Zheng

Department of Earth and Atmospheric Sciences: Faculty Publications

Summer rainfall in the central United States has singular interannual variations of a 3–6-yr period. Identifying the causes of these variations assures improvement in predictions of summer rainfall in the region.

A review of previous studies revealed a puzzling situation: the outstanding interannual variations of the summer rainfall in the central United States showed no persistent correlations with known influential interannual variations in the Northern Hemisphere and the El Nin ̃o–Southern Oscillation (ENSO). This study was undertaken to identify the cause of this situation and ultimately explain the causes of the observed interannual summer rainfall variations. Its results showed a …


Earthquake Stress Drop And Laboratory-Inferred Interseismic Strength Recovery, N. M. Beeler, S. H. Hickman, T. F. Wong Jan 2001

Earthquake Stress Drop And Laboratory-Inferred Interseismic Strength Recovery, N. M. Beeler, S. H. Hickman, T. F. Wong

United States Geological Survey: Staff Publications

We determine the scaling relationships between earthquake stress drop and recurrence interval t, that are implied by laboratory-measured fault strength.  We assume that repeating earthquakes can be simulated by stick-slip sliding using a spring and slider block model.  Simulations with static/kinetic strength, time-dependent strength, and rate- and state-variable dependent strength indicate that the relationship between loading velociety and recurrence intercal can be adequately described be the power law VL ∞ tnr, where n ≈ -1. Deviations from n≈ -1 arise from second order effects on strength, with n> -1 corresponding to apparent time-dependent …


Hydrogeology And Hydrochemistry Of The Jumbo And Pullman Valley Fens, Cherry County, Nebraska, F. E. Harvey, J. B. Swinehart, T. M. Kurtz Jan 2001

Hydrogeology And Hydrochemistry Of The Jumbo And Pullman Valley Fens, Cherry County, Nebraska, F. E. Harvey, J. B. Swinehart, T. M. Kurtz

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Adams County Test Hole Logs, Perry B. Wigley Jan 2001

Adams County Test Hole Logs, Perry B. Wigley

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Modeling Reptile And Amphibian Range Distributions From Species Occurrences And Landscape Variables, Geoffrey M. Henebry, Brian C. Putz, James W. Merchant Jan 2001

Modeling Reptile And Amphibian Range Distributions From Species Occurrences And Landscape Variables, Geoffrey M. Henebry, Brian C. Putz, James W. Merchant

United States Geological Survey: Publications

An international symposium in October 1999 demonstrated the state of the art in modeling species occurrences (Scott et al. 2001). One clear message from the symposium was the broad diversity of approaches that constitute the state of the art. No single method excels, largely because of the very particular and local nature of the problem. Organisms both influence and respond to their local environment; thus, the same species may key in on different resources in different landscapes. Furthermore, modeling methods vary widely in their "transparency," which can inhibit transportability or robustness.
In order to provide an analytical modeling framework that …


At-Satellite Reflectance: A First Order Normalization Of Landsat 7 Etm+ Images, Chengquan Huang, Limin Yang, Collin Homer, Bruce K. Wylie, James E. Vogelmann, Thomas Defelice Jan 2001

At-Satellite Reflectance: A First Order Normalization Of Landsat 7 Etm+ Images, Chengquan Huang, Limin Yang, Collin Homer, Bruce K. Wylie, James E. Vogelmann, Thomas Defelice

United States Geological Survey: Publications

Regional Landsat applications often rely on clear and near cloud-free images. With the spectral value being represented by digital number (DN), however, such images contain substantial noises. A significant proportion of such noises can be normalized by converting the DN to at-satellite reflectance value. Being physically based and ready to automate, the conversion method can serve as a first order normalization of Landsat 7 images, making it possible to derive land surface information from such images more consistently.


A Strategy For Estimating Tree Canopy Density Using Landsat 7 Etm+ And High Resolution Images Over Large Areas, C. Huang, Limin Yang, Bruce K. Wylie, Collin Homer Jan 2001

A Strategy For Estimating Tree Canopy Density Using Landsat 7 Etm+ And High Resolution Images Over Large Areas, C. Huang, Limin Yang, Bruce K. Wylie, Collin Homer

United States Geological Survey: Publications

INTRODUCTION

The Multi-Resolution Land Characteristics (MRLC) consortium was initiated in early 1990s to address the need for consistently developed national and regional land cover data (Loveland and Shaw, 1996). Through this consortium, a 1992-vintage National Land Cover Dataset (NLCD) was developed for the conterminous United States (Vogelmann et al., 2001), and a second generation National Land Cover Dataset (NLCD 2000) will be developed using 2000-vintage Landsat 7 Enhanced Thematic Mapper Plus (ETM+) images and ancillary data. The 2000 NLCD will consist of a suite of data layers relevant to many applications, including a tree canopy density layer describing percentage of …


Regional Variations In Provenance And Abundance Of Ice-Rafted Clasts In Arctic Ocean Sediments: Implications For The Configuration Of Late Quaternary Oceanic And Atmospheric Circulation In The Arctic, R. L. Phillips, A. Grantz Jan 2001

Regional Variations In Provenance And Abundance Of Ice-Rafted Clasts In Arctic Ocean Sediments: Implications For The Configuration Of Late Quaternary Oceanic And Atmospheric Circulation In The Arctic, R. L. Phillips, A. Grantz

United States Geological Survey: Staff Publications

The composition and distribution of ice-rafted glacial erratics in late Quaternary sediments define the major current systems of the Arctic Ocean and identify two distinct continental sources for the erratics. In the southern Amerasia basin up to 70% of the erratics are dolostones and limestones (the Amerasia suite) that originated in the carbonate-rich Paleozoic terranes of the Canadian Arctic Islands. These clasts reached the Arctic Ocean in glaciers and were ice-rafted to the core sites in the clockwise Beaufort Gyre. The concentration of erratics decreases northward by 98% along the trend of the gyre from southeastern Canada basin to Makarov …


Laser-Derived Particle Size Data From Crp-3, Victoria Land Basin, Antarctica: Implications For Sequence And Seismic Stratigraphy, Christopher R. Fielding, G. B. Dunbar, S. M. Bryce Jan 2001

Laser-Derived Particle Size Data From Crp-3, Victoria Land Basin, Antarctica: Implications For Sequence And Seismic Stratigraphy, Christopher R. Fielding, G. B. Dunbar, S. M. Bryce

Department of Earth and Atmospheric Sciences: Faculty Publications

Seven hundred and nineteen samples from throughout the Cainozoic section in CRP-3 were analysed by a Malvern Mastersizer laser particle analyser, in order to derive a stratigraphic distribution of grain-size parameters downhole. Entropy analysis of these data (using the method of Woolfe & Michibayashi, 1995) allowed recognition of four groups of samples, each group characterised by a distinctive grain-size distribution. Group 1, which shows a multi-modal distribution, corresponds to mudrocks, interbedded mudrock/sandstone facies, muddy sandstones and diamictites. Group 2, with a sand-grade mode but showing wide dispersion of particle size, corresponds to muddy sandstones, a few cleaner sandstones and some …


Chronostratigraphy Of The Crp-3 Drillhole, Victoria Land Basin, Antarctica, M J. Hannah, F Florindo, David M. Harwood, Christopher R. Fielding, Cape Roberts Science Team Jan 2001

Chronostratigraphy Of The Crp-3 Drillhole, Victoria Land Basin, Antarctica, M J. Hannah, F Florindo, David M. Harwood, Christopher R. Fielding, Cape Roberts Science Team

Department of Earth and Atmospheric Sciences: Faculty Publications

An 823 m thick glaciomarine Cenozoic section sitting unconformably on the Lower Devonian Beacon Supergroup was recovered in CRP –3. This paper reviews the chronostratigraphical constraints for the Cenozoic section. Between 3 and 480.27 mbsf 23 unconformity bounded cycles of sediment were recorded. Each unconformity is thought to represent a hiatus of uncertain duration. Four magnetozones have been recognised from the Cenozoic section. The record is complex with several “tiny wiggles” recorded throughout. Biostratigraphical or Sr ages, which could be used to link these magnetozones to the magnetic polarity time scale are restricted to the upper 190 m of sediment. …


Chronostratigraphy Of The Crp-3 Drillhole, Victoria Land Basin, Antarctica, M. J. Hannah, F. Florindo, David M. Harwood, Christopher R. Fielding, Cape Roberts Science Team Jan 2001

Chronostratigraphy Of The Crp-3 Drillhole, Victoria Land Basin, Antarctica, M. J. Hannah, F. Florindo, David M. Harwood, Christopher R. Fielding, Cape Roberts Science Team

Department of Earth and Atmospheric Sciences: Faculty Publications

An 823 m thick glaciomarine Cenozoic section sitting unconformably on the Lower Devonian Beacon Supergroup was recovered in CRP –3. This paper reviews the chronostratigraphical constraints for the Cenozoic section. Between 3 and 480.27 mbsf 23 unconformity bounded cycles of sediment were recorded. Each unconformity is thought to represent a hiatus of uncertain duration. Four magnetozones have been recognised from the Cenozoic section. The record is complex with several “tiny wiggles” recorded throughout. Biostratigraphical or Sr ages, which could be used to link these magnetozones to the magnetic polarity time scale are restricted to the upper 190 m of sediment. …


Sedimentary Cyclicity In Crp Drillcore, Victoria Land Basin, Antarctica, T. R. Naish, P. J. Barrett, G. B. Dunbar, K. J. Woolfe, A. G. Dunn, S. A. Henrys, M. Claps, R. D. Powell, Christopher R. Fielding Jan 2001

Sedimentary Cyclicity In Crp Drillcore, Victoria Land Basin, Antarctica, T. R. Naish, P. J. Barrett, G. B. Dunbar, K. J. Woolfe, A. G. Dunn, S. A. Henrys, M. Claps, R. D. Powell, Christopher R. Fielding

Department of Earth and Atmospheric Sciences: Faculty Publications

The upper 1200 m of pre-Pliocene sediment recovered by Cape Roberts Project (CRP) drilling off the Victoria Land coast of Antarctica between 1997-1999 has been subdivided into 54 unconformity-bound stratigraphic sequences, spanning the period c. 32 to 17 Ma. The sequences are recognised on the basis of the cyclical vertical stacking of their constituent lithofacies, which are enclosed by erosion surfaces produced during the grounding of the advancing ice margin onto the sea floor. Each sequence represents deposition in a range of offshore shelf to coastal glacimarine sedimentary environments during oscillations in the ice margin across the Western Ross Sea …


Early Oligocene Siliceous Microfossil Biostratigraphy Of Cape Roberts Project Core Crp-3, Victoria Land Basin, Antarctica, David M. Harwood, S. M. Bohaty Jan 2001

Early Oligocene Siliceous Microfossil Biostratigraphy Of Cape Roberts Project Core Crp-3, Victoria Land Basin, Antarctica, David M. Harwood, S. M. Bohaty

Department of Earth and Atmospheric Sciences: Faculty Publications

Early Oligocene siliceous microfossils were recovered in the upper c. 193 m of the CRP-3 drillcore. Although abundance and preservation are highly variable through this section, approximately 130 siliceous microfossil taxa were identified, including diatoms, silicoflagellates, ebridians, chrysophycean cysts, and endoskeletal dinoflagellates. Well-preserved and abundant assemblages characterize samples in the upper c. 70 m and indicate deposition in a coastal setting with water depths between 50 and 200 m. Abundance fluctuations over narrow intervals in the upper c. 70 mbsf are interpreted to reflect environmental changes that were either conducive or deleterious to growth and preservation of siliceous microfossils. Only …


Saunders County Test Hole Logs, Raymond R. Burchett, Scott E. Summerside Jan 2001

Saunders County Test Hole Logs, Raymond R. Burchett, Scott E. Summerside

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Central Us Earthquake Catalog For Hazard Maps Of Memphis, Tennessee, Russell L. Wheeler, Charles S. Mueller Jan 2001

Central Us Earthquake Catalog For Hazard Maps Of Memphis, Tennessee, Russell L. Wheeler, Charles S. Mueller

United States Geological Survey: Staff Publications

An updated version of the catalog that was used for the current national probabilistic seismic-hazard maps would suffice for preduction of large-scale hazard maps of the Memphis urban area. Deaggregation maps provide guidance as to the area that a catalog for calculating Memphis hazard should cover. For the future, the Nuttli and local netword catalogs could be examined for earthquakes nor presenly included in the cataloge. Additional work on the aftershock removal might reduce hazard uncertainty. Graphs of decadal and annual earthquake rates suggest completeness at and above magnitude 3 for the last three or four decades. Any additional work …


Major Herbicides In Ground Water: Results From The National Water-Quality Assessment, Jack . E. Barbash, Gail P. Thelin, Dana W. Kolpin, Robert J. Gilliom Jan 2001

Major Herbicides In Ground Water: Results From The National Water-Quality Assessment, Jack . E. Barbash, Gail P. Thelin, Dana W. Kolpin, Robert J. Gilliom

United States Geological Survey: Staff Publications

To improve understanding of the factors affecting pesticide occurrence in ground water, patterns of detection were examined for selected herbicides, based primarily on results from the National Water-Quality Assessment (NAWQA) program. The NAWQA data were derived from 2227 sites (wells and springs) sampled in 20 major hydro- logic basins across the USA from 1993 to 1995. Results are presented for six high-use herbicides—atrazine (2-chloro-4-ethylamino-6-iso-propylamino- s-triazine), cyanazine (2-[4-chloro-6-ethylamino-1,3,5-triazin-2-yl]amino]-2-methylpropionitrile), simazine (2-chloro-4,6-bis- [ethylamino]-s-triazine), alachlor (2-chloro-N-[2,6-diethylphenyl]-N- [methoxymethyl]acetamide), acetochlor (2-chloro-N-[ethoxymethyl]- N-[ 2-ethyl-6-methylphenyl]acetamide), and metolachlor (2-chloro-N- [2-ethyl-6-methylphenyl]-N-[2-methoxy-1-methylethyl]acetamide)— as well as for prometon (2,4-bis[isopropylamino]-6-methoxy-s-triazine), a nonagricultural herbicide detected frequently during the study. Concentrations were <1 μg L-1 at 98% …


Impact Of Climate And Parent Material On Chemical Weathering In Loess-Derived Soils Of The Mississippi River Valley, Daniel R. Muhs, E. A. Bettis Iii, J. Been, J. P. Mcgeehin Jan 2001

Impact Of Climate And Parent Material On Chemical Weathering In Loess-Derived Soils Of The Mississippi River Valley, Daniel R. Muhs, E. A. Bettis Iii, J. Been, J. P. Mcgeehin

United States Geological Survey: Staff Publications

Peoria Loess-derived soils on uplands east of the Mississippi River the midcontinent of North America (Ruhe, 1969; Hall valley were studied from Louisiana to Iowa, along a south-to-north and Anderson, 2000), Alaska (Muhs et al., 2001), and gradient of decreasing precipitation and temperature. Major element China (Maher et al., 1994). Critical to paleoclimatic interanalyses of deep loess in Mississippi and Illinois show that the composi- pretations, using paleosols, are reliable climofunctions tion of the parent material is similar in the northern and southern for modern soils, which give an understanding of soil parts of the valley. We hypothesized that in …


Inhibition Of Erythrocyte Δ- Aminolevulinic Acid Dehydratase (Alad) Activity In Fish From Waters Affects By Lead Smelters, Christopher J. Schmitt, Colleen A. Caldwell, Bill Olsen, Dave Serdar Jan 2001

Inhibition Of Erythrocyte Δ- Aminolevulinic Acid Dehydratase (Alad) Activity In Fish From Waters Affects By Lead Smelters, Christopher J. Schmitt, Colleen A. Caldwell, Bill Olsen, Dave Serdar

United States Geological Survey: Staff Publications

We assessed the effects on fish of lead (Pb) released to streams by smelters located in Trail, BC (Canada), E. Helena, MT, Herculaneum, MO, and Glover, MO. Fish were collected by electrofishing from sites located downstream of smelters and from reference sites. Blood from each fish was analyzed for δ-aminolevulinic acid dehydratase (ALAD) activity and hemoglobin (Hb), and samples of blood, liver, or carcass were analyzed for Pb, zinc (Zn), or both. Fish collected downstream of all four smelters sites had elevated Pb concentrations, decreased ALAD activity, or both relative to their respective reference sites. At E. Helena, fish from …


Remnant Colloform Pyrite At The Haile Gold Deposit, South Carolina: A Textural Key To Genesis, Nora Foley, Robert A. Ayuso, Robert R. Seal Ii Jan 2001

Remnant Colloform Pyrite At The Haile Gold Deposit, South Carolina: A Textural Key To Genesis, Nora Foley, Robert A. Ayuso, Robert R. Seal Ii

United States Geological Survey: Staff Publications

Auriferous iron sulfide-bearing deposits of the Carolina slate belt have distinctive mineralogical and textural features—traits that provide a basis to construct models of ore deposition. Our identification of paragenetically early types of pyrite, especially remnant colloform, crustiform, and layered growth textures of pyrite containing electrum and pyrrhotite, establishes unequivocally that gold mineralization was coeval with deposition of host rocks and not solely related to Paleozoic tectonic events. Ore horizons at the Haile deposit, South Carolina, contain many remnants of early pyrite: (1) fine-grained cubic pyrite disseminated along bedding; (2) finegrained spongy, rounded masses of pyrite that may envelop or drape …


2,3,7,8-Tetrachlorodibenzo-P-Dioxin Induces Apoptotic Cell Death And Cytochrome P4501a Expression In Developing Fundulus Heteroclitus Embryos, Barbara Holland Toomey, Susan Bello, Mark E. Hahn, Susannah Cantrell, Peggy Wright, Donald E. Tillitt, Richard T. Di Giulio Jan 2001

2,3,7,8-Tetrachlorodibenzo-P-Dioxin Induces Apoptotic Cell Death And Cytochrome P4501a Expression In Developing Fundulus Heteroclitus Embryos, Barbara Holland Toomey, Susan Bello, Mark E. Hahn, Susannah Cantrell, Peggy Wright, Donald E. Tillitt, Richard T. Di Giulio

United States Geological Survey: Staff Publications

Fundulus heteroclitus embryos were exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during early development using nanoinjection or water bath exposure. TCDD caused developmental abnormalities that included hemorrhaging, loss of vascular integrity, edema, stunted development and death. The LC50 and LD50 of TCDD for Fundulus embryos were ~19.7 ± 9.5 pg TCDD/µl (water bath) and 0.25 ± 0.09 ng TCDD/g embryo (nanoinjection). To identify a possible cause for these developmental abnormalities we analyzed the effects of TCDD on apoptotic cell death and cytochrome P4501A (CYP1A) expression in the embryos. TCDD exposure increased apoptotic cell death in several tissues including brain, …


Fluvial Processes And Passive Rehabilitation Of The Lisbon Bottom Side-Channel Chute, Lower Missouri River, Robert B. Jacobson, Mark S. Laustrup, Michael D. Chapman Jan 2001

Fluvial Processes And Passive Rehabilitation Of The Lisbon Bottom Side-Channel Chute, Lower Missouri River, Robert B. Jacobson, Mark S. Laustrup, Michael D. Chapman

United States Army Corps of Engineers, Omaha District

Multiple large floods in 1993-1997 on the Lower Missouri River carved a side-channel chute through the river bottom at Lisbon, Missouri. Although similar in some respects to engineered side-channel chutes designed for habitat rehabilitation projects, the Lisbon Bottom chute has been unique in that it was allowed to evolve for more than four years with minimal stabilization. During the wet years, 1996-1999, the chute was subjected to abnormally high discharges and passed as much as 20% of the total discharge of the Missouri River. Relatively unrestrained fluvial processes during this time created a wide channel with highly diverse habitats. The …


Origin Of Late Quaternary Dune Fields On The Southern High Plains Of Texas And New Mexico, Daniel R. Muhs, Vance T. Holliday Jan 2001

Origin Of Late Quaternary Dune Fields On The Southern High Plains Of Texas And New Mexico, Daniel R. Muhs, Vance T. Holliday

United States Geological Survey: Staff Publications

Mostly stabilized late Holocene eolian sands on the Southern High Plains of the United States were studied to determine their origins and to assess whether present dune stability depends more strongly on sediment supply, sediment availability, or transport limitations. Geomorphic, sedimentological, and geochemical trends indicate that late Holocene dunes formed under westerly paleowinds, broadly similar to those of today. Mineralogical and geochemical data indicate that the most likely source for the sands is not the Pecos River valley, but the Pleistocene Blackwater Draw Formation, an older, extensive eolian deposit in the region. These observations suggest that new sand is supplied …


Vegetation And Paleoclimate Of The Last Interglacial Period, Central Alaska, Daniel R. Muhs, Thomas A. Ager, James E. Begét Jan 2001

Vegetation And Paleoclimate Of The Last Interglacial Period, Central Alaska, Daniel R. Muhs, Thomas A. Ager, James E. Begét

United States Geological Survey: Staff Publications

The last interglacial period is thought to be the last time global climate was signi"cantly warmer than present. New stratigraphic studies at Eva Creek, near Fairbanks, Alaska indicate a complex last interglacial record wherein periods of loess deposition alternated with periods of soil formation. The Eva Forest Bed appears to have formed about the time of or after deposition of the Old Crow tephra (dated to ~ 160 to ~ 120 ka), and is therefore correlated with the last interglacial period. Pollen, macrofossils, and soils from the Eva Forest Bed indicate that boreal forest was the dominant vegetation and precipitation …


Evolution Of Soils On Quaternary Reef Terraces Of Barbados, West Lndies, Daniel R. Muhs Jan 2001

Evolution Of Soils On Quaternary Reef Terraces Of Barbados, West Lndies, Daniel R. Muhs

United States Geological Survey: Staff Publications

Soils on uplifted Quaternary reef terraces of Barbados, ~125,000 to ~700,000 yr old, form a climo-chronosequence and show changes in physical, chemical, and mineralogical properties with terrace age. Parent materials are dust derived from the Sahara, volcanic ash from the Lesser Antilles island arc, and detrital carbonate from the underlying reef limestone. Although some terrace soils are probably eroded, soils or their remnants are redder and more clay-rich with increasing terrace age. Profile-average Al2O3 and Fe2O3 content increases with terrace age, which partially reflects the increasing clay content, but dithionite-extractable Fe also increases with …


Comparison Of Instream Methods For Measuring Hydrolic Conductivity In Sandy Streambeds, Matthew K. Landon, David L. Rus, F. Edwin Harvey Jan 2001

Comparison Of Instream Methods For Measuring Hydrolic Conductivity In Sandy Streambeds, Matthew K. Landon, David L. Rus, F. Edwin Harvey

United States Geological Survey: Staff Publications

Streambed hydraulic conductivity (K) values were determined at seven stream transects in the Platte River Basin in Nebraska using different instream measurement techniques.