Physical Sciences and Mathematics Commons^™

Multiport Well Design For Sampling Of Ground Water At Closely Spaced Vertical Intervals, Geoffrey N. Delin, Matthew K. Landon

United States Geological Survey: Staff Publications

Detailed vertical sampling is useful in aquifers where vertical mixing is limited and steep vertical gradients in chemical concentrations are expected.

Effect Of Nitrate, Organic Carbon, And Temperature On Potential Denitrification Rates In Nitrate-Rich Riverbed Sediments, K. S. Pfenning, P. B. Mcmahon

United States Geological Survey: Staff Publications

A study conducted in 1994 as part of the US Geological Survey's National Water-Quality Assessment Program, South Platte River Basin investigation, examined the effect of certain environmental factors on potential denitrification rates in nitrate-rich riverbed sediments. The acetylene block technique was used to measure nitrous oxide (N₂O) production rates in laboratory incubations of riverbed sediments to evaluate the effect of varying nitrate concentrations, organic carbon concentrations and type, and water temperature on potential denitrification rates. Sediment incubations amended with nitrate, at concentrations ranging from 357 to 2142 μmol 1^-1 (as measured in the field), produced no significant …

Climatic And Hydrologic Oscillations In The Owens Lake Basin And Adjacent Sierra Nevada, California, Larry Benson, James W. Burdett, Michaele Kashgarian, Steve Lund, Fred Phillips, Robert O. Rye

United States Geological Survey: Staff Publications

Oxygen isotope and total inorganic carbon values of cored sediments from the Owens Lake basin, California, indicate that Owens Lake overflowed most of the time between 52,500 and 12,500 carbon-14 (¹⁴C) years before present (B.P.). Owens Lake desicated during or after Heinrich event H1 and was hydrologically closed during Heinrich event H2. The magnetic susceptibility and organiz carbon content of cored sediments indicate that about 19 Sierra Nevada glaciations occurred between 52,500 and 23,500 ¹⁴C years B.P.

Sea-Level Records At ~80 Ka From Tectonically Stable Platforms: Florida And Bermuda, K. R. Ludwig, D. R. Muhs, K. R. Simmons, R. B. Halley, E. A. Shinn

United States Geological Survey: Staff Publications

Studies from tectonically active coasts on New Guinea and Barbados have suggested that sea level at ~80 ka was significantly lower than present, whereas data from the Atlantic and Pacific coasts of North America indicate an ~80 ka sea level close to that of the present. We determined ages of corals from a shallow submerged reef off the Florida Keys and an emergent marine deposit on Bermuda. Both localities are on tectonically stable platforms distant from plate boundaries. Uranium-series ages show that corals at both localities grew during the ~80 ka sea-level highstand, and geologic data show that sea level …

Pesticides In Streams Draining Agricultural And Urban Areas In Colorado, Robert Kimbrough, David Litke

United States Geological Survey: Staff Publications

A study was conducted from April 1993 through April 1994 to describe and compare the occurrence and distribution of pesticides in streams in a small agricultural and a small urban area in Colorado. Twenty-five water samples collected at least monthly at the mouths of two tributary streams of the South Platte River were analyzed for 47 pesticides. The results indicate that both agricultural and urban areas are probable sources for pesticides in streams. In the agricultural area, 30 pesticides were detected, and in the urban area, 22 pesticides were detected in one or more samples. Most often, the more frequently …

Acetochlor In The Hydrologic System In The Midwestern United States, 1994, Dana Kolpin, Brenda Nations, Donald Goolsby, E. Michael Thurman

United States Geological Survey: Staff Publications

The herbicide acetochlor [2-chloro-N-(ethoxymethyl)- N-(2-ethyl-6-methylphenyl)acetamide] was given conditional registration in the United States by the U.S. Environmental Protection Agency in March 1994. This registration provided a rare opportunity to investigate the occurrence of a pesticide during its first season of extensive use in the midwestern United States. Water samples collected and analyzed by the U.S. Geological Survey during 1994 documented the distribution of acetochlor in the hydrologic system; it was detected in 29% of the rain samples from four sites in Iowa, 17% of the stream samples from 51 sites across nine states, and 0% of the groundwater samples from …

Origin Of Bermuda's Clay-Rich Quaternary Paleosols And Their Paleoclimatic Significance, Stanley R. Herwitz, Daniel R. Muhs, Joseph M. Prospero, Shannon Mahan, Bruce Vaughn

United States Geological Survey: Staff Publications

Saharan dust deposition on Bermuda during successive Quaternary glacial periods is consistent with patterns of general circulation models, which indicate that during glacial maxima the northeast summer trade winds were stronger than at present and reached latitudes higher than 30°N despite lower-than-present sea surface temperatures in the North Atlantic.

Occurrence Of Selected Pesticides And Their Metabolites In Near-Surface Aquifers Of The Midwestern United States, Dana Kolpin, E. Michael Thurman, Donald Goolsby

United States Geological Survey: Staff Publications

The occurrence and distribution of selected pesticides and their metabolites were investigated through the collection of 837 water-quality samples from 303 wells across the Midwest. Results of this study showed that five of the six most frequently detected compounds were pesticide metabolites. Thus, it was common for a metabolite to be found more frequently in groundwater than its parent compound. The metabolite alachlor ethanesulfonic acid (alachlor- ESA; 2-[(2,6-diethylphenyl)(methoxymethyl)amino]-2- oxoethanesulfonic acid) was detected almost 10 times as frequently and at much higher concentrations than its parent compound alachlor (2-chloro-2',6'- diethyl-N-(methoxymethyl)acetamide). The median detectable atrazine (2-chloro-4-ethylamino-6- isopropylamino-s-triazine) concentration was almost half that …

New Palaeothentid Marsupials (Caenolestoidea) From The Early Miocene Of Patagonian Argentina, Todd C. Rae, Thomas M. Bown, John G. Fleagle

United States Geological Survey: Staff Publications

Recent fieldwork in Argentina has resulted in the recovery of numerous new specimens of palaeothentid marsupials, an important component of the Deseadan-Santacrucian (Oligocene-middle Miocene) mammalian fauna of Patagonia. The 1994 collections include a new genus and species from the early Miocene Pinturas Formation at Estancia La Cafnada and the first complete lower dentition of Acdestis oweni from a locality in the Santa Cruz Formation along the Rio Chalia.

Stress Perturbation Associated With The Amazonas And Other Ancient Continental Rifts, Mary Lou Zoback, Randall M. Richardson

United States Geological Survey: Staff Publications

The state of stress in the vicinity of old continental rifts is examined to
investigate the possibility that crustal structure associated with ancient rifts (specifically a dense rift pillow in the lower crust) may modify substantially the regional stress field. Both shallow (2.0-2.6 km depth) breakout data and deep (20-45 km depth) crustal earthquake focal mechanisms indicate a N to NNE maximum horizontal compression in the vicinity of the Paleozoic Amazonas rift in central Brazil. This compressive stress direction is nearly perpendicular to the rift structure and represents a ~75 ° rotation relative to a regional E-W compressive stress direction …

Factors Affecting Attwater's Prairie-Chicken Decline On The Attwater Prairie Chicken, Michael E. Morrow, Robert S. Adamcik, Jenny D. Friday, Lloyd B. Mckinney

United States Geological Survey: Staff Publications

We examined the association between changes in the number of Attwater's prairie- chicken (Tympanuchus cupido attwateri) on the Attwater Prairie Chicken National Wildlife Refuge from 1972 to 1993 and changes in refuge management practices (burning and grazing). We also examined the relationship of prairie-chicken population increases and decreases on the refuge to rainfall and off-refuge prairie-chicken populations. Burning within the prairie-chicken's core habitat on the refuge and variability in grassland structure were directly correlated (P< 0.05) with increases and declines in prairie-chicken populations. Refuge population increases and declines were inversely correlated (P< 0.1) with average April rainfall/event, May absolute departure from long-term average rainfall, May number of rainfall events, annual absolute departure of rainfall from the long-term average, and the annual number of rainfall events. Refuge population increases and declines were directly correlated (P < 0.1) with off-refuge populations, although the off- refuge population decline began 4 years earlier than on-refuge.

Observations On Bats At Badlands National Park, South Dakota, Michael A. Bogan, Jeffrey G. Osborne, Jennifer A. Clarke

United States Geological Survey: Staff Publications

During the summers of 1992 and 1993, we conducted a survey of bats at Badlands National Park, South Dakota. Using mist nets, we captured bats and recorded species, sex, age class, and reproductive condition for each individual netted. We recorded five species, Myotis ciliolabrnm (n = 198), M. thysanodes (29), M volans (13), Eptesicus foscus (91), and Plecotus tawnsendii (43), previously known from the park. In addition, we added four species, M lucifugus (18), M. septentrionalis (9), Lasionycteris noctivagans (1), and Lasiurns cinereus (3) to the confirmed fauna of the park. Most bats captured were male (76.3%) although maternity colonies …

Detailed Observations Of California Foreshock Sequences: Implications For The Earthquake Initiation Process, Douglas A. Dodge, Gregory C. Beroza, W. L. Ellsworth

United States Geological Survey: Staff Publications

We find that foreshocks provide clear evidence for an extended nucleation process before some earthquakes. In this study, we examine in detail the evolution of six California foreshock sequences, the 1986 Mount Lewis (M_L = 5.5), the 1986 Chalfant (M_L = 6.4), the 1986 Stone Canyon( M_L = 4.7), the 1990 Upland (M_L = 5.2), the 1992 Joshua Tree (M_w= 6.1), and the 1992 Landers (M_w = 7.3) sequence. Typically, uncertainties in hypocentral parameters are too large to establish the geometry of foreshock sequences and hence to understand their evolution. However, the similarity …

Origin Of The Late Quaternary Dune Fields Of Northeastern Colorado, Daniel R. Muhs, Thomas W. Stafford, Scott D. Cowherd, Shannon A. Mahan, Rolf Kihl, Paula B. Maat, Charles A. Bush, Jennifer Nehring

United States Geological Survey: Staff Publications

Stabilized eolian deposits, mostly parabolic dunes and sand sheets, cover much of the landscape of northeastern Colorado and adjacent parts of southwestern Nebraska in four geographically distinct dune fields. Stratigraphic and soil-geomorphic relations and accelerator radiocarbon dating indicate that at least three episodes of eolian sand movement occurred between 27 ka and 11 ka. possibly between 11 ka and 4 ka. and within the past 1.5 ka. Thus, eolian sand deposition took place under both glacial and interglacial climatic conditions. In the youngest episodes of eolian sand movement. Holocene parabolic dunes partially buried Pleistocene sand sheet deposits.

Late Holocene sands …

Sources Of Variation In Counts Of Meristic Features Of Yellowstone Cutthroat Trout (Oncorhynchus Clarki Bouvieri), Carter Kruse, Wayne Hubert, Frank Rahel

United States Geological Survey: Staff Publications

We determined variability in counts of meristic features (pyloric caecae, vertebrae, pelvic fin rays, gillrakers, basibranchial teeth, scales above the lateral line, and scales in the lateral series) of Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri ) by 3 independent readers, by the same reader on 3 different occasions, and among fish from 12 sampling sites within a 650-km² watershed. Genetic purity of the cutthroat trout was determined by electrophoretic analysis. Significant differences in meristic counts were observed among 3 readers and among sampling sites, but not among 3 occasions by a single reader. Scale counts were within the …

Late Pliocene Diatoms In A Diatomite From Prydz Bay, East Antarctica, Albert D. Mahood, John A. Barron

United States Geological Survey: Staff Publications

Very well-preserved Pliocene diatoms from a diatomite unit interbedded within glacial sediments at Ocean Drilling Program Site 742 in Prydz Bay, Antarctica are documented and illustrated. The presence of Thalassiosira kolbei, T torokina, Actinocyclus actinochilus, A karstenii and the absence of Nitzschia interfrigidaria, T. insigna and T. vulnifica in Sample 119-742A-15R-4, 44-46 cm constrain its age to ca. 2.2-1.8 Ma (late Pliocene). Diatoms associated with sea ice constitute 35% of the Pliocene diatom assemblage, compared with 71% of the modern sediment assemblage at the site, suggesting that sea ice was present during the late Pliocene period of deposition of the …