Publications

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Near-surface geophysical methods have become increasingly important tools in applied agricultural practices and studies. The great advantage of geophysical methods is their potential rapidity, low cost, and spatial continuity when compared to more traditional methods of assessing agricultural land, such as sample collection and laboratory analysis. Agricultural geophysics investigations commonly f

Understanding the movement of water through thick vadose zones, especially on time scales encompassing long-term climate change, is increasingly important as societies utilize semi-arid environments for both water resources and sites viewed as favorable for long-term disposal or storage of hazardous waste. Hydrologic responses to Pleistocene climate change within a deep vadose zone in the eastern

We present data on the triple Ar isotope composition in trapped gas from clean, stratigraphically disturbed ice between 2800 and 3040m depth in the GISP2 ice core, and from basal dirty ice from 3040 to 3053m depth. We also present data for the abundance and isotopic composition of O2 and N2, and abundance of Ar, in the basal dirty ice. The Ar/N2 ratio of dirty basal ice, the heavy isotope enrichme

Combined petrographic and geochemical methods are used to investigate the microfabrics present in thin sections prepared from representative organic carbon-rich mudstones collected from three successions (the Kimmeridge Clay Formation, the Jet Rock Member of the Whitby Mudstone Formation, and the pebble shale and Hue Shale). This study was initiated to determine how organic carbon-rich materials w

Two uppermost Carboniferous–Lower Triassic fluvial–lacustrine sections in the Tarlong–Taodonggou half-graben, southern Bogda Mountains, NW China, comprise a 1834 m-thick, relatively complete sedimentary and paleoclimatic record of the east coast of mid-latitude NE Pangea. Depositional environmental interpretations identified three orders (high, intermediate, and low) of sedimentary cycles. High-or

New optically stimulated and radiocarbon ages for alluvial fan and lake deposits in the Mojave Desert are presented, which greatly improves the temporal resolution of surface processes. The new Mojave Desert climate-landscape record is particularly detailed for the late Holocene. Evidence from ephemeral lake deposits and landforms indicates times of sustained stream flow during a wet interval of t

The Columbia River Basalt Group (CRBG) eruptions have a well-defined relative magnetostratigraphy but have not been definitively correlated to the geomagnetic polarity time scale. 40Ar/39Ar ages are presented from lavas erupted in the R0 through N1magnetozones of the CRBG and in the transition between R0 and N0. Four ages from transitionally magnetized lava flows at Steens Mountain, Catlow Peak, a

Rock uplift rates can be difficult to measure over 103–105 yr time scales. If, however, a landscape approaches steady state, where hillslope erosion and rock uplift rates are steady and locally similar, then it should be possible to quantify rock uplift rates from hillslope erosion rates. Here, we test this prediction by comparing channel steepness index values and 10Be catchment-averaged erosion

We use geophysical data to examine the structural framework of the northern San Francisco Bay region, an area that hosts the northward continuation of the East Bay fault system. Although this fault system has accommodated ∼175 km of right-lateral offset since 12 Ma, how this offset is partitioned north of the bay is controversial and important for understanding where and how strain is accommodated

In vitro bioaccessibility (IVBA) studies were carried out on samples of mercury (Hg) mine-waste calcine (roasted Hg ore) by leaching with simulated human body fluids. The objective was to estimate potential human exposure to Hg due to inhalation of airborne calcine particulates and hand-to-mouth ingestion of Hg-bearing calcines. Mine waste calcines collected from Hg mines at Almadén, Spain, and Te

echniques for processing frequency-domain electromagnetic (FDEM) data that address systematic instrument errors and random noise are presented, improving the ability to invert these data for meaningful earth models that can be quantitatively interpreted. A least-squares calibration method, originally developed for airborne electromagnetic datasets, is implemented for a ground-based survey in order