Doctoral Dissertation Research: Paleoclimatology and Geochronology of a Late Quaternary Eolian System, Columbia Plateau, U.S.A.

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The paired eolian system of the Columbia Plateau is composed of the extensive Palouse loess of variable thickness and upwind dune fields that are derived from reworking of sand- and silt-rich slackwater deposits from multiple episodes of Wisconsin giant outburst flooding from Glacial Lake Missoula. Few models exist that explain changes in the thickness and distribution of loess accumulations. We will investigate three models that describe the interaction of migrating sands with loess and influences of topography, bioclimate, and source sediment character that control the thickness and distribution of loess. Field mapping will include sample collection on a regional scale to determine the temporal and spatial distribution of saltation- versus suspension-dominated eolian units. Timing of stability (represented by paleosols) and eolian activity (represented by eolian sand an loess units) will be determined by luminescence dating that measures the last time sediments were exposed to sunlight. We will determine 1) when and where loess deposition began following latest-Wisconsin outburst floods, 2) if eolian saltation in upwind dunes was active concurrently with suspension fallout downwind, 3) if periods of saltator release inferred from sand-rich intervals in the loess were associated with periods of heightened aridity, and 4) the mass accumulation rates of loess. Dust emissions on the Columbia Plateau today resulting from dryland farming are hazardous through the presence of particulate matter less than 10 microns in size in the air and reduced visibility. This regional study will show how the Columbia Plateau system has responded to climate change through time, allowing future dust emissions to be predicted. While paired eolian systems do exist elsewhere in the world (China, Europe, Alaska, North American Great Plains), the Columbia Plateau offers the opportunity to study multiple models of loess generation on a workable geographic scale, to add to the knowledge of the dynamics of paired eolian systems, and to enhance the record of late-Pleistocene to Holocene climate change for the Columbia Plateau. As a Doctoral Dissertation Research Improvement award, this award will also provide support to enable a promising student to establish a strong independent research career.