Doctoral Dissertation Research: Holocene Megadroughts of the Central Great Plains

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Historic droughts, like those of the 1930s and 1950s, had severe social, economic, and environmental ramifications for the Great Plains. They were, however, transcended by the more severe and geographically extensive prehistoric megadroughts of the Holocene. Under these massive drought conditions, vegetation cover was diminished, and soils succumbed to erosive winds, causing the widespread mobilization of dust and sand deposits, which mantle much of the Great Plains. Doctoral student Alan Halfen under the guidance of Professor William Johnson in the Department of Geography at the University of Kansas will determine periods of prehistoric megadroughts in the central Great Plains, thereby better defining patterns of past droughts. The chronology of prehistoric droughts will be determined by dating drought-sensitive sand dunes in the Arkansas River valley, southwestern Kansas, using optically stimulated luminescence (OSL). This dating method, which determines when individual sand grains were last exposed to the sun, will provide reliable ages of dune activity and attendant drought conditions. The dune field will also be analyzed to assess its mineralogical maturity, a relative indicator of landscape age. Mineralogical maturity provides information regarding dune sediment provenance, transport history, and weathering history of a dune field. Lastly, periods of dune activity will be compared to similar studies elsewhere in the Great Plains to identify spatial and temporal patterns of prehistoric drought. Given that climate models have predicted increased temperatures and decreased precipitation in the Great Plains this century, this study will further enhance our knowledge of patterns of past drought and will provide vital paleoclimatic data to better calibrate existing climatic models. This study promotes diverse collaboration between academic institutions and government agencies, and enhances the education of undergraduate students.