EVIDENCE FOR LATE HOLOCENE EOLIAN SAND REACTIVATION IN THE GREEN RIVER LOWLAND, NORTHWESTERN ILLINOIS: REGIONAL RESPONSE TO DROUGHT AND POTENTIAL IMPLICATIONS

Dune fields are widespread throughout the Great Plains and Midwest regions of North America. At present most of these dune fields are stabilized, but many contain evidence of episodic Holocene eolian activity. With some notable exceptions, most research focused on deciphering the developmental history of dune fields within the region has been concentrated on the Great Plains. Results of many of these studies have indicated that numerous dune systems within the region were reactivated and/or were developed during the last 2,000 years. These reactivation events were possibly related to periods of reduced soil moisture and vegetation cover related to periods of regional drought, although regional synchronicity between the various records has been hard to establish with certainty. Investigations within the Green River Lowland (GRL) extend the evidence of late Holocene dune reactivation into northwestern Illinois. Soil stratigraphic and OSL and AMS dating of sediments from within scattered dune fields in the GRL, indicate widespread reactivation of sand sheets during the late Holocene at ca 4 ka and multiple periods < 2,000 ka. Further evidence for regional drought during the late Holocene comes from high resolution lacustrine records from the region. Overall, these results suggest that dune fields within the region may be susceptible to variable climatic conditions within the current climatic regime, which would have significant economic impacts.