2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 23-3
Presentation Time: 8:35 AM


HALFEN, Alan F., School of Business, University of Kansas, Lawrence, KS 66045; Department of Geography, University of Kansas, Lawrence, KS 66045, JOHNSON, William C., Department of Geography, University of Kansas, 1475 Jayhawk Blvd, Lindley Hall, Lawrence, KS 66045, MESSNER, Claire A., Department of Geography, University of Kansas, Lawrence, KS 66045, GAINES, Edmund P., AECOM, PMB 193, 3875 Geist Road, Fairbanks, AK 99709, Fairbanks, AK 99709, HANSON, Paul R., Conservation and Survey Division, School of Natural Resources, Univ. of Nebraska, 102 Nebraska Hall, Lincoln, NE 68588-0517, RITTENOUR, Tammy M., Department of Geology, Utah State University, 4505 Old Main Hill, Logan, UT 84322 and YOUNG, Aaron R., Conservation and Survey Division, School of Natural Resources, Univ. of Nebraska, 612 Hardin Hall, Lincoln, NE 68583-0996, afhalfen@ku.edu

Dune deposits are commonplace along the Tanana River and its tributaries in eastern Beringia (central Alaska). The affinity between dunes and early inhabitants is well documented—artifacts and geochronological evidence suggesting human occupation as early as 13 ka. Left unknown is the formation history of these dunes and surrounding sand sheets, in part because typical dating techniques (e.g., radiocarbon, OSL, IRSL) remain problematic for the region. This study employs a post-IR IRSL dating technique, which is used to refine periods of aeolian activity in two regional dune fields: the Wood River and Nenana River dune field. In the Nenana River dune field, luminescence ages indicate initial construction of dunes ~16 ka. Dunes contain visible stratigraphy and are capped with loess that was deposited between 11–10 ka, suggesting that dunes remained stabilized since their formation. Dunes in the Wood River dune field show similar stratigraphy and also formed ~16 ka. Multiple layers of Holocene loess cap the Wood River dunes. This new chronology suggests relatively dry and windy conditions at the end of the Pleistocene, and a landscape void of substantial vegetation. The stabilization of these dune fields by 10 ka supports the argument for increased moisture, and in particular, increased forest vegetation. The number of archeological sites in the region found atop dunes, as well as independent age control on artifacts, suggests that early humans used these sites prior to their final stabilization by forest vegetation, which is also supported by this chronology. Additionally, this new chronology emphasizes the importance of dunes in the search for early archeological records. Considering that dunes in the region were formed almost 4 ka prior to documented human occupation, it is not unreasonable to believe that more and possibly even earlier evidence of human occupation could be found in dune fields of eastern Beringia.