Paper No. 10
Presentation Time: 9:00 AM-6:30 PM
AEOLIAN SAND DEPOSITION OVER THE LAST 20,000 YEARS IN THE MIDDLE TANANA VALLEY, INTERIOR ALASKA
REUTHER, Joshua D., Archaeology Department, University of Alaska Museum of the North, University of Alaska Fairbanks, 907 Yukon Drive, Fairbanks, AK 99775, POTTER, Ben A., Department of Anthropology, University of Alaska Fairbanks, 310 Eielson Building, PO Box 757720, Fairbanks, AK 99775, FEATHERS, James K., TL Dating Laboratory, Department of Anthropology, University of Washington, Seattle, WA 98195, HOLMES, Charles E., Anthropology Department, University of Alaska Fairbanks, Anchorage, AK 99516 and BOWMAN, Robert C., Northern Land Use Research Alaska, LLC, 234 Front Street, Fairbanks, AK 99709, jreuther@alaska.edu
The Tanana Valley Lowlands have been at the center of interest in late Quaternary aeolian sand deposition studies in interior Alaska for over 50 years. The majority of research on dune fields and sand sheets in the region has been relegated to surficial geologic mapping based on aerial photography and limited field reconnaissance. Over the last decade, a florescence of field-based research has concentrated on refining the known distribution of aeolian sand deposits, describing the morphology of related landforms and their stratigraphy, and the chronology of the accumulation and cessation of aeolian deposition. Since 2007, our project has systematically described the stratigraphy and collected luminescence and radiocarbon samples from aeolian sand deposits at several well-stratified archaeological sites, including the Upward Sun River, Mead, and Gerstle River Sites, and across several dune fields between the Gerstle and Salcha Rivers.
Radiocarbon and luminescence ages provide initial age constraints on aeolian sand deposition in the region, indicating that the development of linear dunes and lowland and cliff-head sand sheets are associated with the end of the Last Glacial Maximum and the early Late Glacial period (20,000 to 14,000 years ago) during the waning of outwash deposition and immediately after the introduction of sand and silt sediment sources into the Tanana River basin. By 13,000 years ago, aeolian sand deposition generally transitioned to loess deposition in many areas in the valley and landforms became intermittently stable with soil development associated with the expansion of shrub tundra vegetation throughout the region. During the end of the Late Glacial and throughout the early Holocene (13,000 to 8,000 years ago), aeolian sand deposition was localized throughout the valley and likely occurred in response to different mechanisms including fire cycles, increased wind intensity, loss of vegetation, source exposure, and introduction of source sediment via flooding. At around 8,000 to 6,000 years ago, much of the aeolian sand deposition ceased and loess accumulation rates decreased in response to an increasingly stabilized landscape and the development of forest soils.
