T215 Alluvial Geoarchaeology of Large River Valleys II

Wednesday, 25 October 2006
1:30 PM - 5:30 PM

GEOARCHAEOLOGICAL INVESTIGATIONS OF RELICT SAND DUNES IN THE NORTH CAROLINA COASTAL PLAIN: NEW APPROACHES FOR MODELING TAR RIVER FLUVIAL HISTORY AND PALEOCLIMATE

Paper number: T215-2
Program: Technical Sessions
Time: 1:35 PM – 1:50 PM

Authors

Abstract

Geoarchaeological work on numerous archaeological sites along the Tar River, NC has shown the potential for relict source-bordering dunes to provide high resolution chronological and typological data on early hunter-gatherers in the region, as well as paleoenvironmental reconstructions of the Tar River. Relict sand dunes were identified through the use of high resolution LiDAR (Light Detection and Ranging) elevation data produced by the NCDOT Floodplain Mapping Program. LiDAR data provide extremely high resolution (+/- 25 cm) digital elevation models for the North Carolina Coastal Plain and have allowed the recognition of complex fluvial deposits (braided and meandering) and numerous source-bordering dunes. Potential dunes identified from LiDAR were verified in the field through archaeological testing, GPR, electrical resistivity mapping, sediment collection and characterization. Samples were also taken for Optically Stimulated Luminescence dating with particular emphasis on correlating ages indicated by archaeostratigraphy. Preliminary OSL dating of dune sediments along with evidence of buried archeological materials spanning the last 10,000 years of human history indicate Holocene dune activation and sequential burial of prehistoric remains.

Analysis of LiDAR data suggests source-bordering dunes formed adjacent to previously active fluvial (i.e., braided river) environments where sand would have been continually supplied by the river and made available for transport and deposition along the edges of older alluvial terraces. These terraces are more prevalent on the north side of the river, and therefore dune deposits are more likely to occur there. This depositional pattern appears to repeat itself with sequentially younger dunes occurring along the relict braidplain scarps of the Tar River with decreasing distance to the river. Prehistoric hunter-gatherers tracked these changes through time and document a record of fluvial change and downcutting leading to the modern incised meandering river. These data demonstrate the potential for using stratified archaeological materials to constrain the ages of source-bordering dunes and terraces within the coastal plain and provides a model for identifying probable locations of deeply buried archaeological sites.