GEOARCHAEOLOGICAL INVESTIGATIONS OF CAROLINA BAYS IN SOUTH CAROLINA: METHODOLOGICAL APPROACHES FOR INTERPRETING SITE FORMATION PROCESSES, ARCHAEOSTRATIGRAPHY AND GEOCHRONOLOGY

This long-term Carolina bay study addresses four basic research objectives. These are: 1) determining the age, origin, and evolution of Carolina bays; 2) delineating prehistoric cultural activities and site formation processes on Carolina bay sand rims; 3) determining the role of Carolina bays in prehistoric settlement systems; and 4) exploring linkages at Carolina bays between climate change, depositional processes, and prehistoric adaptations.

Recent geoarchaeological investigations of Carolina bay sand rims indicate they have accreted ~1 meter of sand since the beginning of the Holocene (ca. 11,450 Cal BP). Bay rim deposits at Flamingo Bay (Aiken County, SC), Johns Bay (Allendale County, SC) and Frierson Bay (Barnwell County, SC) were tested to determine archaeostratigraphy and intensively sampled for grainsize, soil chemistry, bulk phytolith, sediment bulk density, LOI, field water content, micromorphology and magnetic susceptibility. Ground Penetrating Radar (GPR) surveys were conducted to broadly delineate bay rim stratigraphy and geomorphology. Sediment samples were taken from continuous columns at 2.5 cm intervals from the ground surface to ~1 to 1.8 meters below surface. In addition, 5 single-grain luminescence (OSL) age estimates were acquired for the upper meter at Flamingo Bay using 2 cm diameter sampling tubes. Eight single-grain OSL ages were acquired for Johns Bay and Frierson Bay, including a basal rim age for Johns Bay at 2.8 meters below surface. Sediments associated with Early and Middle Archaic occupations at all three bay sites were also dated.

Tangentially, our research has implications for the recently proposed comet impact origin for Carolina bays by Firestone et al. (2007), who suggest that such impacts precipitated the Younger Dryas stadial (ca. 12,800-11,450 Cal BP), megafauna extinctions, and the demise of Clovis culture at the end of the last ice-age. Our data, however, demonstrate that Carolina bays were formed by high-energy lacustrine processes over lengths of time far greater than the onset of the YD and that bay evolution is a long-term process rather than a synchronous event.