Southeastern Section - 68th Annual Meeting - 2019

Paper No. 14-1
Presentation Time: 8:20 AM


LEIGH, David S., Department of Geography, The University of Georgia, Geog.-Geol. Building, 210 Field St., Room 204, Athens, GA 30602 and PURDY, Barbara A., Anthropology Department, The University of Florida, Turlington Hall, Gainesville, FL, FL 32611-7305

The CCA site occurs around a small sinkhole pond in north-central Florida 25 km south of Gainesville where we investigated the paleo-landscape to understand a buried pre-Clovis component. Bedrock of Ocala Limestone (Eocene) and the Hawthorne Group (Miocene) occur at this locality, and abundant chert originates from residual nodules and boulders released from weathering of the Ocala Limestone. Copious artifacts surround the sinkhole, including late Pleistocene through late Holocene types arranged in stratigraphic order. Two stratigraphic units on the edge of the sinkhole contain the artifacts, including: (unit 1) basal gleyed dark grey sandy loam, rich in expandable clay minerals, which contains probable pre-Clovis artifacts at 1.0 to 1.5 m depth; which is overlain by (unit 2) oxidized light grey surficial cover sands that are 0.5-0.8 m thick containing Paleoamerican and Archaic artifacts characteristically different from the underlying pre-Clovis assemblage. Colluvial slopewash and gully erosion caused sedimentation of units 1 and 2, but unit 1 appears to have more of an alluvial/lacustrine genesis for its final deposition. An organic-rich buried Ab horizon separates the two units and overlies an argillic Btb horizon formed in unit 1. The Ab horizon appears overprinted by spodic translocations of humus and iron that impart Bhs characteristics into the position of the Ab horizon, creating a compound soil profile. Radiocarbon dating is unreliable because of charred roots and translocated humus. However, optically stimulated luminescence samples from gully fills on the nearby footslope indirectly indicate the basal age of unit 2 cover sands at 12-13 ka. Also, stable carbon isotope values from 10 cm contiguous samples down a 1.5 m deep profile indicate unit 1 has significantly enriched values of delta 13C (-23.5 to -21.0 per mil) compared to overlying unit 2 (-26.5 to -27.5 per mil), which is consistent with late Pleistocene vegetation conditions during sedimentation of unit 1. Pleistocene gullies on the hillside and expandable clays in unit 1 indicate much erosion of clay residuum from the hillslope during the late Pleistocene, whereas prevalence of sand in unit 2 indicates a pronounced shift to sand-dominated sedimentation at 12-13 ka, which may indicate an influx of eolian sand from upslope at that time.