61 Archaeological Geology

Monday, 17 October 2005
8:00 AM - 12:00 PM

ANATOMY OF A BIOMANTLE: OSL DATING RESULTS OF SANDY SITES IN CENTRAL FLORIDA

Paper number: 61-2
Program: Technical Sessions
Time: 8:15 AM – 8:30 AM

Authors

Abstract

Buried archaeological sites in sandy substrates are common in Florida, but away from dynamic depositional environments (e.g. coastal dunes, alluvial deposits) there is debate concerning how such sites are buried, with incremental eolian sedimentation and pedoturbation being the most commonly cited mechanisms. Discerning which process is most likely is impossible on the basis of basic field and excavation evidence alone given that the deposits are lithologically homogeneous and lack primary (depositional) sedimentary structures. However, because the artifact depth-frequency distributions exhibit peaked, and often bimodal profiles (where more than one age component is present), these sites are often interpreted as in situ buried occupation surfaces in incrementally aggrading eolian sand sheet environments.

Test excavation and subsequent detailed study of the deposits of five sandy sites at Avon Park Air Force Range in Highlands and Polk Counties, Florida revealed insights on how such sites are formed and enter the archaeological record. The deposits we examined were exposed in test unit walls and were dated using standard aliquot and single grain optically stimulated luminescence and radiocarbon methods, as well as relative age assessments based upon artifacts recovered from the excavations. The deposit's physical properties were characterized by means of granulometry, organic carbon, and magnetic susceptibility. The results demonstrate that the chronological structure of sites situated on broad, “upland” marine terraces are distinctly different from sites situated in dynamic sedimentary environments and the chronological signature of these sites is best explained by post-depositional disturbance rather than incremental eolian sedimentation.