A LATE PLEISTOCENE-HOLOCENE GENETIC STRATIGRAPHIC FRAMEWORK FOR ST. CATHERINES ISLAND, GEORGIA: IMPLICATIONS FOR ARCHAEOLOGY

Paleosols as allogenic genetic units (now buried cumulic A-horizons) document prolonged episodes of stability and are excellent chronstratigraphic marker horizons which have been recognized throughout the eastern United States. Autogenic genetic units (i.e. a sand horizon from a large flood or hurricane is a one day event), on the other hand, are locally developed, the result of a circumscribed event that is constrained geographically and/or environmentally. Furthermore, genetic units can provide important information on the responses of near shore marine and fluvial systems to Holocene climate change and in archaeological site prediction. The driving mechanism for prolonged changes in the sea levels and fluvial regimes in the eastern United States was due to ablation of the Laurentian ice sheet and changes in atmospheric circulation. Paleosols on stable/fixed barrier islands along the coast of Georgia appear to reflect these changes in eustatic sea level and atmospheric circulation.

Geomorphological investigations at St. Catherines Island, Georgia have identified a series of now buried terrestrial paleosols (at least three distinct soil generations) on the seaward edge of the Pleistocene island core. The lower two buried A-horizons have yielded dates of approximately 13,000 and 22,000 yrs. B.P. while two upper paleosols yielded dates of 11,000 yrs B.P. and 6600 yrs. B.P. These paleosols hold the potential to provide important information on eustatic sea levels, climate change, and the potential for the occurrence of deeply buried prehistoric cultural resources.