Wakulla Springs Karst Plain Symposium

By Joseph M. Latvis

On October 9,1998 the Florida Geological Survey in conjunction with several other agencies sponsored a technical symposium at the Florida State University Turnbull Conference Center. Approximately forty speakers presented their talks in two concurrent sessions. Florida State Representative Janegale Boyd (House District 10) provided Keynote introductory remarks. Topics of particular interest to archaeologists and paleontologists conducting research in the Karst Plain region (which encompasses the study area of the Aucilla River Prehistory Project) included:

Archaeological and Historic Sites Within the Woodville Karst Plain by Mike Wisenbaker, Historic Preservation Planner, Department of State, Bureau of Archaeological Research.

Regional and Local Geologic Setting of the Woodville Karst Plain by Frank R. Rupert, Florida Geological Survey.

Wakulla Springs - Quality of Life by Sandy Cook, Manager Wakulla Springs Park and Lodge, Florida Park Service.

Geomorphology and Extent of the Offshore Woodville Karst Plain, Northeastern Gulf of Mexico, NW Florida, USA by Z.Q. Chen and Joseph Donoghue, Dept. of Geology, Florida State University; R.W. Hoenstine, F. Rupert, S. Spencer, L.J. Ladner and E. Lane, Florida Geological Survey; M.K. Faught, Dept. of Anthropology, Florida State University.

A Geological Investigation of Sedimentation and Acretion Rates of Marine Coastal Wetlands Within Apalachee Bay by L.J. Ladner, R.W. Hoenstine, A.A. Dabous and Debra Harrington, Florida Geological Survey. The Aucilla River Prehistory Projectís contribution to this symposium was presented by project director Dr. S. David Webb, the abstract of which now follows:

TWO CYCLES OF LATE PLEISTOCENE SINKHOLE FILLING IN THE MIDDLE AUCILLA RIVER, JEFFERSON COUNTY, FLORIDA

S. David Webb
Florida Museum of Natural History
University of Florida
Gainesville, FL 32611
Phone: 352/392-1721
FAX: 352/846-0287

During the past decade the Aucilla River Prehistory Project (ARPP) has intensively explored the middle reaches of the Aucilla River in search of relatively thick, continuous sections of late Pleistocene sediments. Teams of paleontologists and archaeologists have successfully excavated more than a dozen such sections using SCUBA, dredges and underwater lights. The various sections studied by the ARPP range from about three to more than five meters thick and represent nearly continuous deposition of fine-grained, highly-organic clastic sediments, including peats, clays, silts and fine sands. Most of these sections lie immediately adjacent to relatively deep holes in the uneven bottom profile of the river. Evidently these sediment packets in the Aucilla River represent sinkhole fillings in the Suwannee Limestone, now partially exposed by the river.

In the course of its excavations, the ARPP has acquired more than 90 radiocarbon dates on river-bottom sections from the middle reaches of the Aucilla River. We anticipated that the dates would represent the last deglacial hemicycle, driven by a rising piezometric surface geared to the latest glacial sealevel rise. For a majority of dated sections these expectations were fulfilled. For example at the Page/Ladson site sediments record fine details of back-filling history between 15,000 and 9,000 radiocarbon years (Oxygen Isotope Stage 2). Quite unexpectedly, however, nearly 40 percent of the sediment packets sampled and dated by the ARPP represent a previous interval of sinkhole filling with dates between about 28,000 and 34,000 radiocarbon years before present. This earlier cycle of sinkhole filling correlates with the next highest oxygen isotopic peaks (Stage 3) (before the latest Pleistocene) in the Greenland Ice Core record. The abundance of such sediments in the Aucilla River, despite being overprinted by a later cycle, suggests that they played an important role in regional karst history.