Paper No. 10
Presentation Time: 11:15 AM


FENTRESS, Samantha, Department of Geological and Mining Engineering Science, 1400 Townsend Drive, Houghton, MI 49931, COOK, Asia, Department of Biology, Albany State University, 504 College Drive, Albany, GA 31705, CONROY, Mary, Geology, University of Vermont, Burlington, VT 05405, MISERIDINO, Daniel, Department of Geological Sciences, State University of New York, Geneseo, 1 College Circle, Geneseo, NY 14454, PARK BOUSH, Lisa, Geology and Environmental Science, University of Akron, Akron, OH 44325, BUYNEVICH, Ilya V., Department of Earth & Environmental Science, Temple University, Philadelphia, PA 19122, MYRBO, Amy, LacCore/CSDCO, Department of Earth Sciences, University of Minnesota, 500 Pillsbury Dr. SE, Minneapolis, MN 55455, BERMAN, Mary Jane, Center for American and World Cultures, Miami University, Oxford, OH 45056, GNIVECKI, Perry L., Miami University, 571 Mosler Hall, Hamilton, OH 45011 and KJELLMARK, Eric, Department of Biology, Florida Southern College, 127 Polk Science Building, Lakeland, FL 33801,

Shad Pond, an enclosed hypersaline lagoon on the southeastern tip of Eleuthera, Bahamas reveals a ~5000-year record of hurricane activity, as well as sea-level and climate change history. Three sediment cores recovered 1.04-2.54 m of sediment over the bedrock along a transect perpendicular to shoreline. Sediment composition and grain size, loss on ignition, X-ray fluorescence (XRF) measurements of the cores along with dune transects and ground-penetrating radar (GPR) profiles adjacent to the lake provide a comprehensive dataset to interpret the history of this coastal water basin.

The sedimentary sequence was composed of alternating lithofacies that included microbial mats, sand, and peat. Laminated mats often alternated with sandy layers in thin to medium-bedded units. Two peat layers were found in the basal part of the shore-distal core (Site 1) between 1.82-2.40 m and 2.53-2.54 m and were separated by a 13-cm-thick gray mud layer. In general, organic matter and carbonate content tracked granulometry and composition in all cores. High-resolution XRF scans of Ca and Sr at Site 1 show elevated levels ~3,700 cal yBP, which correlate with the top of the peat layer, but these elemental concentrations vary at Site 3. XRF measurements of Fe indicate a dust flux that has been recorded regionally throughout the Caribbean.

Dune transects and GPR profiles indicate a phased history of the pond, beginning with initial stages as an open lagoon dominated by red mangrove, with black mangrove and buttonwood also present. The lake likely closed at approximately 3,700 cal yBP indicated by the transition between the upper peat and microbial mat layers. This could have been due to increased storm events in a regime of rising sea level. Aeolian aggradation continued to heighten the barrier between the bedrock headlands to its present position. Hurricane overwash deposits punctuated the algal mat accumulation throughout this time period. Present-day hypersaline conditions sustain algal mats throughout the lake bottom. It is likely that the occupation by Lucayan culture was influenced by the position of the shoreline along southern Eleuthera and this lake was already unsuitable as a water source at the time of their arrival and occupation during 1300-600 years BP (AD 700-1400).