SALT MARSH DYNAMICS AND SEDIMENTATION: JONES CREEK, CHATHAM COUNTY, GEORGIA

Jones Creek Salt Marsh, part of Georgia’s barrier island complex, is located 8 miles inland from the Atlantic Ocean, 10 miles south of Savannah. A detailed record of Quaternary Period sea level rise and landscape evolution that has taken place on the Georgia coast is contained within the sedimentary stratigraphy of its salt marsh depositional basins. Georgia’s barrier islands were formed as a veneer of sediments atop the coastal plain during the Pleistocene Epoch as sea level fluctuated with each interglacial period, dropping after each subsequent period’s rise, building younger barriers seaward through time (Hoyt and Hails, 1967). The current increase in sea level began roughly 20,000 years ago and is currently rising at a rate of 3 mm/year, inundating these barrier islands and accreting sediment within their marshes(Bishop et al., 2011). Increase in the rate of sea level rise is predicted for the coming century, with some predictions estimating rates of rise that exceed the thresholds for salt marsh survival (Kirwan et al., 2010). In addition to their environmental importance, Jones Creek Salt Marsh and Wormsloe Plantation are historically significant in that Wormsloe has been occupied continuously since the initial colonization of Georgia, and one of the state’s early military outposts was located along the banks of Jones Creek (Swanson, 2012). Detailed historical records of activity on the plantation have been kept since its inception, and, through the Wormsloe Institute for Environmental History, in-depth multidisciplinary study of the natural history and human activity on Wormsloe has been carried out. While not only a sentinel for future change associated with climate change and sea level rise, Jones Creek Salt Marsh also provides an opportunity to study the effects of human activity on salt marsh dynamics, as the construction of Diamond Causeway in 1972 created a hydrologic barrier on the southern edge of the marsh, rapidly converting nearly 70 acres of low marsh to high marsh or supratidal sand flat (Rice et al., 2005). Along with the lithologic information obtained through the analysis of vibracores from Jones Creek Salt Marsh, geochemical data from FPXRF analysis of the cores can facilitate a chemostratigraphic study, through which geochemically distinct units may be evaluated (Montero-Serrano, et al., 2010).