Abstract: History of Shoreline Changes by Archeological Dating, Georgia Coast

Chester B. Depratter, James D. Howard

Progradation and erosion of Holocene shorelines on the Georgia coast can be grouped into four basic types: (1) rapid progradation at the mouths of major rivers; (2) parallel progradation of straight beaches typical of the central parts of barrier islands; (3) seaward and southward accretion of recurving beaches at the south ends of barrier islands; and (4) cycles of alternating cuspate progradation and recurving truncations typical of north ends of barrier islands. Although these basic patterns have long been recognized, only recently has a method been developed whereby the time significance of these processes can be quantified.

During much of the past 4,500 years, Indians inhabiting the Georgia coastal area subsisted in large part on littoral mollusks, as evidenced by large shell middens which mark former habitation sites. Aboriginal ceramic styles changed rapidly during this time period and recent work has defined 12 cultural phases based on pottery patterns found in the shell middens. These 12 phases have been calibrated by carbon-14 dating.

A specific example of how archeological dating can be applied to the interpretation of shoreline changes is seen in the intertidal coastal zone directly south of Savannah River. Examination of 31 habitation sites on beach-ridge remnants in this area shows the presence of six cultural phases which become progressively younger in a seaward direction. This sequence defines a dramatic progradation of nearly 10 km in the last 4,000 years.

AAPG Search and Discovery Article #90967©1977 GCAGS and GC Section SEPM 27th Annual Meeting, Austin, Texas