ABSTRACT

Rates of deposition for features associated with progradational shorelines are normally estimated on the basis of direct observation or by the radiocarbon dating of shell or wood fragments recovered from the shoreline depositional features. Archaeological dating provides an alternative to these techniques.

Progradation and erosion of Holocene shorelines on the Georgia coast can be grouped into four basic types:

--Rapid progradation at the mouth of major rivers

--Seaward and southward accretion of recurving beaches at the south ends of barrier islands

--Cycles of alternating cuspate progradation and recurving truncations typical of the northern ends of barrier islands

--Parallel progradation of straight beachlines typical of the central parts of barrier islands.

The temporal significance of each of these types can be determined by archaeological dating.

During much of the past 4500 years. Indians inhabiting the Georgia coastal area subsisted in large part on littoral mulluscs, as evidenced by large shell middens which mark former habitation sites. Aboriginal ceramic styles changed rapidly during this time period and recent work by archaeologists has defined 15 cultural phases based on the ceramic changes. These 15 phases have been calibrated by ¹⁴C dating.

A specific example of how archaeological dating can be applied to the interpretation of shoreline changes is seen in the intertidal coastal zone lying immediately south of Savannah River. Examination of 33 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 past 4500 years.