Holistic Integration: Building Toward Consensus in Georgia Sea Level History

Document Type

Presentation

Presentation Date

3-29-2007

Abstract or Description

Pleistocene sea level dropped and rose in response to glacial and interglacial intervals, causing patterns of coastal erosion and deposition that we are only beginning to understand. Along the Georgia coast these sea level fluctuations resulted in deposition and erosion of a seaward dipping veneer of Pleistocene sediment arranged in a series of barrier island sequences that are younger to the east. The deposition of coastal terraces or barrier island ridges (Wicomico, ~29-30 m; Penholloway, ~23 m; Talbot, ~12-14 m; Pamlico, ~8 m; Princess Anne, ~4.5m; Silver Bluff, ~1.5 m; and Holocene) in Georgia form a continuous veneer of Pleistocene sediment of varying thickness and lithology. Understanding Georgia sea level changes demands accommodation of known data that constrain models and resultant sedimentologic effects on shoreline position and elevation. The height of maximum seal level rise in Georgia is equivalent to the elevation of the highest coastal deposits of the Wicomico Shoreline, or terrace. Although the array of preserved Pleistocene shoreline deposits or terraces provides evidence of progressive lowering of sequential sea level highstands, it says little about the levels of sea level low stands during glacial stages. Vertebrate fossils and archaeological artifacts from the continental shelf allow partial reconstruction of low stands. Differential elevations of ancient barrier island or shoreline complexes and structural evidence suggest that tectonic as well as eustatic controls have been in effect. Superimposed upon these eustatic and tectonic effects are sedimentologic pulses produced by Pleistocene climate changes and evolving physical conditions influenced by possible coastal plain stream capture and "jumping" inlets and sounds along the Georgia coast. Correlation and comparison of disparate data on St. Catherines Island permits the testing of sea level models by integration of ground truthing with field data. This process, although it might occasionally assault our individual hypotheses, can be expected to lead to a better understanding of the history of Pleistocene and Holocene sea levels in Georgia. A Georgia sea level curve is constructed as a model for discussion in this Theme Session.

Sponsorship/Conference/Institution

Geological Society of American Southeastern Section Annual Meeting (GSA)

Location

Savannah, GA

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