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Pleistocene/Holocene Sea Level Change in the Georgia Bight: a paleoenvironmental reconstruction of Gray's Reef National Marine Sanctuary and J Reef
A Thesis submitted to the Graduate Faculty of The University of Georgia in Partial Fulfillment of the Requirements for the Degree of Master of Science, Athens, GA 2000
by: SHERRI LYNN LITTMAN
(under the direction of ERVAN G. GARRISON)
Research at Gray's Reef National Marine Sanctuary, National Oceanic and Atmospheric Administration (NOAA) and nearby I Reef have focused on the study of sub bottom and sea floor sediments of late Pleistocene/early Holocene age. The purpose of this study was to ( I ) map sediments in the Sanctuary and its immediate vicinity (I Reef); (2) describe the lithofacies and their stratigraphy; (3) examine the relationship of the lithostratigraphy to sea level change in the late Pleistocene and early Holocene; and (4) examine the likelihood for human occupation of this now drowned coastal plain. High resolution acoustic reflection and side scan sonar were utilized to map the sea floor and near-sea floor facies. Geophysical data indicates shallow (~5m) sediments at Gray's Reef and I Reef. Both areas were subaerial during the late Pleistocene/early Holocene. In addition to the geophysical data, geological coring was carried out on the Pleistocene and Holocene sediments at both Gray's and I Reefs. These cores were analyzed to illuminate the respective lithofacies and their stratigraphy.
Diver surveys of Gray's Reef and J Reef recovered fossil bones, a burrow cast and relic sedimentological features. Results of these data have been correlated to show when these ancient reefs were subaerial and that a strong possibility exists that this ancient coastal plain was available for human habitation. Since sub-aerial erosional surfaces existed in the vicinity of I and Gray's Reefs, after the time that humans first entered the New World ca 13,400BP, the geoarchaeological reconstruction of plausible paleoenvironments has merit.
INDEX WORDS: Paleoenvironments, Sea Level Rise, Pleistocene, Holocene, Megafauna, Outer Continental Shelf, Paleoindian Clovis, Georgia Bight, Vibracores, Subbottom Profiling, Paleochannels, Lithostratigraphy, Geoarchaeology