Riverine dunes on the Coastal Plain of Georgia, USA (original) (raw)
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Chronology of Inland Eolian Dunes on the Coastal Plain of Georgia, USA
Quaternary Research, 2001
Most inland eolian dunes associated with rivers on the Georgia Coastal Plain probably date to glacial periods. Direct dating of the dune sand by optically stimulated luminescence dating, combined with limiting ages from radiocarbon dating, shows that dunes formed during isotope stage 2, stage 3, the transition between stages 4 and 5, and isotope stage 6 or earlier. Most of the dates indicate dune activity between 30,000 and 15,000 years ago. Holocene activity included limited and local reworking of the crests of some thick dunes along streams that flow from the Piedmont.
Geomorphology, 2017
We report on the age and evolution of five well-developed parabolic dunes that are perched on high (~40 m) bluffs along the southern lip of the Au Sable River valley in northeastern Lower Michigan, U.S.A. These dunes are located on west/northwest-facing exposures and mantle the Jackpines Delta, which formed when the glacial Au Sable River system deposited sands and gravels into glacial Lake Warren in the Huron basin sometime be-tween~15.1 and 14.7 ka. Lake level subsequently fell N 35 m as the ice margin retreated northward during the Twocreekan Interstadial. This regression resulted in abandonment of the Jackpines Delta and incision of the associated surface by the ancestral Au Sable River. Lake level subsequently rose~50 m during the Algonquin transgression , which likely promoted valley widening through channel migration. Eight samples were collected for OSL age determination of the dunes and yielded ages that suggest dune formation occurred mostly betweeñ 13.5 ka and 13 ka. This result, coupled with the landscape position of the dunes (i.e., south side of river; west/northwest-facing bluffs) suggests that the dunes largely formed: 1) during the Algonquin transgression when bluffs were eroded by stream-channel migration, and 2) by west-northwesterly winds that transported eo-lian sands from exposed bluff faces to the adjacent valley edge. This study contributes to the understanding of perched-dune formation in the Great Lakes region and further supports models indicating that westerly winds prevailed within 150 km of the ice margin during the late Pleistocene. It also demonstrates that interior dunes in this region formed in similar environmental settings to interior dunes in northern Europe and suggests that local factors, rather than specific climate intervals, should also be considered as they relate to dune evolution.
Coastal Landscapes and their Relationship to Human Settlement on the Georgia Coast.
Anthropological Papers of the American Museum of Natural History, No. 98, 2013
Local geomorphology and geology are important in understanding human settlement patterns, especially in coastal settings. We attempt to examine these issues in coastal Georgia, USA, through a campaign of vibracoring, radiocarbon and optically stimulated luminescence dating, and sediment analyses. Certain aspects of Georgia coastal geomorphology have been clarified, while at the same time new questions have been raised. One key finding is that pre-existing topography, even in dynamic coastal settings, can be important landscape components. Related is the finding that changes in the coastal landscape are not straightforward, but are significantly influenced by antecedent surfaces. This makes creation of a holistic model for coastal landscape development difficult, while at the same time complicating the retro-diction of human use of these landforms without direct archaeological and/or geomorphological data. We additionally find that new coastal landforms are rapidly utilized by humans as they naturally develop, substantiating conclusions drawn in previous studies. Finally, previous dating of coastal landforms using archaeological techniques has, for the most part, been corroborated, illustrating the complementary nature of archaeological and geological techniques.