River Environments of the at the End of the Pleistocene, Southeast USA David S. Leigh, Director of the Geomorphology Laboratory, University of Georgia Abstract: The end of the Pleistocene was a time of rapid environmental change in river valleys of the southeastern United States. At 20 to 15 ka climate was much cooler and drier than present and rivers were braided with widespread eolian sand dunes blowing over floodplains. At about 15 ka the climate became warmer and more moist, and this shifted the river channel patterns to meandering. The earliest of these meandering channels (circa 15-12 ka) maintained a sandy bed-load, experienced rapid lateral migration, saw eolian dunes blowing off of sandy scroll bars, and endured annual floods that were much larger than present, possibly with a snowmelt component. The terminal Pleistocene and earliest Holocene witnessed a shift toward more modern-like meandering river conditions with clay-rich floodplains, but flood magnitudes probably remained large (compared to modern) until about 5 ka possibly due to a high frequency of tropical cyclones and heavy spring rainfall. David S. Leigh,  Director of the Geomorphology Laboratory The University of Georgia, Athens, GA 30602-2502 Dr. Leigh is a Professor of Geography and the Director of the Geomorphology Laboratory at The University of Georgia He received his doctoral degree from the University of Wisconsin in Madison in 1991. His research is concerned with late Quaternary environmental conditions in the southeastern United States. He has published many papers about how river conditions have changed in response to climate change occurring over the last 80,000 years. Dr. Leigh's work is closely associated with archeology of the Southeast and how the archeological record is associated and preserved in the context of different geomorphic settings.