LATE QUATERNARY FLUVIAL RECORDS IN THE ATLANTIC COASTAL PLAIN: PROBLEMS AND CHALLENGES FOR FUTURE RESEARCH (Invited Presentation)

Five main phases of late Quaternary fluvial systems previously were identified in the Atlantic Coastal Plain (Leigh, 2008) spanning the late Pleistocene to present, including: fluctuations in braiding and meandering (>35-30 ka), braiding with eolian dunes (30-16 ka), large scrolled meanders (16-11 ka), large meanders (11-6 ka), modern-like meanders (6-0 ka). This framework has provided a good general model for late Quaternary fluvial systems behavior in the Coastal Plain, but there is considerable room for development and elaboration in the following areas. The Sangamon stage (OIS-5) and Sangamon-Wisconsin boundary (OIS-5 to 4) is not well resolved in the stratigraphic record, largely due to limitations for chronological control and availability of representative stratigraphic sections. The interplay between isostatic, eustatic, and forebulge crustal movements and river system behavior and the depositional record is not well understood. Periodicity and frequency of riverine eolian dune activity prior to 30 ka is not well known, despite growing numbers of luminescence dates from OIS-3 and OIS-4 dunes on ancient river braid plains. Mega-meanders of the terminal Pleistocene and early Holocene still remain poorly understood in terms of their significance about paleofluvial discharge regime and implications for paleohydrology. Significant global modulations in climate during the Holocene, such as the hypsithermal warm period, 4.2 ka event, and Medieval climate anomaly are not well expressed in the paleofluvial record, possibly due to only a small set of dated examples. Emerging research exists in all of these areas which will be discussed in terms of recent data, technological and chronological developments, obstacles to productive research, and realms of future discovery. Continued research on fluvial systems of the Coastal Plain promises to inform fluvial processes and responses to climatic, tectonic, eustatic, and human impact changes in the past and future.

Citation: Leigh, D.S., 2008. Late Quaternary climates and river channels of the Atlantic Coastal Plain, southeastern USA. Geomorphology 101, 90-108.