Terrace formations along Appalachian streams have been the focus for much debate about the fundamental processes of fluvial geomorphology. In Hack's early view, Appalachian terrace formations were the result of stream piracy between adjacent rivers valleys which occupied different elevations; continuous, long terraces would not be a produced by such a model (and were not found by Hack along the Shenandoah Valley). The diagram below depicts the gradients of the contemporary floodplain and nine older surfaces along the Little Tennessee River in east Tennessee. Radiocarbon dating of the terraces indicates that maximum aggradation occurred during glacial/interglacial or stadial/interstadial transitions, not during glacial maxima as previously proposed by King.
Adapted from pp. 613-614 of Mills, H. H., and Delcourt, P. A. 1991. "Quaternary Geology of the Appalachian Highlands and Interior Low Plateaus." Chpt. 20 in Quaternary Non-glacial Geology: Conterminous United States. Volume K-2 in The Geology of North America series. Boulder, CO: Geological Society of America.