Remnants of old alluvium on bedrock benches, as much as 76 in (250 ft) above the present course of the Cumberland River near Flat Lick, Ky., are associated with meander scars and broad valleys now occupied by underflt streams. The distribution of old alluvium and associated topographic features define two ancestral channels of the Cumberland River. The ancestral channels and the present river channel are superimposed on the crest and flanks of the Flat Lick anticline. All three channels trend westward, roughly parallel to the axis of the anticline. The oldest channel is on the north flank, the second oldest channel is superimposed on the crest, and the modern channel is entrenched in the south-dipping limb of the fold. The sequential pattern of channel downcutting and migration across the crest of the anticline can be explained in terms of structural and lithologic constraints upon fluvial processes without recourse to contemporaneous tectonism. The Flat Lick area apparently has not experienced major deformation during the erosional history interpreted from the surficial geology. Direct evidence for the age of the old alluvium has not been found. However, an estimate based on erosion rates suggests that the ancestral channels could have been established and abandoned as recently as one-half million years ago.
