Both the Tombigbee River, in Mississippi and the Tennessee River, in Hardin County, Tennessee have extensive, well-preserved, depositional terrace systems of Late Paleogene (?)-Neogene age in their valley walls. Field mapping and studies have shown that both depositional terrace systems lie on relatively flat, erosional surfaces (buried erosional stream terraces), cut into unconsolidated, Late Cretaceous sediments; and, while, in many respects, they are similar in gross appearance to one another, there are significant differences in their thickness and lithic content, which directly reflects not only the regimen of the streams in which they were deposited, but dissimilar primary source areas in basal Cretaceous gravels. Based on a comparison of the terrace deposits, there is no physical evidence in the Tombigbee River system to suggest that the Tennessee River has been diverted into that system.