The Tallahatta Formation derives its name from the Tallahatta Hills in Choctaw County (Turner and Newton, 1971a,b). The formation comprises part of the Alabama Coastal Plain, which is one of the major physiographic provinces of Alabama. Stratigraphically, the Tallahatta belongs to the Claiborne Group, a lower-middle Eocene succession of sedimentary rocks deposited primarily within coastal depositional environments. The Tallahatta Formation lies at the base of the Claiborne Group. It disconformably overlies the Hatchetigbee Formation (Wilcox Group) and is overlain sequentially by the Lisbon Formation and the Gosport Sand Formation. The Tallahatta Formation is approximately 40 m thick in southwestern Alabama and thins to less than half that in the southeastern portion of the state (Raymond et al., 1988). According to reports from the Geological Survey of Alabama, the Tallahatta Formation is composed of "pale-green marine siliceous claystone with some beds of glauconitic sand and sandstone" (Copeland, 1968). It contains some fossiliferous intervals in southwestern portions of the state. Fossils also occur in south central Alabama, but lower in the stratigraphy.

In Mississippi, as well as Clarke and Choctaw Counties, the lower portion of the Tallahatta Formation contains a thin (2 to 3 m thick) white to light green, micaceous quartz sand unit designated the Meridian Sand Member.