Tuscaloosa Formation
The sand clay formation here represents the first prominent Coastal Plain deposits laid upon an ancient floor of granites and gneisses. Southward this formation (Tus caloosa Upper Cretaceous) becomes more and more deeply buried and contains marine beds. These rocks are more than 60,000,000 years old. Still older Lower Cretaceous rocks underlie them down the dip.
Oil fields of Alabama and Mississippi are from marine beds of this formation, which occur also in Georgia to the south, indicating oil in Georgia too.
GHM 132-1 Georgia Historical Commission 1959
Plaque courtesy Lat34North.com.
Original page, with additional info, here.
Photo credit: Byron Hooks of Lat34North.com.