Includes Altamaha Grit (Dall, 1892); Citronelle Formation (Matson & Berry, 1916); and "Hawthorn Formation" (Cooke, 1939). (*) - outcrops of indurated sandstone and claystone
Stream alluvium and undifferentiated terrace deposits
It is now recognized that this unit is not the precise lithologic or biostratigraphic equivalent of type Cooper Marl (Huddlestun, Marsalis & Pickering, 1974).
Up-dip equivalent of Twiggs Clay, Sandersville Limestone, and Cooper Marl. As mapped, also includes younger clastics of indefinite Late Tertiary age.