Geologic units in Screven county, Georgia

Neogene undifferentiated (Neogene) at surface, covers 71 % of this area

Includes Altamaha Grit (Dall, 1892); Citronelle Formation (Matson & Berry, 1916); and "Hawthorn Formation" (Cooke, 1939). (*) - outcrops of indurated sandstone and claystone

Stream alluvium (Quaternary) at surface, covers 15 % of this area

Stream alluvium and undifferentiated terrace deposits

Pleistocene-Pliocene sands and gravels (Pleistocene-Pliocene) at surface, covers 12 % of this area

Includes, in part, Sunderland, Coharie, and Brandywine "Formations" of Cooke, 1939

Irwinton Sand (Eocene) at surface, covers 1 % of this area

Up-dip equivalent of Twiggs Clay, Sandersville Limestone, and Cooper Marl. As mapped, also includes younger clastics of indefinite Late Tertiary age.

Alluvial Valley Swamp (Quaternary) at surface, covers 0.4 % of this area

Unconformable on all underlying units, fluvial sand and gravel at base, grading upwards into fine sands and silts, local peat. May be overrun with recent sediments from forest cutting and agriculture.

Suwannee Limestone and its residuum (Oligocene) at surface, covers 0.2 % of this area

As mapped, includes Chattahoochee Limestone in Seminole and Decatur Cos.; Flint River Formation, in part, (Cooke, 1939); Jacksonboro Limestone in Screven Co.; and Glendon and Marianna Limestones in Pulaski Co.

Waccamaw Formation (Pleistocene) at surface, covers < 0.1 % of this area

Another Carolina costalized terrace of early-middle Pleistocene age. Deeply weathered.