Geologic units in Bibb county, Georgia

Cusseta, Blufftown, and Eutaw Formations, undifferentiated (Cretaceous) at surface, covers 22 % of this area

Cusseta, Blufftown, and Eutaw Formations, undifferentiated

Biotite Gneiss (Precambrian-Paleozoic) at surface, covers 19 % of this area

Biotite gneiss

Tuscaloosa Formation (Cretaceous) at surface, covers 16 % of this area

Tuscaloosa Formation

Granite/ granite gneiss (Precambrian-Paleozoic) at surface, covers 15 % of this area

Granite/ granite gneiss

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

Stream alluvium and undifferentiated terrace deposits

Lower Tertiary-Cretaceous undifferentiated (Lower Tertiary-Cretaceous) at surface, covers 9 % of this area

As mapped includes Middendorf Formation (Sloan, 1904); "Channel Sands" (LaMoreaux, 1946); Tuscaloosa Formation (Cooke, 1939); and "Huber beds" (Buie, informal terminology)

Biotite Granite Gneiss/ Feldspathic Biotite Gneiss/ Amphibolite Hornblende Gneiss (Precambrian-Paleozoic) at surface, covers 1 % of this area

Biotite Granite Gneiss/ Feldspathic Biotite Gneiss/ Amphibolite Hornblende Gneiss

Granite Gneiss/ Granite (Precambrian-Paleozoic) at surface, covers 0.9 % of this area

Granite Gneiss/ Granite

Twiggs Clay (Eocene) at surface, covers 0.9 % of this area

Twiggs Clay

Ripley Formation (Cretaceous) at surface, covers 0.6 % of this area

Ripley Formation

Hornblende Gneiss (Precambrian-Paleozoic) at surface, covers 0.3 % of this area

Hornblende Gneiss

Irwinton Sand (Eocene) at surface, covers < 0.1 % 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.