Geologic units in Columbia county, Georgia

Granitic Gneiss undifferentiated (Precambrian-Paleozoic) at surface, covers 62 % of this area

Granitic Gneiss undifferentiated

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)

Sericite Schist (Precambrian-Paleozoic) at surface, covers 6 % of this area

Sericite Schist

Irwinton Sand (Eocene) at surface, covers 4 % 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.

Granite undifferentiated (Precambrian-Paleozoic) at surface, covers 4 % of this area

Granite undifferentiated

Porphyritic granite (Precambrian-Paleozoic) at surface, covers 4 % of this area

Porphyritic granite

Twiggs Clay (Eocene) at surface, covers 3 % of this area

Twiggs Clay

Hornblende Gneiss/ Amphibolite (Precambrian-Paleozoic) at surface, covers 3 % of this area

Hornblende Gneiss/ Amphibolite

Sericite Schist/ Amphibolite/ Granite gneiss (Precambrian-Paleozoic) at surface, covers 2 % of this area

Sericite Schist/ Amphibolite/ Granite gneiss

Ultramafic rocks undifferentiated (Precambrian-Paleozoic) at surface, covers 1 % of this area

Ultramafic rocks undifferentiated

Granite Gneiss/ Granite (Precambrian-Paleozoic) at surface, covers 0.8 % of this area

Granite Gneiss/ Granite

Migmatite paragneiss and schist of Kiokee belt (Cambrian or Neoproterozoic) at surface, covers 0.3 % of this area

Migmatitic hornblende-biotite paragneiss having interlayered sillimanite schist and amphibolite

Granite Gneiss/ Amphibolite (Precambrian-Paleozoic) at surface, covers 0.3 % of this area

Granite Gneiss/ Amphibolite

Felsic Metavolcanics (Precambrian-Paleozoic) at surface, covers 0.2 % of this area

Felsic Metavolcanics

Meta-argillite/ Phyllite (Precambrian-Paleozoic) at surface, covers < 0.1 % of this area

Meta-argillite/ Phyllite

Granite (Carboniferous to Permian) at surface, covers < 0.1 % of this area

Granite

Mylonitic rocks of Modoc Fault Zone (Late Paleozoic) at surface, covers < 0.1 % of this area

Mylonite gneiss

Metavolcanic and metasedimentary rocks of Bel Air Belt (Ordovician to Neoproterozoic) at surface, covers < 0.1 % of this area

Metavolcanic and metasedimentary rocks of Bel Air Belt

Burkes Mountain complex, ultramafic rock (Cambrian or Neoproterozoic) at surface, covers < 0.1 % of this area

Burkes Mountain complex, ultramafic rock