Geologic units in Harris county, Georgia

Biotite Gneiss (Precambrian-Paleozoic) at surface, covers 29 % of this area

Biotite gneiss

Mica Schist/ Gneiss/ Amphibolite (Precambrian-Paleozoic) at surface, covers 19 % of this area

Mica Schist/ Gneiss/ Amphibolite

Mylonite and ultramylonite (Age uncertain) at surface, covers 10 % of this area

Mylonite and ultramylonite

Hornblende Gneiss/ Amphibolite/ Granite Gneiss (Precambrian-Paleozoic) at surface, covers 9 % of this area

Hornblende Gneiss/ Amphibolite/ Granite Gneiss

Mica Schist/ Gneiss (Precambrian-Paleozoic) at surface, covers 7 % of this area

Mica Schist/ Gneiss

Mica Schist (Precambrian-Paleozoic) at surface, covers 7 % of this area

Mica Schist

Granite undifferentiated (Precambrian-Paleozoic) at surface, covers 5 % of this area

Granite undifferentiated

Biotite Gneiss/ Amphibolite (Age uncertain) at surface, covers 5 % of this area

Biotite Gneiss/ Amphibolite

Quartzite (Precambrian-Paleozoic) at surface, covers 3 % of this area

Quartzite

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

Hornblende Gneiss/ Amphibolite

Granitic Gneiss undifferentiated (Precambrian-Paleozoic) at surface, covers 3 % of this area

Granitic Gneiss undifferentiated

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

Granite Gneiss/ Granite

Flinty Crush Rock (Age uncertain) at surface, covers 0.2 % of this area

Flinty Crush Rock

Opelika Complex; Auburn Gneiss (Precambrian to Paleozoic) at surface, covers 0.1 % of this area

Fine-grained biotite-oligoclase gneiss intermixed with coarse-grained muscovite-biotite schist; locally contains muscovite-rich pegmatite.

Dadeville Complex; Ropes Creek Amphibolite (Precambrian to Paleozoic) at surface, covers < 0.1 % of this area

Layered and massive amphibolite; locally includes hornblende migmatite and ultramafic pods.

Charnockite (Precambrian-Paleozoic) at surface, covers < 0.1 % of this area

Charnockite

Mylonitic and Cataclastic Rocks in the Brevard, Towaliga, and Goat Rock Fault Zones (Precambrian to Paleozoic) at surface, covers < 0.1 % of this area

Blastomylonite, mylonite gneiss, locally includes mylonite schist and mylonite quartzite in Towaliga fault zone.

Opelika Complex; Loachapoka Schist (Precambrian to Paleozoic) at surface, covers < 0.1 % of this area

Muscovite-quartz schist; locally contains biotite-garnet-muscovite schist, many layers conatin sillimanite (northeast of Mount Jefferson, Lee County); kyanite (west of Mount Jefferson); locally muscovite-rich schist and quartzite common.

Dadeville Complex; Waverly Gneiss (Precambrian to Paleozoic) at surface, covers < 0.1 % of this area

Feldspathic biotite-hornblende gneiss with thin layers of amphibolite, calc-silicate rock, garnet quartzite, and muscovite schist; locally rich in manganese.

Motts Gneiss (Precambrian to Paleozoic) at surface, covers < 0.1 % of this area

Leucocratic quartz-rich quartz diorite pencil gneiss.

Dadeville Complex; Mafic and ultramafic rock (Precambrian to Paleozoic) at surface, covers < 0.1 % of this area

Ultramafic rock including enstatite pyroxenite, layered actinolite-tremolite amphibolite altered locally to serpentine, anthophyllite, and talc; metanorite; metagabbro; hornblendite; garnet-hornblendite, and massive amphibolite.

Pine Mountain Group; Manchester Schist (Precambrian to Paleozoic) at surface, covers < 0.1 % of this area

Interlayered muscovite-quartz schist and quartzite, locally contains garnet, sillimanite and graphite; commonly intensely shared.

Mylonitic and Cataclastic Rocks in the Brevard, Towaliga, and Goat Rock Fault Zones (Precambrian to Paleozoic) at surface, covers < 0.1 % of this area

Mylonite and blastomylonite; contains minor ultramylonite, mylonite schist, and mylonite gneiss.