Geologic units in Alamance county, North Carolina

Metamorphosed Granitic Rock (Cambrian/Late Proterozoic) at surface, covers 39 % of this area

Megacrystic, well foliated; locally contains hornblende. Chapel Hill, Chatham, Farrington, Meadow Flats, Mt. Moriah, Parks Crossroads plutons, and Roxboro and Vance County suites.

Felsic Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 30 % of this area

Metamorphosed dacitic to rhyolitic flows and tuffs, light gray to greenish gray; interbedded with mafic and intermediate metavolcanic rock, meta-argillite, and metamudstone.

Metamorphosed Gabbro and Diorite (Paleozoic/Late Proterozoic) at surface, covers 17 % of this area

Foliated to massive.

Mafic Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 8 % of this area

Metamorphosed basaltic flows and tuffs, dark green to black; interbedded with felsic and intermediate metavolcanic rock and metamudstone.

Intermediate Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 5 % of this area

Metamorphosed andesitic tuffs and flows, medium to dark grayish green; minor felsic and mafic metavolcanic rock.

Metamudstone and Meta-Argillite (Cambrian/Late Proterozoic) at surface, covers < 0.1 % of this area

Thin to thick bedded; bedding plane and axial-planar cleavage common; interbedded with metasandstone, metaconglomerate, and metavolcanic rock.