USGS Home
Contact USGS
Search USGS

Mineral Resources > Online Spatial Data > Geology > by state > North Carolina Geology

Geologic units in Randolph county, North Carolina

Cid Formation; Mafic Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 2 % of this area

(Southwest of Asheboro); Mafic Metavolcanic Rock - metamorphosed basaltic flows and tuffs, dark green to black; interbedded with felsic and intermediate metavolcanic rock and metamudstone.

Lithology: mafic metavolcanic rock; felsic metavolcanic rock; intermediate metavolcanic rock; metasedimentary rock

Metavolcanic-Epiclastic Rock (Cambrian/Late Proterozoic) at surface, covers 11 % of this area

Metavolcanic-Epiclastic Rock - metamorphosed argillite, mudstone, volcanic sandstone, and conglomerate, and volcanic rock.

Lithology: meta-argillite; meta-conglomerate; metasedimentary rock; metavolcanic rock

Cid Formation; Metamudstone and Meta-Argillite (Cambrian/Late Proterozoic) at surface, covers 3 % of this area

(Southwest of Asheboro); Metamudstone and Meta-Argillite - thin to thick bedded; bedding plane and axial-planar cleavage common; interbedded with metasandstone, metaconglomerate, and metavolcanic rock.

Lithology: meta-argillite; meta-conglomerate; metasedimentary rock; metavolcanic rock

Metamudstone and Meta-Argillite (Cambrian/Late Proterozoic) at surface, covers 9 % of this area

Metamudstone and Meta-Argillite - bedding plane and axial-planar cleavage common; interbedded with metasandstone, meta-conglomerate, and metavolcanic rock.

Lithology: metasedimentary rock; meta-argillite; meta-conglomerate; metavolcanic rock

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

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

Lithology: felsic metavolcanic rock; mafic metavolcanic rock; intermediate metavolcanic rock; meta-argillite; metasedimentary rock

Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 0.6 % of this area

Metavolcanic Rock - interbedded felsic to mafic tuffs and flowrock.

Lithology: felsic metavolcanic rock; mafic metavolcanic rock

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

Mafic Metavolcanic Rock - metamorphosed basaltic flows and tuffs, dark green to black; interbedded with felsic and intermediate metavolcanic rock and metamudstone.

Lithology: mafic metavolcanic rock; felsic metavolcanic rock; intermediate metavolcanic rock; metasedimentary rock

Metamorphosed Granitic Rock (Cambrian/Late Proterozoic) at surface, covers 16 % of this area

Metamorphosed Granitic Rock (520-650 my) - megacrystic, well foliated, locally contains hornblende; Fountain intrusive.

Lithology: metamorphic rock

Metamorphosed Gabbro and Diorite (Paleozoic/Late Proterozoic) at surface, covers 2 % of this area

Metamorphosed Gabbro and Diorite - foliated to massive.

Lithology: metamorphic rock

Tillery Formation; Metamudstone and Meta-Argillite (Cambrian/Late Proterozoic) at surface, covers 15 % of this area

(Southwest of Asheboro); Metamudstone and Meta-Argillite - thin to thick bedded; bedding plane and axial-planar cleavage common; interbedded with metasandstone, metaconglomerate, and metavolcanic rock.

Lithology: meta-argillite; meta-conglomerate; metasedimentary rock; metavolcanic rock

Phyllite and Schist (Cambrian/Late Proterozoic) at surface, covers 0.2 % of this area

Phyllite and Schist - minor biotite and pyrite; includes phyllonite, sheared fine-grained metasediment and metavolcanic rock.

Lithology: phyllite; schist; phyllonite; metasedimentary rock; metavolcanic rock

Uwharrie Formation; Felsic Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 31 % of this area

(at Asheboro and to south); Felsic Metavolcanic Rock - metamorphosed dacitic to rhyolitic flows and tuffs, light gray to greenish gray; interbedded with mafic and intermediate metavolcanic rock, meta-argillite, and metamudstone.

Lithology: felsic metavolcanic rock; mafic metavolcanic rock; intermediate metavolcanic rock; meta-argillite; metasedimentary rock