Geologic units in Union county, North Carolina

Cid Formation; Metamudstone and Meta-Argillite (Cambrian/Late Proterozoic) at surface, covers 57 % of this area

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

Phyllite and Schist (Cambrian/Late Proterozoic) at surface, covers 11 % of this area

Locally laminated and pyritic; includes phyllonite, sheared fine-grained metasediment, and metavolcanic rock. In Lilesville granite aureole, includes hornfels.

Felsic Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 10 % 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.

Floyd Church Formation; Metamudstone and Meta-Argillite (Cambrian/Late Proterozoic) at surface, covers 10 % of this area

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

Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers 4 % of this area

Interbedded felsic to mafic tuffs and flowrock.

Gabbro of Concord Plutonic Suite (Devonian/Ordovician) at surface, covers 2 % of this area

Barber, Concord, Farmington, Mecklenburg, and Weddington intrusives.

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

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

Metamorphosed Mafic Rock (Paleozoic/Late Proterozoic) at surface, covers 1 % of this area

Metagabbro, metadiorite, and mafic plutonic-volcanic complexes.

Newark Supergroup, Chatham Group; Chatham Group, Undivided (Triassic) at surface, covers 1 % of this area

Conglomerate, fanglomerate, sandstone, and mudstone. Conglomerate and fanglomerate shown by pattern.

Granite of Salisbury Plutonic Suite (Devonian/Silurian) at surface, covers 0.9 % of this area

Pink, massive to weakly foliated. Gold Hill, Kannapolis, Salisbury, Southmont, and Yadkin intrusives.

Metamorphosed Granitic Rock (Cambrian/Late Proterozoic) at surface, covers 0.8 % 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.

Metamorphosed Quartz Diorite (Paleozoic/Late Proterozoic) at surface, covers 0.2 % of this area

Foliated to massive.

Granitic Rock (Devonian/Ordovician) at surface, covers 0.2 % of this area

Locally pinkish gray, massive to weakly foliated; contains hornblende.

Metamudstone and Meta-Argillite (Cambrian/Late Proterozoic) at surface, covers 0.2 % of this area

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

Persimmon Fork Formation (Cambrian to Neoproterozoic) at surface, covers 0.2 % of this area

Predominately metatuff

Cid Formation, Mudstone Member (Ordovician to Late Cambrian) at surface, covers 0.2 % of this area

Thin bedded tuffaceous metasiltstone

Metamorphosed Granitic Rock (Cambrian/Late Proterozoic) at surface, covers 0.1 % of this area

Megacrystic, well foliated; locally contains hornblende.

Tuffaceous metasiltstone (Early Paleozoic-Neoproterozoic) at surface, covers < 0.1 % of this area

Tuffaceous metasiltstone

Phyllonite and phyllonitic schist (Late Paleozoic) at surface, covers < 0.1 % of this area

Phyllonite and phyllonitic schist

Metadiorite (Cambrian or Neoproterozoic) at surface, covers < 0.1 % of this area

Metadiorite

Metamorphosed granite and granodiorite (Cambrian or Neoproterozoic) at surface, covers < 0.1 % of this area

Metamorphosed granite and granodiorite

Chatham Group, undivided (Triassic) at surface, covers < 0.1 % of this area

Conglomerate, sandstone and mudstone

Felsic metavolcanic rocks and felsic gneiss interpreted to the metavolcanics (Ordovician to Neoproterozoic) at surface, covers < 0.1 % of this area

Felsic metavolcanic rocks and felsic gneiss interpreted to the metavolcanics

Felsic Metavolcanic Rock (Cambrian/Late Proterozoic) at surface, covers < 0.1 % of this area

Metamorphosed dacitic to rhyolitic flows and tuffs, light gray to greenish gray; minor mafic and intermediate metavolcanic rock.

Waxhaw metagranite (Ordovician to Cambrian) at surface, covers < 0.1 % of this area

Metamorphosed fine- to medium-grained biotite granite and hypabyssal quartz porphyry, non-foliated except adjacent to Gold Hill and Waxhaw shear zones where it is gneissic to phyllonitic