Geologic units in Buncombe county, North Carolina

Additional scientific data in this geographic area

Ashe Metamorphic Suite and Tallulah Falls Formation; Muscovite-biotite gneiss (Late Proterozoic) at surface, covers 51 % of this area

Locally sulfidic; interlayered and gradational with mica schist, minor amphibolite, and hornblende gneiss.

Ashe Metamorphic Suite and Tallulah Falls Formation; Metagraywacke (Late Proterozoic) at surface, covers 19 % of this area

Foliated to massive, locally conglomeratic; interlayered and gradational with mica schist, muscovite-biotite gneiss, and rare graphitic schist.

Migmatitic Biotite-Hornblende Gneisses (Middle Proterozoic) at surface, covers 9 % of this area

Unconformity; layered biotite-granite gneiss, biotite-hornblende gneiss, amphibolite, calc-silicate rock; locally contains relict granulite facies rock.

Biotite Granitic Gneiss (Middle Proterozoic) at surface, covers 5 % of this area

Unconformity; pinkish gray to light gray, massive to well-foliated, granitic to quartz monzonitic; includes variably mylonitized orthogneiss and paragneiss, interlayered amphibolite, calc-silicate rock, and marble. Includes granites of the Bryson City area, Straight Fork window, and Elk Park Plutonic Suite.

Henderson Gneiss (Cambrian) at surface, covers 5 % of this area

Monzonitic to granodioritic; inequigranular.

Coweeta Group; Biotite Gneiss (Middle/Late Proterozoic) at surface, covers 4 % of this area

Migmatitic; interlayered and gradational with biotite-garnet gneiss and amphibolite; locally abundant quartz and alumino-silicates. Stratigraphic position uncertain.

Rocks of Brevard Fault Zone (Uncertain, possibly Permian or Devonian) at surface, covers 3 % of this area

"Fish scale" schist and phyllonite, graphitic; interlayered with feldspathic metasandstone, marble lenses.

Amphibolite (Middle Proterozoic) at surface, covers 2 % of this area

Unconformity; equigranular, massive to well foliated, interlayered, rarely discordant, metamorphosed intrusive to extrusive mafic rock; may include metasedimentary rock.

Biotite Gneiss and Schist (Cambrian/Late Proterozoic) at surface, covers 1 % of this area

Inequigranular, locally abundant potassic feldspar and garnet; interlayered and gradational with calc-silicate rock, sillimanite-mica schist, mica schist, and amphibolite. Contains small masses of granitic rock.

Granite Gneiss (Silurian/Ordovician) at surface, covers 1 % of this area

Poorly foliated; interlayered with biotite augen gneiss.

Meta-ultramafic Rock (Paleozoic/Late Proterozoic) at surface, covers 0.2 % of this area

Metamorphosed dunite, local peridotite; serpentinite, soapstone, and other altered ultramafic rock. Only larger bodies shown.

Ocoee Supergroup; Great Smokey Group, undivided (Late Proterozoic) at surface, covers 0.1 % of this area

Thick metasedimentary sequence of massive to graded beds of metagraywacke and metasiltstone with interbedded graphitic and sulfidic slate and schist.

Alligator Back Formation; Gneiss (Late Proterozoic) at surface, covers < 0.1 % of this area

Finely laminated to thin layered; locally contains massive gneiss and micaceous granule conglomerate; includes schist, phyllite, and amphibolite.