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Geologic units in Alleghany 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 47 % of this area

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

Alligator Back Formation; Gneiss (Late Proterozoic) at surface, covers 33 % of this area

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

Biotite Granitic Gneiss (Middle Proterozoic) at surface, covers 8 % 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.

Ashe Metamorphic Suite and Tallulah Falls Formation; Amphibolite (Late Proterozoic) at surface, covers 5 % of this area

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

Alligator Back Formation; Mica schist and phyllite (Late Proterozoic) at surface, covers 5 % of this area

Laminated to thin layered; interlayered with minor biotite-muscovite gneiss and amphibolite.

Alligator Back Formation; Amphibolite (Late Proterozoic) at surface, covers 0.5 % of this area

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

Ashe Metamorphic Suite and Tallulah Falls Formation; Mica schist (Late Proterozoic) at surface, covers 0.4 % of this area

Locally sulfidic and graphitic; minor interlayered mica gneiss and amphibolite.

Meta-ultramafic Rock (Paleozoic/Late Proterozoic) at surface, covers 0.3 % of this area

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

Quartz Diorite to Granodiorite (Devonian) at surface, covers 0.1 % of this area

Contains biotite, muscovite, and xenocrysts. Includes Whiteside Mountain, Stone Mountain, Mount Airy, Spruce Pine, and other smaller plutons.