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

Geologic units in Alleghany county, North Carolina

[Additional scientific data in this geographic area]

Alligator Back Formation; Gneiss (Late Proterozoic) at surface, covers 34 % of this area

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

Lithology: gneiss; conglomerate; schist; phyllite; amphibolite

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

Meta-ultramafic Rock - metamorphosed dunite and peridotite; serpentine, soapstone, and other altered ultramafic rock. Only larger bodies shown.

Lithology: metamorphic rock; serpentinite

Ashe Metamorphic Suite and Tallulah Falls Formation; Muscovite-biotite gneiss (Late Proterozoic) at surface, covers 48 % of this area

Muscovite-biotite gneiss - locally sulfidic; interlayered and gradational with mica schist, minor amphibolite, and hornblende gneiss.

Lithology: gneiss; mica schist; amphibolite

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

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

Lithology: amphibolite; metasedimentary rock

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

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

Lithology: amphibolite; metasedimentary rock

Biotite Granitic Gneiss (Middle Proterozoic) at surface, covers 8 % of this area

Biotite Granitic Gneiss - 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.

Lithology: granitic gneiss; amphibolite; calc-silicate rock; marble

Alligator Back Formation; Mica schist and phyllite (Late Proterozoic) at surface, covers 4 % of this area

Mica schist and phyllite - laminated to thin layered; interlayered with minor biotite-muscovite gneiss and amphibolite.

Lithology: mica schist; phyllite; gneiss; amphibolite

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

Mica schist - locally sulfidic and graphitic; minor interlayered mica gneiss and amphibolite.

Lithology: mica schist; gneiss; amphibolite

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

Quartz Diorite to Granodiorite (390 my) - contains biotite, muscovite, and xenocrysts. Includes Whiteside Mountain, Stone Mountain, Mount Airy, Spruce Pine, and other smaller plutons.

Lithology: quartz diorite; granodiorite