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

Geologic units in Swain county, North Carolina

[Additional scientific data in this geographic area]

Amphibolite (Cambrian/Late Proterozoic) at surface, covers 0.1 % of this area

Amphibolite - equigranular, massive to well foliated, dioritic to basaltic dikes and sills; variably metamorphosed.

Lithology: amphibolite; basalt; diorite

Coweeta Group; Biotite Gneiss (Middle/Late Proterozoic) at surface, covers 0.1 % of this area

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

Lithology: biotite gneiss; amphibolite

Ocoee Supergroup, Great Smokey Group; Dean Formation (Late Proterozoic) at surface, covers 0.3 % of this area

Dean Formation - sericite schist with cross-biotite, staurolite, and garnet porphyroblasts; interbedded metagraywacke and quartz-pebble metaconglomerate.

Lithology: mica schist; metasedimentary rock

Mineral Bluff Formation (Late Proterozoic) at surface, covers < 0.1 % of this area

Mineral Bluff Formation - quartz-chlorite-sericite schist and phyllite with thin quartzite layers and minor interbedded graphitic schist, garnet-mica schist, staurolite schist, cross-biotite schist, and dark slate.

Lithology: schist; phyllite; quartzite; slate

Murphy Marble, Andrews Formation, and Nottely Quartzite, undivided (Late Proterozoic) at surface, covers 0.2 % of this area

Murphy Marble, Andrews Formation, and Nottely Quartzite, undivided - Murphy Marble: calcareous to dolomitic; Andrews Formation: calcareous cross-biotite schist; Nottely Quartzite: meta-orthoquartzite with slate.

Lithology: marble; schist; quartzite; slate

Ocoee Supergroup, Great Smokey Group; Boyd Gap Formation (Late Proterozoic) at surface, covers < 0.1 % of this area

Boyd Gap Formation - dark gray, highly-sulfidic slate and metasiltstone interbedded and gradational with metagraywacke. Stratigraphic position uncertain. In Cherokee County includes upper part of Buck Bald Formation.

Lithology: slate; metasedimentary rock

Nantahala Formation and Tusquitee Quartzite, undivided (Late Proterozoic) at surface, covers 2 % of this area

Nantahala Formation and Tusquitee Quartzite, undivided - Nantahala Formation: slate and metasiltstone, dark gray, laminated to thin bedded, sulfidic; Tusquitee Quartzite: white to light yellowish gray, numerous, thin slate layers.

Lithology: slate; metasedimentary rock; quartzite

Ocoee Supergroup, Snowbird Group; Longarm Quartzite (Late Proterozoic) at surface, covers 1 % of this area

Longarm Quartzite - cross-bedded, feldspathic, locally conglomeratic; includes dark slate and metasiltstone.

Lithology: quartzite; slate; metasedimentary rock

Ocoee Supergroup, Great Smokey Group; Anakeesta Formation (Late Proterozoic) at surface, covers 2 % of this area

Anakeesta Formation - slate to schist, dark gray, graphitic and sulfidic; includes interbedded argillaceous, feldspathic metagraywacke.

Lithology: slate; schist; metasedimentary rock

Ocoee Supergroup, Great Smokey Group; Metasandstone, Metagraywacke, Metasiltstone, and Mica Schist (Late Proterozoic) at surface, covers 3 % of this area

Metasandstone, Metagraywacke, Metasiltstone, and Mica Schist - beds and lenses of calc-silicate rock locally abundant; garnet, staurolite, and cross-biotite porphyroblasts common in fine-grained layers. Includes Hughes Gap and Hothouse formations in southern area; Horse Branch Member of Ammons Formation and Grassy Branch Formation in northern area.

Lithology: metasedimentary rock; mica schist; calc-silicate rock

Ocoee Supergroup, Great Smokey Group; Copperhill Formation (Late Proterozoic) at surface, covers 62 % of this area

Copperhill Formation - metagraywacke, massive, graded bedding common; includes dark-gray slate, mica schist, and nodular calc-silicate rock.

Lithology: metasedimentary rock; slate; mica schist; calc-silicate rock

Ocoee Supergroup, Snowbird Group, undivided (Late Proterozoic) at surface, covers 0.3 % of this area

Snowbird Group, undivided - feldspathic metasiltstone, metasandstone, and phyllite. Basal schist contains lenses of quartz-pebble conglomerate.

Lithology: metasedimentary rock; phyllite; schist; conglomerate

Ocoee Supergroup; Great Smokey Group, undivided (Late Proterozoic) at surface, covers 6 % of this area

Great Smokey Group, undivided - thick metasedimentary sequence of massive to graded beds of metagraywacke and metasiltstone with interbedded graphitic and sulfidic slate and schist.

Lithology: metasedimentary rock; slate; schist

Ocoee Supergroup, Snowbird Group; Roaring Fork Sandstone (Late Proterozoic) at surface, covers 0.6 % of this area

Roaring Fork Sandstone - greenish gray, fine to medium grained, locally cross-bedded, metamorphosed; interbedded metasiltstone and phyllite.

Lithology: sandstone; metasedimentary rock; phyllite

Ocoee Supergroup, Great Smokey Group; Slate of Copperhill Formation (Late Proterozoic) at surface, covers 4 % of this area

Slate of Copperhill Formation - slate to phyllite, dark gray, graphitic, sulfidic; includes metagraywacke with local graded bedding.

Lithology: slate; phyllite; metasedimentary rock

Brasstown Formation (Late Proterozoic) at surface, covers 2 % of this area

Brasstown Formation - cross-biotite schist; includes micaceous quartzite in lower part.

Lithology: mica schist; quartzite

Biotite Granitic Gneiss (Middle Proterozoic) at surface, covers 9 % 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

Ocoee Supergroup, Snowbird Group; Wading Branch Formation (Late Proterozoic) at surface, covers 0.2 % of this area

Wading Branch Formation - sandy slate to coarse-grained pebbly metagraywacke with local graded bedding. Basal quartz-sericite schist or phyllite.

Lithology: slate; metasedimentary rock; sand; schist; phyllite

Great Smoky Group, including Anakeesta Formation, Thunderhead Sandstone, and Elkmont Sandstone (Precambrian) at surface, covers 0.6 % of this area

Great Smoky Group - Characterized by very massive layers of coarse graywacke and arkose. The formations have been mapped only in the region of the Great Smoky Mountains. Near Ducktown, in ascending order, the Copperhill, Hughes Gap, Hothouse, and Dean Formations are recognized. Thickness 14,000 to about 40,000 feet. Includes Anakeesta Formation - Dark-gray, bluish-gray, and black slate with dark-gray interbeds of fine-grained sandstone. Thickness 3,000 to 4,500 feet; Thunderhead Sandstone - Coarse, gray feldspathic sandstone, graywacke, and conglomerate; occurs in massive ledges; graded bedding and blue quartz characteristic. Thickness 5,500 to 6,300 feet; Elkmont Sandstone - Coarse to fine, gray feldspathic sandstone, graywacke, and fine conglomerate; generally finer grained beds in lower part; graded bedding typical. Thickness 1,000 to 8,000 feet

Lithology: graywacke; arkose; slate; sandstone; conglomerate

Ocoee Supergroup, Great Smokey Group; Wehutty Formation (Late Proterozoic) at surface, covers 6 % of this area

Wehutty Formation - slate to schist, dark gray, graphitic and sulfidic; includes mica schist, metagraywacke, and metaconglomerate.

Lithology: slate; schist; metasedimentary rock