Geologic units in Swain county, North Carolina

Additional scientific data in this geographic area

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

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

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

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

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

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

Slate to schist, dark gray, graphitic and sulfidic; includes mica schist, metagraywacke, and metaconglomerate.

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

Slate to phyllite, dark gray, graphitic, sulfidic; includes metagraywacke with local graded bedding.

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

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.

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

Slate to schist, dark gray, graphitic and sulfidic; includes interbedded argillaceous, feldspathic metagraywacke.

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

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

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

Cross-biotite schist; includes micaceous quartzite in lower part.

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

Cross-bedded, feldspathic, locally conglomeratic; includes dark slate and metasiltstone.

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

Greenish gray, fine to medium grained, locally cross-bedded, metamorphosed; interbedded metasiltstone and phyllite.

Great Smoky Group, includes Unnamed Sandstone Unit, 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 at right have been mapped only in region of the Great Smoky Mountains. Thickness 14,000 to about 25,000 feet; includes Unnamed Sandstone Unit - Gray, coarse sandstone and fine conglomerate, similar to Thunderhead Sandstone. Thickness about 4,500 feet; 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.

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

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

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

Feldspathic metasiltstone, metasandstone, and phyllite. Basal schist contains lenses of quartz-pebble conglomerate.

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

Sandy slate to coarse-grained pebbly metagraywacke with local graded bedding. Basal quartz-sericite schist or phyllite.

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

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

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

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

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

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.

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

Equigranular, massive to well foliated, dioritic to basaltic dikes and sills; variably metamorphosed.

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

Equigranular, massive to well foliated, dioritic to basaltic dikes and sills; variably metamorphosed.

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

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.