Geologic units in Unicoi county, Tennessee

Additional scientific data in this geographic area

Unicoi Formation (Cambrian) at surface, covers 23 % of this area

Sequence of gray feldspathic sandstone, arkose, conglomerate, graywacke, siltstone and shale; greenish amygdaloidal basalt flows near middle and base. Thickness 2,000 to 5,000 feet.

Cranberry Granite (Precambrian) at surface, covers 16 % of this area

Complex of intertonguing rock types including migmatite, granitic gneisses, monzonite, quartz diorite, greenstone, mica and hornblende schists, abundant granitic pegmatite.

Hampton Formation (Cambrian) at surface, covers 13 % of this area

Dark greenish-gray, silty and sandy, micaceous shale; numerous layers of medium-grained, feldspathic, thinly bedded sandstone. Thickness 500 to 2,000 feet.

Erwin Formation (Cambrian) at surface, covers 10 % of this area

White, vitreous quartzite, massive, with interbeds of dark-green silty and sandy shale, minor siltstone, and very fine-grained sandstone. Thickness 1,000 to 1,500 feet.

Roan Gneiss (Precambrian) at surface, covers 7 % of this area

Layered hornblende and garnet gneiss and granitic migmatite with zones of mica schist and amphibolite, foliation commonly contorted; contains numerous granitic and gabbroic dikes.

Beech Granite (Precambrian) at surface, covers 6 % of this area

Granite, porphyritic, light-gray to reddish; coarse potash feldspar crystals and clustered interstitial mafics (chloritized biotite and hornblende) give spotted appearance; includes Max Patch Granite.

Snowbird Group, including Pigeon Siltstone, Roaring Fork Sandstone, Metcalf Phyllite, Longarm Quartzite, and Wading Branch Formation (Precambrian) at surface, covers 6 % of this area

Snowbird Group - The formations at right are applicable chiefly in the area of the Great Smoky Mountains. Thickness 13,000 to about 20,000 feet. Includes Pigeon Siltstone - Laminated, greenish quartzose and feldspathic siltstone; minor fine-grained gray sandstone. Thickness as much as 10,000 feet; Roaring Fork Sandstone - Interbedded massive feldspathic sandstone, greenish siltstone, and greenish phyllite. Maximum thickness 7,000 feet; Metcalf Phyllite - Lustrous, pale-green and silvery sericitic and chloritic phyllite; siltstone interbeds abundant. Thickness uncertain; at least 5,000 feet; Longarm Quartzite - Feldspathic quartzite and arkose, conspicuously light-colored, current bedded and crossbedded. Thickness about 5,000 feet; Wading Branch Formation - Medium- to dark-gray sandy slate to coarse, pebbly feldspathic sandstone and graywacke; basal part is quartz-sericite phyllite; graded bedding common. Thickness about 1,500 feet.

Shady Dolomite (Cambrian) at surface, covers 6 % of this area

Light-gray, well-bedded dolomite with thin- to medium-bedded gray limestone; yellowish-brown residual clays with "jasperoid" diagnostic. Thickness about 1,000 feet.

Sandsuck Formation (Precambrian) at surface, covers 4 % of this area

Olive-green and gray, argillaceous, micaceous shale with coarse feldspathic sandstone and quartz- pebble conglomerate. Thickness about 2,000 feet.

Rome Formation (Cambrian) at surface, covers 3 % of this area

Variegated (red, green, yellow) shale and siltstone; gray, fine-grained sandstone in middle and west part of Valley and Ridge; abundant limestone and dolomite in east. Thickness about 2,000 feet.

Honaker Dolomite (Cambrian) at surface, covers 3 % of this area

Dark-gray, medium-bedded dolomite with minor dark limestone beds; locally cherty; cryptozoans abundant in places. Thickness about 1,500 feet.

Knox Group, including Jonesboro Limestone, Newala Formation, Mascot Dolomite, Kingsport Formation, Longview Dolomite, Chepultepec Dolomite, Copper Ridge Dolomite, Conococheague Limestone (Ordovician to Cambrian) at surface, covers 2 % of this area

Knox Group, including (Ojb) Jonesboro Limestone - Dark bluish-gray, ribboned (silt and dolomite) limestone; numerous interbeds of dark-gray dolomite; quartz sandstone at base. Erosional unconformity at top. Thickness about 2,000 feet; (On) Newala Formation; (Oma) Mascot Dolomite - Light-gray, fine-grained, well-bedded cherty dolomite; mottled (red and green) dolomite characteristic; interbeds of bluish-gray limestone in upper part; chert-matrix quartz sandstone at base. Erosional unconformity at top. Thickness 350 to 800 feet; (Ok) Kingsport Formation - Gray, fine-grained, sparingly cherty dolomite with basal dense, gray limestone sequence. Thickness about 250 feet; (Olv) Longview Dolomite - Siliceous, gray, fine-grained, medium-bedded dolomite; interbeds of gray limestone in upper part. Thickness about 300 feet; (Oc) Chepultepec Dolomite - Light-gray, fine-grained, well-bedded dolomite, moderately cherty; fine-grained limestone locally in upper part; quartz sandstone beds at base. Thickness about 800 feet; (Ccr) Copper Ridge Dolomite - Coarse, dark-gray, knotty dolomite, asphaltic in places; with much gray, medium-grained, well- bedded dolomite; abundant chert; cryptozoans typical. Thickness about 1,000 feet.; (Ccc) Conococheague Limestone - Well-bedded, ribboned (silt and dolomite), dark-gray limestone; interbeds of fine-grained, light- to dark-gray dolomite; sparingly cherty; cryptozoans typical. Thickness about 1,500 feet.

Maynardville Limestone, Nolichucky Shale, and Honaker Dolomite (Cambrian) at surface, covers 0.5 % of this area

Maynardville Limestone - Thick-bedded, bluish-gray, ribboned (silt and dolomite) nodular limestone; light-gray, fine-grained, laminated to thinly bedded, noncherty dolomite in upper part. Thickness 150 to 400 feet; Nolichucky Shale - Pastel-colored (pink, greenish, olive), flaky clay shale; gray, commonly oolitic, shaly limestone lenses; locally stromatolitic limestone layers; thin, blocky siltstone near middle. Thickness 100 feet in the east to 900 feet in the west; Honaker Dolomite - Dark-gray, medium-bedded dolomite with minor dark limestone beds; locally cherty; cryptozoans abundant in places. Thickness about 1,500 feet.

Biotite Granitic Gneiss (Middle Proterozoic) at surface, covers 0.3 % 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.

Bakersville Gabbro (Precambrian) at surface, covers 0.2 % of this area

Metagabbro, dark, porphyritic; contains diorite, basalt, anorthosite, and diabase; occurs as thin to massive dikes and lenticular masses.

Granodioritic Gneiss (Middle Proterozoic) at surface, covers 0.1 % of this area

Unconformity; greenish gray to pinkish gray, porphyroclastic to mylonitic; epidote, sericite, and chlorite common.

Chilhowee Group; Lower Chilhowee (Cambrian) at surface, covers < 0.1 % of this area

Feldspathic arenite, white to yellowish gray. Minor silty shale, feldspathic siltstone, and conglomerate in lower part. Includes Unicoi Formation of Hot Springs window.

Ocoee Supergroup, Snowbird Group, undivided (Late Proterozoic) at surface, covers < 0.1 % of this area

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

Ocoee Supergroup; Walden Creek Group, undivided (Late Proterozoic) at surface, covers < 0.1 % of this area

Slate to metasiltstone, locally limy beds and pods; interbedded with quartz-pebble metaconglomerate and metasandstone.