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Mineral Resources > Online Spatial Data > Geology > by state > Tennessee Geology

Geologic units in Polk county, Tennessee

[Additional scientific data in this geographic area]

Unnamed (upper part of Knox Group), including Newala Formation, Mascot Dolomite, Kingsport Formation, Longview Dolomite, and Chepultepec Dolomite (Ordovician) at surface, covers < 0.1 % of this area

(Onc) Unnamed (upper part of the Knox Group), including the (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. and (Olc) Unnamed (middle part of the Knox Group), including (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. Average thickness about 800 feet.

Lithology: dolostone (dolomite); limestone; sandstone

Copper Ridge Dolomite (Cambrian) at surface, covers 0.2 % of this area

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.

Lithology: dolostone (dolomite); chert

Shady Dolomite (Cambrian) at surface, covers < 0.1 % of this area

Shady Dolomite - Light-gray dolomite and thinly bedded limestone with much shaly gray limestone and calcareous gray shale. Thickness about 1,000 feet.

Lithology: dolostone (dolomite); limestone; shale

Chilhowee Group; Murray Shale (Cambrian) at surface, covers 0.9 % of this area

Chilhowee Group; Murray Shale - Shale, silty, sandy, dull-green to brown, micaceous. Thickness about 500 feet.

Lithology: shale

Nichols Shale (Cambrian) at surface, covers 1 % of this area

Chilhowee Group; Nichols Shale - Olive-gray to green, silty and sandy, micaceous shale and siltstone; local lenses of fine-grained feldspathic quartzite. Thickness about 700 feet.

Lithology: shale; siltstone; quartzite

Walden Creek Group, including Sandsuck Formation, Wilhite Formation, Shields Formation, and Licklog Formation (Cambrian) at surface, covers 22 % of this area

Walden Creek Group - The formations, other than the Sandsuck, are applicable mainly in the region of the Great Smoky Mountains. Thickness about 8,000 feet, Includes Sandsuck Formation - Olive-green and gray, argillaceous, micaceous shale with coarse feldspathic sandstone and quartz- pebble conglomerate. Thickness about 2,000 feet; Wilhite Formation - Gray to green siltstone and slate with interbeds of pebble conglomerate, sandstone, and quartzite. Thickness about 4,000 feet; Shields Formation - Massive conglomerate, sandstone, argillaceous slate; conglomerate (pebbles of various rock types) characteristic. Thickness about 1,500 feet.; Licklog Formation - Feldspathic sandstone, greenish phyllite, and bluish-gray slate. Thickness about 1,500 feet.

Lithology: shale; siltstone; sandstone; conglomerate; slate; quartzite; phyllite

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

Phyllite - dark olive gray, graphitic and sulfidic.

Lithology: phyllite

Conasauga Group, including Maynardville Limestone, Nolichucky Shale, the Maryville, Rogersville, and Rutledge Formations, Pumpkin Valley Shale, Rome Formation, and Shady Dolomite (Cambrian) at surface, covers 2 % of this area

Conasauga Group - Mostly shale northwest of a line connecting Etowah and Bearden (Knoxville); to the east it consists of the six formations at right [Cmn, Maynardville Limestone. Ccl including Cn, Nolichucky Shale, Cmr Maryville, Rogersville, and Rutledge Formations, and Pumpkin Valley Shale; Cr, Rome Formation, and Cs, Shady Dolomite. Thickness about 2,000 feet.

Lithology: shale; limestone; dolostone (dolomite); sandstone; siltstone

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

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

Lithology: slate; schist; metasedimentary rock

Great Smoky Group, including Anakeesta Formation, Thunderhead Sandstone, and Elkmont Sandstone (Precambrian) at surface, covers 32 % 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

Chilhowee Group; Cochran Conglomerate (Cambrian) at surface, covers 1 % of this area

Chilhowee Gourp; Cochran Conglomerate - Quartz-pebble conglomerate, gray pebbly arkose, siltstone and shale; irregular bedding, scour features, crossbedding common; maroon micaceous arkose and shale near middle and base. Thickness about 1,200 feet.

Lithology: conglomerate; arkose; sandstone; siltstone; shale

Athens Shale (Ordovician) at surface, covers 4 % of this area

Athens Shale - Medium- to dark-gray, calcareous, graptolitic shale; calcareous gray sandstone, siltstone, and locally fine-pebble quartz conglomerate; nodules of shaly limestone near base. Maximum thickness 1,500 feet.

Lithology: shale; sandstone; siltstone; conglomerate; limestone

Nolichucky Shale, and Maryville, Rogersville, and Rutledge Formations, and Pumpkin Valley Shale (Cambrian) at surface, covers 5 % of this area

(Cn) 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 500 feet in the east to 900 feet in the west.; (Cmr) Maryville, Rogersville, and Rutledge Formations - Maryvile and Rutledge are gray limestone, in part oolitic, with gray dolomite locally. Rogersville is green clay shale. Thickness 400 to 1,000 feet. Pumpkin Valley Shale - Dull-brown to maroon shale with numerous interbeds of thin, blocky, sandy siltstone. Thickness 100 to 600 feet.

Lithology: shale; limestone; dolostone (dolomite); siltstone

Walden Creek Group; Sandsuck Formation (Precambrian) at surface, covers 14 % of this area

Wladen Creek Group; Sandsuck Formation - Olive-green and gray, argillaceous, micaceous shale with coarse feldspathic sandstone and quartz- pebble conglomerate. Thickness about 2,000 feet.

Lithology: shale; sandstone; conglomerate

Chilhowee Group; Nebo Sandstone (Cambrian) at surface, covers 1 % of this area

Chilhowee Group; Nebo Sandstone - Medium-bedded, fine-grained, white vitreous quartzite, in part feldspathic. Thickness 250 feet.

Lithology: quartzite

Intrusive igneous rocks (Paleozoic (?)) at surface, covers < 0.1 % of this area

Intrusive Igneous Rocks - Metadiorite and metagabbro in Polk County, intrude Great Smoky Group.

Lithology: diorite; gabbro

Knox Group, including Newala Formation, Mascot Dolomite, Kingsport Formation, Longview Dolomite, Chepultepec Dolomite, and Copper Ridge Dolomite (Ordovician to Cambrian) at surface, covers 12 % of this area

Knox Group - Siliceous dolomite and magnesian limestone sequence. Thickness 2,500 to 3,000 feet.

Lithology: dolostone (dolomite); limestone

Ocoee Supergroup, Great Smokey Group; Copperhill Formation (Late Proterozoic) at surface, covers 0.1 % 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

Maynardville Limestone (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 thin-bedded, noncherty dolomite in upper part. Thickness 150 to 400 feet.

Lithology: limestone; dolostone (dolomite)

Chilhowee Group; Hesse Sandstone (Cambrian) at surface, covers 2 % of this area

Chilhowee Group; Hesse Sandstone - White, vitreous quartzite, medium- to coarse-grained, occurs in massive ledges; Helenmode Member at top is gray to greenish sandstone and shale. Thickness about 600 feet.

Lithology: quartzite; sandstone; shale

Rome Formation (Cambrian) at surface, covers 0.3 % of this area

Rome Formation - Variegated (red, green, yellow) shale and siltstone with beds of gray, fine-grained sandstone. Maximum exposed thickness 1,500 feet.

Lithology: shale; siltstone; sandstone

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