USGS Home
Contact USGS
Search USGS

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

Geologic units in Roane county, Tennessee

[Additional scientific data in this geographic area]

Newman Limestone (Mississippian) at surface, covers 0.3 % of this area

Newman Limestone - Gray limestone sequence near Cumberland Plateau and on Whiteoak Mountain. Shaly limestone, shale, siltstone, and sandstone on Chilhowee Mountain. Thickness about 700 feet.

Lithology: limestone; shale; siltstone; sandstone

Crab Orchard Mountains Group (Pennsylvanian) at surface, covers 2 % of this area

Crab Orchard Mountains Group - Only the lowest formation of the group, the Sewanee Conglomerate, is preserved in the area of this sheet. Sewanee is gray to brown, medium- to coarse-grained conglomeratic sandstone, with a thin zone of ferruginous quartz- and shale-pebble conglomerate at base. Maximum preserved thickness 35 feet.

Lithology: conglomerate; sandstone

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 1 % 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

Gizzard Group including Warren Point Sandstone and Raccoon Mountain Formation (Pennsylvanian) at surface, covers 0.7 % of this area

Gizzard Group - Sandstone, conglomeratic sandstone, siltstone, shale, and minor coal. Thickness 100 to 200 feet. Includes Warren Point Sandstone - Gray to brown sandstone and minor conglomeratic sandstone. Thickness 60 to 160 feet; Raccoon Mountain Formation - Siltstone, sandstone, shale, and minor coal. Thickness 0 to 65 feet.

Lithology: sandstone; shale; siltstone; coal

Copper Ridge Dolomite (Cambrian) at surface, covers 6 % 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

Unnamed (upper part of Knox Group), including Newala Formation, Mascot Dolomite, Kingsport Formation, Longview Dolomite, and Chepultepec Dolomite (Ordovician) at surface, covers 10 % 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

Crooked Fork Group (Pennsylvanian) at surface, covers 1 % of this area

Crooked Fork Group - Shale, sandstone, siltstone, and thin coal beds; from top down group includes Poplar Creek coal, Wartburg Sandstone, Glenmary Shale, Coalfield Sandstone, Burnt Mill Shale, Crossville Sandstone, and Dorton Shale. Thickness 200 to 450 feet.

Lithology: sandstone; shale; siltstone; coal

Chickamauga Group, includes Upper part of Chickamauga Group (Reedsville Shale, and Unnamed limestone unit) and Middle and Lower part of Chickamauga Group (Moccasin Formation, Bays Formation, Ottosee Shale, Holston Formation, Lenoir Limestone, Athens Shale, and Sevier Shale) (Ordovician) at surface, covers 15 % of this area

Chickamauga Group - In the northwest part of the Valley and Ridge a predominantly limestone sequence about 2,000 feet thick. Becomes progressively more clastic and thicker to the southeast, including Upper part of Chickamauga Group (Reedsville Shale- Greenish-gray calcareous shale. Thickness 0 to 400 feet, and Unnamed Limestone Unit - Medium-grained, fossiliferous, gray limestone, shaly in part. Thickness as much as 600 feet ) and.Middle and lower parts of Chickamauga Group (Omlc)

Lithology: limestone; shale; siltstone; sandstone

Sequatchie Formation (Ordovician) at surface, covers 1 % of this area

Sequatchie Formation - Maroon and gray shaly limestone, mottled greenish; with interbeds of calcareous, olive to maroon shale and siltstone. Average thickness about 200 feet.

Lithology: limestone; shale; siltstone

Knox Group, including Newala Formation, Mascot Dolomite, Kingsport Formation, Longview Dolomite, Chepultepec Dolomite, and Copper Ridge Dolomite (Ordovician to Cambrian) at surface, covers 21 % of this area

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

Lithology: dolostone (dolomite); limestone

Mississippian, Silurian, Devonian, and Ordovician Formations - containing all or portions of the Newman, Fort Payne, Chattanooga, Rockwood, and Sequatchie formations. (Mississippian to Ordovician) at surface, covers < 0.1 % of this area

Mississippian, Silurian, Devonian, and Ordovician Formations - Structurally complex area containing all or portions of the Newman, Fort Payne, Chattanooga, Rockwood, and Sequatchie formations.

Lithology: shale; limestone; chert; siltstone; sandstone; black shale

Fort Payne Formation (Mississippian) at surface, covers 0.7 % of this area

Fort Payne Formation - Bedded chert, calcareous and dolomitic, somewhat crinoidal; and minor shale. Thin green shale (Maury) at base. Average thickness about 200 feet.

Lithology: chert; shale

Crab Orchard Mounatins and Gizzard Group (Pennsylvanian) at surface, covers 0.8 % of this area

Crab Orchard Mountains and Gizzard Groups - Sandstone, conglomerate, siltstone, shale, and thin coal beds. From top down Crab Orchard Mountains group includes Rockcastle Conglomerate, Vadever Formation, Newton Sandstone, Whitwell Shale, and Sewanee Conglomerate; Gizzard Group includes Signal Point Shale, Warren Point Sandstone, and Raccoon Mountain Formation. Thickness about 1,200 to 1,400 feet.

Lithology: sandstone; conglomerate; shale; siltstone; coal

Rome Formation (Cambrian) at surface, covers 14 % 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

Maynardville Limestone (Cambrian) at surface, covers 2 % 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)

Nolichucky Shale, and Maryville, Rogersville, and Rutledge Formations, and Pumpkin Valley Shale (Cambrian) at surface, covers 16 % 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

Chattanooga Shale (Mississippian and Devonian) at surface, covers < 0.1 % of this area

Chattanooga Shale - Black carbonaceous shale, fissile. Thickness 20 to 30 feet in most areas; thickens abruptly to about 100 feet near east edge of sheet. (Mapped with Mfp on West-Central sheet)

Lithology: black shale

Pennington Formation (Mississippian) at surface, covers 2 % of this area

Pennington Formation - Highly variegated clay shale, distinctive; contains siltstone and locally gray, fine-grained sandstone. Thickness 400 to 700 feet.

Lithology: shale; siltstone; sandstone

Rockwood Formation (Silurian) at surface, covers 2 % of this area

Rockwood Formation - Brown to maroon shale, thin gray siltstone and sandstone, and thin lenticular layers of oolitic and fossiliferous red hematite. Thickness 200 to 800 feet.

Lithology: shale; siltstone; sandstone

Rockcastle Conglomerate (Pennsylvanian) at surface, covers 2 % of this area

Rockcastle Conglomerate - Conglomeratic sandstone and sandstone, gray to brown, fine- to coarse-grained. Thin coal-bearing shale locally present near middle. Thickness 150 to 220 feet.

Lithology: conglomerate; sandstone; shale; coal