Geologic units in Stewart county, Tennessee

Additional scientific data in this geographic area

St. Louis Limestone and Warsaw Limestone (Mississippian) at surface, covers 67 % of this area

St. Louis Limestone - Fine-grained, brownish-gray limestone, dolomitic and cherty. Thickness 100 to 280 feet; and Warsaw Limestone - Coarse-grained, gray, crossbedded limestone; somewhat shaly in the northeast. Thickness 40 to 150 feet.

Fort Payne Formation and Chattanooga Shale (Mississippian) at surface, covers 19 % of this area

Fort Payne Formation - Bedded chert; calcareous and dolomitic silicastone; minor limestone and shale; scattered lenses of crinoidal limestone. Thin green shale (Maury) at base. Average thickness about 250 feet (475 in Wells Creek area); and Chattanooga Shale - Black carbonaceous shale, fissile. Thickness 0 to 70 feet; average about 20 feet. (Mapped as MDc on East-Central and East sheets)

St. Genevieve Limestone (Mississippian) at surface, covers 6 % of this area

Gray limestone, slightly oolitic and cherty, with some green shale and fine-grained sandstone. Maximum preserved thickness 70 feet. (In Western Highland Rim area only.)

Alluvial deposits (Quaternary) at surface, covers 4 % of this area

Sand, silt, clay, and gravel. As much as 60 feet thick in flood plains of Tennessee and Cumberland Rivers; in smaller streams generally less than 20 feet thick.

Tuscaloosa Formation (Cretaceous) at surface, covers 2 % of this area

Poorly sorted, light-gray chert gravel in a matrix of silt and sand; locally interbedded with sand and clay lenses. Thickness 0 to 150 feet.

Ordovician Formations, including Mannie Shale, Fernvale Limestone, Hermitage Formation, and Carters, Lebanon, Ridley, Pierce, and Murfreesboro Limestones (Ordovician) at surface, covers 0.3 % of this area

Ordovician Formations - including Mannie Shale - Shale with thin beds of argillaceous limestone. Thickness 0 to 20 feet; Fernvale Limestone - Thick-bedded, coarse-grained, gray limestone with varicolored grains. Thickness 0 to 30 feet; Hermitage Formation - Gray shale and thin-bedded to laminated, sandy and argillaceous limestone. About 200 to 300 feet thick in Wells Creek Basin; only about 80 feet exposed in Western Valley; and the Carters, Lebanon, Ridley, Pierce, and Murfreesboro Limestones - Thin- to thick-bedded, cryptograined to coarse-grained, yellowish-brown to olive-gray limestones. Thickness about 1,000 feet. (Not exposed in Western Valley.)

St. Louis Limestone and Warsaw Limestone (Mississippian) at surface, covers 0.2 % of this area

St. Louis Limestone - Residuum of nodules and blocks of chert in sandy clay. (Originally grayish-brown, medium-bedded limestone.) Maximum preserved thickness about 50 feet. Warsaw Limestone - Residuum of porous chert blocks in sandy clay. (Originally gray, medium- to coarse-grained, thick- bedded limestone.) Thickness about 60 feet.

Ste. Genevieve and St. Louis Limestones, undivided (Mississippian) at surface, covers 0.2 % of this area

Ste. Genevieve and St. Louis Limestones, undivided; includes Salem Limestone west of Christian County

Silurian Formations, including Decatur Limestone, Brownsport Group (Lobelville Formation, Bob Limestone, Beech River Formation), Wayne Group (Dixon Formation, Lego Formation, Waldron Shale, Laurel Limestone, Osgood Formation) and Brassfield Limestone (Silurian) at surface, covers 0.2 % of this area

Silurian Formations - Characteristically light olive-gray to greenish-gray, with variable reddish-brown color in some areas. Individual formations are generally uniform in thickness, except where truncated by pre- Chattanooga erosion. Most formations are slightly thicker (than indicated) in Wells Creek Basin. Includes Decatur Limestone- Thick-bedded, medium- to coarse-grained limestone, gray with reddish-brown grains. Thickness 0 to 70 feet; Brownsport Group (which includes Lobelville Formation - Shale with thin beds of limestone. Thickness 0 to 30 feet; Bob Limestone - Thick-bedded, medium-grained limestone, locally oolitic. Thickness 0 to 25 feet; and Beech River Formation - Shale with thin beds of limestone. Thickness 0 to 60 feet); Wayne Group (which includes Dixon Formation - Green and reddish-brown argillaceous limestone, shale, and mudstone. Thickness 0 to 40 feet; Lego Limestone - Even-bedded, olive-gray limestone with scattered reddish-brown grains. Thickness 0 to 30 feet; Waldron Shale - Greenish-gray fossiliferous shale. Thickness 0 to 5 feet; Laurel Limestone - Even-bedded, olive-gray limestone with scattered reddish-brown grains. Thickness 0 to 30 feet; Osgood Formation - Greenish- and reddish-gray shale and argillaceous limestone. Thickness 0 to 15 feet); and Brassfield Limestone - Thin-bedded cherty limestone, locally glauconitic. Thickness 0 to 50 feet; generally about 20 feet.

High-level alluvial deposits (Quaternary-Tertiary) at surface, covers 0.1 % of this area

Iron-stained gravel, sand, silt, and clay; variable in thickness but generally less then 60 feet thick.

Wells Creek Dolomite and Knox Group (Ordovician) at surface, covers 0.1 % of this area

Yellowish-gray and light olive-gray dolomite, within partings of grayish-green shale, and pale- orange to yellowish-gray limestone; thin- to thick-bedded, micrograined to coarse-grained. Present only in Wells Creek Basin. Exposed thickness at least 600 feet. (Also mapped with Onc on East-Central Sheet)

Alluvial deposits (Quaternary) at surface, covers 0.1 % of this area

Sand, silt, clay, and gravel. In flood plain of Mississippi River more than 100 feet thick; in smaller streams generally less than 20 feet thick.

Devonian Formations, including Pegram Formation, Camden Formation, Harriman Formation, Flat Gap Limestone, and Ross Formation (Devonian) at surface, covers 0.1 % of this area

Devonian Formations - Characterized by marked north-south facies variations and by very irregular distribution. Individual formations are not uniform in thickness and have been truncated by pre-Chattanooga erosion; includes Pegram Formation - Thick-bedded, gray limestone and gray sandstone. Thickness 0 to 30 feet; Camden Formation - Light-gray novaculitic chert and tripolitic clay; and minor siliceous limestone. Thickness 0 to about 100 feet; Harriman Formation - Light-gray novaculitic chert and tripolitic clay; and minor siliceous limestone. (Harriman and Camden are differentiated paleontologically.) Thickness 0 to 50 feet; Flat Gap Limestone - Thick-bedded, coarse-grained limestone, gray with red and brown grains. Thickness 0 to 13 feet; Ross Formation - Siliceous limestone; gray and variegated shale; and medium-grained glauconitic limestone. Thickness 0 to 75 feet.

Warsaw Limestone (Mississippian) at surface, covers < 0.1 % of this area

Warsaw Limestone; west of Christian County

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

Fort Payne Formation - Bedded chert and calcereous and dolomitic silicastone; minor coarse-grained limestone and shale. Thin green shale (Maury) at base. Thickness about 200 feet. Chattanooga Shale - Black carbonaceous shale, fissile. Thickness 0 to 70 feet.

Tuscaloosa Formation (Upper Cretaceous) at surface, covers < 0.1 % of this area

Tuscaloosa Formation

Renfro and Muldraugh Members of Borden Formation and Fort Payne Formation, undivided (Mississippian) at surface, covers < 0.1 % of this area

Renfro and Muldraugh Members of Borden Formation and Fort Payne Formation, undivided