Geologic units in Rutherford county, Tennessee

Stones River Group; Ridley Limestone (Ordovician) at surface, covers 52 % of this area

Thick-bedded, brownish-gray limestone, fine-grained, with minor mottlings of magnesian limestone; slightly cherty. Thickness 90 to 150 feet.

Stones River Group; Lebanon Limestone (Ordovician) at surface, covers 27 % of this area

Thin-bedded, gray limestone with calcareous shale partings. Thickness 80 to 100 feet.

Stones River Group; Carters Limestone (Ordovician) at surface, covers 11 % of this area

Fine-grained, yellowish-brown limestone; thin-bedded in upper part; thicker bedded and very slightly cherty with scattered mottlings of magnesian limestone in lower part. Contains thin bentonite beds. Thickness 50 to 100 feet.

Nashville Group; Bigby-Cannon Limestone and Hermitage Formation (Ordovician) at surface, covers 6 % of this area

Nashville Group - Bigby-Cannon Limestone - Brownish-gray phosphatic calcarenite and light-gray to brownish-gray, cryptograined to medium- grained, even-bedded limestone. Thickness 50 to 125 feet; and Hermitage Formation - Thin-bedded to laminated, sandy and argillaceous limestone with shale; nodular shaly limestone; coquina; and phosphatic calcarenite. Thickness 50 to 100 feet.

Stones River Group; Pierce Limestone and Murfreesboro Limestone (Ordovician) at surface, covers 2 % of this area

Stones River Group; Pierce Limestone - Gray, thin-bedded limestone with shale partings. Thickness 25 feet; and Murfreesboro Limestone - Thick-bedded, dark-gray, fine-grained limestone, with mottlings of magnesian limestone; somewhat cherty in upper part. Maximum exposed thickness 70 feet.

Ordovician [units] including Richmond Group (which includes Mannie Shale, Fernvale Limestone, Sequatchie Formation, and Arnheim Formation), the Maysville Group (which includes Leipers Formation), the Eden Group (which includes Inman Formation), and the Nashville Group (which includes Catheys Formation). (Ordovician) at surface, covers 2 % of this area

Ordovician [units] including Richmond Group (which includes Mannie Shale - Olive-gray shale. Thickness 0 to 20 feet; Fernvale Limestone - Massive, coarsely crystalline, gray limestone with varicolored grains. Thickness 0 to 50 feet; Sequatchie Formation - Olive-gray and greenish-gray shale, mudstone, and argillaceous limestone; dolomitic, laminated, and sandy. Thickness 0 to 100 feet; and Arnheim Formation Nodular, shaly, gray limestone. Thickness 0 to 20 feet; the Maysville Group (which includes Leipers Formation - Nodular, shaly limestone; fine- to coarse-grained limestone; and phosphatic calcarenite locally. Thickness 0 to 150 feet); the Eden Group (which includes the Inman Formation - Thin-bedded to laminated, fine-grained, gray limestone with shale partings. Thickness 0 to 50 feet); and the Nashville Group (which includes Catheys Formation - Nodular, shaly limestone; fine- to coarse-grained limestone; phosphatic calcarenite; and light-gray cryptograined limestone. Thickness 50 to 175 feet.)

Fort Payne Formation and Chattanooga Shale (Mississippian) at surface, covers 0.4 % 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)

Alluvial deposits (Quaternary) at surface, covers < 0.1 % 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.