Geologic units in Trigg county, Kentucky

Ste. Genevieve and St. Louis Limestones, undivided (Mississippian) at surface, covers 70 % of this area

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

Tuscaloosa Formation (Upper Cretaceous) at surface, covers 12 % of this area

Tuscaloosa Formation

Warsaw Limestone (Mississippian) at surface, covers 10 % of this area

Warsaw Limestone; west of Christian County

Rocks of Chesterian age, lower part (Upper Mississippian) at surface, covers 4 % of this area

Rocks of Chesterian age, lower part

Renfro and Muldraugh Members of Borden Formation and Fort Payne Formation, undivided (Mississippian) at surface, covers 2 % of this area

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

Continental deposits, undifferentiated (Tertiary to Quaternary) at surface, covers 1 % of this area

Continental deposits, undifferentiated; East of the Tennessee River

Alluvium (Pleistocene to Holocene) at surface, covers 0.6 % of this area

Alluvium; includes glacial deposits along the Ohio River and its tributaries west of Cannelton locks

Clayton and McNairy Formations, undivided (Paleocene to Upper Cretaceous) at surface, covers 0.4 % of this area

Clayton and McNairy Formations, undivided

St. Louis Limestone and Warsaw Limestone (Mississippian) at surface, covers < 0.1 % 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 < 0.1 % 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. Louis Limestone and Warsaw Limestone (Mississippian) at surface, covers < 0.1 % 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.

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 (Cretaceous) at surface, covers < 0.1 % 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.