Tuscaloosa Group; Coker Formation

Light-colored micaceous very fine to medium sand, cross-bedded sand, varicolored micaceous clay, and a few thin gravel beds containing quartz and chert pebbles. Beds of thinly laminated finely glauconitic very fine to fine sand, silt and dark-gray carbonaceous clay (Eoline Member) occur locally in the lower part in western AL. Locally quartz and chert gravels at the base of the formation range in size from very fine pebbles to large cobbles. In southeastern Elmore County the formation includes marine sediments consisting of glauconitic, fossiliferous, quartzose fine to medium sand and medium-gray carbonaceous silty clay. Not mapped east of the Tallapoosa River.
State Alabama
Name Tuscaloosa Group; Coker Formation
Geologic age Cretaceous
Lithologic constituents
Major
Unconsolidated > Coarse-detrital > Sand (Bed)Light-colored micaceous very fine to medium sand, cross-bedded sand; beds of thinly laminated finely glauconitic very fine to fine sand; in southeastern Elmore County the formation includes marine sediments consisting of glauconitic, fossiliferous, quartzose fine to medium sand
Unconsolidated > Fine-detrital > Clay (Bed)varicolored micaceous clay, dark-gray carbonaceous clay; medium-gray carbonaceous silty clay
Minor
Unconsolidated > Fine-detrital > Silt (Bed)Beds of thinly laminated finely glauconitic very fine to fine sand, silt and dark-gray carbonaceous clay (Eoline Member) occur locally in the lower part in western AL; In southeastern Elmore County the formation includes marine sediments consisting of glauconitic, fossiliferous, quartzose fine to medium sand and medium-gray carbonaceous silty clay.
Incidental
Sedimentary > Chemical > Chert (Bed)a few thin gravel beds containing quartz and chert pebbles; locally quartz and chert gravels at the base of the formation range in size from very fine pebbles to large cobbles.
Unconsolidated > Coarse-detrital > Gravel (Bed)a few thin gravel beds containing quartz and chert pebbles; locally quartz and chert gravels at the base of the formation range in size from very fine pebbles to large cobbles.
References

Szabo, M.W., Osborne, E.W., Copeland, C.W. Jr., and Neathery, T.L., 1988, Geologic Map of Alabama, Geological Survey of Alabama Special Map 220, scale 1:250,000.

NGMDB product
Counties Autauga - Bibb - Chilton - Elmore - Fayette - Hale - Lamar - Marion - Perry - Pickens - Shelby - Tuscaloosa - Walker - Winston