Selma Group; Blufftown Formation

The Blufftown extends from the Chattahoochee River Valley westward into central Russell County where it is divided into two westward-extending tongues by an eastward-extending tongue of the Mooreville Chalk. In the Chattahoochee River Valley the Blufftown is mainly glauconitic calcareous fine sand, micaceous clay and marl, fossiliferous clay, gray calcareous fossiliferous sandstone, and carbonaceous clay and silt. To the west the lower tongue of the Blufftown is gravelly sand, glauconitic sand, calcareous clay, and sandy clay and merges with the lower part of the Mooreville Chalk in southwestern Macon County. The upper tongue is mainly calcareous sandy clay and micaceous silty fine sand with thin layers of limestone and sandstone. The upper tongue merges with the Mooreville Chalk and the lower part of the Demopolis Chalk in western Bullock County.
State Alabama
Name Selma Group; Blufftown Formation
Geologic age Cretaceous
Lithologic constituents
Major
Unconsolidated > Fine-detrital > Claymicaceous clay, fossiliferous clay, carbonaceous clay, sandy clay, calcareous clay.
Unconsolidated > Coarse-detrital > Sandglauconitic calcareous fine sand, gravelly sand, glauconitic sand, micaceous silty fine sand
Minor
Unconsolidated > Marlmicaceous clay and marl
Unconsolidated > Fine-detrital > Siltcarbonaceous clay and silt, micaceous silty fine sand
Sedimentary > Clastic > Sandstone (Calcareous)gray calcareous fossiliferous sandstone
Incidental
Sedimentary > Carbonate > Limestone (Bed)thin layers of limestone
Comments Note: Printed map uses unit symbol 'Kb'; digital map uses 'KRb'.
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 Barbour - Bullock - Macon - Russell