Geologic units in Prentiss county, Mississippi

Coffee sand (Upper Cretaceous) at surface, covers 43 % of this area

(Selma group), Light-gray cross-bedded to massive glauconitic sand and sandy clay and calcareous sandstone.

Demopolis chalk (Upper Cretaceous) at surface, covers 19 % of this area

(Selma group), Chalk and marly chalk containing fewer impurities than underlying and overlying formations.

Eutaw formation (Upper Cretaceous) at surface, covers 18 % of this area

More or less cross-bedded and thinly laminated glauconitic sand and clay; basal part includes the McShan formation, greenish-gray, micaceous, locally very glauconitic, very fine-grained sand and thin-bedded light-gray clay, small chert gravels may be present in basal beds, not recognized in northern Tishomingo County.

Eutaw formation (Tombigbee sand member) (Late Cretaceous) at surface, covers 13 % of this area

Massive fine glauconitic sand.

Ripley formation (Upper Cretaceous) at surface, covers 5 % of this area

(Selma group), Gray to greenish-gray fine glauconitic sand, clay, and sandy limestone; south of Oktibbeha County is very sandy micaceous chalk.

Ripley formation (McNairy sand member) (Upper Cretaceous) at surface, covers < 0.1 % of this area

(Selma group), Red and white cross-bedded micaceous sand and white sandy clay.