(Selma group), Chalk and marly chalk containing fewer impurities than underlying and overlying formations.
(Selma group), Marly chalk and calcareous clay.
(Selma group), Gray to greenish-gray fine glauconitic sand, clay, and sandy limestone; south of Oktibbeha County is very sandy micaceous chalk.
(Selma group), Prairie Bluff chalk, compact brittle chalk, sandy chalk, and calcareous clay; at base contains many phosphatic molds of fossils; in Ponotoc and Union Counties merges northward into Owl Creek formation, tough blue glauconitic sandy clay.
(Midway group), Upper part, greenish-gray coarsely glauconitic sandy clay and marl; lower part, crystalline sandy limestone and loose sand, represented south of Houston by a discontinuous bed of indurated calcareous sandstone.
Massive fine glauconitic sand.
(Midway group), Dark-gray clay, north of Clay County contains slightly glauconitic, micaceous sand lenses.
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.