Geologic units in Lowndes county, Mississippi

Demopolis chalk (Upper Cretaceous) at surface, covers 26 % of this area

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

Eutaw formation (Upper Cretaceous) at surface, covers 26 % 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 22 % of this area

Massive fine glauconitic sand.

Mooreville chalk (Upper Cretaceous) at surface, covers 18 % of this area

(Selma group), Marly chalk and calcareous clay.

Tuscaloosa formation (Upper Cretaceous) at surface, covers 6 % of this area

Light and vari-colored irregularly bedded sand, clay, and gravel; gravel is mostly in lower portion.

Alluvial, coastal and low terrace deposits (Holocene) at surface, covers 0.2 % of this area

Varicolored fine to coarse quartz sand containing clay lenses and gravel in places. Gravel composed of quartz and chert pebbles and assorted metmorphic and igneous rock fragments in streams near the Piedmont. In areas of the Valley and Ridge province gravel composed of angular to subrounded chert, quartz, and quartzite pebbles. Coastal deposits include fine to medium quartz sand with shell fragments and accessory heavy minerals along Gulf beaches and fine to medium quartz sand, silt, clay, peat, mud and ooze in the Mississippi Sound, Little Lagoon, bays, lakes, streams, and estuaries.

Eutaw Formation (Cretaceous) at surface, covers < 0.1 % of this area

Light-greenish-gray to yellowish-gray cross-bedded, well-sorted, micaceous, fine to medium quartz sand that is fossiliferous and glauconitic in part and contains beds of greenish-gray micaceous, silty clay and medium-dark-gray carbonaceous clay. Light-gray glauconitic fossiliferous sand, thin beds of sandstone, and massive accumulations of fossil oyster shells occur locally in the upper part of the formation in western AL (Tombigbee Sand Member). In eastern AL thin to thick-bedded accumulations of the fossil oyster Ostrea cretacea Morton occur throughout much of the formation.

High terrace deposits (Pleistocene) at surface, covers < 0.1 % of this area

Varicolored lenticular beds of poorly sorted sand, ferruginous sand, silt, clay, and gravelly sand. Sand consists primarily of very fine to very coarse poorly sorted quartz grains; gravel composed of quartz, quartzite, and chert pebbles.

Tuscaloosa Group; Gordo Formation (Cretaceous) at surface, covers < 0.1 % of this area

Massive beds of cross-bedded sand, gravelly sand, and lenticular beds of locally carbonaceous partly mottled moderate-red and pale-red-purple clay; lower part is predominantly a gravelly sand consisting chiefly of chert and quartz pebbles. Not mapped east of the Tallapooza River.