Geologic units in Noxubee county, Mississippi

Demopolis chalk (Upper Cretaceous) at surface, covers 45 % of this area

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

Porters Creek formation (Paleocene) at surface, covers 17 % of this area

(Midway group), Dark-gray clay, north of Clay County contains slightly glauconitic, micaceous sand lenses.

Clayton formation (Paleocene) at surface, covers 11 % of this area

(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.

Mooreville chalk (Upper Cretaceous) at surface, covers 9 % of this area

(Selma group), Marly chalk and calcareous clay.

Ripley formation (Upper Cretaceous) at surface, covers 7 % 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.

Prairie Bluff chalk and Owl Creek formation (Upper Cretaceous) at surface, covers 6 % of this area

(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.

Wilcox formation (Eocene) at surface, covers 4 % of this area

Irregularly bedded fine to coarse sand, more or less lignitic clay and lignite; includes bauxite bearing Fearn Springs sand member at base.

Alluvial, coastal and low terrace deposits (Holocene) at surface, covers 0.3 % 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.

Selma Group; Demopolis Chalk (Cretaceous) at surface, covers 0.1 % of this area

Light-gray to medium-light-gray compact, brittle chalk overlain by abundantly fossiliferous chalky marl, very clayey chalk, and calcareous clay (Bluffport Marl Member). In south-central Montgomery County the Demopolis is split into two eastward extending tongues by a westward-extending tongue of the Cusseta Sand Member of the Ripley Formation. The lower tongue is pale-olive to yellowish-gray silty to finely sand, micaceous, fossiliferous chalk that eastward becomes more sandy and merges with the Cusseta in central Bullock County. The upper tongue is yellowish-gray clayey, very finely sandy, micaceous chalk that merges with the Ripley in southeastern Montgomery County.

Selma Group; Mooreville Chalk (Cretaceous) at surface, covers < 0.1 % of this area

Yellowish-gray to olive-gray compact fossiliferous clayey chalk and chalky marl. The unconformable contact at the base is characterized by a bed of glauconitic, chalky sand containing phosphate pellets and molds of fossils. The Arcola Limestone Member at the top consists of two to four beds of light-gray brittle, dense, fossiliferous limestone seperated by beds of light-gray to pale-olive calcareous clay.

Naheola formation (Paleocene) at surface, covers < 0.1 % of this area

(Midway group), Fine to coarse micaceous sand, kaolin, and bauxitic clay.