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Mineral Resources > Online Spatial Data > Geology > by state > Mississippi Geology

Geologic units in Clarke county, Mississippi

Jackson Group undifferentiated (Eocene) at surface, covers < 0.1 % of this area

Jackson Group undifferentiated - The units of the Jackson Group are the Yazoo Clay and Crystal River and Moodys Branch Formations. Descriptions of the members of the Yazoo Clay follow in decending order. Shubuta Member - in western Alabama consists of light-greenish-gray to white plastic fossiliferous, calcareous clay containing irregular calcareous nodules. From the Tombigbee River eastward the Shubuta becomes more calcareous and grades into massive clayey glauconitic limestone. Eastward from the Alabama River , equivalent beds grade into the Crystal River Formation. Pachuta Marl Member - light-greenish-grey glauconitic, fossiliferous clayey sand and sandy limestone traceable from western Alabama eastward to Covington County where it grades into the Crystal River Formation. Cocoa Sand Member - yellowish-gray firm calcareous, fossiliferous fine to medium sand or sandy limestone or greenish-grey micaceous, calcareous, very clayey sand. Calcareous and clayey sand equivalent to the Cocoa is traceable from western Alabama to the Conecuh River area. North Twistwood Creek Clay Member - greenish-gray plastic calcareous, sparsely fossiliferous, blocky massive clay; grades into Crystal River formation in southeast AL. Crystal River Formation - white to yellowish-grey medium-grained to coquinoid limestone that is soft and chalky to compact and brittle; principally in southeastern AL but interfingers westward with members of the Yazoo Clay. Moodys Branch Formation - greenish-gray to pale-yellowish-orange glauconitic, calcareous, fossiliferous sand and sandy limestone; underlies the Yazoo Clay and the Crystal River Formation.

Lithology: clay or mud; limestone; sand

Catahoula formation (Miocene) at surface, covers 3 % of this area

Catahoula formation - Irregularly bedded gray sand and sandstone; mottled red and gray, green, and chocolate-colored clay; some quartzite, and some gravel; the Paynes Hammock sand, sandy limestone cross-bedded fine green sand, and thin-bedded sand and clay, is mapped with the underlying Chickasawhay limestone in eastern MS.

Lithology: sand; sandstone; clay or mud; quartzite; gravel

Forest Hill formation and Red Bluff clay (Oligocene) at surface, covers 4 % of this area

Forest Hill formation and Red Bluff clay - Forest Hill sand, cross-bedded fine gray sand, laminated fine sand and clay, and a little lignite; in Wayne and Clarke Counties lower part merges eastward into Red Bluff clay, blue-green glauconitic, gypsiferous, fossiliferous clay and thin limestone beds.

Lithology: sand; clay or mud; fine-grained mixed clastic; mixed clastic/coal; evaporite

Tallahatta formation and Neshoba sand (Eocene) at surface, covers 6 % of this area

Tallahatta formation and Neshoba sand - (Claiborne group), Southeast of Pearl River predominantly more or less glauconitic claystone and clay with lenses of sand and some sandstone; highly cross-bedded sand at base; northwest of Pearl river predominantly sand, locally glauconitic, containing claystone and clay lenses and abundant clay stringers; Neshoba sand, sparingly glauconitic fairly coarse sand not recognized southeast of Newton County or north of Yalobusha River.

Lithology: claystone; clay or mud; sand; sandstone

Zilpha formation and Winona formation (Eocene) at surface, covers 6 % of this area

Zilpha formation and Winona formation - (Claiborne group), Zilpha clay, chocolate-colored clay containing some glauconitic sand, not recognized north of Yalobusha River; Winona sand, highly glauconitic sand, more or less clayey.

Lithology: sand; clay or mud

Wilcox Group; Hatchetigbee Formation (Eocene) at surface, covers < 0.1 % of this area

Hatchetigbee Formation - (Wilcox Group), Light to dark-gray laminated carbonaceous clay, silt and very fine to fine sand, and cross-bedded glauconitic sand; one or more thin beds of fossiliferous marly glauconitic sand and sandstone occur in the upper part. Near the base is a prominent bed of glauconitic calcareous sand containing abundant fossils and spheroidal to pillow-shaped sandstone concretions (Bashi Marl Member). In parts of southeast AL the upper beds of the Th were either eroded or not deposited and the overlying Tt formation directly overlies the Bashi Marl Member.

Lithology: clay or mud; sand; silt; sandstone

Claiborne Group; Gosport Sand and Lisbon Formation undifferentiated in part (Eocene) at surface, covers < 0.1 % of this area

Gosport Sand - (Claiborne Group), highly fossiliferous, glauconitic, quartz sand and lenses of greenish-gray clay; occurs between MS state line and AL River.

Lithology: sand; clay or mud

Vicksburg group and Chickasawhay limestone (Oligocene) at surface, covers 0.8 % of this area

Vicksburg group and Chickasawhay limestone - Chickasawhay limestone, sandy limestone, and sand, present only in eastern MS (mapped with it is the overlying Paynes Hammock sand of Miocene age); Vicksburg group, predominantly limestone and marl, but contains some bentonite and near the top, chocolate-colored clay and some sand.

Lithology: limestone; sand; bentonite; clay or mud

Cook Mountain formation (Eocene) at surface, covers 7 % of this area

Cook Mountain formation - (Claiborne group), Southeast of Pearl River, marl, limestone, glauconitic sand, and chocolate-colored clay; northwest of Pearl River, predominantly chocolate-colored clay with some glauconitic sand.

Lithology: clay or mud; sand; limestone

Claiborne Group; Tallahatta Formation (Eocene) at surface, covers < 0.1 % of this area

Tallahatta Formation - (Claiborne group), White to very light-greenish-gray thin-bedded to massive siliceous claystone; interbedded with thin layers of fossiliferous clay, sandy clay, and glauconitic sand and sandstone. White to light-greenish-gray fine to coarse sand and fine gravel occur at the base of the formation in southwest Alabama (Meridian Sand Member).

Lithology: claystone; clay or mud; sand; sandstone; gravel

Cockfield (Eocene) at surface, covers 25 % of this area

Cockfield - (Claiborne group), Irregularly bedded, more or less laminated liginitic clay, sand, and lignite; sparingly glauconitic.

Lithology: clay or mud; sand; coal; mixed clastic/coal

Jackson group (Eocene) at surface, covers 23 % of this area

Jackson group - Yazoo clay, green and gray calcareous clay containing some sand and marl; Moodys Branch formation at base, shells embedded in glauconitic clayey quartz sand.

Lithology: clay or mud; sand

Wilcox Group; Tuscahoma Sand (Paleocene) at surface, covers < 0.1 % of this area

Tuscahoma Sand - (Wilcox Group), Light-gray to light-olive-gray laminated and thin-bedded carbonaceous silt and clay interbedded with fine sand; thin lignite beds occur locally. Lower part of the formation includes beds of fossiliferous, glauconitic fine quartz sand containing speroidal sandstone concretions, gravel and clay pebbles.

Lithology: clay or mud; silt; sand; coal; sandstone; gravel

Kosciusko formation (Eocene) at surface, covers 20 % of this area

Kosciusko formation - (Claiborne group), irregularly bedded sand, clay, and some quartzite.

Lithology: sand; clay or mud; quartzite

Wilcox formation (Eocene) at surface, covers 5 % of this area

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

Lithology: clay or mud; sand; coal