Geologic units in Louisiana (state in United States)

Additional scientific data in this geographic area

Alluvium (Holocene) at surface, covers 24 % of this area

Gray to brownish gray clay and silty clay, reddish brown in the Red River Valley, some sand and gravel locally.

Natural Levees (Holocene) at surface, covers 15 % of this area

Gray and brown silt, silty clay, some very fine sand, reddish brown along the Red River.

Prairie Terraces (Pleistocene) at surface, covers 12 % of this area

Light gray to light brown clay, sandy clay, silt, sand, and some gravels.

High Terraces (Pleistocene) at surface, covers 6 % of this area

Tan to orange clay, silt, and sand with a large amount of basal gravels.

Cockfield Formation (Eocene) at surface, covers 5 % of this area

Brown lignitic clays, silts and sands; some sideritic glauconite may weather to brown ironstone in lower part.

Intermediate Terraces (Pleistocene) at surface, covers 5 % of this area

Light gray to orange-brown clay, sandy clay, and silt; much sand and gravel locally.

Delta Plain, Saline Marsh (Holocene) at surface, covers 5 % of this area

Gray to black clay of very high organic content, some peat.

Wilcox Group (undifferentiated) (Paleocene) at surface, covers 4 % of this area

Gray to brown lignitic sands and silty to sandy lignitic clays, many seams of lignite; some limestone and glauconite.

Delta Plain, Fresh Marsh (Holocene) at surface, covers 3 % of this area

Gray to black clay of very high organic content, some peat.

Prairie Terraces (Pleistocene) at surface, covers 3 % of this area

Light gray to light brown clay, sandy clay, silt, sand, and some gravels. Overlain by 1-9 meters of loess.

Cook Mountain Formation (Eocene) at surface, covers 3 % of this area

Greenish gray sideritic clay in upper part may weather to brown ironstone; yellow to brown clays and fossiliferous marl in lower part may weather to black soil. Ironstone concretions near base.

Chenier Plain, Fresh Marsh (Holocene) at surface, covers 2 % of this area

Gray to brown to black clay and silt of high organic content.

Braided Stream Terraces (Pleistocene) at surface, covers 2 % of this area

Light gray, tan and brown fine to coarse sand; some clay silt and gravel.

Chenier Plain, Saline Marsh (Holocene) at surface, covers 2 % of this area

Gray to brown to black clay and silt of moderate organic content.

Braided Stream Terraces (Pleistocene) at surface, covers 1 % of this area

Light gray, tan and brown fine to coarse sand; some clay silt and gravel. Overlain by 1-9 meters of loess.

Sparta Formation (Eocene) at surface, covers 1 % of this area

White to light gray massive sands with interbedded clays; some thin beds of lignite or lignitic sands and shales.

High Terraces (Pleistocene) at surface, covers 1 % of this area

Tan to orange clay, silt, and sand with a large amount of basal gravels. Overlain by 1-9 meters of loess.

Deweyville Terrace (Pleistocene) at surface, covers 0.7 % of this area

Gray mixed with brown-to-red clay and silty clay; some sand and gravel locally.

Carnahan Bayou Member (Miocene) at surface, covers 0.7 % of this area

Yellow to gray siltstones, sandstones, and clays with thin tuffaceous beds; some lenses of black chert gravel; petrified wood locally.

Catahoula Formation (Oligocene) at surface, covers 0.6 % of this area

Gray to white sandstones; loose quartz sand, tuffaceous sandstone, volcanic ash, and brown sandy clays; petrified wood locally.

Intermediate Terraces (Pleistocene) at surface, covers 0.5 % of this area

Light gray to orange-brown clay, sandy clay, and silt; much sand and gravel locally. Overlain by 1-9 meters of loess.

Jackson Group (undifferentiated) (Eocene) at surface, covers 0.5 % of this area

Light gray to brown liginitic clays with thin interbeds of limonitic sands or lignite; near base,calcareous, glauconitic, and fossiliferous beds may weather to black soil.

Cane River Formation (Eocene) at surface, covers 0.4 % of this area

Brown silty clay with basal glauconitic, fossiliferous silts which may weather to ironstone locally.

Castor Creek Member (Miocene) at surface, covers 0.3 % of this area

Gray to dark gray calcareous clays which may weather to black soil; lignitic clays and noncalcreous clayey silts

Williamson Creek Member (Miocene) at surface, covers 0.2 % of this area

White to gray silts, siltstones, silty clays, and sand beds; some lenses of black chert gravel.

Dough Hills Member (Miocene) at surface, covers 0.2 % of this area

Gray to yellow silty clays; light gray calcareous clays which may weather to black soil; some siliceous silt and volcanic ash beds.

Blounts Creek Member (Pliocene to Miocene) at surface, covers 0.2 % of this area

Gray to green silty clays, siltstones, and silts with abundant sand beds; some lignite and lenses of black chert gravel.

Vicksburg Group (undifferentiated) (Oligocene) at surface, covers 0.2 % of this area

Brown to gray liginitic clays with thin interbeds of lignite or micaceous sands; calcareous shale, petrified wood, and bluish fossilferous clay locally.

Catahoula Formation (Oligocene) at surface, covers 0.1 % of this area

Gray to white sandstones; loose quartz sand, tuffaceous sandstone, volcanic ash, and brown sandy clays; petrified wood locally. Overlain by 1-9 meters of loess.

Lena Member (Miocene) at surface, covers 0.1 % of this area

Gray calcareous clays which may weather to black soil; siltstone, taffaceous clays and some volcanic ash beds

Alluvium (Holocene) at surface, covers < 0.1 % of this area

Loam, sand, gravel, and clay; mapped only in Mississippi River Alluvial Plain.

Alluvium (Holocene) at surface, covers < 0.1 % of this area

Alluvium

Vicksburg Group (undifferentiated) (Oligocene) at surface, covers < 0.1 % of this area

Brown to gray liginitic clays with thin interbeds of lignite or micaceous sands; calcareous shale, petrified wood, and bluish fossilferous clay locally. Overlain by 1-9 meters of loess.

Midway Group (undifferentiated) (Paleocene) at surface, covers < 0.1 % of this area

Dark gray to black shale

Coastal deposits (Holocene) at surface, covers < 0.1 % of this area

Loam, sand, gravel and clay.

Wilcox Group, undivided (Paleocene to Eocene) at surface, covers < 0.1 % of this area

Wilcox Group, undivided

Claibourne Group (Middle Eocene) at surface, covers < 0.1 % of this area

Claibourne Group

Citronelle formation (Pleistocene) at surface, covers < 0.1 % of this area

Red sand and gravel and white clay; may be of Pliocene age; the formation mapped is equivalent to the Willis sand and does not include the terrace deposits, colluvium, and residuum commonly considered "Citronelle".

Pascagoula and Hattiesburg formation (Miocene) at surface, covers < 0.1 % of this area

Green and bluish-green clay, sandy clay, and sand; gray siltstone and sand; locally fossiliferous.

Alluvium (Holocene) at surface, covers < 0.1 % of this area

Alluvial deposits of present streams

Terrace deposits (Late Pleistocene) at surface, covers < 0.1 % of this area

Alluvial deposits on one or more terrace levels

Terrace deposits (Pleistocene and Holocene) at surface, covers < 0.1 % of this area

Terrace deposits

Deweyville Formation (Quaternary; Pleistocene and Holocene?) at surface, covers < 0.1 % of this area

Deweyville Formation

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

Light gray to brown liginitic clays with thin interbeds of limonitic sands or lignite; near base,calcareous, glauconitic, and fossiliferous beds may weather to black soil. Overlain by 1-9 meters of loess.

Queen City Sand (Eocene) at surface, covers < 0.1 % of this area

Queen City Sand

Catahoula formation (Miocene) at surface, covers < 0.1 % of this area

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.

Reklaw Formation (Eocene) at surface, covers < 0.1 % of this area

Reklaw Formation

Quaternary deposit, undivided (Quaternary) at surface, covers < 0.1 % of this area

Quaternary deposit, undivided

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

Fossiliferous limestone and marl

Alluvium - Alluvial deposits of local streams or of overbank flow of major streams (Holocene) at surface, covers < 0.1 % of this area

Alluvial deposits of local streams or of overbank flow of major streams - In some areas includes deposits in abandoned meanders of major streams

Weches Formation (Eocene) at surface, covers < 0.1 % of this area

Weches Formation

Alluvium - Alluvial deposits in major stream channels or in mappable meanders of major streams (Holocene) at surface, covers < 0.1 % of this area

Alluvial deposits in major stream channels or in mappable meanders of major streams - Includes alluvial deposits in natural levees in some areas.

Fill and spoil (Holocene) at surface, covers < 0.1 % of this area

Fill and spoil

Beaumont Formation, areas predominantly clay (Quaternary; Late Pleistocene) at surface, covers < 0.1 % of this area

Beaumont Formation, areas predominantly clay

Fleming Formation (Miocene) at surface, covers < 0.1 % of this area

Fleming Formation

Beaumont Formation, areas predominantly sand (Quaternary; Late Pleistocene) at surface, covers < 0.1 % of this area

Beaumont Formation, areas predominantly sand

Vicksburg group and Chickasawhay limestone (Oligocene) at surface, covers < 0.1 % of this area

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.

Carizzo Sand (Eocene) at surface, covers < 0.1 % of this area

Carizzo Sand