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Cockfield

Cockfield - (Claiborne group), Irregularly bedded, more or less laminated liginitic clay, sand, and lignite; sparingly glauconitic.
State Mississippi
Name Cockfield
Geologic age Eocene
Comments Secondary unit descriptions from USGS Lexicon website (MS002) and MS004: In outcrop in Newton Co., the Cockfield Formation, uppermost unit of the Claiborne Group, appears as massively bedded, very coarse- to very fine- (but predominantly medium-) grained, moderately sorted quartz sand. Colors range from moderate reddish-brown to white. Lignite is not apparent at the surface, though formation was originally described by Vaughan as lignitiferous sands and clays. In the subsurface, the Cockfield can be easily divided into an upper shaly zone and a lower sandy zone. The uppermost 90 ft of the formation are dominated by carbonaceous clays and silts with high percentages of lignitic clay and silt separated by thin beds of glauconitic, micaceous quartz sand and silt. The lower 75 ft are dominantly medium-grained, slightly micaceous, quartz sand, with trace amounts of heavy minerals and occasional thin beds of carbonaceous silt and clay. Maximum known thickness in Newton Co. is 194 ft, but reaches 280 ft in neighboring Scott Co. Lower contact with the Cook Mountain Formation is conformable except locally. Upper contact with the Moodys Branch Formation is erosional. The carbonaceous interbedded shales and sand of the upper Cockfield represent a delta plain depositional environment, and the lower sand facies represents a delta front. Age is Eocene (Merrill and others, 1985).
Primary rock type clay or mud
Secondary rock type sand
Other rock types coal; mixed clastic/coal
Lithologic constituents
Major
Unconsolidated > Fine-detrital > Clay (Bed)Irregularly bedded, more or less laminated liginitic clay, sand, and lignite; sparingly glauconitic.
Unconsolidated > Coarse-detrital > Sand (Bed)Irregularly bedded, more or less laminated liginitic clay, sand, and lignite; sparingly glauconitic.
Minor
Sedimentary > Coal > Lignite (Bed)Irregularly bedded, more or less laminated liginitic clay, sand, and lignite; sparingly glauconitic.
Map references
Moore, William Halsell, 1969, reprinted 1985, Geologic Map of Mississippi, Compiled by Bicker, A. R., Jr., a revision of the geologic map published by the MS Geological Survey in 1945 in cooperation with the USGS, revised from data submitted by Dr. E. E. Russell of MS State University from published reports of the MS Geological Survey and from field revisions, Mercury Maps Inc., Jackson, MS.
Unit references
Moore, William Halsell, 1969, reprinted 1985, Geologic Map of Mississippi, Compiled by Bicker, A. R., Jr., a revision of the geologic map published by the MS Geological Survey in 1945 in cooperation with the USGS, revised from data submitted by Dr. E. E. Russell of MS State University from published reports of the MS Geological Survey and from field revisions, Mercury Maps Inc., Jackson, MS.
USGS Geologic Names Lexicon (GEOLEX)
Merrill, R.K., Sims, J.J., Jr., Gann, D.E. and Liles, K.J., 1985, Newton County geology and mineral resources [Mississippi]: Mississippi Office of Geology Bulletin, no. 126, 108 p.
Counties Attala - Carroll - Clarke - Jasper - Leake - Newton - Scott