|Name||Zilpha formation and Winona formation|
Unconsolidated > Fine-detrital > ClayChocolate-colored clay containing some glauconitic sand.
Unconsolidated > Coarse-detrital > SandHighly glauconitic sand, more or less clayey.
|Comments||Secondary unit descriptions from USGS Lexicon website (MS002) and MS004: Zilpha Formation of Claiborne Group in Newton Co. occurs at the surface as dark yellowish-brown to grayish-brown, sandy, silty, glauconitic, carbonaceous clay, with sand lenses and thin beds in the lower portion. In the subsurface, the Zilpha is dark yellowish-brown, sandy, silty clay. Thickness ranges from 12 ft to 68 ft, varying inversely with that of the underlying Winona. Contact with the Winona is conformable showing only an increase in the glauconite and quartz percentages. Contact with the overlying Kosciusko Formation is also gradational. Depositional environment interpreted as marine shelf and prodelta. Geologic map. Measured sections. Stratigraphic column (Merrill and others, 1985). Nomenclature in this report follows Thomas (1942) and Dockery (1981) in classifying Winona as a separate formation within the Claiborne Group. Unit is well exposed in eastern and northeastern Newton Co. At the surface, it is a dark reddish-brown, medium- to fine-grained, poorly sorted, silty, clayey, glauconitic, fossiliferous sand. Locally, glauconite content exceeds 50 percent. Limonitic ironstone beds common. Weathers to a deep reddish-brown, but fresh exposures are a light olive-gray to greenish-gray. Contains abundant molds and casts of bivalves and gastropods. Most common bivalve fossil occurrences include NEMOCARDIUM sp., CRASSATELLA sp., CHLAMYS sp., and CUBITOSTREA sp. Common gastropods are LACINIA ALVEATA (Conrad), CALYPTRAPHORUS sp., and ATHLETA sp. In the subsurface, the Winona is very fine- to very coarse grained, silty, clayey, fossiliferous, glauconitic sand, with calcite cemented layers of glauconitic sandstone and siltstone, interbedded and interlaminated with non-cemented layers. Maximum thickness in Newton Co. occurs in Test Hole A0-1 where unit is 72 ft. Disconformably overlies the Neshoba Sand Member of the Tallahatta Formation and conformably underlies the Zilpha Formation. Winona represents a destructional shelf facies deposited in a marine transgression. Geologic map. Measured section. Stratigraphic column (Merrill and others, 1985).|
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., scale 1:500,000.
USGS Geologic Names lexicon found at: http://ngmdb.usgs.gov/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 - Grenada - Holmes - Lauderdale - Leake - Montgomery - Neshoba - Newton - Panola - Tallahatchie - Yalobusha|