Odenville Formation

The Odenville Limestone is a geologic formation in Alabama. It preserves fossils dating from the early Ordovician Period.

Odenville Limestone
Stratigraphic range: Ordovician
TypeFormation
Underliespost-Knox formations
OverliesNewala Limestone
Thickness0-366 feet
Location
Region Alabama
Country United States
Type section
Named forOdenville, Alabama
Named byCharles Butts

As first described by geologist Charles Butts in a 1926 report on Alabama’s geology, the Odenville consisted of “impure argillaceous and siliceous dark fine-grained cherty limestone,” about fifty feet in thickness.[1]

Butts’ original type exposure could not be located by subsequent mappers, so the Odenville nomenclature was dropped and the formation was considered a locally-occurring facies of the underlying Newala Limestone.[2]

Keith Roberson in 1988,[3] and Ed Osborne in 1992,[4] demonstrated the Odenville is indeed a distinctive, mappable lithologic unit, and the term was restored to the Ordovician nomenclature used by the Geological Survey of Alabama in the Appalachian fold-and-thrust belt.[5]

As defined today, the Odenville Limestone is described as a dark gray, primarily dolomitic, stylonodular limestone[6] whose fossil assemblage includes brachiopods and sponges. It is the uppermost member of the Knox Group, a related suite of carbonate rocks deposited at the end of the Cambrian and beginning of the Ordovician.[7]

See also

References
  1. "Geology of Alabama" (PDF). Geological Survey of Alabama. p. 99. Retrieved November 13, 2022.
  2. Osborne, W. Edward; Irvin, G. Daniel (2002). Geology of the Odenville 7.5-Minute Quadrangle, St. Clair County, Alabama. Geological Survey of Alabama.
  3. Roberson, Keith (1988). The post–Knox unconformity and its relationship to bounding stratigraphy, Alabama Appalachians. Master's thesis, University of Alabama.
  4. Osborne, W. Edward (1992). Bedrock geology of the Cahaba Valley area between Helena and Lake Purdy, Shelby and Jefferson Counties, Alabama. Geological Survey of Alabama.
  5. "National Geologic Map Database - Geolex". U.S. Geological Survey. Retrieved November 13, 2022.
  6. Osborne, W. Edward; Irvin, G. Daniel (2002). "Cross Section A-A' and Explanation for the Geologic Map of the Odenville 7.5-Minute Quadrangle, St. Clair County, Alabama" (PDF). Geological Survey of Alabama. Retrieved November 13, 2022.
  7. Lacefield, Jim (2013). Lost Worlds in Alabama Rocks (second edition). Alabama Museum of Natural History. pp. 94–95.


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