Odenville Formation

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

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.

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.

Keith Roberson in 1988, and Ed Osborne in 1992, 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.

As defined today, the Odenville Limestone is described as a dark gray, primarily dolomitic, stylonodular limestone 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.