Fossils of Dresbachian and Franconian (Cambrian) Age from the Subsurface of West-Central Indiana

Abstract

"ABSTRACT: Three fossiliferous levels in FMC No. WD-1, a well in Vermillion County, Ind., have yielded Cambrian fossils. The highest level, in the Davis Formation between depths of 4,497 and 4,546 feet, contains 17 distinct layers with trilobites of the Elvinia Zone of early Franconian age. A single horizon, in an upper oolite member of the Eau Claire Formation at a depth of 4,698 feet, contains trilobites, gastropods, and other fossils of the Crepicephalus Zone of middle Dresbachian age. Two lower horizons, in green shales of the Eau Claire Formation at depths of 5,061 and 5,083 feet, contain trilobites of the Cedaria Zone of early Dresbachian age. Characteristic trilobites and gastropods are illustrated and discussed.

The upper oolite member is considered to be a possible extension of part of the Bonneterre Formation of Missouri. If this is correct, the paleogeography of this interval in the eastern midcontinent region suggests an early presence of, or precursory conditions for, the Illinois Basin."