The Age, Stratigraphic Relationships, and Correlation of the Lower Part of the Olentangy Shale of Central Ohio

Abstract

The Olentangy Shale of central Ohio (Delaware County) is made up of two distinct stratigraphic units separated by an unconformity. The Upper Olentangy Shale is Upper Devonian in age, and is both lithologically and paleontologically distinct from the Lower Olentangy Shale, which is Middle Devonian (Hamilton) in age. The age distinction is based primarily on a comparison of the ostracod faunas. Other invertebrates from the Lower Olentangy Shale also suggest a Middle Devonian age. The Lower Olentangy Shale correlates with the lower of the exposed units of the Plum Brook Shale of northern Ohio. Most of the invertebrate species of the Lower Olentangy Shale, as well as several ostracod species from the Plum Brook Shale, are illustrated.