Systematics and Biostratigraphy of Brachiopods from the Chickamauga Group (Middle Ordovician) in the Alabama Valley and Ridge

Twenty-three species of brachiopods belonging to 18 genera were identified from four Chickamauga Group outcrops in the Alabama Valley and Ridge. These outcrops are relatively new and were the topic of two previous Master's theses on the lithofacies and depositional environments of the Chickamauga Group (Lee, 1983 and Ward, 1983). Their measured sections were used as a framework for collecting and their lithofacies results were used to check the species identified for possible facies preference. Due to the sporadic occurrences of the brachiopods within and between the outcrops studied, a satisfactory biostratigraphic zonation or correlation of the Chickamauga Group within Alabama could not be attained using the presently known distribution of brachiopods. The assemblage identified is most similar to the StrophomenaPionodema Suite and represents a typical late Middle Ordovician ScotoAppalachian fauna. This fauna indicates an age of Wildernessian based upon known stratigraphic occurrences of the species identified. Previous work on other fossil groups indicates the Chickamauga Group spans the entire Middle Ordovician. Many additional detailed studies are needed on the distribution of other faunal groups, as well as brachiopods, before Middle Ordovician fossils and strata can be fully evaluated in Alabama.