CRINOID COLUMNALS FROM THE FORT PAYNE CHERT OF MADISON AND LIMESTONE COUNTIES, ALABAMA

Geologic mapping of the Greenbrier and Madison Quadrangles in Madison and Limestone Counties, Alabama, has revealed several new outcrops of Lower Mississippian (Osagian) Fort Payne Chert that contain abundant large crinoid columnals. Abundant chert with large crinoid columnals in residuum is a significant criterion for mapping the top of the Fort Payne in this area of generally low topographic relief. Previous workers in the Fort Payne of Alabama have not attempted to identify crinoid columnals. Moore and Jeffords (1968) classified and identified crinoid columnals from Lower Mississippian rocks of Tennessee, Kentucky, Indiana, and Iowa.

Columnals collected and identified from the top of the Fort Payne represent 7 genera and 11 species. Following the classification of Moore and Jeffords (1968), these include Graphosterigma grammodes, Cyclocaudex aptus, Cyclocaudex congregalis, Platyclonus dispar. Eucladocrinus? kentuckiensis, Eucladocrinus? springeri, Rhysocamax grandis, Rhysocamax cristata, Rhysocamax tuberculata, Ilematerisma sp., and Floricyclus welleri.