Stratigraphic Placement of the Dunkard: A Review of the Paleobotanical and other Evidence


John A. Clendening

Additional Authors:

William H. Gillespie


March – 1972


Dunkard, Paleobotanical, Permo-Carboniferous, Permian, Virgilian, Gearyan, Cimarronian

The age designation of Dunkard strata has been a controversial subject for more than 90 years. These rocks have been designated by various authors as Pennsylvanian, Permian, transitional Permo-Carboniferous and partially Permo-Carboniferous: partially Permian. Evidence cited in substantiation of each of these claims has varied from lithological to paleontological to paleobotanical, but the preserved mega-flora as described by Fontaine and White (Rept. PP., 2nd Pa. Geol. Survey) in 1880 forms the basis for most of the age assignments. In some instances, fossilized organisms have apparently been cited as Permian because of their occurrence in Dunkard strata rather than through interpretation of the organismal characteristics. Palynological studies which contrast the flora of the Dunkard with the Virgilian, Gearyan and basal Cimarronian of the Midcontinent area indicate that the Dunkard is no younger than Virgilian which has always been classified as undoubted Pennsylvanian. In general, there seems to be no lithologic, faunal or floral basis for separating Dunkard strata from those that immediately underlie them. The available evidence seems to substantiate a strictly Pennsylvanian age for the group.