Nomenclature of the Keuper Series

Abstract

IN the announcement in Nature1 of the most interesting results of the recent borings penetrating the Trias of the Cheshire Plain, the Director of the Geological Survey made certain suggestions for the nomenclature of the subdivisions of the Keuper Series which, if adopted, may result in considerable confusion. The Keuper Series has, in the past, been subdivided into Keuper Marl and Keuper Sandstone rather than into Upper Keuper and Lower Keuper respectively, although Wills2 calls the latter usage the “traditional classification”. Keuper Marl and Keuper Sandstone were originally what we would now call rock-stratigraphical units which have acquired a time-stratigraphical significance even though this is probably not justified in view of the paucity of fossils in the Trias and the weight that has to be placed on lithological correlation. Difficulties have not arisen to any serious extent, because the subdivisions of both stages of the Keuper have been in rock-stratigraphical units and have been applicable to quite large but distinct areas. It is also of importance that the terms Lower, Middle and Upper Keuper are in use in Germany which, after all, was the type area, and that, at the moment, there is uncertainty concerning correlations suggested by the flora and fauna of the Bromsgrove Keuper Sandstone with the Lettenkohle and the Muschelkalk of Germany and the Gres a Voltzia of Alsace.