106 proceedings: geological society 



regular program 



Is there a Permian Series?: Laurence La Forge. The question 

 might be better put "Is there a Permian system, or a Permian series in 

 the Carboniferous system?" Probably nowhere is the entire "Permian" 

 found in conformable sequence with Demetian (Pennsylvanian) below 

 and Triassic above. Where lower "Permian" conformably overlies 

 Demetian it is with difficulty separated from it and is limited above by 

 an unconformity and upper Permian is commonly absent; likewise where 

 upper Permian is conformably succeeded by Triassic it is limited below 

 by an unconformity and lower Permian is absent. Where lower and 

 upper Permian are found together they are commonly separated by an 

 interval of mountain-building with a consequent strong unconformity. 

 Evidences of Permian glaciation have been discovered in all the conti- 

 nents, indicating a marked epeirogenic uplift, occurring generally thruout 

 the world and accompanied in several continents by mountain-building, 

 early in Permian time. 



These facts seem to indicate that to form the Permian system or series 

 there were combined formations and stages not properly belonging to- 

 gether, and the earlier and later of which are separated by a deformation 

 of world-wide importance. This time of epeirogenic uplift, glaciation, 

 and mountain-building would seem to be the best-defined and most 

 reasonable point of separation of the Paleozoic and Mesozoic eras. 

 Hence it is suggested that Permian be abandoned as a separate system or 

 as a series in the Carboniferous, and that the lower part be included in the 

 Demetian (Pennsylvanian), while the upper part forms a new series in 

 the Triassic. 



In the scheme of the International Geological Congress the Permian 

 series is subdivided into the Autunian (or Artinskian) , Lodevian, and 

 Thuringian stages. In the United States the Dunkard group of the 

 Ohio valley, the Chase and Wichita groups of the Great Plains, and the 

 Cutler formation of Colorado are Autunian, which stage appears to be 

 wanting in England, but is well developed in continental Europe. In 

 the proposed new scheme it becomes the closing stage of the Demetian 

 (Pennsylvanian) and remains Carboniferous. The Lodevian stage is 

 sparingly developed in America, but the Sumner and Clear Fork groups 

 of the Great Plains are correlated with it. It is well developed in Europe 

 and farther east. In the western United States the Kiger, Salt Fork 

 and Double Mountain groups, and the lower part of the Chugwater 

 group, with perhaps other formations farther west, are Thuringian, which 

 stage includes the typical Permian of Russia, the Zechstein of Germany, 

 and the bulk of the English Permian. In the new scheme the Lodevian 

 and Thuringian stages make up the initial series of the Triassic system, 

 for which scries the name Permian (or Permic) might well be retained. 



This is virtually a return to the original classification, in which the 

 middle and upper parts of the present Permian of Europe were combined 

 with the present Triassic in the New Red Sandstone or Poikilitic system, 

 while the lower part was considered Carboniferous. It is not proposed, 



