THE PERMIAN PERIOD 677 



THE PROBLEMS OF THE PERMIAN 



Between the marvelous deployment of glaciation, a strangely 

 dispersed deposition of salt and gypsum, an extraordinary devel- 

 opment of red beds, a decided change in terrestrial vegetation, a 

 great depletion of marine life, a remarkable shifting of geographic 

 outlines, and a pronounced stage of crustal folding, the events of 

 the Permian period constitute a climacteric combination. Each 

 of these phenomena brings its own unsolved questions, while their 

 combination presents a series of problems of great difficulty. More 

 than any other period since the Cambrian, the Permian is the 

 period of problems. These marked phenomena were probably 

 related to one another, and their explanation is quite sure to be 

 found in a common group of co-operative factors. While it is too 

 much to hope for a full explanation at once, there is no occasion 

 to blink the facts or evade the issues they raise. 



It is to be noted that none of the factors in this combination were 

 wholly new to geological history. There had been glaciations al- 

 most as strange in early Cambrian or pre-Cambrian times (Norway, 

 China, Australia), and perhaps in the Devonian (South Africa); 

 there had been signs of unusual aridity in the salt and gypsum 

 deposits of Silurian and other early times; there had been red beds 

 in the Devonian period, and in the Keweenawan; there had been 

 marked restrictions of life, as at the close of the Ordovician; there 

 had been extensive geographic changes in earlier Paleozoic periods; 

 and there had been foldings of surpassing intensity in Archean and 

 Proterozoic times. The peculiarity of the Permian was the com- 

 plexity of the combination, and the extent of the glaciation and 

 aridity. 



The chronological setting of the combination lends some advan- 

 tages to its study. It lies in the midst of geologic history, with 

 periods of climatic uniformity and polar geniality both before and 

 after it. No appeal can be taken to a supposed final cooling of the 

 earth, or to any senile condition. It was an episode in the midst 

 of a long history, and its problems must be faced with this setting 

 in mind. 1 



1 It is impracticable to discuss these problems here, but they are considered 

 in the authors' larger work, Vol. II, pp. 655-677. 



