678 e. huntington solar hypothesis of climatic changes 



Permian Glaciation 



GENERAL DISCUSSION 



The last test to which we shall subject our theory is that of the peculiar 

 condition of Permian glaciation. This, still less than the snowfall of the 

 Alps and the loess of Eurasia and x\merica, was not even remotely con- 

 sidered until the cyclonic hypothesis had reached its present form. Per- 

 haps the most striking characteristic of Permian times Avas glaciation 

 between 20° and 40° south of the present equator and to a less extent in 

 the same latitudes north of the equator. The extent of the evidences of 

 glaciation is sufficient to imply the existence of considerable bodies of 

 land. The actual regions where the ice laid down its burden were in 

 many cases at or near sealevel. This, however, indicates nothing as to 

 the conditions far back where the glaciers took their origin. At the 

 present time glaciation is universally associated with mountains or with 

 regions such as Greenland and Antarctica, which are presumably high 

 plateaus. In the Pleistocene glacial period the great areas of the accu- 

 mulation of ice were all of considerable elevation. Therefore, we seem 

 to be led to the conclusion that during Permian times considerable 

 areas of high land or mountains must have existed in latitudes 20° to 40°, 

 where they served as a gathering ground for great quantities of ice. 

 Even with this assumption, however, the peculiar location of Permian 

 glaciation has been an even greater puzzle than the juxtaposition of 

 glaciers and loess in Pleistocene times. The problem has been so difficult 

 that some of the best geologists have thought that it might indicate a 

 change in the location of the earth's poles. Others have endeavored to 

 explain it by a complete readjustment of oceanic and atmospheric circu- 

 lation. Such a readjustment must certainly have taken place, no matter 

 what hypothesis we accept in explanation of it, but its mode of occur- 

 rence would xsltj according to whether it was due to crustal deformation, 

 changes in the composition of the atmosphere, or changes in the cyclonic 

 movements of the air. 



According to the cyclonic hypothesis, the Permian period was a time 

 when the activity of the sun was even greater than during the Pleistocene 

 glacial period. This, as we have seen, would involve the formation of a 

 storm belt in subtropical latitudes, together with an increase of tropical 

 hurricanes in subequatorial regions. Both of these types of cyclonic 

 activity would involve a rapid upward movement of the air, which would 

 be at its greatest intensity in a broad subtropical belt centering 25° or 

 30° from the equator on either side. Under such conditions two factors. 



