408 MESEOSBRE AND PALEOSERE. 



and Cascade mountains. Submergence then followed in the earlier part of 

 the Comanchean, and was succeeded by the emergence which separated this 

 period from the Cretaceous. Schuchert's chart (p. 321) epitomizes the cycles 

 in graphic fashion. The beginning of the Permian was marked by major 

 deformation, while the close of the Triassic, Jurassic, and Comanchean shows 

 a lesser deformation. The Permian and Triassic deformations were accom- 

 panied by major eruptive activities, and those of the Jurassic and Comanchean 

 by lesser vulcanism. 



In addition to the deformational cycles, the Permian in particular was 

 marked by glacial-interglacial cycles, which Huntington regards as primarily 

 of solar origin. A section through the Permian of Australia (fig. 43, page 

 407), shows 9 or 10 glacial beds separated by beds of clastic material and of 

 coal. The glacial beds bear witness to the recurrence of as many glacial 

 phases, and the clastic beds and coal-beds to the existence of interglacial 

 conditions. The most plausible explanation of Permian climates has been 

 advanced by Huntington (1914 : 2 : 578) : 



"According to the cylonic 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, as we have already seen, would tend 

 toward glaciation. One would be a pronounced increase of snowfall on the 

 mountains and the other the general lowering of the temperature because of 

 the great amount of heat carried upward by the storms. Conditions would 

 apparently resemble those which would prevail in New Zealand if the tem- 

 peratiu-e should become somewhat lower than now and the snowy precipitation 

 on the mountains should increase. At the present time the glaciers of New 

 Zealand descend ahnost to sea-level. For instance, the Aorangi glaciers push 

 their way down into the forests as low as 400 feet above the sea. With an 

 increase in snowfall and a slight lowering of temperature, these glaciers would 

 descend still lower. They would coalesce with one another and might spread 

 out over a considerable area of land at approximately sea-level. In order to 

 get such conditions during the Permian era, the only requirements seem to 

 be that the phenomena which now prevail at times of maximimai sun-spots 

 should become even more intensified than we have assumed to be the case in 

 Pleistocene times." 



Climate of the periods.— The occurrence of glaciation in every continent 

 of the globe stamps the Permian as a glacial period. The latter must have 

 been long, as shown by the number of glacial and interglacial cycles. The 

 Permian could hardly have failed to cool the chmate of the entire globe, 

 in addition to producing a differentiation of cUmates about the centers of 

 glaciation. This is shown by the great reduction in life throughout all regions, 

 the disappearance of many types, and the entrance of gymnosperms and fern- 

 worts which bear the stamp of aridity. The frequent occurrence of beds of 

 salt and gypsum and of red beds in the Great Plains region is also thought 

 to prove the existence of arid climates. These evidences continue through 

 much of the Triassic, and the latter is considered to have been characteris- 



