354 ANNUAL KEPOET SMITHSONIAN" INSTITUTION, 1908. 



the east of a gulf to the northwest of Australia. In all probability 

 there was a large extent of land stretching southward and cutting off 

 the cold southern ocean from the seas, which extended southward 

 from the Tropics. Under such conditions the wind systems would 

 have traversed the Australian lands upon a different path from that 

 which they follow now, and they would not have advanced so 

 steadily. The winds would have carried large quantities of moisture 

 southward, from the warm northern seas, and it would have been pre- 

 cipitated on the mountains of that period, which were kept cold by 

 southerly winds, chilled by their passage over the former extension 

 of Australia to the south. In South Africa and South America the 

 question is simpler, as there is no proof of the glacial deposits hav- 

 ing been laid down at sea level ; they may have been formed upon the 

 flanks of mountain areas, kept abundantly supplied with snow, by 

 west winds blowing in from the adjacent oceans. In India the condi- 

 tions were probably meteorologically similar, the glaciation having 

 been on the cooler edge of Gondwana Land, where it was bounded by 

 a temperate siea ; and though the glaciers ranged into the Tropics in 

 southern India as far south as latitude 17° 20' N., there is no proof 

 that they occurred there at low levels. 



It appears, therefore, probable that variations in climate, 

 which have been established on adequate evidence, can be accounted 

 for by differences in atmospheric circulation, due to different distri- 

 butions of land and water. All the evidence available regarding the 

 Upper Paleozoic glaciation of Gondwana Land appears to be con- 

 sistent with the view that the glaciers developed, like those of the 

 Pleistocene glaciation of North America and of northwestern 

 Europe, in a number of scattered localities, where mountains oc- 

 curred beside the sea, and where the meteorological conditions pro- 

 duced a high snowfall and a low summer temperature. 



