Proceedings of the Ohio State Academy of Science 29 



and Icebergs in the Permian epoch" was the first geologist to an- 

 nounce glaciation previous to the last or Pleistocene epoch. Geikie 

 {Text-hook, 4th eel, 1893) states that "the evidence now accumu- 

 lated in South Africa, India, Cashmere and Australia seems to 

 point to some general operation on a gigantic scale in the south- 

 ern hemisphere at the close of the Carboniferous or in the Per- 

 mian period, whereby boulder beds were produced and limestones 

 and rocks in situ were polished, striated and grooved," proving 

 "the occurrence of a former ice-age in later Paleozoic time, which 

 rivalled in its extent and seemed to have surpassed in the magni- 

 tude of its deposits, the glaciation of the northern hemisphere" 

 in pleistocene times. "From the fact that the boulder beds are in- 

 tercalated among marine strata it is clear that, to' some extent at 

 least, the ice reaches sea-level. We are still in ignorance, however,, 

 of the position of the high grounds from which the ice sheets 

 descended." Twenty-five years ago, the attitude of geologists to- 

 wards Permian glaciation was an attitude of scepticism. Even in 

 1893, Geikie (Text-book, 3d ed.) would say only, of the glacier- 

 like deposits of the English Permian, that "Ramsey had no doubt 

 that they were ice-borne, and consequently that there was a 

 glacial period during the accumulation of the Lower Permian de- 

 posits of the center of England." And the American texts of the 

 time were silent on the subject. Today, however, Geikie's later 

 statement is generally accepted as true. And from Norwav and 

 China there comes similar evidence of glaciation which is re- 

 ferred "either to very early Cambrian or to pre-Cambrian time." 

 (Chamberlin and Salisbury, Geology, II, 273.) It yet remains to 

 be seen whether evidence brought forward for a still earlier 

 Huronian ice age will be generally accepted. 



The importance of Carboniferous and Cambrian glaciation 

 lies not so much in the fact itself, interesting as that may be, as 

 in its bearing on general geological theory. Clearly, with these 

 remote periods of glaciation, there can have been no general pro- 

 gressive climatic change throughout geological time, from an 

 earlier warm to a present cooler condition. Rather, there has 

 been from time to time a recurrence of colder periods, and 

 climatic changes have been in the nature of swings to one side 



