Mild Polar Climates. 283 



tropical nature of the climate during portions of the Tertiary 

 period was due not so much to that peculiar distribution of 

 land and water existing then, as it was to the fact that this 

 peculiar distribution enabled the physical agents in operation 

 during a high state of eccentricity to impel a vastly greater 

 amount of warm intertropical water into the temperate and 

 Arctic seas than they could have done under the present geo- 

 graphical condition of things. 



Those very same geographical conditions enabling the 

 physical agents to raise the temperature exceptionally high 

 daring the warm periods would, on the other hand, prevent 

 them from being able to lower the temperature exceptionally 

 low during the alternate cold periods. Nevertheless, I think 

 it probable that at the two periods referred to, when the 

 eccentricity was much greater than it was during the glacial 

 epoch, the temperature would be lowered to an extent that 

 would produce glaciation, although the glaciation might not 

 perhaps approach in severity to any thing like that of the 

 glacial epoch. The negative evidence which has been adduced 

 against the existence of such glacial conditions during the 

 Tertiary period is certainly far from being conclusive. 



The opinion is concurred in by Mr. Wallace that the Table of 

 Eccentricity for the past three million years, given in ' Climate 

 and Time,' probably includes the greater part, if not the whole, 

 of the Tertiary period. He states that during the 2,400,000 

 years preceding the last glacial epoch there were, according 

 to the table, no fewer than sixteen separate epochs when the 

 eccentricity reached or exceeded twice its present amount. 

 But it does not follow, according to the Physical Theory, that 

 there ought, on that account, to have been sixteen epochs of 

 more or less glaciation. Whether such ought to have been 

 the case or not would depend on whether or not the geogra- 

 phical conditions were the same during these epochs as they 

 were at the glacial epoch, a thing regarding which the theory 

 is not responsible. The question is not were there sixteen 

 glacial epochs during the Tertiary period, but were there any? 

 Even granted that those channels assumed by Mr. Wallace 

 did exist, they would not, I feel assured, wholly prevent gla- 

 ciation taking place at the two periods to which reference 

 has been made, although the glaciation might not be severe. 



In support of the opinion that there is no evidence of 

 glaciation during the Tertiary period, Mr. Wallace quotes the 

 views of Mr. Searles V. Wood, Jun., on the subject. Mr. Wood 

 states that the Eocene formation is complete in England, and 

 is exposed in continuous section along the north coast of the 

 Isle of Wight and along the northern coast of Kent from 



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