NO. 6 PAST CLIMATE OF NORTH POLAR RECION HERRV 25 



This idea, as applied to the Pleistocene glaciation, was first advanced, 

 I believe, by Lyell, and in its more general application has been re- 

 cently put upon a scientific basis by Brooks, with whom I am in perfect 

 agreement to the extent of the evaluation of these as major factors, 

 but also in my firm conviction that arm chair philosophy with its 

 fondness for highly speculative and catastrophic hypotheses, has no 

 place in a uniformitarian world or in 20th century science. 1)ut be- 

 longs in the medieval age of human thought. 



Climate, in a uniformitarian geology, occupies a somewhat anoma- 

 lous position, which the scientific world has been slow to recognize, 

 namely, that the history of the human race has been run unrler cli- 

 matic conditions which, from the jxjint of view of earth history, are 

 exce])tional. Man was evolved subsequent to the relative elevation 

 and the great extension of the continents which ushered in the Pleis- 

 tocene glaciation, and therefore what is normal in human experience, 

 is abnormal for the bulk of geological climate. 



While, therefore, we recognize that the climatic factors and the 

 meteorological elements are the same now as always, their combina- 

 tion to form actual climates has depended upon a great many factors, 

 among the chief (jf which was the size, shape, position, and relative 

 elevation of the land masses. It may be remarked parenthetically 

 that numerous theories of the causes of, or descriptions of geological 

 climates have been advanced by students ignorant of meteorology, 

 and also usually ignorant of the relationship of organisuLs to their 

 environments, and the last is strikingly true of Koppen & Wegener's 

 recent Die Klimate der geologischen V^orzeit (1924). 



In attempting, a few years ago, to explain the extension of floras 

 nearly to the poles during the late Eocene, I relied chiefly on the sub- 

 mergence of continental areas in the middle Eocene and the resulting 

 free oceanic connections at that time between equatorial and Arctic 

 waters, pointing out that these Arctic floras were coastal floras and 

 therefore under the regime of an oceanic climate.^ Essentially the 

 same explanation was put forward independently in connection with 

 Jurassic climates a few months later by Kerner von Marilaun.^ An 

 additional and imix)rtant factor has since been brought forward by 

 Brooks,' who points out that the temperate gradient is a simple func- 

 tion, whereas the influence of the ice increases as the square of the 



^ Berry, Edward VV., A possible explanation of upper F.ocene climates. Proc. 

 yVmer. Phil. Soc., Vol. 61, pp. 1-14, 1922. 



" Kerner von Marilaun, F., Sitz. k. Akad. Wiss. Wien, 1922. 



^ Brooks, C. E. P., The problem of mild polar climates. Quart. Journ. Roy. 

 Meteor. Soc., Vol. 51, pp. 83-94, 1925- 



