432 MK. F. W. HARMER ON THE [^Ug. IQOIy 



evidence to show that any other part of the Tertiary Era was cha- 

 racterized by marked fluctuations of climate, still less that any 

 Great Ice Age occurred, even during Pliocene times. With the 

 advent of the Pleistocene Epoch, however, an era of climatic dis- 

 turbance commenced/ 



It seems to me that it is a jyviori less probable that important 

 alterations of climate, more than once occurring at intervals of a 

 few thousand years only, were due to astronomical or physical causes 

 affecting the whole of the Northern Hemisphere, than that the Glacial 

 and Interglacial deposits of different regions may represent one era 

 only of greater cold, with local changes in the distribution of climatic 

 zones. 



It will be urged perhaps that the value of some of the conclusions 

 here arrived at is seriously affected by the fact that geologists are by 

 no means unanimous in their interpretation of the geological record. 

 It is widely believed, to take one example only, by such authorities as 

 Warren Upham,- Le Conte,^ Chamberlin,^ and others that at a period 

 immediately preceding the Glacial Period, for which the name 

 Ozarkian has been proposed,' the North American continent stood 

 at a level greatly higher than that of our own era : the supposed eleva- 

 tion being regarded by the first-named of those writers as the direct, 

 and by Prof. Chamberlin as the indirect, cause of the Glacial cold. 

 Prof. J. W. Spencer believes, moreover, that an elevation of the 

 Antillean region took place in Pleistocene times, which may have 

 reacted upon climate.^ Prof. Hull argues in a similar wa)^, con- 

 tending that the Pleistocene elevation which affected America was 

 continuous round the northern and eastern shores of the North 

 Atlantic." Prof. James Geikie, on the other hand, adversely 

 criticizes these views.^ Some persons may, therefore, feel that 

 until a more approximate consensus of opinion has been attained 

 on these and other points which it is not necessary to mention, 

 it is premature to discuss the meteorology of the Glacial Period 

 at all. There seems, however, sufficient general agreement as to 

 certain facts to justify a preliminary enquiry, it being understood 

 that any conclusions arrived at must be subject to such modifications 

 as may hereafter be necessary. 



W^e may, I think, accept, as a working hypothesis, the view 

 that in the New World there were certain definite centres of ice- 

 accumulation, one in Labrador, another west of Hudson Bay, and 



^ The earliest evidence of this kind in Great Britain is that of the Cromer 

 (so-called) Forest Bed, containing Elephas meridionalis, and other mammalian 

 remains preponderatingly southern, together with a temperate flora, which is 

 intercalated between the Weybourn Crag (with the Arctic mollusca, Astarte 

 borealis and Tellina lata) on the one hand, and the Arctic freshwater-bed (with 

 Salix jpolaris and Betula nana) on the other. 



2 Journ. Vict. Inst. vol. xxix (1897) p. 201. 



3 Journ. Geol. Chicago, vol. vii (1 899) p. 525. * Ibid. p. 667. 



5 Hershey, ' Science ' vol. iii (1896) p. 620. ^ Qeol. Mag. 1898, p. 38. 



^ Journ. Vict. Inst. vol. xxxi (1899) p. 141. " Ibid. vol. xxvi (1893) p. 22L 



