ON THE CAUSE OF THE ICE AGE 15 



Wright * and Mr. Upham, two well-known authorities on 

 glacial phenomena expressed the view that the northern lands 

 must have been gradually elevated in Pliocene times, be- 

 coming continuous before the Ice Age. Further particulars 

 on this subject are contained in Dr. Spencer's articlef on 

 high continental elevation. 



Sir Henry Howorth opposes this view, urging that Green- 

 land, Scandinavia, and North America were all at a much 

 lower level in so-called Glacial times than they are now. If 

 this be so, then the epeirogenic theory has no base to stand 

 upon. I do not think that Sir Henry Howorth's J statement 

 is applicable to southern Greenland or eastern North America. 

 At any rate, it is not contended by anyone that the high level 

 condition of these countries persisted during the whole of 

 the Ice Age. 



The theory that the Ice Age or Glacial Epoch was brought 

 about mainly by the closing of the Arctic Ocean to the influence 

 of the Gulf Stream is a very tempting one. The temperature 

 of the Atlantic Ocean would under such conditions have been 

 higher than it is now, because its heat would not have been 

 modified by cold arctic currents, as it is at present. Southern 

 Greenland, Iceland, and the lands on both sides of the 

 Atlantic should also have had a more favourable climate than 

 obtains under existing circumstances, since the warm ocean 

 would have had considerable influence upon their climate for 

 a certain distance inland. There is evidence, on the European 

 side of the Atlantic, that, at a not very distant geological 

 period, and presumably at a time when the coasts of France, 

 south-west of England and south of Ireland were still united, 

 the southern fauna and flora crept steadily northward along 

 the ancient shore-line. That this did not take place in very 

 recent times is evidenced by the fact that the southern marine 

 shore forms of mollusks, crustaceans and other invertebrates 

 have a somewhat discontinuous range on the west coast pf 

 the British Islands, and do not occur in the English Channel 

 or in the southern part of the North Sea, 



* Wright, G. F., and Warren Upham, " Greenland Icefields " p. 331. 

 f Spencer, J. W., " High Continental Elevation." 

 \ Howorth, H. H., " Ice or Water," Vol. I., p. 136. 



