116 W. Upharn — Epeirogenic Movements 



great and comparatively long continued uplift, which in its 

 culmination appears to have given a high plateau climate with 

 abundant snowfall forming an ice-sheet, whose duration ex- 

 tended until the land sank somewhat lower than now, leading 

 to amelioration of the climate and the departure of the ice, 

 followed by re-elevation to the present level. The coincidence 

 of these great earth movements with glaciation naturally leads 

 to the conviction that they were the direct and sufficient cause 

 of the ice-sheets and of their disappearance ; and this conclu- 

 sion is confirmed by the insufficiency and failure of the two 

 other chief theories which have been advanced to account for 

 the Glacial period. 



During ten or fifteen years next following the publication of 

 Dr. James Croll's very valuable work, " Climate and Time," 

 and of the equally grand work by Prof. James Geikie, tc The 

 Great Ice Age," a quite general opinion among American 

 glacialists favored the astronomical theory of the causes of 

 glaciation which these authors so ably advocated. But in later 

 years a similarly general opinion among us sets against that 

 theory because of the uniqueness and the demonstrated geo- 

 logic recency of the Glacial period ; and therefore for a time 

 some, who were specially impressed with the low level of our 

 continent during the maximum and wane of its glaciation, 

 looked with careful inquiry toward the doctrine of changes in 

 latitude and in the position of the earth's poles, which was set 

 forth in 1866 by Sir John Evans, with the suggestion that it 

 might explain the remarkable Pleistocene changes of climate. 

 Within the past two years, however, the brilliant discoveries 

 by Dr. S. C. Chandler* of the periods and amounts of the 

 observed variations of latitude, showing them to be in two 

 cycles respectively of twelve and fourteen months, with no 

 appreciable secular change, forbid reliance on this condition as 

 a cause, or even as an element among the causes, of the Ice 

 age. The second of these theories is out of the field, and the 

 first, even in the modified form given to it by Wallace in 

 "Island Life," cannot be admitted, in the opinion of most 

 American students of this subject, when we find that the Ice 

 age ended probably only 6,000 to 10,000 years ago. 



The epeirogenic movements of the countries which became 

 glaciated were only a portion of wide-spread oscillations of 

 continental areas during the closing part of Tertiary time and 

 the ensuing much shorter Quaternary era. !N"ot only was 

 northwestern Europe uplifted thousands of feet, but probably 

 all the western side of Europe and Africa shared in this move- 

 ment, of which we have the most convincing proof in the 



* Astronomical Journal, vol. xii, pp. 57-62, 65-72, and 97-101, Aug. 4 and 23,. 

 and Nov. 4, 1892. 



