120 THE WONDERFUL CENTURY. 



really exists at the present time in Greenland, in the 

 same latitude as nearly the whole of Sweden and Nor- 

 way, which enjoy a comparatively mild climate. 



The first clear statement of the evidence for a former 

 ice age was given, in 1822, by a Swiss engineer named 

 Yenetz. He pointed out that, where the existing 

 glaciers have retreated, the rocks which they had cov- 

 ered are often rounded, smoothed, and polished, or 

 grooved and striated in the direction of the glacier's mo- 

 tion; and that, far away from any existing glaciers, there 

 were to be seen rocks similarly rounded, polished, and 

 striated; while there also existed old moraine heaps 

 exactly similar to those formed at present ; and that these 

 phenomena extended as far as the Jura range, on the 

 flanks of which there were numbers of huge blocks of 

 stone, of a kind not found in those mountains but exactly 

 similar to the ancient rocks of the main Alpine chain. 

 Hence, he concluded that glaciers formerly extended 

 down the Rhone valley as far as the Jura, and there de- 

 posited those erratic blocks, the presence of which had 

 puzzled all former observers. 



Soon afterward, Charpentier and Agassiz devoted 

 themselves to the study of the records left by the ancient 

 glaciers; and from that time to the present a band of 

 energetic workers in every part of the world have, by 

 minute observation and reasoning, established the fact 

 of the extension of glaciers, or ice-sheets, over a large 

 portion of the north temperate zone; and have also de- 

 termined the direction of their motion and the thickness 

 of the ice in various parts of their course. These con- 

 clusions are now admitted by every geologist who has de- 

 voted himself to the subject, and are embodied in the 



