356 CLIMATIC CONDITIONS OF THE GLACIAL EPOCH. 



We may now proceed to consider specially the course of geological events 

 during the Glacial epoch in those regions where, as already suggested, the 

 phenomena and conditions of former glaciation are on so large a scale, and 

 of so peculiar a character as to involve decided changes of climate or topog- 

 raphy, or perhaps of both simultaneously. Of the probable extent and 

 character of these changes something will be said after giving a necessarily 

 brief sketch of the facts themselves. And for this purpose it will be con- 

 venient to begin with the region of Southern Europe, taking the chain which 

 naturally follows next in order to the Caucasian Range, the former glaciation 

 of which has been already indicated. 



It was in the Alps that attention was first called to the fact that ice had 

 once covered a larger area than it now does, and it is there that the 

 phenomena of present and past glaciation have been most carefully observed 

 and studied. The principal facts are indeed easily made out, and are consid- 

 erably less complicated than those of the Scandinavian Range. The essential 

 point is, that at a former period the present glaciers extended inuch f^xrther 

 down the valleys than they now do, and the evidence by which this assertion 

 is supported is clear and convincing. There is little in the phenomena pre- 

 sented by the Alpine region of former glaciation which cannot be recognized 

 at once as exactly similar in kind to that which is now going on there, 

 although on a much diminished scale. For instance, it is easy to see that 

 glaciers carry the detritus which falls upon them and deliver it at the point 

 where the ice comes to an end, as a cjeneral thino:, in an antrular form and 

 imstratified. In accordance with this we find aloncj the edges of the Jura, 

 on the side facing the great Swiss plain, accumulations of angular debris 

 piled up just like the frontal moraines of the present day. We see at once 

 that these materials must have been left by a glacier, and on tracing them 

 back to their source, as has long since been done with infinite pains by Guyot 

 and others, we have no diflRculty in locating that source somewhere higher 

 up in the Alpine Valley down which we are authorized by all the topo- 

 graphical and other conditions to believe that the magnified glacier moved. 

 In the same way within the Alpine Range itself, at innumerable points, we 

 have the remains of old moraines, both lateral and tei'minal, piled up in the 

 bottoms of the vallevs or alontr tlieir sides, furnishina; the most conclusive 

 testimony that the ice has once occupied the places thus covered with debris 

 which can have had no other than a i^lacial origin. 



It is especially on the south side of the Alps that the phenomena of a 



