^ A Period in the History/ of our Planet. 



towards the rocks of our lofty mountains, and to the ice-bound 

 continents of the north. 



Manifestations of retreat 1 will it be asked me. Whence, 

 then, the retreat 1 For that there has been a retreat, can- 

 not well be a matter of doubt to us, whose life could only 

 exist by dint of, and subsequent to, such a retreat. The fact 

 is just as undeniable as its causes are hypothetical. A short 

 time ago I could have assigned a probable cause, founded 

 upon the beautiful investigations of one of the ablest of our 

 geologists, Elie de Beaumont, and on his confident dictum, 

 that the Alps had arisen from the bosom of the earth at two 

 different epochs ; Mont Blanc, with its chains to north and 

 southward, being more ancient than the chain of the Eastern 

 Alps, which were the most recent of all the elevated moun- 

 tain chains, and formed a wall of separation betwixt the 

 diluvium and our present epoch. Just as the violent revolu- 

 tions, whose results were the elevations of more ancient moun- 

 tain chains, had on every occasion swept off a phasis of deve- 

 lopment of animal life upon the earth, in order to make room 

 for one newly commencing, so, I imagined, might the eleva- 

 tion of the eastern great Alpine chain have been that last 

 struggle of the powerful internal forces of our globe, which 

 had put an end to the glacial period, and rendered possible the 

 existence of our present creation. Following E. de Beaumont's 

 views, I have in my last published work* expressed the follow- 

 ing opinions : — " That only Mont Blanc, with the chain of the 

 maritime Alps, existed when the ice enveloped the northern 

 hemisphere ; but that when the chain of the great Alps rose 

 from the bosom of the earth, the icy covering which had rested 

 upon the position they now came to occupy, was elevated along 

 with them, formed thus an inclined surface, and was covered 

 with the ruins of the rocks which were shattered by this im- 

 mense revolution ; that the temperature of the earth was al- 

 tered by this elevation ; and that a consequence of this altera- 

 tion was the retreat of the ice covering to the northern regions 

 and the Alpine mountain summits." 



More recent inquiries, however, of two friends, which, to be 



* Unterauchungen iiber die Glctschcr. 1841. 



