Charpentier's Etfsa)/ on Glaciers. 11? 



poses to liave taken place before the final elevation of the 

 Alps, anymore than those which have induce J a milder climate. 

 He is of opinion, that if it be necessary to admit a cooling, 

 which he is ready to do, although to a much less degree than 

 M. Agassiz, this cooling must have taken place after the ca- 

 tastrophe which gave the Alps their present form, and that 

 it has even been the consequence of it. He cannot compre- 

 hend how a single winter could have been sufficient to accu- 

 mulate ice to the height of 3100 feet above the plain ; and 

 consequently the excessive cold necessary to freeze the lakes, 

 such as that of Geneva, which does not freeze at — 25°C.,(-13 F.) 

 must have continued without mitigation for many years. But 

 then this cold must have dried up all the running water, rain 

 wouhl naturally cease, and even snow, wliich is very rare in 

 very intense colds. But even if we were to admit a thick bed 

 of snow, it would have been too soft and rough to allow the 

 blocks to slide on it to any considerable distance. 



Again, when M. Agassiz supposes that, at the moment of 

 the elevation of the .high Alps, the sheet of ice, pierced 

 and raised upwards, became a bed for the blocks, M. de 

 Charpentier remarks that, by calculating the mean height of 

 the Alps at 11,000 feet, the greatest elevation of the blocks at 

 4250 feet above the sea, and the mean distance of the highest 

 parts of the Alps from the Jura at 25 leagues, we find that 

 the supposed surface of ice would only have an inclination of 

 1° 8' 50". Now this slope is too small to admit of blocks with 

 a rough surface and sharp angles sliding upon it such a dis- 

 tance. In fact, according to M. de Charpentier, we never see 

 blocks sliding downwards even on the steepest glaciers, even 

 although the surface is free from snow and hardened by the 

 cold, as sometimes happens in the end of autumn. M. de 

 Charpentier then asks why the limits of the erratic deposit 

 describe on the sides of the Jura a curve and not a horizontal 

 line, such as one would expect from a frozen lake .'' Why 

 the greatest accumulation of these blocks is found at the 

 highest part of this cun^e or in its vicinity, the very place 

 where the inclination must have been least ? And, lastly, why 

 this accumulation is precisely in front of the great valley of the 

 Rhone, which did not exist before the elevation of the Alps, 



VOL. XXXIII.--^N0. LXV. JULY 1842. H 



