&• 



Charpentier's Kami/ on Glaciers. 121 



With regard to the crossing the Lake of Geneva, or otherlakes 

 tilling up the openings of the great valleys, such an obstacle was 

 inadequate to stop the progress of glaciers. When once the wa- 

 ter of the lake cools to zero by the melting of the ice, the water 

 will support the glacier, if it is so deep that it cannot reach tlie 

 bottom. In fact the density of ordinary ice is about 0.92, 

 and that of the porous ice of glaciers must be still less con- 

 siderable. Thus, the glacier of Panerossaz, in the Alps of 

 Bex, is in great part supported by a lake ; in like manner, 

 in 1817, the glacier of Schwartzberg crossed the whole breadth 

 of the lake of Matmarck ; and we also know, as Scoresby ob- 

 served on the coast of Greenland, and quite recently as Cap- 

 tain Ross found near the islands he discovered in the neighbour- 

 hood of the south pole, that glaciers advance into the sea to 

 the distance of many miles. 



We pass over without remark other objections of detail to 

 which M. de Charpentier endeavours to give answers, either 

 by taking it for granted that they will be urged against him, 

 or, because they have really been started since his hypothesis 

 of diluvial glaciers has been made known to the scientific 

 world : and we terminate this short analysis of his work, by 

 a few words on the influence which he ascribes to glaciers on 

 the diluvial phenomena. The three principal of these phe- 

 nomena are : the configuration of the surface of the valleys, 

 and of the plain between the Alps and the Jura, — the deposit 

 of diluvial matter, — and the transport and dispersion of erratic 

 blocks. These three phenomena, which are continued to our 

 own day, although on a very reduced scale, have been in some 

 degree contemporaneous in the diluvial epoch ; but the actions 

 which predominated, succeeded each other in the order in 

 which they are announced. In fact, if, as M. Agassiz thinks, 

 the dispersion of the erratic debris had taken place first, 

 and at the moment when the Alps pierced the sheet of ice, 

 which he supposes to have then existed, we ought to find 

 these debris generally covered and buried up by the diluvium, 

 which has not been observed to be the case. 



The partial filling up of crevices, whether by means of 

 large fragments of broken rocks which still project from the 

 bottom of the vallevs, or bv the substances earned down by 



