34 On the Revolutions which have 



dence, or a sort of tassement^ until all the parts which were ill 

 supported or ill placed, had taken their proper position, and 

 acquired the solidity and stability which the mass presents at 

 the present day. 



The effect of such a soulevement to so great a height above 

 the level of the sea, combined with the diminution of the ter- 

 restrial heat, must have effected a great change on the tempe- 

 rature of the climate of these countries. The climate fit for 

 the growth of the chamaerops, and other plants of warm coun- 

 tries, became similar to that of the north ; the atmosphere was 

 cooled ; the Alps were covered with snows, which, descending 

 continually into the valleys, formed immense glaciers. Not 

 only did these glaciers gradually invade all the valleys, but they 

 reached and even covered all the low part of Switzerland, and 

 extended their moraines so far as the top of the Jura. 



But, in consequence of the general sinking, this vast coun- 

 try having diminished in elevation above the sea, its climate 

 was insensibly ameliorated, by which means it arrived at its 

 present temperature. These enormous glaciers diminished in 

 their turn, retiring according as the surface of the land sub- 

 sided, and the temperature increased. They left, in the track 

 of their passage, as witnesses of their former existence, those 

 blocks of rocks from the Alps, which are found sometimes iso- 

 lated, sometimes in a heap (in the form of a dike or rampart), 

 from the summit of the Jura to the summit of the Alps, and 

 they also left those marks of friction and attrition so apparent 

 on the surface of the rocks which bound the valleys, and which 

 rise to a height corresponding to the thickness of those vast 

 primitive glaciers.* Those blocks of alpine rocks, dispersed to 

 such great distances, are known to geologists by the name 

 of Boulders (Blocs erratiques), and their mode of transport has 

 long been a subject of investigation ; but it is to M. Venetz, 

 engineer in the canton of the Valais, that we owe the knowledge 

 of the true agent alone capable of producing this great pheno- 

 menon, and all the accidens which accompany it.-(- 



* The great moraines in valleys in Norway, where now no glaciers occur, 

 are here deserving of notice. EDIT. 



-j- In a Memoir, read to the Socicte Helvttique des Sciences Naturelles, at their 

 meeting at Lucerne, now translated into German in Nos. 3. and 4. of the 



