OF THE EARTH'S SURFACE. 143 



and the lake, at an elevation of 2000 feet above the latter. A 

 set of low hills also intervene, which occasionally hide that cen- 

 tral ridge from the view ; and it is principally where the snowy 

 summits are visible from the fice of Jura, by means of some 

 depression in these intervening hills, that we find those travel- 

 led masses ; as I remember well to have witnessed, at some of 

 the places which Saussure has pointed out, where, in high 

 situations, on the face of Jura, I rode through great assem- 

 blages of granitic blocks, three or four feet in diameter. 



The force of this fact is admitted, but an attempt is made *, 

 even under that admission, to refer the whole to diurnal ac- 

 tions, by supposing, that from the spot where these blocks lie, 

 up to the summit of Mont Blanc, one continued solid plane 

 has ascended, along which, on a declivity computed at one in 

 thirty, these blocks may have been hurried by a stream of wa- 

 ter ; and that subsequently, in the course of ages, all the inter- 

 vening mass had been washed away, so as to reduce the coun- 

 try to its present situation. But this hypothesis removes the 

 difficulty of the intervening valleys only ; for the transporta- 

 tion in this case would be scarcely less difficult than it would 

 be to Geneva, as matters stand at this day ; — and a circum- 

 stance occurs, founded upon the observations of Sir George 

 Shuckburgh, which seems entirely to preclude this hypothe- 

 sis. 



According to his measurement and scale, as given in the 

 Philosophical Transactions, vol. lxvii. the height of Mont Blanc 

 is 14,432 feet above the lake, and the distance in a straight line 

 from Jura to Mont Blanc, I find, by his scale, to be nearly fif- 

 ty-four miles, and 2000 feet is the height at which these gra- 

 nite blocks occur on Jura. The slope, therefore, along which 

 these blocks must have descended, would be nearly that of one 



in 



* Illustrations, art. 345, page 385. 



