386 



ILLUSTRATIONS OF THE 



graphic miles. Though we fuppafe Mont Blanc, 

 and the reft of thofe mountains, to have been ori^ 

 ginally much higher than they are at prefent, the 

 ridge of Jura muft have been fo likewife ; and 

 though probably not by an equal quantity, yet 

 It is the fairell way to fuppofe the difference of 

 their height to have been nearly the fame in for- 

 mer ages that it is at prefent, and it may there- 

 fore be taken at 10,000 feet. The declivity of 

 a plane from the top of Mont Jura to the top of 

 Mont Blanc, would therefore be about one mile 

 and three quarters in fifty, or one foot in thirty ; 

 an inclination much greater than is neceflary for 



w 



to run on, even with 



eme rapidity 



and more than fufficient to enable a river or a 

 torrent to carry with it ft ones or fragments of 

 rock, almoft to any diftance. 



Saufliire, in relating the fad that pieces of 

 granite are found among the high paffes near 



th 



fummits of Mont J 



alleges, that they 



ly found in fpots from which the 



chain of the Alps may be fee 



•fe 



th 



this 



id 



is 



But it ftiould 

 ccidental, be- 



caufe, from whatever caufe the tranfportation 

 of thefe blocks has proceeded, the form ot the 

 mountains, efpecially of Mont Jura, muft be too 

 much changed to admit of the fuppofition, that 



the places of it from which Mont Blanc is now 



vifible,. 



