LYELL ( 



OX CRATERS OF ELEVATION'. 



321 



This part first enters into the origin of the Val del Bove, and how 

 it is due to aqueous erosion. 



The origin of that large crateriform valley has been sometimes 

 attributed to a sudden catastrophe connected with those movements 



which are supposed to have given rise to the mountain itself ; but if 

 the doctrine of a double axis be admitted, and the reasoning advanced 

 in this paper be conceded, it is certain we must come " to the con- 

 clusion that the mountain, with its lavas and tuffs sloping away from 



