102 frEWER PLIOCENE PERIOD. 



[Ch. VIII. 



trees and herbage, which protect them from waste ; and in 

 regard to the newer ones, such is the porosity of their compo- 

 nent materials, that the rain which falls upon them is instantly 

 absorbed, and, for the same reason that the rivers on Etna have 

 a subterranean course, there are none descending the sides of 

 the minor cones. 



No sensible alteration has been observed in the form of 

 these cones since the earliest periods of which there are memo- 

 rials ; and we see no reason for anticipating, that in the course 

 of the next ten thousand or twenty thousand years they will 

 undergo any great alteration in their appearance, unless they 

 should be shattered by earthquakes, or covered by volcanic 

 ejections. 



We shall afterwards point out, that, in other parts of Europe, 

 similar loose cones of scoriae, which we believe to be of higher 

 antiquity than the whole mass of Etna, stand uninjured at 

 inferior elevations above the level of the sea. 



