120 RAMBLES OF A NATURALIST. 



cause that we must more especially attribute that 

 general character of flatness which is exhibited by 

 the entire mass of the mountain, notwithstanding its 

 great height. It may be that, in the course of ages, 

 the surrounding land may in this manner be so much 

 raised, that the greater part of Etna may be buried 

 beneath the products of its own craters. 



It is not probable, however, that the primitive 

 nucleus will ever wholly disappear. The quantity 

 of matter ejected by the terminal crater is so small, 

 that it scarcely suffices to cover the slightly inclined 

 surface of the Piano del Lago ; while on the steeper 

 declivities this material is only accumulated in the 

 crevices and ravines, in the same manner as we 

 observe in the case of a slight layer of snow. 



This fact, which at first sight is almost incredible, 

 and which is so strongly opposed to many commonly 

 received opinions, admits nevertheless of a very ready 

 proof. The Torre del Filosopho is only separated 

 from the terminal cone by a distance of about 100 

 yards. This monument is more than 2000 years 

 old, and yet the volcanic products accumulated round 

 its base had only acquired in 1807 a thickness of nine 

 feet one inch.* The Piano del Lago, which is situ- 

 ated immediately at the foot of the great crater, does 

 not therefore rise each year on an average more than 

 one twenty-fifth of an inch from the accumulation of 

 the direct products of the volcano, together with the 

 materials which atmospheric agents may carry away 



* These measurements were taken by Dr. Mario Gemellaro, and 

 confirmed by Signer Agatino Recupero. 



