1859.] 



SCKOPE — COliTES AND CRATEKS. 



517 



and the terminal cone of Etna to be eruptive cones *. But, on the 

 other hand, M. de Buch, in the passage I have already referred to, 

 affirms the extreme regularity of the entire figure of Etna to be a 

 proof that it could not be the product of eruptions, but must have 

 been upheaved at a single stroke, '^a V instant meme de sanaissancef.^' 

 In fact, M. de Buch's test is the precise reverse of M. de Beaumont's. 

 Suppose, however, we take M. de Beaumont's as that of the latest 

 authority on the point. Surely it is trifling with the subject to rest 

 so important a distinction as to origin upon a difference in outline 

 so slight, so disputable, nay, so necessarily variable under varying 

 circumstances of composition, dilapidation, &c., independently of all 

 question of origin. In the first place too, it is undeniable that 

 many, perhaps the majority of the acknowledged cones of eruption 

 about Etna, and in Central France, show a sloping outline by no 

 means '^ rectilinear," but sweeping downwards in a gradual curve 

 that lessens in steepness till it meets the base, which is M. de Beau- 

 mont's characteristic of an " upheaved cone." In the second place, 

 the slightest consideration makes it obvious that great differences in 

 this respect must be occasioned by casual differences in the size, 

 shape, or mineral character of the ejected fragments, by their more 

 or less heated state and consequent coherence or non- coherence at 

 the time of their fall and accumulation, by their greater or less degra- 

 dation by storms of rain accompanying the eruption, or by a longer 

 or shorter subsequent exposure to atmospheric influences. In the 

 case of the larger volcanic mountains, if we suppose them the pro- 

 duct of repeated eruptions, a graduated slope towards the base must 

 necessarily have been occasioned, not only by longer exposure to the 

 agents of degradation, but still more by the accumulation of the 

 lavas and scorioe emitted from lateral vents on the lower flanks of 

 the mountain. Indeed, M. de Beaumont, by admitting the many 



Fig. 5. — Outline of Etna, as seen from near Catania. (From Mem. 

 Soc. Geol. de France, vol. iv. pi. 2.) 



hundred parasitic cones of Etna and their lava-streams to be eruptive, 

 himself accounts, on the theory of accumulation, not of upheaval, for 

 the graduated slope of the mountain as a whole into the plain 

 around. And, in truth, the visible portion of his '' central up- 



* Memoires, iv. p. 157. 



t Canaries, p. 326-7. 



