Ch.VIII.] DILUVIAL WAVES. 101 



There seems nothing in the deep sections of the Val del 

 Bove, to indicate that the lava currents of remote periods 

 were greater in volume than those of modern times ; and 

 there are abundant proofs that the countless beds of solid 

 rock and scoriae were accumulated, as now, in succession. 

 On the grounds, therefore, already explained, we must infer 

 that a mass, eight thousand or nine thousand feet in thick- 

 ness, must have required an immense series of ages anterior 

 to our historical periods, for its growth ; yet the whole must 

 be regarded as the product of a modern portion of the newer 

 Pliocene epoch. Such, at least, is the conclusion that we 

 draw from the geological data already detailed, which show- 

 that the oldest parts of the mountain, if not of posterior date 

 to the marine strata which are visible around its base, were at 

 least of coeval origin. 



Whether signs of Diluvial Waves are observable on Etna. 

 Some geologists contend, that the sudden elevation of large 

 continents from beneath the waters of the sea, have again and 

 again produced waves which have swept over vast regions of 

 the earth, and left enormous rolled blocks strewed over the 

 surface*. That there are signs of local floods of extreme 

 violence, on various parts of the surface of the dry land, is 

 incontrovertible, and in the former volumes we have pointed out 

 causes which must for ever continue to give rise to such phe- 

 nomena ; but for the proofs of these general cataclysms we 

 have searched in vain. It is clear that no devastating wave 

 has passed over the forest zone of Etna, since any of the lateral 

 cones before mentioned were thrown up ; for none of these 

 heaps of loose sand and scoriiB could have resisted for a moment 

 the denuding action of a violent flood. 



To some, perhaps, it may appear that hills of such incoherent 

 materials cannot be of immense antiquity, because the mere 

 action of the atmosphere must, in the course of several thou- 

 sand years, have obliterated their original forms. But there is 

 no weight in this objection, for the older hills are covered with 

 * Sedgwick, Anniv. Address to the Geol. Soc., p. 35. Feb. 1831. 



