228 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 19, 



Beaumont has adopted ; and he has well remarked that it could not 

 be attributed to explosions, for in that case vast showers of ejected 

 matter comprising the former contents of the deep gulf or valley 

 would have been apparent on the flanks of Etna. Without denying 

 that some part of the missing rocks may be referable to engulfment, 

 I am now disposed to suspect that their removal may have been 

 chiefly due to the denuding action of the sea, which probably availed 

 itself of a breach in some lateral crater, or perhaps some partial sub- 

 sidence, to gain access to and scoop out a circular bay, and carry out- 

 wards in the course of ages the debris of the undermined rocks. On 

 consulting my notes made in 1828, I find that this was my first im- 

 pression on entering the great valley ; but the extent of surface covered 

 by modern lava-streams, under which the bottom of the Val del 

 Bove, as well as the north side of the Val di Calanna are buried, con- 

 ceals so much of the ground, as to render it diflicult and somewhat 

 dangerous to speculate on the origin of the vast hollow. I may how- 

 ever remark, in reference to aqueous action, that although no signs 

 have been discovered of marine shells in any beds of fragmentary 

 matter, composing the clifl's which bound the Val del Bove, yet ma- 

 rine organic remains have been traced to the height of 800 feet above 

 the sea near Trezza. Nor can there be a reasonable doubt, that if the 

 lower parts of the great mountain were not covered with modern 

 lava and ashes, similar proofs of the former presence of the sea would 

 be discoverable at much greater heights. We might indeed expect 

 to find them at a higher elevation than any of the marine tertiary 

 strata in Sicily, and these occur in the centre of the island as high as 

 3000 feet above the sea. If in the vicinity of Vesuvius beds contain- 

 ing marine shells of recent Mediterranean species have been upraised 

 to heights of between 2000 and 3000 feet, we are prepared to sup- 

 pose that the uplifting force may have been developed with equal, if 

 not greater intensity on the site of Etna, although no sections can be 

 obtained in consequence of the enormous outpourings of lava and 

 showers of scorise by which the older portions of the mountain are 

 masked. 



The marine strata, containing shells of recent species, which crop 

 out along the eastern and southern base of Etna, consist in great part 

 of volcanic materials, of tufl^, scorise, and ashes washed down into the 

 sea, and of rolled pebbles of lava, as at La Motta near Catania, such 

 as the destruction of the ancient denuded parts of a great cone may 

 have furnished. The origin of some^of these may have been contem- 

 poraneous with the excavation of the Val del Bove when the cliffs 

 encircling that valley were washed by the waves of the sea. 



In reference to the question of denudation, I may ask those who 

 have visited and may revisit Etna to consider whether the rocks called 

 Musarra and Capra, which appear to be outstanding masses of ancient 

 lavas intersected by dikes, rising up near the middle of the Val del 

 Bove, are not best explained by supposing them to be remnants of the 

 once continuous cone not entirely carried away by the waves and cur- 

 rents ; also, whether the ridges of very ancient and crystalline volca- 

 nic rocks called Rocca Giannicola and Rocca del Solfizio, which stand 



