886 M. L. Elie de Beaumount on the Structure afid 



of the vegetable kingdom, we should commit the same error as 

 if we attributed to an ivy plant the growth of the old dead tree 

 to wiiose trunk it is attached. 



The features truly characteristic of the form of Etna, those in 

 which its mode of enlargement and its first origin occur most 

 distinctly displayed, are then, on the one hand, the feebleness and 

 the uniformity of the inclinations presented by its base from the 

 foot of its central gibbosity to the banks of the rivers and the sea- 

 shore which surround it ; and on the other, the abrupt relief", the in- 

 sulated position, and the disjointed condition of the internal nucleus 

 of that same gibbosity. The gentle slopes of the base have been pro- 

 duced by the deposition of debris (un remblai); but the bold pro- 

 jecting outline, the insulated position, and the broken up structure 

 of the central gibbosity, owe their first origin to a souhvement ; 

 and such in a few words is the theory of Etna. The structure of 

 the internal nucleus of the central gibbosity is exhibited in the 

 escarpments of the vast elliptical amphitheatre, termed the Vol 

 del Bove. These escarpments are composed of many hundred 

 layers, formed alternately of rocks of fusion, which differ from 

 modern lavas by certain shades, and of fragmentary and pulve- 

 rulent matters more or less solidly aggregated. Their thickness 

 varies from half a yard to several yards. These layers, whose 

 regularity is hardly ever deranged, except to a limited extent, 

 by the crossing of veins or by other accidental circumstances, 

 frequently form undulations which remind us of those of sedi- 

 mentary beds in the high chains of mountains, and they do so with- 

 out even having their parallelism or consequently their thickness 

 altered, although in these undulations their inclination sometimes 

 amounts to 27°. This absence of all variation in the general 

 arrangement of the layers prevails through the entire circuit of 

 the Vuldel Bove, and it has struck me forcibly each time I have 

 had occasion to direct my attention to the ensemble of its escarp- 

 ments. My observations on this subject may be summed up by 

 saying, that the numerous layers of melted and fragmentary mat- 

 ters which alternate in order to form the nucleus of the central 

 gibbosity of Etna become curved simultaneously, and pass in se- 

 veral difTerent directions, from a position nearly horizontal, to 

 an inclination of 25° to 80°, without having their structure or 

 thickness altered in a constant manner. These layers tre cut 



