884? M. li. Elie de Beaumount on the Structure and 



ready consecrated, we recognise in the older of these two forma- 

 tions tlie summits of an ancient world buried wider a world of 

 modern origin. 



The products of the present volcanic vent form on the mass 

 of Etna a mantle nearly continuous, which is interrupted only 

 at certain parts of the central gibbosity, so as to permit the 

 more ancient rocks to appear. 



This arrangement might surprise at first sight, for it would 

 have been natural to presume that the ejected loose matters, which 

 form the chief mass of the products of the great crater, would 

 have covered the entire surface of the central gibbosity wiih a 

 thick bed of cinders and lapilli. It is, however, sufficient to 

 cast a glance, when the weather is clear, on the eastern part of 

 Etna, in order to perceive that several very extensive portions 

 of the central gibbosity have not been completely covered by 

 the ejections alluded to; but they have only been, as it were, 

 sprinkled over with a small quantity of these matters, which in 

 time have been collected in the ravines, whose bottoms they 

 mark by a black train, while all the rest is left uncovered. In 

 the" places n^ar those where it becomes interrupted, the mantle 

 of ejected matter is, of course, extremely thin, and we can, in 

 fact, ascertain that these recent volcanic products are accumu- 

 lated on the Piano del Lago, and even at the foot of the upper 

 cone, only to a very inconsiderable thickness. 



The observations already cited relative to the Torre delFilosofo^ 

 whose foundations only have been concealed by the eruptions of 

 fifteen or twenty centuries, prove the extreme slowness with 

 which modern ejected matter accumulates on the central gib- 

 bosity. The accumulation of these recently ejected matters'pro- 

 ceeds much more rapidly on the portions of the mass of the 

 mountain which are removed from the centre. The base of the 

 Greek and Roman monuments, which still exist in the- town of 

 Catania, has been enveloped to a much greater extent than the 

 foundation of the Torre del Filosofo by products of eruption. 

 The port of Ulysses, near Catania, was overwhelmed by a cur- 

 rent of lava, and the relief of the whole surface of the vicinity of 

 that town has been much more changed than that of the Piano 

 del Lago during the last 1500 or 2000 years. 



It is on the lateral talus?s of Ema, and on tha slightly inchned 



