Origin of Mount Etna. 385 



platform which terminates them, that the largest mass of modern 

 volcanic matter is accumulated. The lavas and the loose vol- 

 canic substances are there stratified bed by bed, and it is to the 

 regular laws according to which their accumulation has taken 

 place that we are to attribute the softness and regularity of the 

 acclivities presented by these places. The flatness of Etna, al- 

 ready particularly mentioned, is the expression on the great scale 

 of a part of these laws. The successive materials, which the 

 eruptions add year after year to the mass of Etna, are, in fact, 

 the elements of a cone extremely flattened, whose inclination 

 does not exceed 8°. The extreme limit to which we can ima- 

 gine that the indefinite repetition of these eruptions tends to give 

 the form of Etna, would be a cone infinitely less elevated than 

 that of which the nucleus of the central gibbosity seems to be 

 the debris. If this nucleus did not exist, Etna would not be 

 elevated at the present day above the point of meeting of the' 

 prolonged edges of the lateral taluses ; — that is to say, it would 

 not have been more than 1600 to 2000 yards in height. It is 

 evident that the central gibbosity owes its existence entirely to 

 the pre-existing nucleus which forms its chief mass. Far from 

 continuing the formation of this nucleus, the eruptions of the 

 present day tend, on the contrary, to sink it, and to make it dis- 

 appear. The philosophers and geologists who, since the days of 

 Empedocles to the present time, have seen Etna cover almost 

 periodically its flanks with new layers of cinders, scoria?, and 

 lava, have admitted, almost without examination, and as a fact 

 which was, as it were, self-evident, that the entire mountain was 

 simply the result of the repeated gradual additions of materials, 

 all similar to each other, and similar also to the products of 

 eruptions taking place under their own observation. Indeed, at 

 first sight this appears almost as natural as to attribute the en- 

 tire growth of an oak to the repetition of the phenomena of ve- 

 getation Avhich had been observed in it during one summer. 

 But the observations and reflections, of which I now present the 

 analysis, appear to me to prove that the whole mass of Etna 

 cannot be reduced to elements all analogous to each other, and 

 having a similar origin, in the same manner as the successive 

 layers of which the trunk of an oak is composed ; and that in com- 

 paring the increase in size of Etna to the growth of an individual 



