INTRODUCTION. Xlli 



been followed by many natural philosophers who have given 

 it all possible extension, and, from physical truths and exact 

 observations, have conducted this theory to a degree of veri- 

 similitude of which the others are not capable. I adopt it, 

 not only as it appears to me the most consonant to the 

 theorems of natural philosophy, but as I find it most proper 

 to give the most natural and easy explanation of the facts 

 which we observe in Sicily, and which seem to add additional 

 proofs to those observed in other regions." * 



Bouguer, and many other naturalists, have observed, that Subsidence, 

 in South America the plains have palpably subsided, and left 

 the rocks elevated in many fantastic forms. It is indeed to 

 be conceived that the earth, originally in a fluid state, as 

 appears from the depression of the poles, and many other cir- 

 cumstances well known in natural philosophy, and replete 

 with innumerable vapours and gases, could only acquire its 

 present comparative solidity by prodigious subsidences, arising 

 from the gravitation of the solid and semifluid parts towards 

 the centre. The most prodigious of the subsidences must 

 have been that which sunk two thirds of the globe to make 

 room for the present oceans, sufficient receptacles for the 

 primeval waters, if the idea of this vast subsidence can be 

 supported. Ferrara, arguing only on that subsidence which 

 gave place to the Mediterranean, says that the mountains 

 above Reggio are very sensibly inclined towards the sea, 

 which indicates that their base sunk to form the channel 

 which divides Italy from Sicily. He also observes, that the 

 inclination of the strata towards the sea may be seen in all 

 the mountains which border the southern side of Sicily f. 

 The following passage likewise deserves observation : " Where 

 the mountains are formed of soils in which the lavas are 

 united with the calcareous masses, or, to explain myself more 

 clearly, where a frontier of consolidated lava was filled from 

 the bottom to the top with calcareous masses, the series of 

 these heights is calcareous on the one side, and volcanic on 



* Ferrara. 354. f Ferr. 371, 374. 



