^66 Analysis qf'Sdentifie Books atid Memoirs* 



planation than that of Daubuisson and Ramond. Von Buch supposes the 

 Doinite to have been '* granite liquefied by volcanic heat." I also con. 

 ceive it to have been, like all lavas, a mass of granite, or some congenerous 

 crystalline rock, which, while confined beneath the surface of the globe at 

 an intense temperature, was suddenly allowed to expand by the bursting 

 of the overlying rocks, and was consequently liquefied, or so far softened 

 by the immediate generation of highly elastic fluids, both gases and 

 aqueous vapour, through every part of its texture, as to be protruded, by 

 the tumefaction incident to this process, through the clefts of the over- 

 lying crust. 



" The part of Von Buch's theory with which I agree the least, is his sup- 

 posing these hills to be hollow, and blown up like a bladder. I imagine, 

 on the contrary, the aeriform and highly elastic fluids the expansion of 

 which elevated the lava, to have remained chiefly where they were gene- 

 rated, viz. in a state of uniform and intimate dissemination throughout the 

 texture and between the solid crystalline particles of the porous and elas- 

 tic mass; and not by any means to have united into one great bubble or 

 volume beneath an overlying cake of the lava, as is implied in Von Buch's 

 theory, a theory which Humboldt has adopted and applied I think with 

 rashness, to all trachyte formations." 



In the same region occurs the Piiy de Pariou, which, from its aspect and 

 that of its lava, is supposed by Mr Scrope to be the result of one of the 

 last eruptions which convulsed the country. The following description 

 of it is peculiarly instructive. 



'* It is one of the most considerable and regular cones of the chain. A 

 segment of a former crater half encircles it on ths north, and here the 

 whole process of this and similar formations is manifest. (See Mr Scrope's 

 Considerations on Volcanos, p. 67.) * * * The new crater of Pariou, form- 

 ed upon the brink of the older one, has the figure of an inverted cone. 

 It is clothed to the bottom with grass, and it is a somewhat singular spectacle 

 to see a herd of cattle quietly grazing above the orifice whence such fu- 

 rious explosions once broke forth. Its depth is 300 and its circumference 

 3000 feet. The inclination of the sides of the cone and of the crater are 

 both about 35°. The acute ridge resulting from their junction is so little 

 blunted by time that in some parts it scarcely affords space to stand on. 

 Its highest point is 738 feet above the southern base of the Puy. 



" The first direction of the lava of Pariou is to the N. E. and the current 

 appears to have set with fury against a long-backed granitic eminence op- 

 loosing it on that side. Hence, led by a considerable slope towards the 

 S. E. it coasted the base of this hill, and leaving to the right another pro- 

 tuberance of the primitive plateau on which now stand the church and 

 hamlet of Orcines, advanced to a spot called La Barague. Here it met 

 with a small knoll of granite capped with scoriae and volcanic bombs. 

 Impeded in its progress the lava accumulated on this point into a long and 

 elevated ridge, which still Ijears the appearance of a huge mass, about to 

 break over the seemingly insignificant obstacle. BiU an easier issue offered 



