134 Volcanos. 



less solid state, together with the heaving, dislocation, and con- 

 tortion of the strata on either side the cleft, that process, in short, 

 to which he attributes the production of mountain ranges, was 

 the immediate and primary result of partial expansions of the sub- 

 terranean lava-bed at a great depth ; while the fissures of eruption, 

 which give rise to the properly so called volcanic eruptions, on 

 different points of these cracks, were secondary and incidental 

 results of this process, being chiefly occasioned by the lateral 

 drag of the superficial strata towards the line of elevation, which 

 the action of a powerful force, heaving them upwards on this 

 line, must necessarily produce. The author remarks, that the 

 generalization of this important fact, that the elevation, en 

 masse, of the solid strata, composing the crust of the earth, has 

 been inversely proportional to the developement of the volcanic 

 phenomena in the same quarter of the globe, demonstrates, that 

 the subterranean bed of intensely heated crystalline rock, (or 

 lava,) whose local existence was proved in the early part of his 

 essay, must extend generally beneath the whole surface of the 

 globe. The transmission of caloric to this bed, from within, ap- 

 pears also to have been uniform and constant, having produced 

 successive expansions in it, and proportional elevations of the 

 overlying surfaces in those parts where no facilities existed for 

 the outward escape of the caloric, and continual eruptions attend- 

 ed with little or no elevation, wherever vents were created for 

 the extravasation of the heated and intumescent matter. 



" In the Xth Chapter, " on the Developement of Subterrane- 

 an Expansion in the elevation of strata, and production of con- 

 tinents above the surface of the ocean," the author quits the 

 volcanic phenomena, properly so called, to apply the knowledge 

 with which the investigation of these phenomena has furnished 

 him, on the nature and mode of action of subterranean caloric, 

 to account for the geological features of the continental forma- 

 tions. And herein appears to consist a main distinction between 

 the geological theory brought forward by Mr. Poulett Scrope, 

 and those of Hutton, or other writers on the same subject, 

 who may seem to have forestalled him in some of his principal 

 conclusions ; viz. that, while the latter class of theorists directed 

 their efforts to prove that the chief appearances in the constitu- 

 tion of the earths crust could only, or could most rationally, be 

 explained by the hypothesis of an intense central heat producing 

 elevations, &c, the author we are at present reviewing, direct- 

 ly demonstrates the existence of this central heat, and elevating- 

 power, from the phenomena of volcanos and earthquakes ; draws 

 from the same source, conclusive evidence of the laws under 

 which it acts ; and goes on to show, that such a power must, in 

 the nature of things, have given rise to those elevations of con- 



