500 ON THE SUCCESSIVE FORMS 



of history, have witnessed similar ones ; as the nature 

 of these islands is also perfectly explained in this man- 

 ner, and can be explained in no other. To have seen 

 Ovvhyhee brought up from beneath the ocean, could 

 scarcely afford more perfect conviction. 



Again, we find that the rocks produced by these 

 fluids resemble others which are disposed all over the 

 earth, consisting in the trap rocks, including all por- 

 phyries, and the granites* the volcanic rocks being 

 gradually undistinguishable from the traps and porphy- 

 ries, and the latter as gradually passing into the granites. 

 In the next place, the collateral appearances attending 

 the trap rocks resemble so exactly those of the volcanic 

 ones, that geologists have never yet been able to draw a 

 line between them, either on this point or in their mi- 

 neral characters : while, in the same manner, those 

 which attend the granites resemble those belonging to 

 the traps, precisely. Andlastly, what is here the most im- 

 portant fact, the connexions of the superincumbent and 

 neighbouring strata with the traps and the granites, are 

 exactly those which subsist between the former and the 

 volcanic rocks ; consisting in the elevation, displacement 

 and fracture of all the strata with which they interfere. 



In every point therefore, the cases are identical ; 

 and thence I conclude without fear, that wherever any 

 of these rocks occur, or can be inferred, there have ex- 

 isted volcanic actions, if not eruptions, and that these 

 have been the causes of the elevations of the strata, 

 or of the revolutions of the earth ; which consist in 

 such elevations, or in elevations balanced by depres- 

 sions ; that is, by a vacillating or interchanged con- 

 dition of the surface of the solid sphere as that re- 

 lates to the surface of its fluid portion. And the ge- 

 neral conclusion consequently is, that the Earth has, 

 from any beginning which we can trace, been the seat 

 of a succession of similar actions, produced at dif- 



