Ch. XIV.] OF THE STRATIFIED ROCKS. 315 



and tertiary deposits. " The principal effect of these volcanic 

 operations in the nether regions," says Lyell *, " during the 

 tertiary periods, or since the existing species began to flourish, 

 has been to heave up to the surface hypogine (primary) form- 

 ations of an age anterior to the carboniferous." Now, if he 

 admits that these primary rocks are older than the carboni- 

 ferous series, our assertion holds good, and it follows that the 

 central fire did, according to the views under consideration, 

 extend to the surface, once more reducing the whole globe to 

 a state of incandescence. But we presume that this is not 

 his meaning : he only intends to assert that their original 

 deposition as aqueous sediments, and not their altered or 

 metamorphic state, preceded the carboniferous formation. It 

 matters however little which view be adopted, for the latter 

 must be ultimately reduced to the same terms as the former ; 

 for since it is a well-attested fact, that the oldest fossiliferous 

 strata contain, and indeed sometimes are made up of portions 

 of the primary strata, or the so-called metamorphic rocks, 

 which are immediately adjacent ; it seems to be a necessary 

 consequence, that the primary slates could not have been in 

 the nether regions of the earth when the oldest secondary 

 strata were forming, and not upraised until the tertiary 

 period ; for under such circumstances, how could their frag- 

 ments and debris enter into the composition of the latter 

 deposits ? On the contrary, if we estimate former changes by 

 reference to causes now in action, this fact clearly indicates, 

 that the primary slates must have existed before the oldest 

 secondary rocks ; that is, the parent must have been in being 

 before the birth of its offspring : and not only so, but the 

 former could not have been situated deep in the bowels of the 

 earth when the latter were formed, but must have been 

 previously in an elevated position at the surface, in order to 

 have been subject to atmospheric and aqueous operations, 

 which alone are capable of producing the detritus found in 

 the composition of these secondary formations. 



* Principles of Geology, vol. iii. p. 382. 



