Ch. XIV.] OF THE STRATIFIED ROCKS. 313 



previously existing rocks ; and, therefore, the melted granite 

 must have been injected between the sediments and funda- 

 mental rock, or the latter must have been converted by 

 fusion into granite. The latter idea appears to be enter- 

 tained by Lyell, for he imagines that the repetition of another 

 series of movements, similar to those that have taken place 

 during the secondary periods, may upraise the hypogene 

 rocks (granite and crystalline slates) formed, and now form- 

 ing, during the tertiary and recent epochs ; " by which time, 

 we imagine, that nearly all the sedimentary strata now in 

 sight would either have been destroyed by the action of water, 

 or would have assumed the metamorphic structure, or would 

 have been melted down into plutonic and volcanic rocks." * 

 This is certainly a very ingenious and beautiful theory : it 

 maintains a most perfect balance of power between the con- 

 flicting elements of fire and water, since the earth, the sub- 

 ject of these contentions, is always preserved nearly in statu 

 quo; for whilst the water overruns and subjugates the upper 

 regions, the fire, pari passu, takes possession of the nether- 

 most aqueous conquests, and annexes them to its dominions. 



Such a successive series of action and reaction is certainly 

 in accordance with the usual routine of natural operations ; 

 but it is not sufficient that a theory be ingeniously devised to 

 meet the exigencies of certain difficulties, but its principles 

 must be deduced from facts. Before, therefore, this theory 

 be accepted, it ought to be clearly demonstrated that the 

 internal fire is gradually extending its influence farther from 

 the centre of the earth, contrary to the common opinion that 

 the crust of the earth is increasing by secular refrigeration ; 

 and, in the next place, it ought also to be proved, that the 

 internal fire has converted sedimentary deposits into granite 

 and crystalline slates : and if these points cannot be esta- 

 blished, of what value is the conjecture, however ingenious ? 



Some may think it a great waste of time to enquire into 



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



