MATERIAL UNIVERSE. 43 



centre, in proportion to their density, or specific 

 gravity, \rhere (except in cases where a portion 

 of them have been thrown to the surface by 

 subterranean convulsions, either in the form of 

 oxidized metals, if near the surface, or metallic 

 solids or fluids, below the reach of their action,) 

 they still remain. These subterranean convul- 

 sions gradually diminished in frequency, but 

 increased in power ; but not for many ages was 

 their energy sufficient to protrude the crust to 

 an elevation above the level of the waters that 

 surrounded the earth, after the action of the in- 

 ternal heat had ceased to affect them. 



As the internal heat was gradually diminished 

 at the surface, the aqueous vapor became con- 

 densed near it, and, being attracted towards the 

 earth, was finally deposited on its surface to a 

 great depth. Further, while the internal heat 

 acted upon the water, in such a degree as to 

 vaporize it freely, it would necessarily rise to a 

 certain distance from the earth, where, being con- 



