OF THE EARTH. 471 



first revolution which displaced them; but as they 

 were again elevated a second time, or oftener, together 

 with the secondary strata, other rocks, or fresh por- 

 tions, must have emerged at the same periods. And 

 all these must have emerged for the first time, which 

 are now covered by the secondary strata ; though they 

 had previously been displaced beneath the sea, since 

 these strata were deposited on them beneath the 

 waters. If as has been supposed, the present secon- 

 dary strata did once entirely cover the primary, the 

 whole of these latter must have remained at the bot- 

 tom of the ocean, after their displacement; and no 

 dry land, consisting purely of the primary rocks, ever 

 existed. But we are sure of the contrary; because 

 it is only in such a situation that they could have 

 furnished the materials of the secondary. Hence 

 therefore I must conclude, that some of the primary 

 strata never were covered by any secondary ones; 

 while the others have emerged during that subsequent 

 change which brought these to the surface. In some 

 places, these have probably been laid bare by the 

 actions of waste now going on; thus preventing us 

 from distinguishing the two cases: in others they con- 

 tinue covered. To assume, as has been done, that 

 the whole of the primary strata were once covered by 

 the secondary, we must conceive, that, after one 

 elevation, they were again entirely depressed beneath 

 the sea for the purpose of receiving these; while, 

 even then, their production cannot be explained, as 

 there could have been no supramarine land. This is 

 to invent an impossible hypothesis to account for that 

 which cannot be proved to have existed. 



Having thus examined the successive conditions of 

 the globe that were anterior to the appearance of the 

 secondary strata above the ocean, it is proper to en- 



