34 THEORY OF THE EARTH. 



the sea, so as to form islands, or at least rocks and 

 inequalities; and this must have happened whe- 

 ther one of their edges was lifted up above the water, 

 or the depression of the opposite edge caused the 

 water to subside. This is the second result, not 

 less obvious, nor less clearly demonstrated, than 

 the first, to every one who will take the trouble of 

 studying carefully the remains by which it is illus- 

 trated and proved. 



5. Proofs that such Revolutions have been numerous. 



If we institute a more detailed comparison be- 

 tween the various strata and those remains of ani- 

 mals which they contain, we shall soon discover 

 still more numerous differences among them, indi- 

 cating a proportional number of changes in their 

 condition. The sea has not always deposited 

 stony substances of the same kind. It has observed 

 a regular succession as to the nature of its deposits ; 

 the more ancient the strata are, so much the more 

 uniform and extensive are they ; and the more re- 

 cent they are, the more limited are they, and the 

 more variation is observed in them at small dis- 

 tances. Thus the great catastrophes which have 

 produced revolutions in the basin of the sea, were 

 preceded, accompanied, and followed by changes 

 in the nature of the fluid and of the substances 

 which it held in solution ; and when the surface of 

 the seas came to be divided by islands and project- 



