52 THEORY OF THE EARTH. 



quired of them, that we have been enabled to dis- 

 cover the little that we yet know respecting the 

 nature of the revolutions of the globe. From 

 them we have learned, that the strata in which 

 they are buried have been quietly deposited in a 

 fluid ; that their variations have corresponded 

 with those of the fluid in question ; that their be- 

 ing laid bare has been occasioned by the transpor- 

 tation of this fluid to some other place ; and that 

 this circumstance must have befallen them more 

 than once. Nothing of all this could have been 

 known with certainty, had no fossil remains ex- 

 isted. 



The study of the mineral part of geology, 

 though not less necessary, and even of much more 

 utility to the practical arts, is yet much less in- 

 structive with reference to the object of our pre- 

 sent inquiry. 



We remain in utter ignorance respecting the 

 causes which have given rise to the variety in the 

 mineral substances of which the strata are com- 

 posed. We are even ignorant of the agents 

 which may have held some of these substances in 

 solution ; and it is still disputed, respecting seve- 

 ral of them, whether they have owed their origin 

 to water or to fire. After all, philosophers are only 

 agreed on one point, which is, that the sea has 

 changed its place ; and how should this have been 

 known, unless by means of the fossil remains ? 

 The organic remains, therefore, which have 



