the Tertiary Formations. 271 



of the remains of organic bodies belonging to one zone, with 

 those belonging to another. 



3dly, That the tertiary deposites produced in the basin of the 

 ancient sea (with the exception of the diluvium and the upper 

 fresh-water formations formed after the retreat of the seas), are 

 so much the older, the more remote the basins in which they 

 are observed are from the present seas, and so much the newer, 

 the nearer these basins are to our seas. 



Wily, That the tertiary deposites of the basins depending up- 

 on the ocean seem older than the same kinds of deposites of the 

 littoral basins of the Mediterranean, since the second tertiary 

 limestone is almost the only one that occupies a great extent in 

 the Mediterranean basins, while the first occupies almost the 

 whole extent of the oceanic basins. 



bthly, That the tertiary deposites have been produced by 

 causes similar to those stiU acting, although with less energy, 

 and that the great number of species, similar to ours, which 

 they contain, indicate that their depositions have not much pre- 

 ceded the present geological period. 



The interesting nature of the subject to which these observa- 

 tions refer, will perhaps induce you to pardon their length. 

 You will judge better than any one how far the geological phe. 

 nomena accord with the causes which are still acting ; and it 

 should not be forgotten how much the progress of geology has 

 been retarded by the idea, generally admitted, that these phe- 

 nomena could only be accounted for by supposing them produ- 

 ced by causes that have ceased to operate. In consequence of 

 this manner of considering the modifications which the terres- 

 trial globe has undergone, the extinct volcanoes have been looked 

 upon as effects of a different nature from those which our pre- 

 sent volcanoes exhibit ; and it has been refused to see in the 

 crystalline beds, and the heavings which have raised them above 

 their original level, proofs of the elevated temperature which 

 the now soUd crust of our globe possessed at its commencement. 



t2 



