14 



ILLUSTRATIONS OF THE 



of an animal and vegetable fyftera. They do 

 indeed prove this in the ftrideft fenfe, only of 

 the particular beds in which they are found ; 

 but as thefe beds are in all other refped;s as 



i 



much to be accounted primary as any part of 

 the mineral kingdom, it is evident that the ne- 

 gative inflances are here of no force, and that 

 nothing can be gained to the adverfaries of this 

 opinion by denying it in general, if they are 

 obliged to admit it in a iingle cafe. 



9. Again, it is certain, as Dr Hutton remarks, 

 that there are few coniiderable bodies of fchiftus, 

 even the moH decidedly primitive, where fand 

 and gravel m.ay not in fome parts be obferved. 

 Indeed, it is not only true that they are to be 



found in fome parts of them ; but, in fad, among 

 ~ many of the primitive mountains, we find large 

 ■ trads, compored entirely of a fchillofe and much 

 indurated fand-ftone, in beds highly inclined, 

 fometimes alone, fometimes alternated with 

 other fchiili. In many of them, the fand of 

 which they conlilt appears to be entirely of 

 granite, from the detritus of which rock it fhould 

 feem that they were chiefly formed. 



F 



10. Thus we conclude, that the ftrata both 

 primary and fecondary, both tliofe of ancient 

 and thofe of more recent origin, have had their 

 materials farnifhed from the ruins of former 

 continents, from the diffolution of rocks, or the 



dellrudion 



