380 NATURE AND CHARACTERS 



forms, as in their mineralogical characters, and, 

 in a similar manner, intruding in the shape of 

 veins, not only among the stratified members of 

 this class, but extending their ramifications even 

 through the whole of the primary rocks, whether 

 stratified or unstratified. 



That interference affords, in itself, ample evi- 

 dence of the secondary nature of these unstratified 

 substances ; and is a sufficient proof of their pos- 

 teriority to all the rocks with which they are 

 connected, to supersede the necessity of any fur- 

 ther remarks on that subject in this place. The 

 peculiarities of character which render them 

 objects of the greatest interest in the history of 

 the earth, will, with more propriety and utility, 

 be examined, as far as is admissible in a work of 

 this nature, in the preliminary remarks that pre- 

 cede the synoptic catalogue. The observations 

 that here follow, must therefore be considered as 

 extending solely to the secondary strata. 



These strata, thus once determined by the 

 characters above mentioned, are discovered to 

 possess, like the primary, other peculiarities, by 

 which they may be recognized when the species 

 of evidence derived from relative position, is in- 



