71 



the secondary unstratified substances are equally 

 remarkable ; and the chief of these is a frequent 

 or predominant superiority. There is thus a com- 

 mon geological feature by which this arrange- 

 ment is distinguished. There is further a com- 

 mon set of general mineral characters in all the 

 unstratified rocks which are not granite, wherever 

 they may be found ; serpentine being here exclud- 

 ed : these characters being so strong as to render 

 it often impossible to distinguish between those 

 now exclusively connected with the primary, and 

 those connected in the same manner with the se- 

 condary strata. 



This arrangement, which thus appears natu- 

 ral, as well as convenient, will even become ne- 

 cessary, if it is impossible to discover a criterion 

 by which these two can be certainly recognized 

 and distinguished. The nature of the remaining 

 doubts respecting these rocks, are too intimately 

 connected with their geological history to admit 

 of being here stated more fully : but they are not 

 such as apparently to supersede the convenience 

 which will be found to result from the method of 



