99 



CHAP. VII. 



ON THE EXTERNAL CONFIGURATION OF ROCKS. 



ROCKS are found under the following different 

 forms : 



IRREGULAR MASSES. 



These may be of any size, even of moun- 

 tainous bulk. Examples of them are afforded by 

 granite, and by the overlying rocks, or the traps 

 and porphyries. 



to -PSEUDO-STRATA: Beds of some geologists. 



These forms belong to the same rocks, distin- 

 guished in the arrangement by the term unstrati- 

 fied. They are often combined with the preced- 

 ing, and pass imperceptibly into them. The 

 mode of distinguishing them from real strata will 

 be pointed out hereafter. 



This form is sometimes the apparent result of 

 la peculiar concretionary structure, as in granite ; 



n 2 



