OVERLYING ROCKS. OlKJ 



FIFTH DIVISION. 



Conglomerates. 



It has been held necessary to place this 

 title here because of the student's convenience, 

 although the substance included under it is also 

 enumerated under the head of the conglomerate 

 rocks. 



A. Fragments of different trap rocks and of 

 various sizes, angular, and re-united into a solid mass. 

 Trap tuff. 



a. Fine, tufaceous. 



b. Conglomerated, coarse. Trap conglo- 



merates. 



These form beds or masses, intermixed with 

 other varieties in different modes. Rarely, and 

 unexpectedly, they are even found in veins. 



They occasionally contain fragments of car- 

 bonized wood or of foreign rocks, and, in this 

 case, they are ranked with the transported con- 

 glomerates. Occasionally they are also found to 

 contain cavities ; or, the fragments of which they 

 are composed, adhere in such a manner as to 

 leave interstices. 



