MONIAN SYSTEM OF ROCKS. 483 



Fig. 5. — Plcm of Ground west of Uyn Trefwll. 



1. Chloritic schist. 

 4. Eeach-breccia. 



2. Diabase. 



5. Conglomerate. 



3. Granite. 

 6. Lake. 



it is a beach- breccia of large gneissic fragments. Close upon the 

 junction at one spot, over an area not more than 3 feet long by 

 8 inches wide, the diabase becomes very slaty, and contains frag- 

 ments of granite ; but its true character is seen, under the microscope, 

 to be retained. Near here, also, and enclosed in the diabase, is a 

 small mass of diorite, with granite bands in it. To the east, again, 

 are two smaller ridges of coarse granite-conglomerate passing into 

 grit, and still further east, by the lake side, two tall bosses of finer 

 conglomerate. This is all that is seen. Thus some of the slates of 

 Dr. Callaway are diabase ; and, if there is any slate at all, it is in 

 the beach-breccia, which may very well contain such material, en- 

 closing, it might be, even pebbles of granite *. Thus there is no 

 part of the later series here at all, except in the form of fragments, 



* I have little doubt that it was really part of this series tha yieldea the 

 rocks examined by Prof. Bonney (Quart. Journ. Geol. Soc. vol. xl. p. 584). 



