660 



ME. C. A, MATLET ON THE 



[Aug. 1899,. 



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I 



II II 



phyllites. The ex- 

 posure is important 

 in that it is not 

 complicated by lime- 

 stones and qnartzites 

 as in the crush-zones 

 nearer Cemaes, nor 

 has the crushing so 

 completely disinte- 

 grated the beds as 

 in that area. We 

 have here a zone of 

 rocks identical in 

 composition with the 

 contorted beds on 

 either side of it, 

 consisting of those 

 beds brecciated and 

 displaced, and with 

 some of the frag- 

 ments more or less 

 rounded ; it is evi- 

 dently authiclastic 

 in origin. 



(ii) Forth y 

 Corwgl. — At the 

 extreme east of the 

 Northern District 

 the thrust between 

 the Ordovician and 

 the Gnarled Series 

 reaches the coast 

 at Forth y Corwgl. 

 Black shales occur 

 immediately south 

 of the junction, but 

 within a few yards 

 they are interstrati- 

 fied with grits of 

 various degrees of 

 coarseness, and some 

 of the shales also 

 take on a pebbly 

 character. The grits 

 are evidently inter- 

 bedded, but at the 

 southern end of 

 the Forth they are 

 much disrupted and 



