648 



MR. C. A. MAT LET ON THE 



[Aug. 1899, 



(ii) Proofs of an 

 IJnconformity. 



The evidence detailed in 

 the foregoing pages affords 

 ample proof that the Green 

 Series is older than the re- 

 cognized Ordovician rocks 

 of the district. It rem ains 

 to be seen whetlier the 

 two sets are conformable 

 or unconformable to each 

 other. If unconformable, 

 we may hope to find some- 

 where the Ordovician 

 (1) lying on the denuded 

 edges of the Green Eeds, 

 or (2) containing frag- 

 ments derived from them. 

 An example of the first 

 kind has been instanced 

 by Prof. Blake at Ogof 

 Gynfor, and of the second 

 by Dr. Callaway in the 

 included fragments of the 

 conglomerates of Pyttiau 

 near Llaneilian.^ 



Ogof Gynfor lies on the 

 north coast near Llanba- 

 drig, among the rocks 

 which I have called the 

 Northern Complex. 

 There is a consensus of 

 opinion that the rocks 

 occurring here are an up- 

 ward continuation of the 

 Greeii Series : so that, if 

 there is an unconformity 

 of the Ordovician in re- 

 spect to this northernmost 

 group, there must be a 

 still greater unconformity 

 with regard to the Green 

 Series. I have ventured 

 to produce a figure of 

 the coast- section (fig. 3), 

 partly because it illus- 

 trates how very broken 

 even the Ordovician beds 

 are, and partly because it 



^ Quart. Journ. Geol. See. 

 vol. xliv (1888) p. 519 & vol. xl 

 (1884) p. 568. 



