502 Dr. Wheelton Hind ^ John T. Stohhs— 



palaeontology. Wherever the cherts are present in North Wales in 

 sequence we find that they rest on limestones with tlie Cijnthnxouia 

 fauna, that is, the uppermost part of the Dibnnophylhim zone. There 

 are three sections in North Wales which show this sequence ; the 

 most easterly is in the road from Brynford to Holywell, where 

 cherts are seen to rest on whitish limestones of the Cynthixonia 

 beds, to be succeeded by black shales and limestones of the Pendle- 

 side Series with a typical fauna. Here the cherts are probably not 

 more than 30 to 40 feet thick. Further west, about one mile north- 

 west of Holywell, is the section at the Grange Quarry, HoUoway. 

 Here there is the following succession {vide ante, pp. 394-395) : — 



Cherts with a hand of (?) crushed chert. 

 Shales with Fosidonomya membranacea. 

 Cherts, 25 feet ; Acrolepis Hopkinsi. 

 Aherdo Limestones {Cyathaxonia beds). 



Upper Bibunophyllum beds. 



_l 



r 



Fig. 5. — Grange Quarry, HoUoway. See also Fig. 1 (xvii). 



That is to say, shales with a Pendleside fauna appear between two 

 chert series. 



The quarry at Trelogan, four miles further north-west, shows the 

 same sequence. At Pentre, near Gronant, and Talacre the chert 

 beds are very thick, much more evenly bedded than the beds further 

 south-east, and it is not apparent on what beds they rest, but we 

 collected in the clierts Prodnctns loiigispmiis, P. punctatiis, and a spinose 

 form. At these places the cherts are succeeded by black calcareous 

 shales with a Pendleside fauna. At Waenbrodlas the cherts succeed 

 the Gynihaxonia beds, and there is no black shale series intercalated 

 in them. In the ujiper decomposed cherts we collected the fauna, 

 p. 396 (xix), which has a distinctly Upper Carboniferous Limestone 

 character, rather than a Pendleside tacies. The fish are certainly 

 Lower Carboniferous forms. South of Waenbrodlas, about ten miles, 

 is a chert quarry at Pant-y-Terwyn, resting on the calcareous pebbly 

 grit of Graiani-yd, which we think re{)resent8 the Cyathaxonia beds. 



So far, then, whenever the chert beds occur they rest on the 

 Cyathaxonia beds of the limestone, and the fauna, sparse though it 

 be, has a Carboniferous Limestone facie s ; but when we examine the 

 sequence in the neighbourhood of Prestatyn, Gwaenysgor, and Teilia 

 we find that its lithological character is completely changed. 



Resting apparently conformably on the Cyathaxonia beds are 

 some 70 feet of dark limestones of peculiar character, different in 

 numerous details (vide ante, p. 451) from the dark limestones of 

 Aberdo character, which it must be remembered also contain a 

 Cyathaxonia fauna. The limestones are seen at Teilia, Gwaenysgor, 

 and the hill above Prestatyn. The fauna and flora of these lime- 

 stones at once fixes their horizon to be the base of the Pendleside 

 Series, and we find the limestones occupying the same relation to 



