30^ 



REPORTS ON THE STATE OF SCIENCE i 



important still tho upper series of black lime«toiies contain a totally 

 difierent fauna and flora from the lower series. 



The two series have unfortunately been mistaken owing to insufficient 

 attention being paid to the fauna, and in places have been mapped as 

 occurring on the same horizon. The mistake is unfortunate, because the 

 junction of the Ujjper and Lower Carboniferous beds occurs at this 

 point, and it is of the utmost importance that the junction should be 

 accurately mapped. I therefore propose to go into the matter here in 

 some little detail ; and this is the more necessary because within a few 

 miles certain very definite changes of lithological character set in appa- 

 rently on the same horizon. 



Commencing in the eastern part of the area, a little east of llolywell, 

 on the road from Brynford, the upper beds of the Carboniferous Lime- 

 stone are seen to be succeeded by cherts, which in turn are succeeded by 

 the black shaley limestones of the Holywell shales, containing a Pendle- 

 side fauna and flora ; that is to say, a Pendleside fauna succeeds the cherts. 



Further west, at the Grange Quarry, a series of sections show 



VendUsidc >'er. 



Cimlliaruiiia beds. 



Upper Dihuiiophijllion. 



(Jlicrts with a pcciiliiir (iruslit'il bed. 



Black slialerf and liiiiestuuos and I'o^i- 

 doiioinya Jtiembraitta'ra. 



Cherts. 



Aberdo black Uiuestouc wltli Amplexi- 



zaplirontis, B, and an Upper Dibuiio- 



phyllum fauna. 

 White liiiiestoue witli Luitsdoh-iajlvri- 



formis, Lithosti'otiitH irrennliti't^^ Pro- 



diictiis ijignnU'us, /*. hemixphcricm. 



The black shales at Holloway, which are apparently intercalated 

 between two series of cherts, contain Posidonomya memhranacea, M'Coy, 

 and Acrolepia Ilopk'msi, M'Coy, both of which species are typical of the 

 Pendleside series, and have never been found in beds below. 



At Treloggan, about four miles N.W., quarries show a similar suc- 

 cession. Here there appear to be two cherty series with some black shales 

 between them. 



Three miles N.W. are the chert quarries of Pentre, near Gronant. 

 The cherts here are finely bedded, and there is a face of 70 feet. Jn the 

 cherts we obtained — ■ 



Pt Ion;, i 



P. inuictatits. P. sp., a spinose form. 



The cherts are succeeded by fissile shales, which are also seen in the 

 road by some cottages some half-mile east, dipping off tlie cherts beds 

 near Talacre. The shales at Pentre contained Posidonomya Becheri (rare 

 here), Acroleins HopHusi, Cladodiis (teeth), and plant remains. 



Here, too, at any rate, a Pendleside fauna succeeds the cherts. 



•Some isolated exposures of cherts are seen nearly a mile further west, 

 south of tlie main road to Prestatyn ; but here the beds are thin and 

 yellowish and much tilted, and we have no evidence of their relation to 

 beds above or below them. Up to this point the succession soems to be 

 Pendleside Series, cherts, and Cyathaxonia beds. 



The Teilia section demonstrates that the Pendleside iSeries lie directly 

 and apparently conformably on the Cyathaxonia limestones. 



