586 LOWER CARBONIFEROUS OE Is^ORTH-WESTERX ENGLAND. [DeC. I9I2, 



at first with a few newcomers, it changed to the true C^ fauna — not 

 at the base but a short distance above. Hence it seemed possible 

 that the Ailiyris-glabristria Zone was no lower than the base of C^ 

 of the South- Western Province. 



This x^ossibility, which accorded with Dr. Yaughan's view that the 

 Thysanopliyllum-pseudovermiculare Baud at the top of the Atliyris- 

 glahristria Zone should be placed well up in C.,, would become a strong 

 probability were it certain (as the Author adduced evidence for 

 believing) that the Sioirlfer-pinskeyensis Beds are separated from 

 the overlying A.-glabristria Zone by the conglomerate exposed in 

 Pinskey Gill. Por the conglomerate, and the change in the character 

 of sedimentation which it accompanied, would together point to an 

 unconformity ; and the beds below, although of uncertain age, were 

 by consent either Upper Devonian or Tournaisian. As no break, 

 apparently, Avas known to occur in the Upper Devonian-Tournaisian 

 sequence, whereas in the South-Western Province the mid-Avonian 

 unconformity existed in places at the top of the Tournaisian, and 

 the Visean (the base of which is CJ transgressed across various 

 lower horizons on to pre-Carboniferous rocks, an unconformity, 

 if existent, at the transgressive base of the AtJiyris-glahristria 

 Zone would probabl}' be this mid-Avonian unconformity, and the 

 zone itself, despite its Tournaisian aspect, would accordingly be 

 correlative with the lower part of C^. The A.-glabristria Zone 

 was shown by its fauna to lie in or near C^, but its exact position 

 might, possibly, be best determined by a comparison of the earth- 

 movements of Avonian time in the ^"orth-AYestern Province Avith 

 those in other areas. 



The Author thanked the Pellowsfor the cordial reception which 

 they had given to his paper. In reply to Dr. Yaughan and 

 Mr. Dixon, who referred to the age of the beds below those in which 

 Miclielinia occurred in the north, that was, from the Thysano- 

 2)JiyIlurji Band downwards, he remarked that the succession which 

 he had established in the north-west was essentially a local 

 classification, and he did not wish to press unduly the correlation 

 of the beds with those in the Bristol area which he had suggested 

 in the last column of the table. He hoped that any value that 

 the work might possess would be judged independently of such 

 correlation ; at the same time, he thought it improbable that the 

 whole of the succession in the north could be included in Cg, and 

 was inclined to think that a certain amount, at all events, of C^ of 

 the Bristol succession was represented by the lowest beds above 

 the conglomerate in the Shaj) area. He would like to add that 

 he had frequently consulted Dr. Yaughan with regard to the 

 equivalents of these beds in the Bristol area, and he had always 

 been under the impression that Dr. Yaughan agreed with the cor- 

 relation suggested in the table. He did not quite understand 

 Dr. Yaughan's present contention, that there was nothing older than 

 0*2 of the Bristol area in the succession which he had described. 



The Author thought that he had dealt in the paper itself with 

 most of the other questions raised in the course of the discussion. 



