Prof. Sedgwick on the May Hill Sandstone, 



each sj^eaker absolutely evaded the 2nd, 3rd, and 4th questions, and 

 left the obvious inference drawn from my own affirmative answers 

 untouched. Whether this was done out of forbearance towards 

 myself I must leave the reader to judge. As a matter of fact 

 my questions were evaded, and both the facts and inferences of 

 my paper remained absolutely untouched. 



One of the leading members of the Government Survey affirmed 

 that I had only raised a question of words — a question already 

 settled. I reply that, between us, it is not a question of words 

 but of facts, and of the classification of certain natural groups. 

 If my interpretation of the sections of Castell Craig Gwyddon, 

 of the great group between Dol Fan and Garn Fawr, and of cer- 

 .tain groups south of Llandovery be right, the Government Sur- 

 veyors have misinterpreted them. If they have understood 

 thetn, I have blundered in their interpretation. There is a plaih 

 question of fact between us ; and till it is settled the discussioti 

 is by no means one of mere words. Again, the disdussion of the 

 May Hill sandstone, and of its place in the lower Palaeozoic divi- 

 sion, offers us no mere question of words, but a vital question of 

 classification, on which absolutely depends the existence of the 

 so-called " Middle Silurian ^' group of the Government Map. 



More than one speaker suggested the separation of Cam- 

 brian from Silurian rocks by a line drawn immediately above the 

 Lingula flags. I doubt the possibility of finding such a line ; 

 and were it possible, it would be of no value to classification. 

 The slates of Festiniog are as true Cambrian slates as those of 

 Nant Francon. Each of these slate groups forms a great and cha- 

 racteristic Cambrian sub-group, one of them is above, and the 

 other below, the Lingula beds, and neither of them is seen in 

 Siluria. The only natural break in our older palaeozoic series is 

 where Ihave placed it — immediately below the May Hill sand- 

 stone, which is both the physical and palaeontological base of 

 the Silurian series. 



One thing was admitted, that my Cambrian smes was phy- 

 sically and geographically true, and that I was the first person 

 who had worked out its analysis. If it be so, who^ I ask, has a 

 right to change my nomenclature ? Certainly no one, unless he 

 can somewhere find a more perfect type of development, and a 

 be.tter base for a more perfect nomenclature. 



Finally, at the end of a second day's discussion, I obtained by 

 a direct question, this acknowledgement from the President of 

 the Section, that he admitted the May Hill sandstone as a true 

 palseontological and physical group. On this point, therefore, 

 the two palaeontologists of the Govelnment Survey are now with 

 me ; while once on this very important poiut they were my stout 

 opponents. 



