158 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 25, 



But my friend and fellow-labourer, and in this instance my anta- 

 gonist, has told the Society, more than once, that in his final scheme 

 of nomenclature he has only been following out the principles of the 

 Father of English Geology — William Smith. Now this I unequi- 

 vocally deny. Smith never gave the name to a group first, and made 

 out its place in his sections afterwards. In every instance in which 

 he gave us geological names, his actual sections had the priority of 

 his names by many years : and he never gave a name to any group 

 until he had determined its relations to the groups above it and below 

 it. From his several ascertained groups he collected fossils which he 

 afiirmed to be characteristic, and, therefore, a means of identifying 

 distant contemporaneous groups. He used palaeontology as a principle 

 of identification only where a typical group had been already well 

 established : but palaeontology was not the foundation of his nomen- 

 clature ; for his names were local or provincial. He never gave a 

 premature name to a local group ; and then, on finding that his 

 fossils were not confined to it, proceeded to develope this local group, 

 upwards as well as downwards, through many thousand feet of strata, 

 without changing its original and local name. 



In establishing the upper groups of his " Silurian System,^' the 

 author nobly followed out the principles and practice of Smith. His 

 Silurian sections and fossil lists were side by side ; the groups and 

 their relations were well made out ; and his names were local or pro- 

 vincial. Thus we all admit the groups in Siluria, so far as they were 

 made out on the principles of Smith ; and from Upper Ludlow down 

 to Caradoc they have become typical and classical. But below the 

 Caradoc group the whole base-line of the " Silurian System," from 

 one end of the map to the other, is laid down upon an erroneous 

 interpretation of the real position and relations of both the " Lower 

 Silurian" groups, — first by a mistaken identification of the Caradoc 

 sandstone with a portion of the Llandeilo group ; and secondly, by a 

 fatal mistake as to the position of his Llandeilo group, which the 

 author placed ahove the whole undulating series of South Wales*. 



* It has been insinuated (not however by Sir R. I. Murchison) that I was the 

 author of this mistake : but I deny the charge should any one repeat it. When I 

 visited the Silurian country in 1834, I did not go to criticise the " System," but 

 to learn the Silurian alphabet from its author. As a matter of fact, we critically 

 examined the base-line together only at one single point, on the north side of 

 Noedd Grugg, where we probably misinterpreted the phaenomena ; for on revisiting 

 the Noedd Grugg section in 1846, I drew a conclusion from it very different from 

 that at which we had arrived in 1834. My friend has told us that the boundary- 

 line marked on his Silurian map '* was simply a geographical and not a true geo- 

 logical line" between the Cambrian and Silurian rocks. That it was not a true 

 geological line is most certain ; but was it without meaning ? Has he not re- 

 peatedly stated the evidence on which the base-line was determined by himself ? 

 Assuredly it conveyed the author's views that the rocks on one side of the line were 

 older than the rocks on the other, — that the country coloured Cambrian was older 

 than the country coloured Silurian. Yet through a great part of South Wales the 

 colours are absolutely erroneous, not simply in their geographical distribution, but 

 in their geological conception. Precisely the same error is exhibited in the ideal 

 fundamental section upon which the whole scheme of the Silurian nomenclature is 

 erected (see Map of the Silurian System). There is not either in North or South 

 Wales a single actual section corresponding with the fundamental and ideal section 



