Silurian Discussion. 107 



Caradoc fossils which were figured in his work. On a Silurian 

 question I believed him infallible ; and on the principle of common 

 justice above laid down, I struck out the calcareous slates, east 

 of the Berwyns, from my Cambrian series, and coloured them as 

 they afterwards appeared in the first great Silurian map. This I 

 did without reserve, though I thereby threw my own upper Cam- 

 brian sections into inexplicable difficulties. How completely I 

 was misled by this misinterpretation of my friend, and when, and 

 by what means, I afterwards returned to right views, which con- 

 firmed my original sections, cannot be discussed here. 



Finally, we visited the Bala limestone, and on the evidence of 

 sections (though a single eye-glance was enough to shew that the 

 Bala fossils were very nearly the same with those of Meifod), my 

 friend accepted my interpretation of its geological place, and, spite 

 of its fossils, pronounced it to belong to an undoubted Cambrian, 

 and not a Silurian group. And the conclusion, so long as he 

 maintained the integrity of his own lower Silurian sections, was 

 irrisistible. If it has since been proved that the Llandeilo flag is 

 the equivalent of the Bala limestone, there arises this question, 

 By whose mistake were these two groups ever separated ? I reply, 

 they were kept asunder by a great fundamental mistake in the 

 Silurian sections, and by no mistake I ever committed in my Cam- 

 brian sections. This mistake is stamped on my friend's great 

 map, as well as on a page of his first paper that was written after 

 there arose a controversy between us.* Here, therefore, I apply 

 the principle (above laid down) of common sense and common 

 justice, and claim the Bala limestone and the groups immediately 

 above it, and all their equivalents wherever found, as true and 

 integral parts of the upper Cambrian series. 



In the sense in which our author first used the words Silurian 

 System, his nomenclature was not only premature, but erroneous. 

 For the fundamental sections on which his nomenclature was 

 grounded were untrue to nature ; and we cannot have a true 

 system that is built upon a false base. I think I may again 

 " appeal to the sense of mankind" in vindication of this last con- 



* See Journal of the Geological Society, 1847, p. 167. The section given on 

 this page is, in fact, the foundation of the whole Silurian nomenclature. But 

 my friend's statement is entirely incorrect when he adds, that its lowest beds 

 were intended only " to represent certain inferior unfossiliferous rocks, such 

 as those of the Longmynd." The section does not at all apply to the case of 

 the Longmynd; and the inferior (or Cambrian) rocks of his original sections 

 were not considered unfossiliferous either in 1834 or in 1839, when his System 

 was published. He knew the contrary. And when he adds, that his sections 

 were meant to represent what is stated in this page (167), he does not give his 

 original interpretation of them, but he entirely shifts his ground, and puts upon 

 them a new meaning, in order to bring them into conformity with a new map 

 founded on a new scheme of nomenclature. 



