﻿22 O. A. Lebour — On the Terms " Bernician " and " Tuedian." 



that part of Britain in which the beds which it denotes are most 

 largely developed, where especially the characters marking the 

 series elsewhere are found associated, as, I believe, they are nowhere 

 else. There numerous beds of limestone represent the massive 

 calcareous mass of Derbyshire ; there occur the Coal-bearing beds 

 of Enssia and the Posidonomya Becheri shales of the Culm ; there 

 the sandstone and grit facies of the Series is most strongly developed; 

 and there finally are the paleeontological characters of the Silesian, 

 Belgian, and Scotch series blended in an almost unique manner. 

 These are all qualities which eminently fit Bernicia to be looked 

 upon as a type locality or region. In the second place, the name 

 " Bernician " gives rise to no preconceived notion that experience 

 can prove untrue, it expresses a geographical truth and nothing more. 



Dr. Woodward and Dr. Karl Mayer evidently intended to include 

 everything between the Millstone Grit and Devonian under the term 

 " Bernician," whereas in the paper to which I have already referred, 

 and which was purely local in character, I retained the name 

 " Tuedian " for the Calciferous sandstone series. I, however, also 

 showed that the line of division between Tuedian and Bernician 

 was a variable one, that the one series ran into the other as it were, 

 and that moreover the base of the Tuedians (in which I include the 

 so-called Upper Old Eed Conglomerate) in a similar manner ran 

 into the Old Eed, and was not sharply divided from it. The former 

 of these points I again urged more strongly at the Glasgow Meeting 

 of the British Association in September last. The question left to 

 be decided is this: — Is "Bernician" to be distinct from Tuedian, 

 or is it to contain it as a subordinate member ? This is not an easy 

 question to answer at present, but I incline to think that the last 

 will be nearer the truth, and that in time the Tuedians will come 

 to be looked upon as passage-beds from Old Eed to Bernician, parts 

 of which may be claimed by both. 



The word Tuedian which I emiDloy is in much disfavour in 

 Scotland. The only objections to its use that I have heard, however, 

 are, — first, that the " Cement-stone and red-sandstone series" occurs 

 throughout all the Carboniferous disti-icts of Scotland, and is in the 

 Lothians much more typically developed than in the Tweed Basin ; 

 and, secondly, that the name " Calciferous sandstone series " given 

 to these rocks by Maclaren in 1839 is a good one. 



To the second objection it may be at once replied that as a purely 

 lithological term of necessarily only local application, exception 

 might well be taken to Maclaren's name even were it not so 

 dangerously similar to the Potsdam " Calciferous series " of North 

 America, or even to our Oxfordian " Calcareous grit." The first 

 objection is a stronger one, but it does not show that " Tuedian " is 

 a bad name — only that a better might be invented. If a better 

 one had thus been proposed before 1855, so much the better; but 

 " Tuedian " came out then, and if not the best possible is yet a 

 geographical name, and not a bad one in itself ; is it not better to 

 retain it, whatever the classificatory value of the beds which it 

 represents may prove to be ? 



