Rev. INfr WhewelPs Address to the Geological Society. 149 



seemed irresistibly to prove the culm-bearing beds of Devon to 

 be the same formation with the culm or coal-bearing measures 

 of Pembrokeshire on the opposite side of the Bristol Channel. 

 How far this apparent anomaly admits of explanation, and in 

 what manner it is to be allowed to modify the conclusion pre- 

 viously drawn, we may perhaps most properly consider as ques- 

 tions hereafter to be decided. The rocks which support the 

 culmiferous formation on the north, are conceived by Messrs 

 Sedgwick and Murchison to be a series, of which the last 

 ascending term is probably of the date of the lowest portion of 

 the Silurian system. On the south the culmiferous strata rest 

 partly upon the granite, and partly upon the oldest slate rocks 

 of Devon and Cornwall. 



The same general vi^w of the nature of the transverse sec- 

 tion of Devon, and of the age of the culm, has been presented, 

 perhaps I ought to say adopted, by the authors of two other 

 papers upon the same region which have been brought before 

 us — Mr Austen and Mr Weaver ; and also, at least so far as 

 the section is concerned, by the Rev. D. Williams, in a com- 

 munication made to the British Association in September last. 

 Nor am- 1 aware that it has been dissented from by any one 

 who has examined the county in question since this view was 

 made generally known. Resting on the concurrence of so many 

 able observers, I should conceive, therefore, that we may look 

 upon this view as established, so far as the time which has 

 elapsed allows us to use the term. No truths should be termed 

 incontestable till a considerable period has been left for the an- 

 tagonists to show themselves and to try their force. 



Although this view has thus ^o good a claim to acceptance, 

 you are aware. Gentlemen, that it is entirely different, both as 

 to the form of the section and the age of the members, from- 

 that which was entertained up to the time when these gentle- 

 men turned their attention to the subject. Their opinion re- 

 specting Devonshire being adopted, along with the views of 

 the same eminent geologists respecting Cumberland and North 

 and South Wales, one-third of our geological map of England 

 will require to be touched with a fresh pencil. 



Nor is this wonderful. It is rather a matter of extraordi- 

 nary surprise, that when the rest of the geological map of 



