510 Geological Society. 



upon the earlier stratified rocks, I am first led to notice the important 

 memoir of the two gentlemen I have just mentioned, ui)on the struc- 

 ture of North Devonshire*. According to the views of these gentlemen, 

 founded upon an extended examination of the county, this portion 

 of England forms a great trough, having an east and west position, in 

 which a series of culmiferous beds rest at their northern and southern 

 extremities upon older rocks. The plants found in the culmiferous 

 beds are said to be all identical with species which are abundant in 

 the coal-fields of the central counties of England, and of the South 

 Welsh coal basin : and it was at first conceived that these plants 

 differed essentially from the scanty and imperfect remains of vege- 

 tables which are found in the older rocks. More recently, how- 

 ever, the same fossil plants which occur in the culm measures are 

 said to have been detected in the subjacent strata. Before this fact 

 was known, the identity of the fossils and the resemblance of mine- 

 ralogical character 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 Chan- 

 nel. How far this apparent anomaly admits of explanation, and in what 

 manner it is to be allowed to modify the conclusion previously drawn, 

 we may perhaps most properly consider as questions 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 view of the nature of the transverse section 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 f; and also, at least so far as the section is concerned, by 

 the Rev. D. Williams in a communication made to the British As- 

 sociation in September last. Nor am I 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 al- 

 lows us to use the term. No truths should be termed incontestable 

 till a considerable period has been left for the antagonists to show 

 themselves and to try their force. 



Although this view has thus so 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 gentlemen turned their atten- 

 tion to the subject. Their opinion respecting Devonshire being 



[* An abstract of this memoir will be found in Lond. and Edinb. Phil. 

 Mag. vol. xi. p. 311.] 



ft Abstracts of Mr. Austen's and Mr. Weaver's papers will appear in 

 future Numbers.] 



