352 Proceedings of the British Association. 



many places destitute of any trace of coal, still these beds do not 

 differ from the great unproductive coal-field of Pembrokeshire. The 

 authors consequently concluded, that from the order of superposi- 

 tion, — from mineral structure — from absence of slaty cleavage pecu- 

 liar to the older rocks on vs^hich this deposit rests, and from the spe- 

 cific character of its organic remains, it may without hesitation be 

 referred to the regular carboniferous series. In the course of the 

 details, the authors alluded to a remarkable elevated beach, occupy- 

 ing two miles of coast on the north side of Barnstaple Bay, a more 

 special account of which is being prepared for the Geological Society, 

 M. De la Beche objected to the conclusions of Messrs. Sedg- 

 wick and Murchison, although he did not dispute the correctness of 

 the section of the country which they had exhibited to the meeting. 

 He conceived that he had traced the carbonaceous rocks passing 

 into what had been termed the Cambrian system, although he was 

 not prepared to say that it really was that system. He was also 

 unable to make that separation of the contorted rocks, suggested by 

 the authors of the paper. He spoke of the overlying greenstones 

 in different places, and considered that these were of different ages ; 

 also of the changes produced by granite on rocks of every kind in 

 contact with it. He alluded to the former opinions of the rocks- 

 called by the general name, Greywacke, which opinions have, of 

 late years, been totally altered. He attached very little importance 

 to mineral characters : unless the consideration of the imbedded or- 

 ganic remains was made of the first importance, we were sure of 

 falling into error. Are the organic remains in these carbonaceous 

 rocks of Devon really the same as those of the general carbonifer- 

 ous system ? He stated, that he conceived there was evidence to 

 prove that there was a regular band of rocks surrounding Dartmoor,- 

 which had been thrust up through the hollow in the middle. He 

 could nowhere discover any line of separation between the carbo- 

 naceous and the older rocks, so that he was unable to reconcile the 

 deposits of coal with those of other parts of England, and as to the 

 age of these older rocks all were agreed. In the Alps, organic re- 

 mains of the coal formation are found in beds, alternating with 

 oolites, so that we must not limit too strictly the range of these or- 

 ganic remains, as we should be certain of all the conditions under 

 which coal plants can be accumulated. We should recollect, that 

 the remains of the vegetation of a mountain may be entombed at 

 its base, so as to be shifted from its original habitat ; and that, althougb 



