Geology and Geographtj, 339 



Barnstaple Bay, a more special account of which is being prepared 

 for the Geological Society. 



Mr De la Beche objected to the conclusions of Messrs Sedgwick 

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

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

 He conceived tliat 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 green- 

 stones in different places, and considered that these were of differ- 

 ent 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. Grey wacke, which opinions have, 

 of late years, been totally altered. He attached very little im- 

 portance to mineral characters : unless the consideration of the im- 

 bedded organic remains was made of the first importance, we were 

 sure of falling into error. Are the organic remains in these carbo- 

 naceous rocks of Devon really the same as those of the general 

 carboniferous system ? He stated, that he conceived there was evi- 

 dence to prove that there was a regular band of rocks surrounding 

 Dartmoor, which had been thrust up through the hollow in the mid- 

 dle. He could nowhere discover any line of separation between 

 the carbonaceous and the older rocks, so that he was unable to re- 

 concile 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 remains of the coal formation are found in beds, alternat- 

 ing with oolites, so that we must not limit too strictly the range of 

 these organic 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, 

 although the disposition of organic remains may hold true for a cer- 

 tain extent of the earth's surface, we have no right to consider such 

 a disposition universal — Mr Sedgwick remarked, that he could 

 with certainty distinguish four calcai*eous zones in North Devon — 

 viz. one at Linton, a second at Ilfracombe, and two others at Barn- 

 staple. The difference of the limestones of South Devon was also 

 very remarkable ; that of Plymouth being essentially distinct from 

 that of Dartmoor. These carbonaceous strata also extended seve- 

 ral miles into Cornwall. — Mr Conybeare considered that the public 



