498 Mr. CoNYBEARE on the Strata near 



they are, will perhaps convey a clearer notion of the singular con- 

 figuration of these rocks than could be done by words alone. With 

 the exception of one, which gives a faithful resemblance of some 

 remarkable curvatures in the grauwacke of Hartland Point, the whole 

 of the subjects are selected from those which occurred within the 

 first four miles of our walk from Clovelly westward. 



Although these singular contortions are not entirely confined to 

 the dunstone and shillat of Devonshire, they yet occur much more 

 constantly in that rock than in the metalliferous schist of Cornwall. 

 In travelling westward we appeared to lose them gradually. At 

 Bosscastle where the rock evidently approaches nearer to the cha- 

 racter of killas, (as it is termed by the miner) they still appearpretty 

 frequently : at St. Agnes they are much rarer and less capricious. 



It is possible that more accurate and minute researches may carry 

 the subdivision of the stratified rocks of this country much further 

 than the present state of our knowledge appears to authorize ; but I 

 cannot think that, even with the limited information which we al- 

 ready possess on this subject, it would be assuming too much to 

 establish a line of separation between the rock, which under the pro- 

 vincial names, already mentioned, of dunstone and shillat covers so 

 large a portion of the North of Devon, and that metalliferous slate 

 which lying immediately upon the granite of Dartmoor and Cornwall 

 forms the most considerable portion of the mining tract in both 

 counties. * 



The former of these, besides the peculiarities already noticed. Is 



* I would wish to be understood as speaking exclusively of the metalliferous slate. 

 That which alternates with limestone at Vcsyan, at Pailstow, (where it is accompanied 

 by greenstone) and some other spots in Cornwall, will probably be regarded as belonging 

 to a distinct formation. 



