358 PROCEEDINGS OF THE GEOLOGICIL SOCIETY. [Mar. 7, 



rocks, but in vain. The beach is backed by lofty sand-dunes piled 

 against the foot of the Down. Nothing seemed to be shown before 

 reaching the farm called " Yention," where I had previously seen 

 rocks identical in character with the upper part of the Old Eed 

 Sandstone of county Cork (see Journ. Dublin. Geol. Soc. vol. x.). 



Taking, however, what I did see in connexion with what I had 

 previously seen, north of Braunton, on the road from Barnstaple to 

 Ilfracombe, near Span Head, and north of Dulverton, I can have no 

 hesitation in affirming the existence of a band of Old Red Sandstone 

 striking from Morte Bay, for a distance of about thirty-five miles 

 into the country, with a general dip to the south, at a very high 

 angle. 



The surface-width of this band appears to be about two miles ; 

 and if we estimate its average dip at 40°, it will give us a thickness 

 of about 7000 feet. It is, however, quite possible that undulations 

 in the beds, if we could see them, would greatly reduce this amount, 

 and that the actual thickness of Old Eed Sandstone which reaches 

 the surface may not be more than half that calculated above. 



Walking along the beach toward Tracey, I found some crags in 

 situ on the beach, and also in a quarry in the side of the lane going 

 up to Pickwell Down. These are, about " Potter's Hill," as marked 

 in the Ordnance map. The crags on the beach are described in my 

 note-book, as "pale-grey grits and slates, dipping south at 70°, cleavage 

 perpendicular, with nodular" bands, as if calcareous, but I believe 

 ferruginous (?). Are these Carboniferous Slate or Old Eed Sand- 

 stone?" The quarry up the lane is described as showing " softish 

 purple and green sandy slate, dip (?) south at 70°." These beds are so 

 very indefinite in character that I must frankly give them up. They 

 might possibly be deep in the Old Eed Sandstone, or they might 

 be part of the Carboniferous Slate. 



North of Tracey, however, where the rocks are well shown on 

 the coast, and thence to Mortehoe, and down again into Lee Bay, 

 all the rocks are identical in character with parts of the Carboni- 

 ferous Slate of CO. Cork, such as are shown about Bandon and 

 Kinsale, or about Eosscarrberry, or between that and Dunmanway. 

 There are scarcely any grit-bands, the whole mass being a smooth, 

 shining clay-slate, black when fresh and damp, but weathering to a 

 pale greenish-grey. It all seems at first sight to have a steady dip to 

 the south. The cleavage certainly does dip steadily at 50° or 60°, 

 but the more I worked with the hammer at the slate rocks near 

 Mortehoe, the less persistent appeared to be the dip of the beds. 

 Over large spaces I could not succeed in bringing out any structure 

 that could be depended on as the stratification of the rock. On 

 some parts of the low rocky clift's near Mortehoe, the true bedding 

 of the rocks coincided with the cleavage. In other parts the beds 

 dipped northwards, while the cleavage dipped south. This was cer- 

 tainly the case near a place called " Yard," about a mile north-east 

 of Mortehoe. 



YiTiile, then, I agree with all previous observers in assigning a 

 general southern dip to the whole of the rocks of North Devon, and 



