OF THE ROCKS OF THE SOUTH OF IRELAND, 27 « 



DiSCUSSIOK-. 



Mr. Champeenowne, speaking of Xorth Devon, agreed that tho 

 Pilton and Marwood beds should be referred to the Carboniferous, 

 down to the top of the Pickwell-Down Sandstones. As for the latter, 

 he considered them, -with similar beds in South Devon, Upper 

 Devonian, and, with equal justice, true Old Eed Sandstone. He 

 thought the Morte and Dartmouth slates corresponded. The cal- 

 careous horizons of the Ilfracombe Morte series were inconstant ; 

 and in the South-Devon reefs a certain amount of irregularity might 

 cause the Pickwell beds to rest on limestone, as at several points 

 the)' appeared to do. As for the Foreland grits, he was inclined 

 to think they might be the same as those of the Hangman, thrown 

 down on the north by a fault. In the Quantock HilJs it seemed to him 

 that we have a great grit series, combining in itself the characters, 

 colours, &c. of both the Hangman and Foreland series, in which 

 case the basement series (supposed to be the Lynton grey beds) would 

 be buried beneath them, as there is not a trace of them to bo seen 

 in these hills. In all other points he fully agreed with Prof. HuU. 



Prof. Eamsat said that he was not aware that Mr. Godwin- 

 Austen had published an opinion that the Old Eed Sandstone was 

 a freshwater deposit. There were two important points in this 

 valuable paper : — (1) The gap in Ireland between the Upper Old 

 Eed Sandstone and the Glengariff grits. In Wales there was a 

 perfect passage from the uppermost Silurian into the Old Eed Sand- 

 stone. South of Llandovery the Upper Silurian was overlapped by 

 sandstone and conglomerates, which at last got to overlie the Lower 

 Silurian in Pembrokeshire ; and there was very probably a break 

 towards the middle of the Old Eed Sandstone. The upper part 

 also passed gradually into the Carboniferous series. In Scotland 

 there are two Old Eed Sandstones, viz. a lower and upper series, sepa- 

 rated in places by well-marked unconformity. (2) The position of 

 the Glengariff beds. He did not see why these might not be of 

 the age of the Lower Old Eed Sandstone of Scotland and South 

 Wales, though there were lithological differences. He thought the 

 abnormal conditions under which these appear to have been accu- 

 mulated justified retaining for them the name of Old Eed Sandstone. 

 Mr. UssHER objected to the name Upcot Flags beiog applied to 

 any part of the Devonian series below the Eaggy beds. He 

 pointed out the uncertainty of correlating the Pickwell-Down grey 

 sandstones with the •' Psammitcs du Coudroz " by lithological affi- 

 nities, as the grey sandstones are merely local basement-beds of the 

 Pickwell (Upper Devonian series), and when traced towards West 

 Somerset, give place to purple slates, which pass down into the pale 

 greenish Middle Devonian slates. He hinted at the bare possibility 

 of the Foreland grits being a faulted repetition of the Hangman, as 

 suggested by Mr. Champernowne, though the general dissimilarity 

 between the two series, and the superposition of Lynton beds on the 

 Foreland grits at Oare, were strongly against such a supposition. 



