Silurian Rocks of the South of Ireland to those of North Devon. LAY 
recent writers, including Rev. Dr. Haughton,) they are thrown into the form of an 
arch, one limb of which dips under the sea, the other below the Lynton beds. Under 
the guidance of Mr. Ussher, r.¢.s., of the Geological Survey, I examined the fine 
section laid open in the coast cliff, about a mile west of Minehead, and was greatly 
struck with the likeness between the rocks there forming the coast, and those 
belonging in some places to the Glengariff Series in county Cork.* 
The Foreland Grits consist of deep purple and greenish-grey grits and quartzites, 
sometimes massive and coarse-grained, at other times flaggy and lenticular, and 
containing bands of reddish slate or indurated shale. Pebbles of quartz, quartzite, 
and banded slate are scattered through the rock, which is perforated by annelid 
burrow-holes. Mr. Ussher pointed out to me linear plant-like markings very much 
resembling those of the Glengariff slates ; and, on the whole, I became, at the 
time of my visit, strongly impressed with the resemblance, and probable identity, of 
the Foreland beds to those of that formation. 
_ There is besides strong presumptive evidence in favour of this view when we 
consider the geological position of the Foreland Grits. It has been shown that they 
lie at the base of all the Lower Devonian fossiliferous beds. Now, although the rela- 
tionship of the Devonian to the Upper Silurian formations is unknown, and undis- 
coverable in North Devon, we cannot be far wrong in assuming the lowest Devonian 
beds to be at or near the position of the Uppermost Silurian. If the Foreland Grits 
form the connecting link between the Devonian beds and the Silurian, the Glengariff 
Grits and Slates form the connecting link between the Silurian and the Devonian.t 
They are thus brought very nearly on to the same geological horizon; and this, 
combined with their petrographical resemblances, leaves very little doubt in my 
own mind that they are really representative sets of beds. 
Vi.—Lower and Middle Devonian Beds absent in Ireland. 
In describing the succession of beds in descending order, as they occur in North 
Devon, we were able to recognise the similarity of the beds to those of the south of 
Ireland as far down as a certain stage in the series, namely, to the base of the 
Pickwell Down Sandstone. We were able to recognise in the Barnstaple Slates 
the equivalents of the Lower Carboniferous Slate; in the Pilton and Marwood 
beds the equivalents of the Coomhola grits and slates ; in the Upcct Flags those of 
the Kiltorcan beds, and in the Pickwell Down Sandstone those of the Old Red 
Sandstone. But at this point our identification ends, and we can nowhere find 
in the Irish area any representative whatever of the fossiliferous Ilfracombe series 
of the Middle Devonian, nor of the Lynton series of the Lower Devonian. As Iam 
unable to accept Professor Jukes’s interpretation of the problem, according to which 
* Professor Jukes alludes to these rocks, and identifies them with ‘‘The Old Red Sandstone ” rising 
from below the Lynton Rocks, which he considered to be “ Carboniferous Slate.” Supra cit., p. 351. 
+ This is the view I have stated in my paper on ‘The Dingle Beds, &ec.” Supra ctt., p. 721. 
