10 
PROCEEDINGS OE SOCIETIES. 
The invariability of these junctions between the two series leaves no 
room for doubt as to the age and position of the uppermost of the two, 
which everywhere, as in the valley of Tralee, and at the southern side 
in the valley of Castlemaine, conforms to the overlying Carboniferous 
strata. 
We have now arrived at the question relative to the second class of 
vertical and much disturbed beds of the Dingle promontory, which imme¬ 
diately underlie the Old Red Sandstone, there quietly reposing on them ? 
That they are not Old Red we have seen. Then, are they Devonian or 
Silurian? Hot the former, certainly, if we adhere to the idea at pre¬ 
sent suggested by that term, such a violent application of it requiring 
an entire change of signification, it having been hitherto considered to 
be synonymous with Old Red Sandstone. Mr. Jukes has proposed that 
they should be recognised as the “ Glengarriff Grits,” a term of which I 
highly approve, as indicating their complete identity with the rocks of 
the Glengarriff district, to which I shall presently refer. 
I need not here enter into the consideration of some local difficulties 
connected with certain rocks with which these Glengarriff beds are asso¬ 
ciated, such as the black slates of Anna#all, as I await with plea¬ 
sure to hear from my friend Mr. Jukes, who has fully examined them, 
the opinion he has formed. I shall confine myself to explain the 
grounds upon which I have classed them in my Geological Map, and it 
will be seen by reference to that document that I have been aware 
from the commencement of the question that might be raised, from an 
anticipatory note which I have appended on the margin, in which the 
pith of the considerations by which I was influenced is stated. 
The Glengarriff grits in the Dingle district consist of reddish-brown, 
and greenish indurated sandstones, alternating with red, brownish, and 
purple slate, and reddish-brown slaty conglomerate, and they are identical 
with the strata which occupy the most part of the two remarkable pro¬ 
montories which lie between the bays of Dingle and Rantry, and which 
extend in a north-east and south-west direction from the western shores 
of these promontories respectively, until they unite about twelve miles 
north-east of Kenmare, and continue inland still to the north-east, ter¬ 
minating at Mount Hilary and the Roghra Mountains. 
In tracing the line of section from the great Silurian district of the 
south-east of Ireland, through the Silurian outliers of the Welsh and 
Galty Mountains (or, making a detour to the Silurian and Old Red 
Sandstone rocks of the barony of Hpperthird, and the Knockmeildown 
Mountains, in the county of Waterford), in passing to the boundary of 
the Glengarriff grits of Dingle, no change of relative position will be ob¬ 
served in the whole line, the Silurian invariably underlying the Old 
Red Sandstone unconformably, in vertical and contorted strata; and, 
seeing that the Old Red rocks of Dingle, in continuation, for a distande 
of 160 miles, and identical, as I have already mentioned, with those of 
Kilkenny, Waterford, Cork, and Limerick, occupy a similar position 
in regard to the Glengarriff grits, also in contorted and vertical beds : it 
appeared to me at the time, that they must form a portion of the one great 
