176 
SILUKIA. 
[Chap. VIII. 
alluded to, reappearing in the promontory of the Dingle. Traversing these 
tracts from Bantry to Killarney in 1842, I even then, I repeat, came to 
the conclusion that all these rocks must form a large portion of the Devonian 
system ; for, together with certain red conglomerates and sandstones which 
overlie them, they are seen in several synclinal troughs to lie below the 
very base of the Carboniferous system. 
It was, however, still requisite to explain the physical relations of 
these masses to the well-known fossiliferous Silurian deposits of Ferriter's 
Cove, Smerwick Harbour, and other places in the Dingle district. Were 
the Glengariff grits and Macgillicuddy's Reeks really superior to the Silu- 
rian Rocks of the Dingle ? 
To solve this question, Mr. Du Koyer made a detailed survey, and in 
August 1856 I revisited that ground, accompanied by Sir E. Griffith, Mr. 
Jukes, and Mr. Salter, to endeavour to detect the real physical relations of 
the fossil-bearing Silurian rocks to the great schistose and quartzose masses 
termed the ' Glengariff grits ' *. 
However difficult we found it to fix upon the precise spot where the 
oldest of the Silurian fossils could be detected f , it was quite manifest that 
in the westernmost headlands, Ferriter's Cove, Smerwick Harbour, Clogher 
and Doonquin Bays, there were unquestionable Wenlock remains in abun- 
dance, and that the strata containing those fossils were overlain by an 
unequivocal representative of the Ludlow rocks, in which, though the 
strata are to a great extent lithologically different from those of the 
Silurian region, the same typical species of fossils occurred as in rocks 
of the same age in England and Wales. 
Notwithstanding the obscuration of the interior country, these facts are 
plainly set forth, particularly in the coast-cliffs between the Sibyl Head 
and Dunmore Head, which face the Blaskett Islands. There the Silu- 
rian strata occupying ledges on both sides of Ferriter's Cove, contain 
Wenlock fossils. To the north these are succeeded by pale purple unfos- 
siliferous sandstones, including some lenticular beds of conglomerate ; and 
these are overlapped unconformably by the younger part of the Old Red 
sandstone and conglomerate, the beds of which rise into the rugged Sibyl 
Head to the height of 670 feet above the sea. 
When, however, we follow the Silurian rocks to the south along the 
coast to Clogher Bay, and thence to Doonquin, we meet with a true 
ascending order, after a great fold in the beds at the Clogher Head. 
A series of green, grey, and purple schists and sandstones containing 
semicalcareous and nodular bands, and associated with much interstra- 
* This term, 4 Glengariff grits,' was suggested with true Wenlock fossils into the Pentamerus or 
by Mr. Jukes ; and in the last published maps and Llandovery rocks. At this spot occurs a Penta- 
sections they are included by him in the Old Eed merus (apparently identical with P. oblongus), 
Sandstone (according to my view, Devonian). Palseocyclus porpita, Favosites and Heliolites, 
t In one locality, however (the small cove and many large hollow-stemmed Encrinites, which 
called Coosathurig, under the Bull's Head pro- are very characteristic of the Llandovery rocks, 
montory to the east of Dingle), certain species Further collections are much wanted from this 
were found which Mr. Salter considers definitely wild spot, 
to indicate a passage downwards from rocks 
