SYMONDS NOTES OF A GEOLOGIST IN IRELAND. 
331 
amount of contortion and twisting in the rocks of that coast is extreme ; 
but for the minutite of detail, we refer the ti-aveller to the maps and 
printed papers of the gentlemen attached to the Geological Survey of 
Ireland. 
In the west of England, the Bala or Caradoc-beds are overlaid by the 
May Hill or Llandovery rocks, which are really the base of the Upper 
Silurians, and it is said that a portion of this May Hill Sandstone group 
underlies the representatives of our Wenlock and Ludlow rocks at 
Dingle. In Gal way, on the shores of Lough Mask, and at Ughool, in 
the county of Mayo, my friend Dr. Melville informs me that Ireland 
furnishes, what he considers to be, the exact equivalents of our English 
May Hill deposits, and their passage upwards into true Wenlock deposits. 
That the Dingle promontory contains the representatives of the Wenlock 
and Ludlow rocks, we cannot doubt. The uppermost Silurian beds 
are overlaid by the Glengariff-grits and Dingle-beds, which are esti- 
mated by Professor Jukes and Mr. Du if oyer at the enormous thickness 
of 10,000 or 12,000 feet. 
The red slates which cover up conformably the upper Ludlow 
deposits with Pentamerus Knightii, must be the Irish representative of 
the English Tilestone group ; and the overlying Glengariff-grits and 
Dingle slates are, we imagine, the local representatives of our masses 
of Cornstones and Erownstones, which are so well developed in the 
Brecon Van district, and in the cornstones of Herefordshire and Brecon, 
and which, with the Tilestones, I believe to be rightly denominated 
by the good old term of " Old Red Sandstone." Thus we have in the 
Dingle rocks, 1. Dpper Silurians, 2. Tilestones, 3. Glengariff-grits. 
4. Dingle-beds. The tilestones are red slates and sandstones, the 
Glengariff-grits green and purple grits with red and greenish slates, 
and the Dingle-beds consist of red sandstone and slates with thick beds 
of conglomerate, which contain pebbles of Silurian limestone and 
fragments of horustone and jasper. Now, over all these beds are 
deposited, uuconformably, red sandstone and conglomerates, which are, 
I have no doubt, the representatives and correlatives of our English 
red sandstone and conglomerates, which overlie our Upper Cornstone 
series or Brownstones, and are, in some instances, as at Dean Eorest 
and on the Blorenge, unconformable to the Brownstone below. This 
so-called "Old Red conglomerate" in England and Scotland passes 
upwards conformably into the yellow sandstone and carboniferous shales, 
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