138 Epwarp Huri—The Relations of the Carboniferous, Devonian, and Upper 
immediately overlie them in those districts; resulting in the entire absence of the 
Old Red Sandstone at the base of the Carboniferous beds.* 
In order to render the real significance of this condition of the formations 
apparent, it is necessary that we should clearly understand the succession of the 
beds as they occur in the south of Ireland. It is generally admitted, and the 
evidence seems conclusive, that from the base of the Old Red Sandstone and Con- 
glomerate upwards into the Carboniferous Limestone, there is an unbroken (or at 
least conformable) series of beds, which may be arranged as follows :— 
Descending Series of Formations; South of Ireland. 
Thickness, 
e. Carboniferous Limestone, . : : ‘ . 2,500 feet. ] Orta 
Upper |{q. Carboniferous Slate, | 9) 95) 2) 1000) ys queer em 
Conformable C Thala, Gos . 3,00 J 
Group. c. Coomhola Grit series, 5 ‘ : : o SOO) 
ee Kiltorcan Beds (or “ Yellow Sandstone of Griffith,’) 1,500 _,, \ Old Red Sand- 
a. Old Red Sandstone, with base of conglomerate, 2,000 ,, stone. 
(Great Hiatus and Unconformity.) 
( Glengariff Beds, 
Mowers sired Upper 
Conformable? e os S$ Silurian 
Group. 1 Wesleds 5 | Series. 
| Llandovery ,, J 
From the above it will be seen that there are two great conformable groups of 
strata, between which the /iatus or unconformable gap occurs. Now, when it is 
found that the Glengariff beds are overlain (as at Kenmare) by the Carboniferous 
Slate (d), it must be in consequence of the absence of the underlying formations, 
c, b, and a, constituting a gap or diatus. Again, when it is found that the Glen- 
gariff beds are overlaid (as at Glengarifl, Coomhola-bridge, Dunmanway, &c.) by the 
Coomhola grit series (c), it must be in consequence of the absence of the underlying 
formations 6 and a; or, lastly, when, as in the districts of Cork and Blarney, we 
find the Glengariff beds overlaid by the Kiltorcan beds (6), it is clear that this is 
because the Old Red Sandstone (a) is not present; and it is only, in fact, in the 
Dingle promontory on the north-west of the district, and in the direction of Fermoy, 
Waterford, and Tallow on the east that the Old Red Sandstone is found resting 
upon the Glengariff grits and slates.t 1 now proceed to give a few illustrations 
of the relations of the beds above referred to :— 
Kewymare District (a), Roughty Bridge.—The beds of the Glengariff series, which 
rise along the slopes on both sides of the Kenmare River, consist of strong purple 
*« On the Geological Age of the Rocks forming the Southern Highlands of Ireland, &c.” Quart. 
Journ. Geol. Soc. Lond., Vol. XXXV., 699 et seg (1879). 
+ Though the re-survey of the south is still far from completion, we already know that the Glengarift 
beds stretch much farther east than the meridian of Cork, and may possibly be found entering the sea 
about Youghal Bay. 
