Dingle and Glengavriff Grits. 229 
rocks, having marked lithological differences. This is also 
applicable to the “Old Red Sandstone” of Cork and Kerry; 
but at the same time in these counties there seems to be no 
very sudden change, as almost invariably the rocks of one 
type graduate into those of the others, while certain peculiarities 
are very constant. The most constant character seems to be the 
“ Metalliferous Beds” in the upper portions of the “Old Red 
Sandstone.” These are best developed in the country south-east 
of Bantry Bay, but they are also well marked in the country 
north and south of Kenmare River, and can be traced eastward 
from Cork into Waterford and Kilkenny ; while northward they 
are found in the Tralee district, and farther north margining 
the Kerry Head tract of “Old Red Sandstone;” and to the east 
of the co. Kerry, traces of them can be observed in the “Old Red 
Sandstone” of the cos. Limerick, Clare, and Tipperary. 
On the north side of Dingle Bay the lower portion of the “ Old 
Red Sandstone” is more or less conglomeritic, and the same 
character is found on the south side in Iveragh, immediately 
adjoining Dingle Bay. In the latter country the most typical 
conglomerates occur to the west, at Doulus Head, while eastward 
the rocks gradually lose this character, and at Killarney they 
have assumed many of the West Cork types. When, however, we 
proceed eastward from Cork into Waterford the conglomeritic 
rocks again appear; as, however, I have elsewhere fully entered 
into this subject, it is unnecessary to follow it further. 
Subsequently to the close of the Carboniferous Period, a rupture 
took place along the line of the Valley of Dingle Bay, ex- 
tending eastward along the Flesk and Blackwater Valley, which 
was evidently a downthrow to the northward.* It is along this 
same line that we have contemplated a great antecedent fiex- 
ure, or a fault with an upthrow to the northward. However 
it is readily conceivable that here, as elsewhere, along great lines 
of successive faults, this newer displacement along the same line of 
weakness need not by any means have necessarily the same hori- 
zontal extent, any more than it must have the same amount of ver- 
tical throw. The downthrow to the north of this newer fault varies 
* Associated with this were branch faults, one conspicuous one, extending from the 
Killarney Lakes to Glenbehy, on Dingle Bay; it is, however, unnecessary to go into 
these now. 
Scren. Proc., R.D.S. Vou, 11, Pv. m1. R 2 
