"Dalradian" schists and gneisses, with some dark limestones, come out in the north-east of the county, forming a moorlandregion between Cushendun and Ballycastle.
The wild and barren west of this county, including the great hills on Achill Island, is formed of "Dalradian" rocks, schists and quartzites, highly folded and metamorphosed, with intrusions of granite near Belmullet.
Carboniferous Sandstone against the Dalradian on the west.
The central, southern and eastern Highlands are occupied by metamorphosed sedimentary and igneous rocks, to which has been provisionally assigned the name of Dalradian, from the old Celtic kingdom of Dalriada.
Hence it is useful to speak of them merely as " Dalradian," a convenient term invented by Sir A.
The red gneisses near Tarr Head probably represent intrusive granite; and this small north-eastern exposure is representative of the Dalradian series which covers so wide a field from central Londonderry to the coast of Donegal.
Massive conglomerates occur in these series, which are unconformable on the Dalradian rocks of Connemara.
The quartzites, like those of the Dalradian series, weather out in cones, such as the two Sugarloaves south of Bray, or in knob-set ridges, such as the crest of Howth or Carrick Mt.
These occurrences of granite, with that of Leinster, in connexion with the folding of the Silurian strata, make it highly probable that many of the granites of the Dalradian areas, which have a similar trend and which have invaded the schists so intimately as to form with them a composite gneiss, date also from a post-Silurian epoch of earth-movement.
Certain western and northern granites are however older, since granite boulders occur in Silurian conglomerates derived from the Dalradian complex.
I Silurian (and Cambrian?) "Dalradian" Metamorphic Series .Diorite and allied Basic Rocks '?-t =i=' Granite and allied Acid Rocks montory the conglomerates of this period rest with striking unconformity on the Dingle Beds and Upper Silurian series.
Loughs Mask and Corrib are thus bounded on the west by rugged Silurian and Dalradian highlands, and on the east appear as mere water-filled hollows in the great limestone plain.
And S.E., broke through the region now occupied by the British Isles, and basalt was pressed up along these cracks, forming thousands of dikes, from the coast of Down to the Dalradian ridges of Donegal.