The headlands of Glenarm on the south, land the bold promontory of Gerron on the north, include a bay which extends for six miles between them. Towards the centre of this bay the coast is generally flat, but a low bank of trifling extent called the braes of Carnalloch, here displays the red marle and sandstone (No. 4. of the Introduction); and the lias and green sand (No. 3 and 2.) may be traced between the chalk of Bellaire hill and this point; these formations occupy the base of the mountains which are seen skirting this bay at a small distance inland, and of which the superior regions are exclusively composed of rocks of the floetz trap formation. The summits of these mountains considerably exceed 1000 feet in height. The cliffs of Gerron point are formed by the abrupt termination against the coast of a ridge connected with them.
These cliffs exhibit basalt towards the summit, and chalk in their central regions; the beds on which the chalk reposes are concealed along the base of the promontory by enormous masses of the superior strata, which have subsided in this direction and form a range of advanced terraces, causing the headland when viewed at a small distance, to appear as if composed of four strata alternately chalk and basalt. Those who have visited the southern coast of the Isle of Wight will on seeing Gerron point be strongly reminded of the similar subsidence there distinguished by the name of the under-cliff.
After doubling Gerron point a scene of the greatest magnificence gradually discloses itself; the ridge running westward from Gerron is seen extending far inland on the south of the valley of Glenarif and crowned by the conical summit of Cruach-a-Crue; while on the opposite side of that valley a similar but more lofty ridge terminates in the singular mountain of Lurgethan, which appears as
