304 



ochre is of a red colour, sometimes of a brilliant scarlet, which makes a 

 striking contrast with the black layers as they alternate in the face of 

 the precipice. 



Wade. — Lyall says " this is a soft and earthy variety of trap, having 

 an argillaceous aspect ; it resembles indurated clay, and, when scratched, 

 exhibits a shining streak." I have seen specimens of rock called wacke, 

 named by a German mineralogist, not at all answering to this description. 

 Nevertheless, the description appears to me to be a good one, and appli- 

 cable to a great quantity of rock in Antrim. It has very much the 

 aspect of certain thick-bedded black shales, containing round balls, which 

 occur in coal-measures in Limerick and Kerry, but is of course, as com- 

 pared to those of Limerick shales, deficient in the accompanying stratified 

 beds. Like those shales, the wacke decomposes when exposed to the 

 weather. It appears to have been the first trap formed in Antrim, as it 

 lies in many places the first layer over the chalk. This is the case at 

 Aughnahough, at No. 3 in the Table, and a great part of the way from 

 that to Cave Hill ; at Lundrossan, a mile north of Portmuck in Island 

 Magee. At Lunluce Castle it is mixed with harder layers, and' the same 

 condition of it is visible in the cliffs at Garron Point (Pig. 4). In short 

 there is no kind of trap so general. 



Pair Head (PI. XXVI.) and Bengore Head (PI. XXIV.) are the 

 two most prominent features on the northern part of the coast of An- 

 trim ; and, for reasons which I shall adduce, it appears to me that there 

 was a volcanic vent, or crater on the great scale, in* the vicinity of each 

 of those headlands. Probably there were more than two, but those 

 two localities exhibit features which cannot be ascribed to any other 

 origin. 



At the east side of Pair Head, the greenstone is seen at Murlogh 

 Bay, resting on chalk, and on coal-measures at its southern boundary, 

 on the flank of Carnanmore Mountain. It is quite thin ; but proceed- 

 ing northward it gets thicker, until at last it is terminated at the point 

 of Fair Head (PI. XXVI.) by a perpendicular precipice, 317 feet high, 

 all one kind of greenstone, without horizontal joints. Prom the base of 

 this precipice there is a talus, sloping down to the sea, principally com- 

 posed of huge blocks of greenstone which fell from the face of the pre- 

 cipice. These blocks are of monstrous size, and are scattered wildly 

 about. Immediately about Pair Head this mass of greenstone rests on 

 coal-measures. Prom the northern end of the trap, which is the highest 

 (636 feet), the surface slopes inwards to the south. This slope indi- 

 cates that the source from which the flow came, in a fluid state, lay to 

 the north, and that the vent by which it was emptied lay in that direc- 

 tion ; also that there was in fact a mountain of it to the north of Fair 

 Head, of which the present headland is but a small remnant. The pre- 

 cipitous character of the shore about Pair Head, and along the north 

 coast, through the colliery from this to Ballycastle, gives the idea of a 

 great broken-down volcanic crater — accompanied, perhaps, by a fault. 

 The shore from Pair Head to Ballycastle is the south side of such fault ; 

 the north side is gone down, and sunk under the ocean. 



