the Counties of Mayo and Sligo in Ireland. 153 



very interesting ; but we there arrive at the termination of the inferior and the 

 commencement of the intermediate order of rocks, including- the carboniferous 

 limestone ; and these beds extend without interruption to Ballyshannon in 

 Donegal. 



From Pohurlin to Kilcummin, west of Killalla Bay, the cliffs present strata 

 of sandstone, occasionally containing vegetable remains^ and alternating with 

 shale and argillaceous limestone; the whole dipping regularly to the south- 

 east, when undisturbed by the intrusion of trap veins. 



Very fantastic scenery, resembling arches, and towers, as well as caves of 

 unusual forms, abound along this part of the coast. In some places, the sea, 

 having penetrated the lower strata of the cliff to a considerable distance, 

 has excavated spacious caverns, at the extremity of which a portion of the 

 roof having fallen and been also washed away, an opening to the surface 

 has been formed, by means of which the waves are seen to rush with vio- 

 lence against the end of the cavern. One of these excavations extends across 

 the headland of Downpatrick, a distance of about 500 yards, and in the centre, 

 a large chasm, or, as it is locally called, a pigeon-hole, has been formed, and is 

 120 feet deep to the water below. Downbrista rock, which resembles an enor- 

 mous, insulated, and inaccessible tower, 130 feet high, has been probably 

 separated from the main land ; as the continuation of a wall, whose remains 

 are plainly traceable to the very edge of the cliff, stands on the summit of 

 the rock. The powerful surge of the Atlantic breaking on the north-west 

 face of the headland, also 130 feet high, rises with such force and momentum 

 as to tear up the rocks at the summit edge of the cliff, and in many instances 

 to raise on their edges, fragments from among the debris, weighing at least 

 half a ton. In the north-westerly gales, the spray ascends in a magnificent 

 column, to twice the height of the precipice against which the swell breaks, 

 and is carried to a great distance inland. 



On the west side of Downpatrick Head, between Downbrista Rock and 

 Buntraher Bay, the Horse Island Dyke (No. 2.) is again seen ; and on doubling 

 the head, passing eastward, another dyke, a continuation of No. 1, lies against 

 the cliff, like an immense wall. On the sandy beach of Tracal Bay is a creek, 

 called Poolagranny, which deserves careful examination. Proceeding around 

 the promontory of Kilcummin, a range of elevated and perpendicular preci- 

 pices, bounds the coast as far as Poolaclogher ; whence the shore is chiefly 

 composed of gravel in waved beds, apparently much disturbed. Crossing the 

 estuary of Palmerstown River, and following for some distance the sandy 

 beach of Ross, the porphyry or trachyte formation, described in the 2nd sec- 

 tion, occurs. Thence to Enniscrone, the Bay of Killalla, is bounded by the 



VOL. V. SECOND SERIES. X 



