O'Eeilly — 0/i the Waste of the Count of Ireland, i<^~e. 155 



inlet between steep walls of granite, has been hollowed out by the 

 sea along a line of fissure, now partly • filled with broken rock and 

 boulder clay. This break, which is accompanied with little or no 

 dislocation, seems to run across the western part of the island, 

 appearing again at Scoltnalinga north of Allagh Island. A small 

 arch occurs in the prolongation of the same line east of Tornamullane, 

 forming a gully with an ovei'hanging eastern wall 50 feet high, that 

 on the west, reaching 80 or 90 feet." 



(p. 74.) — "TJmfin Island has an exceedingly irregular outline, and 

 is bounded by steep rugged cliffs, pierced by caves and natural arches. 

 At about 50 yards from the extreme western point, one of the arches 

 runs north-north-east, along the lines of jointing quite through the 

 promontory. It has a length of 60 or 70 yards, and the opening forms 

 a conspicuous feature as viewed from Gola Island. A cave 70 yards 

 in length cuts through the northern part of the island." 



(p. 74.) — ^" The main portion of the granite on Inishbogin (Sheet 3) 

 is coarsely crystalline, and it is sometimes largely porphyritic. The 

 junction with the schists is clearly traceable across the highly 

 glaciated surfaces of the latter on the north coast of the island. At 

 Illanamarve, the shore line is broken by deep narrow inlets, one of 

 which is spanned by a natural arch, the apex being formed of a band 

 of fine-grained schistose granite, 4 yards wide." 



(p. 75.) — " Rosguil Bidrict. — The northern portions of this 

 promontory are mainly composed of granite, which has been intruded 

 amongst the metamorphic rocks. It has been intruded amongst 

 quartzites generally, and along the coast of Doagh Bay, breaks across 

 them in numerous dykes and off-shoots, which are visible in the coast 

 cliffs. 



(p. 84.) — " Gweedore and Aranmore Districts. — Numerous dykes 

 of felstone penetrate the granite and metamorphic rocks, chiefly in 

 the rugged area south of Inishfree Bay and in the western half of 

 Aran Island. Yariations of colour and character are frequently 

 noticeable in the same dyke ; and the felstone forming the dykes of 

 this and other localities, in this portion of the district, weathers 

 rapidly into cream-coloured or light brown kaolinized rock. North 

 of Kincaslough, the dykes consist usually of dark-brown rock, with 

 pink felspar crystals porphyritically developed, dark mica, and occa- 

 sionally blebs of free quartz. The trend here is mostly northerly. 

 Caves and precipitous inlets mark the point of the coast line where 

 such dykes exist, as at Scalpnadinga and Illion in Aran Island, and at 

 the northern extremity of Cruit, near Owey Island, a dyke of coarse- 



