O'Reilly — On the Waste of the Coad of Ireland, ^c. 145 



25 to 40 feet above the sea, reaching, however, about 100 feet in the 

 vicinity of Island Doo. This island is one of a number of outliers 

 belonging to the basalt, which lie at a short distance out from the 

 shore, some being separated from the mainland merely by narrow necks 

 of water at full tide. The rocks are often traversed by fissures, 

 some of them being open up to the sm-face so as to form ' puffing 

 holes' or ' blow holes,' through which the air, accompanied by spray 

 is projected with more or less force by the waves rushing into the 

 cavities below. One of these occurs at Blackcastle rock close to 

 Portstewart, the fissure here communicating with a cave which runs 

 southward between the rock itself and the mainland. Another is 

 found on an island south-west of Blackrock. Of the few caves that 

 occur on this part of the coast, none are of large dimensions. Close 

 to the ruins of Ballyreagh Castle, an opening of this nature runs in for 

 about 18 yards, being 7 yards wide at the entrance and at most 7 feet 

 in height." 



(p. 9.) — '■'■ Rathlin Island. — Although so close to the mainland, 

 llathlin Island is very difficult of access, owing to want of proper 

 harbour accommodation and the liability to dangerous seas due to 

 tidal currents between the island and the mainland. The northern 

 coast face, consisting of tabular and columnar basalt resting on chalk, 

 is formed of bold, often inaccessible cliffs, between 300 and 400 feet 

 in height, while along the opposite side of the island the sheets slope 

 towards the south, and along their seaward faces, show a similar 

 superposition of the basaltic and Cretaceous beds." 



(p. 20.) — " The next westward outcrop of the chalk is to be found 

 at low water on either side of Dunluce Castle ; whence the rock gradu- 

 ally rises and forms a cliff at the ' White liocks ' of about 150 feet. 

 This cliff as seen from the sea presents a varied aspect owing to the 

 numerous caverns and fantastic forms into which the rock has been 

 carved by the erosion of the sea, a process which is still going 

 on." 



(p. 21.) — ^'' Rathlin Island. — The Chalk formation is the foimdation 

 rock of the Island of Rathlin : the thickness of the formation is about 

 220 feet, and is the greatest of the chalk either in Rathlin or on the 

 mainland. 



"Good sections of this division of the basalt (Lower Basalt) are 

 exposed to view in the steep sea-cliff faces between Ballycastle and 

 Ballintoy, in which latter dii'ection it thins out to not more than a 

 hundred feet or so; while in the vicinity of Ballycastle, the mass 

 cannot be less than 350 feet thick." 



N'2 



