O'Eeilly — On the Waste of the Coast of Ireland, d^c. 149 



of amydaloiclal basalt, standing out from the cliff at the western end 

 of the temple tunnel — a remnant of the northern wall of a spacious 

 cave, the eastern portion of which is still to he seen penetrating the 

 rock for a short distance (see fig. 1)." 



(p. 8.)^" The raised beach, traces of which exist at various places 

 around the coasts of Derry, Antrim, and Donegal, and which represent 

 the 25 feet terrace of the western coast of Scotland, here extends 

 inland as far as the margin of drift composing the sloping ground west 

 of the basalt escarpment." 



(p. 26.) — '■'■Raised Beach. — An extensive raised beach, at an 

 average height of about 25 feet, fringes the southern and eastern 

 shores of Lough Foyle, extending to Bellarena and Magilligan, where 

 it has a width of from two to four miles. It is also seen on the 

 north-western shore in Donegal, where, owing to the nature of the 

 ground, it is much narrower, being only a quarter of a mile wide at 

 Quigley's Point. 



"The Robbers' Cave and the Pipers' Cave, which penetrate the 

 Chalk at about one or two hundred yards, respectively, east of the 

 stream that joins the sea a little east of Umbra, in Sheet 6, standing 

 at about the 25 feet contour line, belong, no doubt, to the period of 

 this raised beach. These openings were occasionally within reach of 

 the waves, during the prevalence of storms, till the construction of the 

 railway presented a barrier ; and the floors are now strewn with 

 rolled blocks and pebbles of basalt and broken shells. In a place 

 where the basalt is laid bare among the sand dunes, 400 yards east 

 of Castlerock, at about the level of the 25 feet contour Kne, the 

 surface of the rock bears clear evidence of the rounding action of the 

 sea, and the crevices are filled with sand and shell fi-agments — pro- 

 bably remnants of an old beach." 



Memoir of Geological Survey of Ireland, Sheets 1, 2, 5, 6, and 11 

 (in part), (1889). 



(p. 9.) — " The district described forms a remarkable promontory, 

 bounded on either side by Lough Swilly and Lough Poyle, and jutting 

 out far into the Atlantic Ocean, where it terminates in the cliffs of 

 Malin Head. Though not actually an island, as its name indicates, 

 being connected with the mainland by a neck of alluvial soil, yet the 

 name is not without significance, as pointing to the inference that 

 within the historic, or at least traditionary, period it may have been 

 really an island, at least during high tides. As a physical fact, the 



