170 Proceedings of the Royal Irish Academy. 



irregular, being cut into numerous inlets, among rapidly weathering 

 rusty -looking schists. In the guts the sea is rapidly cutting its way 

 between the foliation planes. 



Memoir, Geological Survey of Ireland (Sheets 73 and 74 (in part), 

 13 and 84) (1876). 



The country described includes a part of the county Mayo with a 

 small portion of the county Gal way. This tract is bounded on the 

 west by the Atlantic, and on the north by the southern shore of Clew 

 Bay, and on the south by Killary Bay. 



(p. 12.) — "In the Atlantic, off the mainland, are some islands, 

 the largest being Clare Island, which is about four and a-half miles 

 long from east to west, while its greatest breadth is not more than 

 two and a-half. To the west of this island are the steep cliffs of Knock- 

 more, which rise directly from the ocean to the height of 1520 feet. 

 Next in importance are Inishbofin, Inishark, Inishturk, and Cahir. 

 Most of those islands would appear to be the peaks of submerged 

 ridges. Cahir and Inisturk lying in a line with the ridge that extends 

 from the Mweelrea Mountains, towards the north-west, north of 

 Loughs Cunnel and Glencullin, and the valley of the Owennadornaun 

 to Cross Lough ; while Inishbofin and Inishark may be either on 

 the ridge that forms the Rinvyle Promontory or on the continuation 

 of the ridge forming the promontory called Cleggan Head, both of 

 which are included in the district to the south." 



(p. 14.) — " Clare Island. — On the eastern side of this rugged and 

 wild island is the only landing-stage, which is afforded by a smooth 

 beach. Between the western and eastern coasts the island is traversed 

 by several ridges of moderate elevation, culminating in that of Knock- 

 more, which, as abeady stated, presents a bold and steep face to the 

 Atlantic. The northern portion of the island presents a very rugged 

 appearance due to the unequal denudation of strata formed of different 

 materials." 



(p. 14.) — ^^ Islands in Wesiport Bay. — These islands are remark- 

 able for their uniformity both in shape and composition, while their 

 summits never rise to more than about 100 feet above the level of the 

 sea. 



"Their form is apparently connected with the direction of the 

 original glaciation of the district ; but on the western side of each — 

 save that of Inishgort, which is protected by Dorinish — marine action 

 is making a preceptible change, leaving perpendicular cliffs, while 

 towards the east the ground slopes to the water's edge." 



