132 jproceedings of the Roijal Trisk Academy. 



alternations of sand and marl, witliin places, Grlacialoid Drift ; also to 

 the south, of Ballyvalloo, the previously mentioned rib of Boulder 

 Clay Drift (fig. o}. The denudation of the cliff is considerable, rarely 

 less ihan 2 feet per annum ; and in some places, as in the vicinity of 

 Ballvvalloo House, it is over 3 feet. 



In the !iiIemoir to sheets 169, 170, 180, and 181 of the 

 Geological Survey of Ireland by Mr. &. H. Kinahan, m.e.i.a. (1879), 

 p. 14, the author states ; — 



(p. 15.) — "In connexion with this area, the denudation of the 

 coast line should be described, as a considerable waste of land yearly 

 takes place. The Ordnance maps of the country were published 

 about 1840 or thirty-five years ago. {Xote. — The cliffs were examined 

 in 1875.) If, therefore, the present coast line is mapped, an estimate 

 can be made of the annual waste of the drift cliffs. '^Tiile examining 

 these cliffs, it was observed that the effects of denudation varied 

 accordingto the nature of the drift. The Grlacial Drift, in general, best 

 resisted the encroachment of the sea ; but in a few places it has been 

 considerably wasted. In such places the sea undermined the bottom 

 of the cliffs, causing great falls, principally due to their own weight. 

 Joints open in the marl during the dry weather ; if these are 

 perpendicular or oblique to the line of the cliff the water percolates 

 through them, and the cliffs remain more or less perpendicular ; but if 

 they are parallel or nearly so to the line of cliff, they fill with water, 

 c-ausing great slips, which masses, after coming under the infiuence 

 of the waves of the sea, are dissolved and wasted away. Such cliffs 

 gave way in mass, but the slips are so extensive, that it takes years 

 before the sea can remove the debris, thus giving time to a protecting 

 slope to form. If marl is interstratified with sand, gravel or other 

 drift, the waste of the cliff is usually very rapid." 



To the south-west, the Baginbun promontory is margined with 

 rocks, and very little denudation is apparent, except in the black 

 shales at Petit's Bay, between Camivan and Baginbun Heads. To 

 the east of Bannow Bay, for about 3 miles, the sea cliffs, in general, 

 have a rock foundation, over which the drift may be glacial, aqueous, 

 or meteoric. In a few places the rocks have protected the cliffs, but 

 in many places they have been eaten away. In the townland of 

 Bannow, to the south of the old church, over 60 feet in depth have 

 been cut away since 1840, or at a rate of 1*71 feet per annum. In 

 the vicinity of Kilu Bay, and at the east margin of the townland, 

 there has also been considerable waste, respectively, of about 2 and 



