260 Scientific Proceedings, Royal Dublin Society. 



sections. As, however, so little was seen of the inner margin of 

 the shore-platform, and as the amplitude of the tide is somewhat 

 greater here than on the Cork coast, it is difficult to be certain on 

 this point. The difference in level between the pre-glacial beach 

 and the modern one appears to be about 12 feet. 



The beach-deposits consist of stratified gravel and sand commonly 

 cemented into a hard conglomerate or sandstone by oxides of iron 

 (see PI. XXX.). They vary in thickness from a few inches to 12 feet. 

 Shingle is usually found near the buried cliff, whilst further sea- 

 wards there is generally a bed of gravel overlain by fine sand or 

 sand with pebbly layers. The pebbles have smooth worn surfaces, 

 and, especially in sections on the open coast, take the form of 

 flattened ellipsoids — a shape characteristic of pebbles subject to 

 continued wave-action on a beach. The sand varies from coarse 

 to fine ; but the grains forming any particular bed are of about 

 equal size. The sorting of the material into sizes is also noticeable 

 in the gravel. In sections at right angles to the trend of the 

 coast-line, the bedding is often seen to dip seawards at angles 

 slightly greater than the slope of the platform. This structure is 

 particularly well seen in a section 80 yards south of Myrtleville 

 Cottage, Crosshaven (see Plate XXVII.) . The section is also of 

 interest on account of Jukes having sketched it on the 6-inch map 

 deposited in the Geological Survey Office, and noted that it was a 

 " small raised sea-beach about 8 or 10 feet above ordinary high- 

 water mark." 



The shingle and sand are almost entirely composed of the 

 local rocks. In some places, indeed, the sections were searched 

 over long stretches of coast without bringing to light any foreign 

 pebbles. In others, however, a small proportion of flints and 

 igneous rocks occurred. The search made was by no means, 

 exhaustive, owing to the very limited time available at each section, 

 nor can the list given below be taken as indicating the relative 

 proportion in different places. It can be definitely stated, how- 

 ever, that at Ballymadder, on the coast of Wexford, which is 

 nearer the outcrop of some of the igneous rocks, pebbles of 

 them are much more abundant. 



