80 Scientific Proceedings, Royal Dublin Society. 



the compass. Eising rather suddenly from about sea-level on the west, by 

 far the greater part of it is composed of steep precipices, varying in height 

 from 100 to 300 feet. These are broken up by shallow bays and narrow inlets, 

 and here and there are rocky outliers, the most important of these last being 

 the quartzite pinnacles known as the Needles, which lie between Drumleck 

 Point and the Broad Strand. The upper part of the cliffs is covered by 

 drift and Boulder-clay, in which marine shells and other calcareous matter 

 are embedded, and which in many of the bays descend to the beach, and 

 obscure the rocky surface. 



The south and south-west coasts are the most accessible. On tlie south- 

 west the sea washes the base of tlie clifEs at ordinary high water, but as the 

 tide retreats a low stretch of foresliore is laid bare, which enables one to 

 explore almost the wliole of this coast. Towards the Sutton end, and as far 

 as Old Boat-house, the foreshore is for the most part composed of strewn 

 boulders on a sandy bottom, but from Old Boat-house to Drumleck Point it 

 is largely solid rook. The south shore has a narrow beach uncovered at 

 high water, which varies with the undulations of the coastline, being low 

 and sandy or pebbly in the shallow bays, and higher and composed of large 

 blocks of rock on the more outstanding parts, so tliat even at full tide, 

 except at Lion's Head, one can walk all along this shore from Hippy Hole 

 to the Baily Lighthouse. The eastern coast is much more precipitous, the 

 cliffs descending steeply into deep water. Only at one or two places, as at 

 White "Water Brook, the bay between High Room Bed and Lough Leven, 

 and at Casana, where there are grassy slopes with accumulations of dislodged 

 rock about high-water mark, is it possible to reach sea-level. Balscadden 

 Bay on the north coast is easy of access ; along the greater part of this coast 

 there is a rough, rocky tract exposed at low water over which one can 

 scramble to examine the vegetation on the rock-surfaces, and on the 

 cliff-faces. 



Tides rise and fall all round the coast. Spring rise is about 13 feet, but 

 with southerly winds it may be as much as 15 feet, and with northerly 

 winds low water may be a couple of feet below low water of ordinary tides. 

 Neap-rise is 10 feet; neap-range, 8 feet. The higliest tides are always about 

 midday, which limits low-water collecting to the summer months. 



Winds. — The prevalent winds are from the south-west and west, and are 

 warm and moist. The force of these winds is greatly moderated by the 

 liighlands of County Wicklow, which lie in their track, and on wliich they 

 deposit a good share of their moisture before reaching the north shores of 

 Dublin Bay. In the spring months there are spells of north and east winds, 

 which are cold and parching. 



