Clare Island Survey — Geology. 7 IT 



Modified Boulder-clay. 



In the zone between the outcrop of the boulder-clay and the hills, there 

 occurs a drift consisting of boulder-clay that has been considerably modified 

 by detrital matter washed down from the higher ground. The distribution 

 and extent of the deposit are indicated by a slate-colour on the accompanying 

 map. 



Local Drift, 



A local drift, consisting of morainie material, and possessing few glacial 

 characters, clothes the rough projections of the rock-floor, in the undulating 

 central area, between the mountains of Croaghmore and Knocknaveen. The 

 deposit, which is generally about 3 or 4 feet in thickness, is derived entirely 

 from the debris of the local rocks. 



Moraines. 



Another interesting drift is that produced by the local mountain-glaciers, 

 in the final stages of the glaciation of the island. One example of this deposit 

 occurs at Loughanaphuca, where a series of parallel terminal moraines marks 

 the pauses in the retreat of a shrunken glacier that debouched through a 

 small rock-bound valley to the east. Another small terminal moraine stretches 

 across the hollow of a cirque, about half a mile farther north. These moraines 

 once banked up small lakes now drained dry by a streamlet which has cut its 

 way through the morainie barriers that confined them. 



Eecent Drifts. 



Aeolian Deposits, Storm-leach, Peat, and Alluvium. 



The newest drifts on the island consist of aeolian deposits, a storm-beach, 

 peat, and alluvium. Along the margin of the storm-swept western coast, 

 there occurs an inextensive aeolian drift, composed of material driven inland 

 from the cliff-faces by the force of the prevailing western winds. The 

 material has been laid down in stratified layers, sometimes intermingled with 

 peat, hill-wash, or local detritus. Another wind-borne deposit is the barrier 

 of blown-sand which separates the bay, north of the harbour, from alow-lying 

 marshy flat, situated immediately to the west. 



R.I. A. PKOC, VOL. XXXI. C 7 



