282 Proceedings of the Royal Irish Academy. 



marginal drainage was carried by the different channels for very short periods 

 only, and has rarely recognisably modified the extremely irregular surface. 

 Yet the shrinkage of the eastern margin of the Mulroy Glacier can in places 

 be followed with considerable ease. Thus a lake was held up in the recess 

 east of Garrowkeel, and drained by a series of channels in parallel sequence. 

 They are all in " solid," and fall north or north-east. 'I'he highest and 

 earliest of these intakes about 400 feet, O.D. ; the second is the poor channel 

 east of Murren Hill ; the third, the lowest and best formed of all, intakes 

 just below 200 feet, and X.-E. of Upper Town. 



The only undoubted channel between Milford and Garrowkeel, is the short 

 notch at about 300 feet, O.D., about one-and-a-lialf miles south of the latter 

 place. A series of morainic mounds was observed south of Milford and east 

 of Maggy's Burn ; corresponding with this ice position is the short glen, now 

 streamless, falling to the Quay, and ending at about 50 feet, O.D. 



The shrinkage of the western margin of the Mulroy Glacier is wrapped 

 in obscurity, one channel only, that to the west of Devlinmore Hill, furnishing 

 any indication of the mode of retreat, though the valleys to the west of 

 Milford were probably to some extent modified by streams draining directly 

 from the ice-front. 



Marginal channels mark the progress of the recession of this glacier along 

 the Ijcnuan valley ; they all occur along its western side and fall north. 

 Among these may be mentioned the gash on the eastern slopes of Cabra Hill, 

 notching the 300- and 200-foot contours, and the glen west of Cottan; the 

 valley at Treautagh is less clearly glacial in origin.^ 



"With the single exception of a small channel falling north from Leadbeg 

 Hill (about two-and-a-half miles N.-E. of Carrigart),no trace of the retreat was 

 discovered in the Fanad, Eosguill, or Horn Head peninsulas. Tsvo channels 

 discovered in the coimtry between Dunfanaghy and Barnes Gap, though 

 small in themselves, are important as furnishing clues to the mode of 

 recession of the Sheephaven Glacier. The one occurs at Cashelmore, the 

 other 2 intakes at 200 feet, O.D., at the School, two mUes south of Greeslough; 

 they fall north. 



The mass of ice north of the Muckish range cleaved somewhere on the 

 line Muckish, Dunfanaghy, Horn Head, the one part shrinking eastward to 

 form the Sheephaven Glacier, the other falling away westward and retreating 

 through the breaks in the Muckish range and by the Glenna valley. Of this 

 retreat a few traces exist. A small lake was held up in the Augher Pdver 



' Some melt waters would seem to have availed themselves of the Barnes Gap, as the 

 ice shrank off the Salt range. * 



' The railway runs along its western side. 



