Charlesworth — Glacial Geology of North- West of Ireland. 293 



from the valley of the Finn. The irregular mounds in' the Eeelan valley 

 (e.g., E. of Meenasrone South) are probably not to be regarded as due to 

 unevenness of the original deposition but as residual features produced by 

 river erosion. 



The glacier, which receded southwards along the Daurnett valley, 

 impounded a lake on the site of the present Mourne Lough, which drained 

 northward by an indubitable " dry " valley, excavated in rock, at the head 

 of the Burn Daurnett. The large glacier retreating westwards up the 

 valley of the Mourne Beg River, after parting from the Derg Glacier, formed 

 a temporary lake south of ileenglass, which discharged northward along the 

 glen west of Trusk Hill. 



The series of marginal lakes on the northern edge of tlie " Great Finn 

 Glacier " discharged therefore by a number of channels into the Swilly valley, 

 from which, in the absence of channels along its southern side, it may be 

 inferred the ice had already retreated. 



11. The Barnesmoro Hills. 



Moraines are only found in tlie valleys on the northern side of the 

 Barnesmore Hills where the ice would seem to have lingered longer than on 

 the southern side. 



The finest of these are associated with the Barnesmore Gap. While the 

 humniocky country to the south of the Gap is doubtless primarily due to the 

 irregular outcropping of schist and less to the occurrence of morainic material, 

 the irregular ridges and mounds, encountered S.-E. of Ardeevin and seen to 

 consist of angular local material, may represent one of the earliest of these 

 moraines. 



A pronounced ridge of hummoeky aspect and convex to the south 

 occurs at the southern end of the Gap. It represents a terminal moraine of 

 a glacier occupying the Gap. ISTo sign of an intermediate halt is observed 

 till the northern end is reached, where the Barnes Piiver enters from the west. 

 Here, magnificent morainic heaps and ridges occur, presenting a chaotic and 

 tumbled appearance, strongly contrasting with the more regular surface of 

 the adjacent country, and are probably to be regarded as one more or less 

 continuous moraine, convex eastwards. 



These great accumulations are without doubt, as suggested by J. E. Kilroe,' 

 the product of a glacier advancing down the valley of the Barnes Eiver. The 

 water-worn and stratified sands and gravels exposed in the large railway 

 ballast-pit are clearly part of the outwash-fan of the ice. 



' An attempted restoration of these glaciers is given in the Donegal Memoir (Map, 

 p. 41). 



