204 Proceedings of the Royal Irish Academy. 



ripped off by ice advancing from the south. The quartzifce dihris so removed 

 was deposited to considerable depths in the valley which lies to the north, its 

 unequal distribution resulting in tlie production of Lough Adoochro. 1"he 

 striae and rounded western slopes of this valley clearly demonstrate the 

 oblique transgression of the depression by the ice. 



' Beefan and Garveros mountains were severely glaciated by ice passing 

 westwards along the broad valleys of Glencolumbkill and the Murlin river, to 

 the north of which they lie. 



Striae going S. 20° W. occur on both sides of the \alley of the Glen rivei, 

 above Carrick. At Malin Beg and Malin More the drift attains a thickness 

 exceeding that found elsewhere in the Glengesh Plateau, as is shown in several 

 good stream sections. The direction of the ice-flow in this corner of the upland 

 is clearly given by t]ie drumlin mound at Malin More and by the striae at the 

 quay at Ouhig, which bear W. 20"^ S. 



The north-east shoulder of Slieve League doubtless split the ice flowing 

 southwards, causing some to flow westwards towards Malin Beg and Malin 

 More, and diverting some to Teelin Harbour, where, as J. F. Campbell long ago 

 pointed out,^ " the rounded, curved, glaciated rock surfaces " distinctly show 

 the direction of ice-motion. 



Ice passed seawards over Crockrawer (S.E. of Slieve League) ; its north- 

 eastern slope is beautifully rounded, its sea-face sheer, while a number of 

 erratic blocks lie strewn over the higher parts of the ridge. The distribution 

 of the drift at and near Teelin, and south of Teelin Bay, indicates the south- 

 ward trend of tlie ice, and confirms the striae which, all over this area and 

 on both sides of the bay, bear steadily S. 20° W. They show no trace of a 

 deflection of the glaciers flowing over Teelin, by any ice-mass pressing sea- 

 ward along Donegal Bay. Ice passed along the broad valley of the Ballaghdoo 

 river, and overrode the hill at Drumveagh, piling up the drift on its northern 

 side. It then flowed southwestwards over the finely striated diorite and schist 

 of Tawny Hill. 



The fine TT valley of Glenaddragh shows several large and small examples 

 of truncated spurs, while its moulonnee sides, though only occasionally grooved 

 or striated, clearly indicate the direction of ice-motion. The ridge between 

 this valley and that of Ballaghdoo, on the west, is well rounded and smoothed, 

 suggesting the coalescing along its length of the glaciers flowing in the adjacent 

 valleys. The result of this great press of ice was to cause the glaciers to 

 continue their course straight over the hills of Croaghmuckros and Croaghbeg 

 (north of Gortalia), which stood opposite their mouths. These hills in 



' Glaciation of Ireland, Quart. Jour. Geol. Soc, vol. xxix (1873), p. 205- 



