230 Proceedings of the Royal Irish Academy. 



Barnesniore. Thus, no erratics from these sources were ohserved south of 

 their parent outcrops, while on the north they have been traced into the 

 Inishowen drifts.' 



12. South-Ea-stern Area. 



In all the southeru and south-eastern parts of the country wliieh was 

 investigated, the ice-sheet moved, in general, from a direction somewhere 

 in the west or north-west, towards the plains of Tyrone, Monaghan, and 

 Fermanacrli. 



The glaciers which iu the neighbourhood of Strabane streamed roughly 

 X.-E. appear farther south to have had a more easterly component in their 

 motion, as is shown by the few erratics which are traceable to their parent 

 sources.- The striated siuface, going S'.20"E., east of Movie House,^ probably 

 indicates a local deflection due to the relief. Bessy Bell was glaciated from 

 the S.-W. or S.S.-W. 



The ice-masses, pent up against the slopes of the Sperrin Mountains, found 

 relief by a great thrust to the east and south-east, in the direction of Cooks- 

 town and DuDgannon, as is suggested by the few drumlins, the form of the 

 ground, and by an occasional scratched surface. A mighty glacier swept 

 along the broad " Omagh-Draperstown corridor," as is shown by a number of 

 striae.* This ice transported north-eastward the boi\lders of the Tyrone 

 granites, occxuTing in great numbers to the north-east of their outcrops and 



' A few only of the observations made during this investigation can here be mentioned. 

 The rock of Coram (ca. 2 miles due E. of Stranorlar) was found as a boulder at Roosky. 

 Boulders of the rock occurring !S'. of Liscooly and at Farland were found in the drift at 

 half a mile S.-E. of Convoy, near the main road east of Black Repentance, at Knocklee 

 and Ar. Roosky. The hornblende lamprophyres from these and other localities just If. of 

 the Finn valley were observed at Dooish, Glentown, Berry HUl, Eden, Caw House, 

 Prospect, Stradreagh, Toulett Upper, Lundondeiry (e.g., Lone Moor Road), as far E. 

 as She-skin River and Gortnessy, and as far N. as Cabry River, Bogstowu River, Aught 

 River, Clunelly, Bredagh Glen, and OwenkUlew River. 



The hornblende lamprophyre fiom Inch Top occurs as erratics in the Crana River 

 (e.g., above Mullinderry Bridge and at Cock Hill). The Tooban Junction lamprophyre 

 has contributed to the drifts of the Inishowen slopes K.-W. of Muff. The hornblende 

 lamprophyre occurring E. of Cullion was traced in the drifts by Knock and Gortica to 

 Gortnessy and Sheskin River. Pebbles of pinkish lelsite found in the Bogstown and 

 adjacent rivers may have been derived from the rock near Kilfrum. I have been unable 

 to refer to their parent sources a considerable number of erratics of lamprophyre and of 

 felspar porphyry. It was found impossible to match, with any degree of confidence, the 

 great numbers of pebbles of epidiorite, both porphyritic and non-poii)hyritic, which were 

 obtained from the drifts of the strips of country bordering the Foyle both !s. and S. of 

 Londonderry. 



- E.g., the porphyiitic rock from just K.-E. of Newtown Stewart, which was observed 

 as erratics at Woodstock. 



^ Just E. of Ife«-town Stewart on the right bank of the River Strule. 



» See Mem. Geol. Survey, Sheet 34, p. 23 ; also map accompanying this paper (PI. IX). 



