300 Proceedings of the Royal Irish Academy. 



of the Burntollet Eiver out of its pre-glacial valley, which lay just south of 

 the present position, as is indicated by the line drift section, sixty feet high, 

 exposed just south of the fall. 



The Dungeon Waterfall, south of the Faughan Valley, is probably of the 

 same origin, much gravel occurring at its side. 



The Ballinderry Eiver would appear to have lost its way in that part of 

 its course wliich runs from Corkhill to Kildress Bridge (about three miles W. 

 of Cookstown), its former valley, infilled with drift, lying to the south, near 

 the road skirting the Drummanor demesne. 



Tlie Gleuelly and Owenkillew Elvers have been diverted from their pre- 

 glacial courses by lake deposits and transverse morainic ridges. The position 

 of the pre-glacial channel of the Owenkillew Eiver is probably indicated by 

 the present small stream entering tlie river below Athahole. The general 

 direction of these obliterated channels is given on the'map (fig. 5). 



Fig. 5. 



Map showing the pre-glacial course of tte Glenelly and Owenkillew 

 riTers. Scale — 2 miles = 1 inch. 



Numerous oiher post-glacial diversions were observed, e.g., the gorge in 

 the O.E.S. at the " Leap " on the Camowen Eiver, to the S.E. of Omagh, the 

 pre-glacial valley lying somewhere to the east of this ; the Termon Eiver, near 

 Pettigo, which flows through a small gorge in the gently-dipping, thick- 

 bedded Carboniferous Limestone ; the Owenbrack Eiver, at the " Mills," S.-E. 

 of Six Mile Cross, which has bitten into the O.E.S. and formed a small gorge ; 

 the Mill Eiver, which has cut into the rock, some miles N.-E. of Buncrana ; 

 the Eiver Deele, which has missed its old valley in two places above Drumkeen 

 and also near Convoy ; the Lennan Ei\er, which has been deflected into the 

 rock by drumlin mounds, east of Garton Bridge ; the Eiver Faugliau, which 

 has cut into the rock in one or two places below its confluence with Bond's 

 Glen. 



The Eiver Erne, above Belleek, flows in a wide, open and drift-floored 

 valley. At this place it suddenly changes its direction, pursuing a south- 

 north instead of the east-west course which had previously characterized it, 



