656 tfroc. B.N.F.C, 



One of the most interesting geological features in the region 

 is a remarkable esker on the east side of the Roe Valley. It 

 commences at a height of 850 feet on the Keady high ground, 

 crosses the valley of the Curly River, northward, and wastes 

 itself in scattered moraine hillocks near the Largantea burn. It 

 rises on the north side of the Curly valley to a height of above 

 700 feet; and, connecting this by an imaginary line with its height 

 above datum on the south side, the englacial river in which the 

 materials of the esker were collected will be seen to have flowed 

 in its ice-channel at least 150 feet above and across the Curly 

 river-bed, this being 550 feet above datum at the point in question. 

 The esker river flowed, in fact, in a temporary aqueduct at this 

 height. 



Another esker is to be seen two miles south of Ballydarrog, 

 pursuing a curved, interrupted course south-eastely, through Moys 

 and Ardinarrive ; and an important, though short, ridge — The 

 Mullagh — associated with moraine mounds of sand, occurs on the 

 west side of Roe Park demesne, at Limavady. 



In the Bann Valley, a curved esker is crossed by the main 

 road southward at Killykergan, near Garvagh ; others no doubt 

 would be traceable in this valley, and on the ground between the 

 Bann and Main, but I am unable to speak of them with any 

 definiteness. 



It will be noticed that the eskers mentioned pursue courses 

 independent of those followed by the present drainage (a fact 

 accounted for by the accumulation of the sands and gravels now 

 forming the ridges) in rivers which furrowed the latest ice-sheet, 

 before its surface had declined so far, through the melting, as to 

 conform to the present shape of the ground. No better instance 

 of this could be known than that of the first esker mentioned 

 above : the second, though not so striking, is equally illustrative, 

 for it crosses the stream bounding the two townlands. 



