Charlesworth — Glacial Geology of North- West of Ireland. 277 



represented bj' the longitudinal valleys between the successive ridges.^ 

 Lakes were occasionally produced, their waters rising until they found 

 escape by cutting across the barrier of the previously formed moraine, even 

 through places where the latter chanced to be superimposed upon a low 

 " solid " eminence.^ 



This Fintona glacier shrank westwards by successive stages; the last 

 moraines, marking its front, curve out of the lateral ridges to the east and 

 south-east of Bandoran Junction, and die out on the elevated rocky ground 

 extending northwards from Irvinestown.' 



From the above description it will be seen that the mode of recession from 

 this plain differed from that in the Clogher valley. Here the ice withdrew 

 obliquely across the valley, while there it retreated as a huge glacier from 

 east to west, parallel with the trend of the depression. This difference is 

 manifestly to be ascribed to the difference in the direction of thrust: this 

 being in the one case obliqiie to the axis of the valley, in the other, coincident 

 with it. 



The ice retreated northward along the depression of Upper Lough Erne. 

 This is shown by the effect on the drainage, i.e. the constant southerly 

 diversion of the courses of the existing streams, e.g. along the S.-E. slopes of 

 Slieve Eushen. Some of these valleys lie between morainie ridges, and 

 doubtless served as channels carrying off the marginal drainage of the ice, 

 but, as in the case of the southern slopes of Slieve Beagh, the waters were 

 chiefly those issuing from the melting ice-fi'ont and not from impounded lakes. 



The hill-slopes north-west of Clones show the same easterly trend of the 

 streams and aberration of the contours as observed on Slieve Beagh. These 

 features point, as in the latter area, to a great thrust of ice from the west in 

 the closing stages of the retreat. This would seem to prove the wheeling of 

 the ice out of the Erne valley about ISTewtown Butler into the comparatively 

 flat country to the south of the Slieve Beagh hills,* the ice, as suggested by 



' These valleys are in consequence only in part due to accumulation . They are much 

 too large for the present streams, even when sufficient allowance is made for the 

 incoherent nature of the materials which form the ridges. 



"A very good example of such is seen in the pretty valley falling N,-E., and situated 

 about one and a half miles S.-W. of Omagh, and through which runs the main road from 

 this town to Dromore. This valley is about 30 feet deep, flat-floored, and contains only 

 a very small stream. It is carved iu "solid." 



5 A small valley at Croneeu Barr, to the S.-E. of Lack, probably drained a small lake 

 at one of these stages. 



The moraines near Bundoran Junction trend roughly W.-N.-W.-E. -S.-E. ; the road 

 and railway between Irvinestown and Bundoran Junction run roughly between two of 

 them. 



* Yet most of the mounds and ridges trending S.-W.-N.-E. in the Clones-Monaghan 

 depression are, as already pointed out (p. 2fi6), morainie in origin ; some, as Mr. Hallissy 



