W. B. VTright—The Brumims of South Donegal. 155 



the form of these drumlins is the result of a change in the direction of 

 the ice-flow. There is a certain similarity to the crescentic sandhills 

 known as barkhanes, the concave sides of which face away from the 

 prevalent winds. 



In the case of these sandhills, however, there seems to be no 

 necessity for any change in the direction of the wind, the cusps being 

 built up by the natural creep of the sand round the flanks rather than 

 over the crest. This flanking action, though no doubt occurring to 

 a slight extent in the case of ice-motion, is not likely to have any 

 powerful efi'ect. Moreover, there certainly seems in the present case 

 to be a distinct connexion with change in the direction of flow.^ 



If now we cross over to the second district, which lies to the north- 

 west of the metamorphic moorland, in the neighbourhood of Ballintra, 

 Laghy, and Donegal, we find quite a different type of topography. 



Ik "^iffi 



Fig. 2. Map of the distiict west of Pettigo, with contoms every 25 feet to 

 show the triangular and crescentic drumlins and the accompanying stride 

 indicating two directions of ice-motion. The heavy broken line marks the 

 boundary of the Boulder-clay. Scale one mile to an inch. Eeproduced 

 with modifications from the Ordnance Survey Maps by permission of the 

 Controller of H.M. Stationery Office. 



Here the great majority of the drumlins are of hog-backed form 

 and distinctly crested. An attempt is made in Fig. 3 to indicate the 



* character of the country. The drumlin which stands out prominently 

 in the centre of the picture is in every respect a perfect example of 

 the class of hill which abounds in this district. Fig. 4 gives a more 



s oblique view of the same class of drumlin. In both these sketches 

 the undulating or serrated character of the crest is shown, and this is 

 also well brought out in PI. IX, Fig. 2. A curious feature is the 

 intermixture of drumlins of other types. Thus Fig. 4 shows in the 

 middle of the picture a small drumlin of the well known half-cigar 



^ See Vaughan Cornish, " On the Formation of Sand-dunes " : Geogr. Journ.,. 

 vol. ix, p. 290, 1897. 



