156 JF. B. Wright— The Drumlins of South Donegal. 



shape, without any marked crest and with an even unserrated profile. 

 In the foreground on the right of Figs. 3 and 4 and also in the distance 

 can be seen drumlins of gently domed outline without even a trace of 

 a crest. Portion of the area depicted in Fig. 4 is shown as a contour 

 map on the scale of 3 inches to a mile in Fig. 5. The drumlins 

 numbered 1 to 5 in Fig. 4 bear corresponding numbers in the map. 

 The contours, being at intervals of 25 feet, bring out the form of the 

 ground with admirable precision. They show distinctly the narrowness 

 of the crest and its serrated character, and make very apparent another 

 peculiarity of certain of these drumlins, namely the forked outline 

 at the downstream end. This forking is by no means a universal 

 character, but a tendency to its development has been noticed in 

 several parts of the Donegal and Ballintra area. Analogy with the 

 crescentic drumlins to the west of Pettigo suggests that it is due to 

 slight oscillation of the ice-motion. 



Some cuttings on the Donegal and Ballyshannon Light Railway 

 display very clearly the composition and structure of the drumlins of 

 this area. The main mass of the hill is composed of stiS compact 

 boulder-clay, but the upper 5 feet more or less is always relatively 





Fig. 3. View of drumlin topography looking west from Trumman, one mile 

 south of Laghy, co. Donegal. The drumlins are viewed from the upstream 

 ends. Both rounded and crested types come within the field of view. 

 Donegal Bay and St. John's Point are seen in the distance. 



loose and loamy. The junction between this upper boulder-clay and 

 the compact till is generally fairly well defined. PI. IX, Fig. 3, 

 shows the top of a railway-cutting through the end of one of the 

 drumlins, in which the line between the upper and lower boulder-clay 

 is marked by calcareous oozings due to the escape of water along the 

 junction. It is not unlikely that the upper boulder-clay is englacial 

 material let down on the surface during the decay of the ice, and so 

 never compacted by the ice-motion. 



On first visiting the Ballintra district I was under the impression 

 that the crested nature of the drumlins might be due to landslipping, 

 and I was encouraged in this belief by observing an obvious recent 

 landslip on the slope of one of these drumlins near Rossnowlagh. 

 Landslips, however, possess as a general rule well marked and easily 

 recognizable features, and these I have not observed in connexion 

 with any other drumlins in the district. Mr. Hallissy has suggested 

 to me a much better explanation in soil creep, which would naturally 

 be at a maximum on the steep side slopes, and almost negligible along 

 the median line. Such action might in time lower the slopes and 



