832 J. GEIKIE ON THE GLACIAL PHENOMENA 



tonnees being very persistent, notwithstanding the ragged configura- 

 tion of the ground. On the north side of the Cliseam, however, the 

 glaciation trends rather more to the north, the average direction 

 over the area that extends eastwards to the shores of Loch Seaforth 

 being from S. 32° E. to N. 32° W., a direction that coincides with 

 that of the glaciation in the adjacent districts of Lewis. 



In short, an examination of the roches moutonnees and stria? in 

 North Harris leads irresistibly to the conviction that the whole of 

 that country has been smothered in a sheet of ice, the surface of 

 which attained an elevation of not less than 1600 feet above what 

 is now the sea-level. It is further certain that that ice-sheet moved 

 across the land from south-east to north-west, ignoring the minor 

 undulations of the ground, but being to some extent deflected by 

 the great masses of the Cliseam and the Langa, the summits of which 

 rose above the surface of the mer de glace. In the bottoms of several 

 of the valleys of North Harris that intersect the general direction of 

 glaciation, striae and roches moutonnees afford indications of the ice 

 having been slightly deflected by the contour of the ground, and 

 similar minor deflections may be observed upon steep hill-slopes that 

 face the south-east. As examples, I may point to the glaciated rocks 

 in Gleann Abhuinn-eadar and in Bealach na Ciste, and to the fine 

 display of roches moutonnees between the Tarbert and Loch Lacas- 

 dail. 



South Harris is not less well glaciated than the area just described. 

 Indeed it is even more so ; for while the tops of several of the highest 

 mountains in Forth Harris have never been overflowed by ice, there 

 is but one point in the southern part of the island which seems to 

 have escaped the grind of glacier-ice. The point referred to is the 

 dominant part of the high ground between West Loch Tarbert and 

 Traigh Losgcinntir, which reaches an elevation in the Tarcul of 1654 

 feet. With the exception of this insignificant area, all the ground 

 lying between West Loch Tarbert and the Abhuinn Lacasdail is 

 highly glaciated, the roches moutonnees on the East Stoc-cleit and the 

 hills overlooking Traigh Losgcinntir being especially noteworthy. 

 In the neighbourhood of East and West Lochs Tarbert the average 

 direction of the striae in South Harris is about E. 20° S. to W. 20° N. ; 

 but as the valley of the river Lacasdail is approached they take on 

 a little more northing, the average being as near as may be 

 W. 30° N". 



The roches moutonnees in the district lying between Miabhaig and 

 Greosbhag are smoothed off in the same direction, the striae occa- 

 sionally pointing to N. 40° W. Conspicuous roches moutonnees occur 

 in the valley of the river Lacasdail, those in the vicinity of the lake 

 being very well marked. Finely glaciated faces may also be ob- 

 served again and again along the whole way between the mouth of 

 the river Lacasdail and Scarrasta, the striae having an average trend- 

 of W. 30° N. Indeed all the hills along the west coast bear evident 

 marks of having been smothered under glacier-ice ; they are abun- 

 dantly rounded, and, notwithstanding the weathering which the 

 roches moutonnees have experienced, striae are yet occasionally well 



