OF THE OUTER HEBRIDES, 843 



direction of the general glaciation. Good examples of such local 

 glacier-lakes occur in Gleann Abhuinn-eadar and Bealach na Ciste; 

 and Loch Lacasdail itself is another excellent example. In the case 

 of this lake, however, it is highly probable that the work of excava- 

 tion was partly accomplished during the time of general glaciation. 

 The same to some extent holds true, I am inclined to believe, of 

 some of the lake-basins in the mountain-tracts of Lewis, — of Loch 

 Suainabhal, for example. That rock-basin, however, -has evidently 

 been occupied by a large local glacier in late glacial times, and 

 doubtless experienced considerable erosion then. The moraines of 

 the glacier in question are seen crossing the valley below Loch 

 Stacsabhat. Of rock-basins which are entirely due to the action of 

 local glaciers the mountain-valleys of Lewis afford a number of good 

 examples ; but the lakes are usually small. Among these may be 

 mentioned Loch Eaouasgail, between Mealasbhal and Taithabhal, 

 which is half a mile in length and about a sixth of a mile in breadth. 

 Loch Dhibadail, about the same length but only half as broad, is 

 another good example; it lies at the base of the steep slope of 

 Tamanaisbhal. 



Of the sea-lochs that intersect Lewis and Harris not much need 

 bo said. In none of them are found the great depths which are so 

 characteristic of the fiords of YVestern Sutherland and Ross. And 

 this might well have been expected. There are deep rock-basins in 

 Loch Torridon, Loch Ewe, and Loch Broom, because all those fiord- 

 valleys were once filled by gigantic local glaciers, fed from some of 

 the loftiest and most extensive snowfields in glacial Scotland. But 

 in late glacial times only inconsiderable glaciers occupied the 

 mountain-valleys of Harris and Lewis, and it is extremely doubtful 

 whether many of these lingered for a prolonged time in the sea-lochs 

 after they had ceased to be confluent with the mer cle glace of the 

 Minch*. There is a depression in Loch Seaforth that reaches a 

 depth of 138 feet, and another occurs in Loch Shell which is 60 feet 

 deeper than the outlet of the Loch. The bottoms of Loch Claidh 

 (Clay) and Loch Bhrollum seem to be similarly excavated ; but the 

 soundings given upon the Admiralty charts are not sufficiently 

 numerous to make this quite certain. It is interesting and sug- 

 gestive to find that these depressions occur in the very places that 

 must have been occupied by considerable local glaciers, which, when 

 the pressure and obstruction of the mer cle glace of the Minch were 

 beginning to decrease, would commence creeping out from the 

 mountains down all the main lines of drainage. In some cases 

 these local glaciers would flow at right angles to the course followed 

 by the general ice-sheet in the same localities, as was certainly the 

 case with those glaciers that descended from the Forest of Harris 

 towards West Loch Tarbert. In other instances the course of the 

 local glaciers would even be directly contrary to that of the mer cle 

 glace, as we have seen was the case with the glacier of Loch 



* It may be as well to state here that I take the liberty throughout this 

 paper of applying the term " the Minch " to all the sea that lies between the 

 Outer and Inner Hebrides. 



