OP THE OUTER HEBRIDES. 821 



The same strike continues west of Stornoway for a distance of eight 

 miles or thereabout, and ranges over nearly all the area between 

 Beinn Barabhais in the north and the river Laxay in the south. 

 South-east dips also predominate near the Butt, the strike being ap- 

 proximately N.E. and S.W. as far south at least as Aird Dhail. In 

 the mountainous district of the south-west, however, the strike is 

 persistently JST.W. and S.E., with a prevalent dip towards N.E. The 

 same dip is also conspicuous over the Great Bernera, along all the 

 sinuous coast-line of Loch Roag, in the neighbourhood of Barabhais 

 &c. Throughout wide areas traces of bedding are often faint and 

 deceptive,, and frequently the gneiss appears to be quite amorphous. 

 Crumpled and contorted stratification is of course a very common 

 phenomenon. I give these additional notes on the dip and strike 

 of the gneiss; for without an adequate knowledge of the "lie" of 

 the rocks, it is hardly possible to realize the effect produced by gla- 

 ciation on the contour of the ground. 



2. Direction of Glaciation in hilly Districts. — In the paper 

 already referred to mention has been made of the fact that, while 

 ice-worn hummocks of rock abound in the low grounds of Lewis, it 

 is yet rarely that glacial striae appear upon them. In the hillier 

 districts, however, ice-markings are much more frequently met with. 

 Thus, in the district of Uig, which I visited in company with Mr. 

 Etheridge, a number of well-striated rock-faces were noted, all of 

 which pointed from S.E. to N.W. 



The hill- slopes overlooking Loch Stacsabhat are not only distinctly 

 glaciated from S.E. to N.W., but here and there the roches mouton- 

 nees are covered with striae, more especially where the rock is close- 

 grained and hard. Even in cases where the striae have been effaced 

 from the gneiss they may still be detected upon quartz-veins, which, 

 being harder than the rock they traverse, usually project beyond its 

 weathered surface. 



We ascended Suainabhal (1300 feet) and found these appearances 

 at many points along its steep flanks. This bleak hill, which stands 

 comparatively isolated, is glaciated from base to summit, being in 

 fact only a huge ice-worn hummock. It has been completely 

 smothered in ice, and there are no contiguous high grounds from 

 which that ice could have been derived. Looking from the top of 

 the hill in what direction we may, we see nothing but a dreary, 

 verdureless expanse of bare, grey, ice- worn hummocks, hills, and 

 mountains, interspersed with innumerable lakes, and intersected by 

 long straggling arms of the sea. The highest hills lie to the south- 

 west, and even these appeared from our point of view to be glaciated 

 very nearly up to their summits, which are between 1600 and 1700 

 feet in height. Not a few, however, showed steep cliff-faces, a fea- 

 ture which will be described in connexion with the glacial pheno- 

 mena of North Harris. A narrow dark lake, some 2\ miles in 

 length, that separates these sorely glaciated hills from Suainabhal, 

 occupies a rock-basin which has evidently formed the path of a huge 

 mass of ice that flowed north-west, the mountain-slopes on both 

 sides of the lake being well glaciated. It is obvious therefore that 



