848 J. GEIKIE OE THE GLACIAL PHENOMENA 



most part blunted, and showed traces of glacial abrasion, but now 

 and again they were quite angular. But even amongst the hills of the 

 east-coast range large angular erratics appeared to be by no means 

 so common as in North Harris, and I saw no trace of terminal 

 moraines. In short, evidence of local glaciation appears to be 

 wanting, and if any local glacier ever did exist it must have been 

 of insignificant dimensions. 



6. Freshwater Lakes and Sea-lochs. — The low-lying parts of North 

 Uist are thickly interspersed with shallow lakes that wind about in 

 the most intricate manner, although they appear upon the whole to 

 have a tendency to lengthen out in the direction of glaciation. 

 Most of them have peaty margins, and seem to rest partly in till and 

 partly in gneiss. The sea-lochs are of the same general character. 

 They are very shallow, the soundings showing that an elevation of 

 only 50 or 60 feet would be enough to dry up Loch Maddy and 

 Locheport. Their coasts are low and flat, and save the saltness of 

 their water they have hardly any thing else in common with the fine 

 sea-lochs of the mainland, or even with those of Lewis and Harris. 

 As no local glaciers existed in North Uist, mountain-valley lakes do 

 not occur. 



VI. Benbecula. 



The physical aspect of Benbecula is much the same as that of the 

 low-lying flats of North Uist and Lewis, but the proportion of water 

 to land is greater. In fact it is hard to sa}^ whether land or water 

 occupies the larger area in Benbecula. The island measures 6^ miles 

 or so from west to east, and about a mile or so less in the opposite 

 direction. It has only one hill ; and if we except the " Machair," as 

 the " good land " along the west coast is called, all the rest of the 

 island consists of low-lying moor, bog, and lake, with long shallow 

 inlets of the sea straggling in, chiefly from the east coast. 



Till of the usual character is widely diffused, with here and there 

 worn and glaciated rocks peering through. Striae appear to be 

 seldom preserved. I noticed only one example, and the markings 

 were rather faint ; their direction was W. 12° N. I saw no erratics 

 that might not belong to the till, and it need hardly be added that 

 there are no moraines. The dip of the gneiss, I should mention, is 

 towards north-west at various angles, from 25° up to nearly vertical. 

 In Euitheidh, however, the strike is almost at right angles to that 

 of Benbecula, and the dip is south-west. The hills on the latter 

 island are highly glaciated. 



VII. South Uist. 



1 . Physical Features. — South Uist is some 20 miles in length, and 

 has an average breadth of 5 or 6 miles. It is separated from Ben- 

 becula by a narrow channel, which at low water may be forded. 

 Its west coast is somewhat regular ; but the opposite coast-line is 

 extremely intricate, especially north of Huisnis. South of that 

 point there are only two large inlets of the sea, Lochaoineart and 

 Loch Baghasdail (Loch Boisdale); but they ramify far into the 



