1873.] GEIKIE GLACIAL PHENOMENA OE OUTER HEBRIDES. 535 



phenomena; and hence I have been able to add nothing to our 

 knowledge of Lewisian petrology. 



IY. Glaciation of the low grounds of Lewis. 



As he approaches Stornoway from the sea, the glacialist cannot 

 fail to observe that the rocky and broken ground along which he 

 coasts, presents much of that same worn and mammillated appearance 

 which forms so striking a feature in the coast-scenery of the western 

 sea-lochs. The hills appear to be smoothed off, but, strange to say, 

 against the general slope of the land, or, in other words, from 

 the shore to the interior. But when the observer subsequently 

 rambles over the same ground, the glaciated aspect which the 

 rocks appeared to assume while viewed from the deck of the 

 steamer, becomes much less conspicuous. Broken and irregular- 

 shaped masses of gneiss, with confused and straggling hollows between, 

 meet his eye on every hand. The rounded mammillated appearance 

 has seemingly vanished ; and he searches in vain for any striations. 

 But as he makes his way towards the road leading from Stornoway 

 to Luirbost, he becomes aware that the broken and rocky hills have 

 a tendency to arrange themselves along a line stretching approx- 

 imately north-east and south-west, and that for the most part they 

 present an abrupt face to the north-west, with gentler and less broken 

 acclivities sloping away in the opposite direction. In short, this 

 rough ground consists of a series of interrupted and ragged es- 

 carpments of gneiss. It would have occupied much more time than 

 I had at my disposal, had I tried to ascertain whether these es- 

 carpments owed their existence in the first place to any differences 

 in the texture and durability of the gneiss. But from what I was 

 able to make out, it appeared to me that such would very likely 

 prove to be the case. At all events, of this there can be no doubt — 

 namely, that the line of the broken escarpments answers precisely 

 to the strike of the gneiss. These escarpments, as I have just 

 said, face to the north-west ; and the slope of the ground behind 

 corresponds exactly with the direction of dip, but seldom, if ever, 

 with its angle. A hasty observer of the dip and strike might 

 therefore be apt to conclude that the appearance of glaciation as 

 noted from the sea is delusive, and that what seem to be roches 

 moutonnees are features due simply to strike and bedding. But one 

 familiar with the phenomena of an ice-worn country would not 

 fail to remark the presence of those peculiar flowing lines and flutings 

 which mark the hills when these are viewed at a little distance. He 

 would note, moreover, that the tops of the crags and knolls are rounded 

 off in a way which is at least strongly suggestive of glacial action, 

 and he could hardly doubt that the presence of a deposit of till in 

 sheltered nooks and hollows between the hills was good evidence in 

 the same direction. 



I have referred to this barren rocky district because, owing to its 

 accessibility from Stornoway, it is most likely to be the first visited 

 by geologists who may think of going to Lewis. The appearance 



