200 DR. W. T. BLANEORD ON THE APPARENT RESULT [Feb. I90O, 



sides of the Great Glen in general, and those watercourses being 

 deeper and more sharply cut. It is, of course, quite possible that 

 the tendency to disintegration in this sandstone has facilitated 

 glacial as well as stream-erosion. 



Here and there, in going along the surface and examining the 

 small sections recently exposed by the cuttings for the new railway 

 from Spean Bridge to Fort Augustus, patches of boulders and gravel, 

 evidently of the nature of moraine, are found filling hollows in the 

 slope. But these patches are of small extent ; in each case that 

 I observed ihem rock appeared in place in the neighbouring 

 stream-beds, and it is not improbable that the hollows thus filled 

 were the result of irregular erosion by either ice or running water, 

 during Glacial times. 



The explanation of the surface-features described is, I think, the 

 following: — The sloping plane must have been produced, like other 

 parts of the side of the Great Glen, by the planing action of a glacier. 

 The patches of moraine, while filling up small hollows and rendering 

 the slope more uniform, afford additional evidence of its Glacial origin. 

 The small channels cut in the slope are clearly due to freshwater 

 erosion since the glacier disappeared. The deeper lateral glens in 

 the higher hills must be of pre-Glacial origin, and the rounding of 

 their upper edges shows the action of ice upon them. 



The general effect produced by the whole evidence is that which 

 has impressed so many previous observers : the small amount of 

 denudation that has taken place since the Great Ice Age, and the 

 necessary deduction that not many thousands of years can have 

 elapsed between the Glacial Epoch and the present day. 



There were two points, illustrated by the surfaces of which I have 

 endeavoured to indicate the principal features, that are worthy of 

 notice, and they will, I hope, serve to excuse my calling attention 

 to what may be, to many, a familiar variety of the surfaces affected 

 by glacial action. I may premise by saying that in glaciated surfaces 

 it is generally very difficult to determine precisely how much of the 

 erosion is post-Glacial, whereas in the peculiar case presented by 

 the slopes here described it is easy to recognize which portions owe 

 their moulding to Glacial, and which to post-Glacial action. It may 

 be urged with apparent justice that some post-Glacial erosion must 

 have affected the whole slope ; but on the other hand it should be 

 remembered that this erosion is excessively small, else the moraine- 

 patches would have been worn more deeply. Moreover, in com- 

 paring the amount of denudation in the ravines and on the inter- 

 vening slopes, we may neglect that on the latter because it has been 

 uniform throughout the whole surface, and it is the excessive 

 denudation of the stream-beds which alone has to be considered. 



(i) In the first place I think that this case constitutes a particularly 

 good example of the erosion produced by a glacier. It has become a 



