204 GLACIAL EROSION AT LOCH LOCHY. [Feb. I 9OO. 



shown by the Author, were not in the parent rock, but in material 

 which could be compared only to the Contorted Drift of the Norfolk 

 coast. Yet the ' roads ' were rarely cut into for half their width by 

 subaerial denudation; whereas in the East of England the Boulder 

 Clay was often completely removed or only capped hills, while 

 valleys were excavated in the underlying deposits, which appeared 

 to show that denudation had done comparatively little to alter the 

 West of Scotland since the Great Glaciation. 



The Author, in reply, expressed his satisfaction at the remarks 

 mado by Mr. Haiker and Mr. Barrow. Replying to Mr. Hill, he 

 regretted that he had not sufficiently insisted upon the fact that a 

 sloping plane, like that seen on Loch Lochy, could not be due to 

 freshwater erosion ; it must be, he thought, of glacial origin, and the 

 higher glens were clearly truncated by this sloping plane. The 

 point noticed by Prof. Seeley, that the Parallel Roads of Glen Roy 

 showed less post-Glacial stream-erosion than the hillside on Loch 

 Lochy, was due to the latter being composed of a Devonian rock 

 which appeared to undergo comparatively rapid disintegration near 

 the surface. 



