28 STTPPLEMEFTAKT EEMAEKS OIT GLEN EOY. 



except that Ben Nevis would not equal the greater peaks in 

 height. 



Mr. Maee observed that no diagram had been made to illustrate 

 the paper ; he therefore showed on the blackboard the alteration in 

 the horizontal extent of the terraces as indicated on the new Ordnance 

 maps, and showed how, according to the Author's account, the expla- 

 nation of the lakes having been caused by glacial dams was thus 

 simplified. The speaker himself believed that this explanation was^ 

 the correct one ; and he cited, in illustration of the extraordinary 

 manner in which valleys were left free of ice in a glaciated district, 

 the remarkable cases described in the ' Meddelelser om Gronland.' 



The Peesident agreed that no explanation that had yet been 

 proposed for the Parallel Eoads of Lochaber was free from difficulties. 

 Yet he had long felt that these were far fewer and less formidable in 

 the glacier theory than in any other. Had the terraces been marine, 

 there ought surely to be similar terraces in some at least of the 

 hundreds of sheltered glens in the Scottish Highlands, where the 

 conditions for their formation and preservation were at least as 

 favourable as in Glen Eoy and its adjacent valleys. And though 

 the absence of marine shells in the Lochaber shelves might not be a 

 serious difficulty, it was hard to understand why such shells should 

 not be found in many localities had the whole country been sub- 

 merged to the height of the highest Glen Roy ' road,' Then no 

 satisfactory explanation on the marine theory had ever been given 

 of the coincidence of the terraces with well-marked cols ; while a 

 further formidable objection to this theory lay in the nature and 

 distribution of the detritus of the shelves, which, in his opinion, was 

 very unlike material arranged in a tidal sea, but was quite what 

 might be looked for in a freshwater lake. He thought that the 

 Author's present paper lessened some of the difficulties of the 

 glacier theory by simplifying the grouping of the ice-dams. There 

 still remained the objection that, if the Great Glen and the valleys 

 round Ben Nevis were choked up with ice. Glen Roy and its neigh- 

 bours could hardly have been filled with water. But this difficulty, 

 which every glacialist must have felt, was probably more formidable 

 in appearance than in reality. As Mr. Marr had pointed out, con- 

 ditions did actually now exist in Greenland very similar to those 

 which, according to the theory so ably expounded by the Author, 

 formerly existed in Lochaber. 



