1841 1880] GLEN ROY 189 



comparing the glacial scratches under a lake (formed by a Letter 525 

 moraine and which must have existed since the Glacial 

 epoch) and above water, and I could perceive no difference. 

 I believe I saw many such beds of good pebbles on level of 

 lower shelf, which at the time I could not believe could have 

 been found on shores of lake. The land-straits and little 

 cliffs above them, to which I referred, were quite above the 

 highest shelf ; they may be of much more ancient date than 

 the shelves. Some terrace-like fringes at head of the Spey 

 strike me as very suspicious. Mr. J. refers to absence of 

 pebbles at considerable heights : he must remember that 

 every storm, every deer, every hare which runs tends to roll 

 pebbles down hill, and not one ever goes up again. I may 

 mention that I particularly alluded to this on S. Ventanao 1 

 in IN. Patagonia, a great isolated rugged quartz-mountain 

 3,000 ft. high, and I could find not one pebble except on 

 one very small spot, where a ferruginous spring had firmly 

 cemented a few to the face of mountain. If the Lochaber 

 lakes had been formed by an ice-period posterior to the 

 (marine?) sloping terraces in the Spean, would not Mr. J. 

 have noticed gigantic moraines across the valley opposite 

 the opening of Lake Treig? I go so far as not to like 

 making the elevation of the land in Wales and Scotland 

 considerably different with respect to the ice-period, and 

 still more do I dislike it with respect to E. and W. Scotland. 

 But I may be prejudiced by having been so long accustomed 

 to the plains of Patagonia. But the equality of level (barring 

 denudation) of even the Secondary formations in Britain, 

 after so many ups and downs, always impresses my mind, 

 that, except when the crust-cracks and mountains are formed, 

 movements of elevation and subsidence are generally very 

 equable. 



But it is folly my scribbling thus. You have a grand 

 problem, and heaven help you and Mr. Jamieson through it. 

 It is out of my line nowadays, and above and beyond me. 



1 Geolog. Obs. on South America, p. 79. "On the flanks of the 

 mountains, at a height of 300 or 400 feet above the plain, there were a 

 few small patches of conglomerate and breccia, firmly cemented by 

 ferruginous matter to the abrupt and battered face of the quartz traces 

 being thus exhibited of ancient sea-action." 



