OP LOCHABEIV. 45 



Particular Tlieory of the Causes wfiich may be supposed to have 

 operated in producing the Shelves in the Glens of Lochaber. 



Althoi)gh it appears to me, that no one can examine even 

 a portion of these shelves with attention, without ascribing 

 them to an aqueous origin, and without being hiiewise perfect- 

 ly satisfied, that they were formed by the level waters of lakes, 

 yet I have been taught by experience, that it is impossible to 

 go farther in speculation, without a thorough knowledge of all 

 the glens, as well as of every part of the tortuous course of 

 the linear appearances to be found in them. Almost every step 

 I took in this interesting investigation, seemed to lead to some 

 new conclusion, as to what was the probable topography of the 

 ancient lakes ; and it was not until I had collected all those 

 facts which I have stated in the foregoing pages, in what 1 

 fear will be considered as rather tedious detail, that any thing 

 resembling a satisfactory theory of their distribution, shape, 

 extent, and final evacuation, suggested itself to me. This I now 

 venture to lay before the Society, trusting to its indulgence. 



It appears that Glen Gluoy possesses Shelf 1st, which is the 

 highest of all ; and that it is to be found in no other glen. 

 From this I would infer, that Glen Gluoy was at one period 

 an independent lake, having a level higher than any of the 

 others in its vicinity. The next two shelves in elevation, 

 which are Shelf 2d and Shelf 3d, are confined entirely to Glen 

 Roy, and its smaller tributary glens; and are found to run 

 down and terminate, nearly together, in the Gap of Glen Col- 

 larig, on the north side, and in the mouth of Glen Roy on the 

 south side of the round hill of Bohuntine, as represented in 



the 



