OF LOCHABER. 5 



sweep out to right and left, from its mouth into Glen Spean ; 

 running on the one hand, by various sinuosities, in the direc- 

 tion of Highbridge, and extending up the north side of Glen 

 Spean, and round the upper extremity of Loch Laggan, 

 whence it returns on the south side of the same valley. There 

 are thus four distinct ranges of these shelves, which, to avoid 

 circumlocution, and for the sake of greater perspicuity, I shall 

 uniformly number from above downwards. I shall, therefore, 

 call that having the highest level, and belonging exclusively to 

 Glen Gluoy, Shelf 1st; those two coming next in elevation, 

 and which are to be found in Glen Roy alone, I shall call 

 Shelf 2d and Shelf 3d ; and, lastly, That which is lowest, and 

 which being common to both Glen Roy and Glen Spean, is 

 by far the most extensive, I shall designate as Shelf Ath. All 

 these will be found in the map, with their respective numbers 

 attached to them. There are also some other indications, in 

 the bottom of Glen Spean, to be afterwards described, to 

 which, as they appear to owe their formation to causes similar 

 to those of the shelves above mentioned, I have affixed the 

 numbers 5, 6, and 7. All these different shelves are found to 

 maintain the horizontality characterizing the surface of water, 

 throughout all the various windings of their linear extent, and 

 round the hollows and projections of the hills, whether these 

 are small or great, sudden or otherwise ; and each respective 

 range, on one side of any of the glens, is exactly on the same 

 level with that corresponding to it on the opposite side. In- 

 deed these lines, which are thus of similar level on different 

 sides of the glens, are manifestly identified. For whenever 

 the level of the bottom of a glen, by rising above that of any 

 one particular shelf, obstructs its farther progress upwards, that 

 shelf immediately winds round, and crosses the bottom of the val- 

 ley on the same level, in the form of a broad shelving plain, 



whence 



