46 



ON THE PARALLEL ROADS 



the map, or perhaps more satisfactorily in the following dia- 

 gram, in which Shelves 2d and 3d alone are marked, 



and where A is the Gap of Glen Collarig, B the hill of Bo* 

 huntine, C the mouth of Glen Roy, and D the angle of the 

 mountain Crag-dhu. From these facts it would seem, that 

 Glen Roy must have been for some time an independent lake 

 also, having its south-west extremity situated somewhere near 

 the hill of Bohuntine, where it must have terminated in two 

 bays, one on each side of that round hill. And as we see that 

 there are two shelves of different elevations, which are the pro- 

 perty of Glen Roy alone, it is equally evident, that its lake must 

 have once existed for a time at the level of Shelf 2d, and must 

 have afterwards subsided to that of Shelf 3d. But we find that 

 Shelf 4th is common to both Glen Roy and Glen Spean ; con- 

 sequently this implies a second subsidence of the Glen Roy 

 lake, reducing it to the same level, and making it a portion of 

 a lake which must have pre-existed in Glen Spean. In the 

 primary state of things therefore, we find an independent lake 

 in Glen Gluoy, which may be called Loch Gloy ; another in 

 Glen Roy, at a level about twelve feet below that of Loch 

 Gluoy, which may be called Loch Roy ; and a third, covering 



the 



