OF LOCHABER. 59 



and south sides of its present upper extremity. Whilst Loch 

 <jluoy existed, the water of these streams was all discharged 

 by the High Glen, into Glen Turret. But no sooner was the 

 lake broken up at its other extremity, than the water would 

 cease to flow in that direction, and would instantly rush into 

 that which it follows at present. An attention to the south- 

 ern branch of the river, at the head of Glen Gluoy, (to which, 

 in the map, as well as in my description, I have given the 

 name of the River Gluoy), as well as a remembrance of its va- 

 rious accompaniments in that quarter, will afford matter for 

 some curious remark. It is discovered to descend from the 

 hill, by a fall, upon that broad part of the shelf which must 

 have been formerly a gently shelving bay of the ancient lake ; 

 where, whilst the water existed, its force would be immediate- 

 ly broken, and the stream would then have no effect in cut- 

 ting, but would rather add to the shoal, by the deposition of 

 the debris brought down with it from the mountain. But no 

 sooner was the lake evacuated, than all check to the full exer- 

 tion of the force of its descent would be removed, its powers 

 of excavation would be brought into perfect action ; and the 

 violence of its descent would soon cut open the deep ravine 

 which I have described, and marked in the map, as dividing 

 the shelf across its whole breadth ; and its power would conti- 

 nue undiminished, as long as any material difference existed, 

 between the degree of declivity of the bottom of the ravine, 

 and that of the lower part of the glen into which it issues. I 

 therefore conceive, that this part of Glen Gluoy is particular- 

 ly interesting, because it displays in a most satisfactory man- 

 ner the mode in which running-water always operates, in 

 bringing its course to a regular equality of fall, throughout all 

 its parts. The present depth of Glen Gluoy, at its lower end, 

 «ut as it is also into a deep ravine, furnishes no proof that the 



H 2 original 



