344 Mr Milne o?i the Parallel Bonds of Loc/iaber, 



course to shelf 4 in Loch Laggan, which is at a lower level by 212 

 feet. 



Whilst on this subject, I may mention farther, that I examined 

 narrowly the interval of space between shelf 1 at the head of Glen 

 Gluoy, and shelf 2 at the head of Glen Turret, where the last shelf 

 is nearest to Glen Gluoy. This space also appeared to me to exhi- 

 bit the features of an ancient river-course, though they are not so 

 striking as those just described. The distance from the one shelf to 

 the other, is about a mile. Where the Glen Gluoy shelf ends, 

 I'ockly knolls rise above the moss, water-worn below the level of the 

 shelf, but rough above that level. Their smooth faces are all 

 towards Glen Gluoy. Near shelf 2, in Glen Turret, the rocks have 

 evidently been excavated and cut into by some considerable stream ; 

 at present a very small burn runs in this rocky channel, quite inca- 

 pable of producing the appearances. 



The grandest exhibition of an ancient and deserted river-course 

 is, however, at the head of Loch Laggan. The Pass of Mukkul is 

 a channel, the bed and sides of which are entirely rock. It is, at 

 its narrowest part, about 70 feet wide, the wall faces being on each 

 side from 40 to 50 feet high. The rocks at the sides are evidently 

 water- worn for about 30 feet up. To the eastward, this gorge ex- 

 pands into a broad channel of several hundred yards in width, di- 

 vided in the middle by what has formerly been a rocky islet, against 

 which the waters of this large river had chafed in isuing from the 

 pass. For nearly a mile towards the east, the rocky banks continue 

 on each side, but they gradually diverge, having between them a 

 mossy flat sloping gently eastward. The smooth faces of the rocks 

 within the probable reach of the river-waters, are all towards the 

 west, where Loch Laggan is situated. The height of shelf 4 above 

 the highest point of this deserted channel, is, by barometric mea- 

 surement, about 21 feet, which affords, therefore, some probable 

 estimate of the average depth of the river. I have only to add, 

 that no stream whatever now occupies this water-course, except 

 where, for a short part of it, the river Pattaig flows in a reverse 

 direction into the head of Loch Laggan. This stream was, when I 

 visited it last September, only about 18 inches deep and 30 feet 

 wide, and must be quite inadequate to have formed the rocky banks 

 on each side of it. 



The ancient river-course now described is of much greater size 

 than that at the head of Glen Glaster, just as the Glen Glaster 

 river-course is of greater dimensions than those respectively at the 

 head of Glen Gluoy and Glen Roy. The reason is obvious. The 

 river at Mukkul had to discharge not merely the waters which be- 

 longed to Glen Spean, but also those which flowed out from Glen 

 Glaster, comprehending Glen Roy, Glen Collarig, and Glen Gluoy. 

 The Glen Glaster river-course discharged the waters of Glen Col- 



