398 MR MILNE ON THE PARALLEL ROADS OF LOCHABER. 
mit of the waters flowing over that level as over a lip. Thus the uppermost shelf 
of Glen Gluoy No. 1, in Sir Tuomas Dick Lauper’s Memoir, is (as he explains) 
exactly coincident with the water-shed ridge which divides Glen Gluoy from Glen 
Roy, so that the waters (whatever they were) which stood at that height and 
formed the beach No. 1, must have fiowed out at the head of Glen Gluoy into 
Glen Roy. In like manner, the uppermost shelf in Glen Roy, No 2 in Sir Tuomas 
Dick LaupER’s Memoir, is (as he also mentions) exactly coincident with the water- 
shed ridge which divides Glen Roy from the valley of the Spey; so that the waters 
which stood in Glen Roy at No. 2 beach, must have flowed over the head of the 
Glen into Spey valley. In like manner, the only shelf which occurs in Glen Spean, 
No. 4 in Sir THomas Dick LauDER’s Memoir, is exactly coincident with, or rather is 
a few feet above, the pass of Mukkul at the head of Loch Laggan, through which 
pass, the waters standing at the level of No. 4 must have flowed eastward into 
Spey valley. These coincidences, as Mr Darwin admits, “ are so remarkable, 
that they must (I use his own words) be intimately connected with the origin 
of the shelves; although such relation is not absolutely necessary, inasmuch as 
the nuddle shelf of Glen Roy, is not on a level with any water-shed.” (P. 43.) 
The middle shelf here alluded to is No. 3 in Sir THomas Dick LaupEpr’s list. 
The discovery which I made, was its exact coincidence with a water-shed at the 
head of Glen Glaster, a glen which, though branching up from Glen Roy near the 
bottom of it, oddly enough does not appear to have been visited, and certainly not 
to have been described, by any former observer. 
Shelves 3 and 4 are the only shelves which enter and run up this glen. Sir 
Tuomas Dick LAuDER’s map inaccurately represents shelf 2 as marking it on both 
of its sides. Shelf 2 stops. however, on both sides of Glen Roy a little to the east- 
ward of, or above the mouth of Glen Glaster. 
In following shelf 3 to the head of this glen, I found that it was there lost in 
a low mossy flat. A little beyond this flat, and a few feet below the summit-level, 
an old river-course can be distinctly traced down a slope towards Loch Laggan. 
It has a rocky bed, over which a great body of water had evidently flowed at some 
former period. The breadth of the rocky bed is from 30 to 40 feet ; the knolls of 
rock are from 2 to 5 feet high, and amongst them are rounded blocks of stone, 
such as occur in all great Highland rivers. I traced this rocky channel for about 
a mile towards Loch Laggan; and I afterwards found the place where it had 
discharged its waters into Loch Laggan, when that loch stood at shelf 4. It is 
marked by a huge delta, forming a projecting buttress at the level of that shelf, 
and bulging far beyond the general side of the Laggan valley. 
On examining the rocky knolls attentively in this ancient river-course, I 
found that the smooth faces were all towards Glen Glaster, and the rough faces 
in the opposite direction, affording proof, if such were needed, that the stream 
which flowed there had come from Glen Glaster. 
