614 D. MILNE HOME ON THE PARALLEL ROADS OF LOCHABER. 
At the summit level between the two valleys, the hills on each side approach 
one another. The shelf there is only about 20 feet above the dividing summit 
ridge, and the space there, between the shelves is from 230 to 250 yards. 
On the hills here, as elsewhere, there is a large amount of drift, consisting 
of huge deposits of sand and rounded gravel. I saw it up to the highest level 
of the hill reached by me, viz., 1516 feet above the sea. 
The shelves in this valley, as elsewhere, have been formed on the detritus. 
This detritus therefore had come anterior to the formation of the shelf. 
I agree with Mr Darwin that this Kilfinnin shelf is of the same character as 
the Lochaber shelves. The width of the shelf is not nearly so great as those in 
Glen Roy. The smallness of the lake would account for this difference. It has 
another feature of importance, the same as the Glen Roy shelves. Its slope 
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Plan (not to any scale) of part of Loch Ness, to show where deposits of detritus now exist. 

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oe 12. 
down from the hill-side towards the centre of the valley is exceedingly slight— 
indeed, hardly perceptible. 
On this account I am inclined to think that this shelf was made, not by the 
sea, as Mr Darwin thought, but by a lake. A sea beach, owing to the action 
of the tides and waves, never can be so horizontal as the beach of a small lake. 
But if a lake, where was the blockage both for Glen Laggan and for Glen 
Buck ? 
The most probable explanation seems to be, that the Great Glen had here 
also, been filled by detritus up to a height exceeding 1300 feet. Indeed, I cannot 
doubt that the whole of that great valley, from Fort William to Inverness, must 
have been, at the epoch now referred to, filled with detritus ; and that the 
extensive gravel hills at the East end near Inverness (Tor Vane and Tom- 
nahurich) are remnants of this detritus. 
That this was really the case seems plain, from the numerous remnants of 
detritus which occur along both sides of the Caledonian Canal. 
Fig. 12 represents a small portion of Loch Ness near Foyers. The parts 
marked 1, 2, 3, 4, 5,* represent accumulations of drift, which in some cases 
* No. 1 is Ruiske. No. 2, Lein. No. 3, Urquhart. No. 4, Foyers. No. 5, Inverfarrigaig. 

