OF THE PARALLEL ROADS OF LOCHABER. 
713 
other portion of the Glen Roy barrier is placed on the Ordnance map, but this I have 
not seen. 
This moraine detritus is overlaid by a thick mass of loam and gravel, generally 
roughly stratified, but with some portions finely laminated, and showing in places 
reversed or contorted layers. The following is a section exposed on the right of the 
road, about a mile beyond Bohuntine, and about 650 feet above the sea-level. A 
short distance further the road rises to 752 feet, still on the same deposits. 
Fig. 19. 
W E 
Section transverse to Glen Roy and nearly opposite Glen Glaster. 
a. Light coloured loam with seams of darker gravel, a'. in. Grey Moraine detritus or Till. 
The loam, a, is full of slightly-worn angular and subangular fragments of mica-schist, 
with a proportion of well-worn and rounded pebbles. The upper part contains beds 
of subangular gravel, a, often ferruginous, of the same materials, which at places have 
the appearance of having been thrown down and back by ice or water pressing on and 
moving over it rapidly, as might have been caused by the bursting of the Glen Roy 
barrier and the escape of the lake waters. Thence, to Achavady, these roughly- 
stratified beds of loam gravel and till attain a considerable thickness, dipping always 
towards the centre of valley ; while beyond this point the road descends, these deposits 
become less important, and the moraine detritus disappears or is hidden by the gravel 
which is spread over the bed of the valley. 
Before reaching this place, however, several good sections of these deposits are met 
with: one in particular exposes them to a depth of from 100 to 150 feet. The upper 
20 to 30 feet consist of the reconstructed moraine detritus, horizontally arranged by 
the action of water. The lower 80 to 100 feet consist of sloping moraine detritus 
somewhat roughly bedded. From the top of this bank there is a fine view up Glen 
Roy, while the height from which one looks down gives a vivid impression of the 
importance of the detrital bank beneath. A general idea of the structure of this 
bank is given in the following sketch, fig. 20. The thickness of the beds is only 
estimated. 
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