616 D. MILNE HOME ON THE PARALLEL ROADS OF LOCHABER. 
exceeding that level, occupying not only the Great Glen, but also the entire 
district of Unachan towards Fort William, 
6. Having in the foregoing remarks explained my reasons for thinking that 
the whole of this part of the Highlands was covered by drift, the next point to 
which I would advert is the facility with which this detrital matter can be and 
has been removed by natural streams and rivers. 
As an example, I may refer to a deep gulley near the Old Catholic Burying 
Ground near Achleuereuch in Glen Spean, called Cillochrill. It is situated 
on a flat bit of ground, part of the old lake bottom when the water stood at 
the lowest shelf. This ground consists of an immense mass of gravel, which 
presents, towards the turnpike road, steep banks of from 300 to 350 feet in 
height. My guide, ANcus M‘Master, had been resident in the Glen since 
boyhood, and he pointed out to me the gully above referred to, which he stated 
had been formed within his own recollection. He said that it had originated 
from the plough having formed a “/fur7” on the flat land too near the edge of 
the bank. The rain scooped out a channel through the detritus and formed 
the gully. The banks of the gully are from 40 to 50 feet high, and the width 
in some places about 80 yards. 
In Glen Roy there are numerous examples of burns having formed deep 
gashes through the original beds of clay, which had formed the bottoms of the 
old lakes. At the road on the east side of Bohuntine, which descends to Cran- 
achan Bridge, there are vertical cliffs of clay, full of pebbles and boulders, 240 
feet high, due to the erosion and undermining of the river Roy. It has even 
cut for itself a passage through the rocks lying beneath the boulder clay, in 
some places 60 to 80 feet in depth. This stream has enormous power. 
Any one who walks along the banks of the River Spean from Spean Bridge 
to its mouth in Loch Lochy, will not fail to be struck by the height of the 
detrital cliffs liming its course. 
The river channel is in some places at least 300 feet below the adjoining 
general surface, and there are terraces corresponding with the successive 
subsidences. The diagram, shown in fig. 13, is a view taken from the left 
bank of the River about a mile below Spean Bridge. The old Haugh-land 
next the river is about 35 feet above it, bounded by a detrital cliff about 20 
feet high. Above this cliff there is a second haugh about 60 feet above the 
river, Which is bounded by another detrital cliff about 20 feet high. As these 
banks and haughs slope with the river, there can be no doubt that it produced 
them. Even still, the old banks are so distinct as to show that the river Spean 
here ran along a channel more than 100 feet above its present level; so that 
the quantity of drift removed by it has been enormous.* 
* Since this passage was written, I have again examined the Spean. ‘The banks and cliffs referred 
to in the text, are situated on the east side of the river, about half a mile below Kilmonivaig church. 

