164 
Proceedings of the Royal Society 
and striated ; it was at the side of the highroad. The surface of 
the rock sloped due south at an angle of about 15°. The striae had 
a direction bf. 55° W. ; whilst the axis of the valley here was bf. 
65° W. There was nothing to indicate whether the striating agent 
had moved up or moved down the glen. 
One of the most interesting spots in Glencoe is where the valley 
is narrowest, i.e ., where the hills on each side approach so near, that 
their respective rocky cliffs front each other at a distance of only 
about 300 yards. This narrow defile occurs about a mile to the 
west of Buchanan’s cottage. The river here has cut through the 
slaty schist rocks to a depth of about 60 feet. 
Fig. 38 will give some idea of this defile. There is a large 
plateau of rocks, consisting of slaty schist, which has been evidently 
ground down by a heavy body or bodies passing and pressing over 
it from the east , i.e., down the valley. There are elongated shallow 
hollows also on these rocks parallel with the axis of the valley, which 
hollows are near the middle, as if the pressure there had been much 
greater (viz., at A and B) than higher up at C. The smoothing and 
the hollowing seem to have commenced on the east side, as the edges 
of the strata are mostly smoothed on the edges facing the east. On 
the west side they are somewhat rough and jagged. 
The figure represents a boulder lying on the smoothed rocks on 
the north side. It had not fallen from the cliffs. If it had, it 
would assuredly not have stuck in its present precarious position. 
It is a true erratic, and must have been brought up the glen at a 
period subsequent to the smoothing of the rocks. The surface of 
the rock on which it lies, slopes down towards the west. 
About a quarter of a mile lower down the glen another 
smoothed rock occurs, which in like manner shows frictional agency 
over and upon it from the eastward. The rough parts of the rock 
face the west, and there form a cliff about 50 feet high, which 
has evidently stopped a number of erratics in their progress up the 
glen, as they lie in great numbers at the foot of the crag, some rest- 
ing on others. Fig. 39 represent these boulders, showing how they 
have been obstructed, and how the uppermost boulder of the 
two must have come from the west to obtain its position above the 
other. The rocks in the cliff are a reddish felspar. The boulders 
are a fine-grained gneiss. 
