GLEN ROY, IN SCOTLAND. 
G7 
These two glaciers for a long time formed bar¬ 
riers across the western and eastern extension 
of this valley, damming back the waters which 
filled Glen Roy and the central part of Glen 
Spean. 
Evidently the glacier descending from Loch 
Treig was the first to yield, for, by the time 
the Glen Roy lake had sunk to the level of the 
lowest terrace, the entrance to the eastern 
extension of the valley must have been free, 
otherwise the water could not have spread 
throughout that basin as we find it did ; but 
it would seem that by the time the western 
barrier, or the glacier from Ben Nevis, was 
removed, the sheet of water was too far re¬ 
duced to have left permanent marks of its 
outflow into the Great Glen, except by disturb¬ 
ing and remodelling the large moraines of the 
older Glen Spean glacier. There are faint in¬ 
dications of other terraces in Glen Roy, even 
at a higher level than the uppermost parallel 
road, owing their origin probably to the short 
duration of a higher level of the glacier-lake, 
when the great general glacier had not yet 
been lowered to a more permanent level deter¬ 
mined by a limited circumscription within the 
