THE PARALLEL ROADS OF GLEN- ROY. 167 
act upon the mountain drift. A second reason is that 
they were laud-locked in the higher portions and protected 
from the southwesterly winds, the stillness of their waters 
causing them to produce but a feeble impression upon the 
mountain sides. From Glen Gluoy we passed down Glen 
Turrit to Glen Roy, and through it homeward, thus 
accomplishing two or three and twenty miles of rough and 
honest work. 
Next day we thoroughly explored Glen Glaster, following 
its two roads as far as they were visible. We reached the 
col discovered by Mr. Milne-Home, which stands at the 
level of the middle road of Glen Roy. Thence we crossed 
southward over the mountain Creag Dliubli, and examined 
the erratic blocks upon its sides, and the ridges and - 
mounds of moraine matter which cumber the lower flanks 
of the mountain. The observations of Mr. Jamieson upon' 
this region, including the mouth of Glen Trieg, are in the 
highest degree interesting. We entered Glen Spean, and 
continued a search begun on the evening of our arrival at 
Roy Bridge the search, namely, for glacier polishings 
and markings. We did not find them copious, but they 
are indubitable. One of the proofs most convenient for 
reference, is a great rounded rock by the roadside, 1,000 
yards east of the milestone marked three-quarters of a mile 
from Roy Bridge. Farther east other cases occur, and 
they leave no doubt upon the mind that Glen Spean was 
at one time filled by a great glacier. To the disciplined 
eye the aspect of the mountains is perfectly conclusive on 
this point; and in no position can the observer more readily 
and thoroughly convince himself of this than at the head 
of Glen Glaster. The dominant hills here are all intensely 
glaciated. 
But the great collecting ground of the glaciers which 
dammed the glens and produced the parallel roads, were the *^- 
mountains south and west of Glen Spean. The monarch 
of these is Ben Nevis, 4,370 feet high. The position of 
Ben Nevis and his colleagues, in reference to the vapor- 
laden winds of the Atlantic, is a point of the first impor- 
tance. It is exactly similar to that of Carrantual and the 
Macgillicuddy Reeks in the southwest of Ireland. These 
mountains are, and were, the first to encounter the south- 
western Atlantic winds, and the precipitation, even at 
present, in the neighborhood of Killaruey, is enormous. 
