REPORTS ON EXCURSIONS. OTe. 
range of mountains, the highest in the country, was, like all the 
other Highland hills, a vast feeding-ground for very large glaciers, 
From ‘the peculiar physiographical conditions of the district, an 
immense accumulation of ice took place in Glen Spean and in the 
Great Glen. During the coldest period the pressure from the south 
and west was so great as actually to force the ice up Glen Roy 
into Strath Spey, and so seaward. As the climate moderated, a 
lake was formed in Glen Roy, but, as all southern outlets were 
blocked by glaciers, the water could only escape at the head of the 
valley, over the col, or dividing ridge, into Strath Spey. The height 
of the col is 1,151 feet, while the uppermost road is 1,155 feet at 
highest and 1,148 feet at lowest. When the ice had further 
diminished in Glen Spean, so as to leave free the col between 
-Glen Glaster (a side valley to Glen Roy), and the valley of the 
Rough Burn, a tributary of the Spean, the water found an outlet 
in this direction, and the second road was formed at a height of 
1,077 feet at highest and 1,062 feet at lowest, that of the col 
being 1,075 feet. The ice continued to shrink until Glen Spean 
was nearly free, but the higher valleys and the Great Glen were 
still full of it. The lake now occupied Glen Roy and Glen Spean, 
escaping at the head of the latter through the pass of Makoul into 
Strath Mashie, and thence into Strath Spey. The height of this 
col is 848 feet; of the lowest road in Glen Roy, and the only 
one in Glen Spean, 862 feet at its highest and 850 feet at its 
lowest. 
With the further amelioration of the climate the ice gradually 
disappeared, and the drainage assumed its present flow. 
Survivals of the plant life of these arctic conditions are to be 
found plentifully on the high hills to the south of Glen Spean, 
but we saw none except Saaifraga aizoides, Linn. Other plants 
observed were—Asplenium viride, Huds., Fissidens adiantoides, 
Hedw., Hylocomium triquetrum, B. & 8., Hylocomium splendens, 
B. & 8. 
At Keppoch, an ancient seat of the MacDonalds, or Mac- 
Donnells, of Keppoch, at the confluence of the Roy and the 
Spean, are some fine trees. Two Larches were measured, and 
found to have a girth of 13 feet 7 inches at 6 feet 7 inches, and 
12 feet 8 inches at 5 feet respectively. These are the largest 
trees of their kind yet seen at any of our excursions. 
