This is an instructive case, showing how
little disintegration has gone on since the drift-period. All the
currents that have swept over it, all the rains that have beaten upon
it, have not worn away one inch from the original surface of the hill. I
have observed many other _roches moutonnees_ in Scotland, especially
about the neighborhood of Loch Awe, Loch Fyne, and Loch Etive. In fact,
they may be found in almost all the glens of Scotland, in the
lake-region of England, and in the valleys of Wales and Ireland.
Following the glacial indications wherever we could find them in the
country about Glen Roy, it became evident to me that the whole western
range of the Grampian Hills had once been a great centre of glaciers,
that they had come down toward Glen Spean through all the valleys on the
mountain-slopes to the north and south of it, so that this valley had
become, as it were, the great drainage-bed for the masses of ice thus
poured into it laterally, and moving down the valley from east to west
as one immense glacier. It is natural to suppose, that, at the
breaking-up of the great sheet of ice which, if my view of the case is
correct, must have covered the whole country at this time, the ice would
yield more readily in a valley like that of Glen Roy, lying open to the
south and receiving the full force of the sun, than in those on the
opposite side of Glen Spean, opening to the north.
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