Again, why
should the lower terrace alone be continued into the eastern end of the
valley of Glen Spean, while there are no terraces at all in its western
part, since both must have been as fully open to the sea as Glen Roy
valley itself? This seemed the more inexplicable since all the terraces
exist on the valley-wall opposite the outlet of Glen Roy, showing that
this sheet of water, wherever it came from, filled the valley itself and
the space between it and the southern wall of Glen Spean, but failed to
spread, on either side of that space, into the eastern and western
extension of Glen Spean. It is evident, that, at the time the water
filled Glen Roy, some obstruction blocked the valley of Glen Spean, both
to the east and west, leaving, however, that space in the centre free
into which Glen Roy opens, while, by the time the water had sunk to the
level of the lowest terrace, one of these barriers, that to the east,
must have been removed, for the lowest terrace, as I have said, is
continuous throughout the eastern part of Glen Spean.[B]
Prepossessed as I was with the idea of glacial agency in times anterior
to ours, these phenomena appeared to me under a new aspect. I found the
bottom of Glen Spean so worn by glacial action as to leave no doubt in
my mind that it must have been the bed of a great glacier, and Dr.
Pages:
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234