I have long
thought it a probable conjecture that when a rising surface becomes
stationary it becomes so, not at once, but by the movements first
becoming very slow; this would greatly favour the cutting down many gaps
in the mountains to the level of the stationary periods.

GLACIER THEORY.

If a glacialist admitted that the sea, before the formation of the
terraces, covered the country (which would account for land-straits
above level of terraces), and that the land gradually emerged, and if
he supposed his lakes were banked by ice alone, he would make out, in my
opinion, the best case against the marine origin of the terraces. From
the scattered boulders and till, you and I must look at it as certain
that the sea did cover the whole country, and I abide quite by my
arguments from the buttresses, etc., that water of some kind receded
slowly from the valleys of Lochaber (I presume Mr. Milne admits this).
Now, I do not believe in the ice-lake theory, from the following weak
but accumulating reasons: because, 1st, the receding water must have
been that of a lake in Glen Spean, and of the sea in the other valleys
of Scotland, where I saw similar buttresses at many levels; 2nd, because
the outlets of the supposed lakes as already stated seem, from Mr.
Milne's statements, too much worn and too large; 3rd, when the lake
stood at the three-quarters of a mile shelf the water from it must have
flowed over ice itself for a very long time, and kept at the same exact
level: certainly this shelf required a long time for its formation; 4th,
I cannot believe a glacier would have blocked up the short, very wide
valley of Kilfinnin, the Great Glen of Scotland also being very low
there; 5th, the country at some places where Mr. Milne has described
terraces is not mountainous, and the number of ice-lakes appears to me
very improbable; 6th, I do not believe any lake could scoop the rocks
so much as they are at the entrance to Loch Treig or cut them off at the
head of Upper Glen Roy; 7th, the very gradual dying away of the terraces
at the mouth of Glen Roy does not look like a barrier of any kind; 8th,
I should have expected great terminal moraines across the mouth of Glen
Roy, Glen Collarig, and Glaster, at least at the bottom of the valleys.
Such, I feel pretty sure, do not exist.

I fear I must have wearied you with the length of this letter, which
I have not had time to arrange properly. I could argue at great length
against Mr. Mil