ing to send a letter to the
"Scotsman," in which I give briefly my present impression (though there
is not space to argue with you on such points as I think I could argue),
and indicate what points strike me as requiring further investigation
with respect, chiefly, to the ice-lake theory, so that you will not care
about it...

P.S.--Some facts mentioned in my "Geology of S. America," page 24
(521/6. The creeks which penetrate the western shores of Tierra del
Fuego are described as "almost invariably much shallower close to
the open sea at their mouths than inland...This shoalness of the
sea-channels near their entrances probably results from the quantity of
sediment formed by the wear and tear of the outer rocks exposed to
the full force of the open sea. I have no doubt that many lakes--for
instance, in Scotland--which are very deep within, and are separated
from the sea apparently only by a tract of detritus, were originally
sea-channels, with banks of this nature near their mouths, which have
since been upheaved" ("Geol. Obs. S. America," page 24, footnote.), with
regard to the shoaling of the deep fiords of T. del Fuego near their
mouths, and which I have remarked would tend, with a little elevation,
to convert such fiords into lakes with a great mound-like barrier of
detritus at their mouths, might, possibly, have been of use to you with
regard to the lakes of Glen Roy.

LETTER 522. TO C. LYELL. Down, Wednesday, 8th.

Many thanks for your paper. (522/1. "On the Ancient Glaciers of
Forfarshire." "Proc. Geol. Soc." Volume III., page 337, 1840.) I do
admire your zeal on a subject on which you are not immediately at work.
I will give my opinion as briefly as I can, and I have endeavoured my
best to be honest. Poor Mrs. Lyell will have, I foresee, a long letter
to read aloud, but I will try to write better than usual. Imprimis, it
is provoking that Mr. Milne (522/2. "On the Parallel Roads of Lochaber,
etc." "Trans. R. Soc. Edinb." Volume XVI., page 395, 1849. [Read March
1st and April 5th, 1847.]) has read my paper (522/3. "Observations on
the Parallel Roads of Glen Roy, etc." "Phil. Trans. R. Soc." 1839, page
39. [Read February 7th, 1839.].) with little attention, for he makes
me say several things which I do not believe--as, that the water sunk
suddenly! (page 10), that the Valley of Glen Roy, page 13, and Spean was
filled up with detritus to level of the lower shelf, against which there
is, I conceive, good evide