facts mentioned in the letter from Mr. Darwin would seem to show that the
boulder must have fallen through water from floating ice with a force
sufficient to split the underlying lump of sandstone, but not sufficient to
crush it.") which I had undermined on the summit of Ashley Heath, 720 (?)
feet above the sea, rested on clean blocks of the underlying red sandstone.
I was also greatly interested by your long discussion on the Loss (514/4.
For an account of the Loss of German geologists--"a fine-grained, more or
less homogeneous, consistent, non-plastic loam, consisting of an intimate
admixture of clay and carbonate of lime," see J. Geikie, loc. cit., page
144 et seq.); but I do not feel satisfied that all has been made out about
it. I saw much brick-earth near Southampton in some manner connected with
the angular gravel, but had not strength enough to make out relations. It
might be worth your while to bear in mind the possibility of fine sediment
washed over and interstratified with thick beds of frozen snow, and
therefore ultimately dropped irrespective of the present contour of the
country.

I remember as a boy that it was said that the floods of the Severn were
more muddy when the floods were caused by melting snow than from the
heaviest rains; but why this should be I cannot see.

Another subject has interested me much--viz. the sliding and travelling of
angular debris. Ever since seeing the "streams of stones" at the Falkland
Islands (514/5. "Geological Observations on South America" (1846), page 19
et seq.), I have felt uneasy in my mind on this subject. I wish Mr. Kerr's
notion could be fully elucidated about frozen snow. Some one ought to
observe the movements of the fields of snow which supply the glaciers in
Switzerland.

Yours is a grand book, and I thank you heartily for the instruction and