information on the amount of sediment brought down by rivers, see
Nature, Sept. 23rd, 1880. Mr. T. Mellard Reade has published some
interesting articles on the astonishing amount of matter brought down in
solution by rivers. See Address, Geolog. Soc., Liverpool, 1876 77.
{213} An account of the fine dust which often falls on Vessels in the
Atlantic Ocean, Proc. Geolog. Soc. of London, June 4th, 1845.
{215} For La Plata, see my Journal of Researches, during the voyage of
the _Beagle_, 1845, p. 133. Elie de Beaumont has given ( Lecons de
Geolog. pratique, tom. I. 1845, p. 183) an excellent account of the
enormous quantity of dust which is transported in some countries. I
cannot but think that Mr. Proctor has somewhat exaggerated ( Pleasant
Ways in Science, 1879, p. 379) the agency of dust in a humid country
like Great Britain. James Geikie has given ( Prehistoric Europe, 1880,
p. 165) a full abstract of Richthofen s views, which, however, he
disputes.
{217a} These statements are taken from Hensen in Zeitschrift fur
wissenschaft. Zoologie. Bd. xxviii., 1877, p. 360. Those with respect
to peat are taken from Mr. A. A. Julien in Proc. American Assoc.
Science, 1879, p. 354.
{217b} I have given some facts on the climate necessary or favourable
for the formation of peat, in my Journal of Researches, 1845, p. 287.
{220} A. A. Julien On the Geological action of the Humus-acids, Proc.
American Assoc. Science, vol. xxviii., 1879, p. 311. Also on Chemical
erosion on Mountain Summits; New York Academy of Sciences, Oct. 14,
1878, as quoted in the American Naturalist. See also, on this subject,
S. W. Johnson, How Crops Feed, 1870, p. 138.
{222} See, for references on this subject, S. W. Johnson, How Crops
Feed, 1870, p. 326.
{223} This statement is taken from Mr. Julien, Proc. American Assoc.
Science, vol. xxviii., 1879, p. 330.
{224a} The preservative power of a layer of mould and turf is often
shown by the perfect state of the glacial scratches on rocks when first
141