{59} A. Tylor "On changes of the sea-level," &c., ' Philosophical Mag.' (Ser. 4th) vol. v., 1853, p. 258. Archibald Geikie, Transactions Geolog. Soc. of Glasgow, vol. iii., p. 153 (read March, 1868). Croll "On Geological Time," 'Philosophical Mag.,' May, August, and November, 1868. See also Croll, 'Climate and Time,' 1875, Chap. XX. For some recent 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.
{60} "An account of the fine dust which often falls on Vessels in the Atlantic Ocean," Proc. Geolog. Soc. of London, June 4th, 1845.
{61} 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.
{62} 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.
{63} I have given some facts on the climate necessary or favourable for the formation of peat, in my 'Journal of Researches,' 1845, p. 287.
{64} 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.
{65} See, for references on this subject, S. W. Johnson, 'How Crops Feed,' 1870, p. 326.
{66} This statement is taken from Mr. Julien, 'Proc. American Assoc. Science,' vol. xxviii., 1879, p. 330.
{67} 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 uncovered. Mr. J. Geikie maintains, in his last very interesting work ('Prehistoric Europe,' 1881), that the more perfect scratches are probably due to the last access of cold and increase of ice, during the long- continued, intermittent glacial period.
{68} Many geologists have felt much surprise at the complete disappearance of flints over wide and nearly level areas, from which the chalk has been removed by subaerial denudation. But the surface of every flint is coated by an opaque modified layer, which will just yield to a steel point, whilst the freshly fractured, translucent surface will not thus yield.
The removal by atmospheric agencies of the outer modified surfaces of freely exposed flints, though no doubt excessively slow, together with the modification travelling inwards, will, as may be suspected, ultimately lead to their complete disintegration, notwithstanding that they appear to be so extremely durable.
{69} 'Archives de Zoolog. exper.' tom. iii. 1874, p. 409.
{70} 'Nouvelles Archives du Museum,' tom. viii. 1872, pp. 95, 131.
{71} Morren, in speaking of the earth in the alimentary canals of worms, says, "praesepe cum lapillis commixtam vidi:" 'De Lumbrici terrestris Hist. Nat.' &c., 1829, p. 16.
{72} Perrier, 'Archives de Zoolog. exper.' tom. iii. 1874, p. 419.
{73} Morren, 'De Lumbrici terrestris Hist. Nat.' &c., p. 16.
{74} 'Archives de Zoolog. exper.' tom. iii. 1874, p. 418.
{75} This conclusion reminds me of the vast amount of extremely fine chalky mud which is found within the lagoons of many atolls, where the sea is tranquil and waves cannot triturate the blocks of coral. This mud must, as I believe ('The Structure and Distribution of Coral-Reefs,' 2nd edit. 1874, p. 19), be attributed to the innumerable annelids and other animals which burrow into the dead coral, and to the fishes, Holothurians,&c., which browse on the living corals.
{76} Anniversary Address: 'The Quarterly Journal of the Geological Soc.' May 1880, p. 59.
{77} Mr. James Wallace has pointed out that it is necessary to take into consideration the possibility of burrows being made at right angles to the surface instead of vertically down, in which case the lateral displacement of the soil would be increased.
{78} 'Elements of Geology,' 1865, p. 20.
{79} 'Lecons de Geologie pratique, 1845; cinquieme Lecon. All Elie de Beaumont's arguments are admirably controverted by Prof. A. Geikie in his essay in Transact. Geolog. Soc. of Glasgow, vol. iii. p. 153, 1868.
{80} 'Illustrations of the Huttonian Theory of the Earth,' p. 107.
{81} Mr. E. Tylor in his Presidential address ('Journal of the Anthropological Institute,' May 1880, p. 451) remarks: "It appears from several papers of the Berlin Society as to the German 'high- fields' or'heathen-fields' (Hochacker, and Heidenacker) that they correspond much in their situation on hills and wastes with the 'elf-furrows' of Scotland, which popular mythology accounts for by the story of the fields having been put under a Papal interdict, so that people took to cultivating the hills. There seems reason to suppose that, like the tilled plots in the Swedish forest which tradition ascribes to the old 'hackers,' the German heathen- fields represent tillage by an ancient and barbaric population."{82} White of Selborne has some good remarks on the service performed by worms in loosening, &c., the soil. Edit, by L. Jenyns, 1843, p. 281.
{83} 'Zeitschrift fur wissenschaft. Zoolog.' B. xxviii. 1877, p. 360.