Note 15 — Chapter II
Reading edition
Charles Darwin, Journal of Researches, etc., during the Voyage of the "Beagle" (London, 1912), pp. 471 sqq.; Sir Charles Lyell, Principles of Geology, Twelfth Edition (London, 1875), ii. 602 sqq.; T. H. Huxley, Physiography (London, 1881), pp. 256 sqq.