[59] See Jukes, Manual of Geology, pp. 138-141; Lyell, Elements of Geology, p. 500.
[60] Jukes, Manual of Geology, p. 140.
[61] See Mantell, Wonders of Geology, pp. 680-2; also 760; Lyell, Elements of Geology, 464, 465.
[62] Elements of Geology, p. 488.
[63] Mantell, Wonders of Geology, p. 67.
[64] Mantell, Wonders of Geology, p. 66.
[65] Id. Ib.
[66] Chemical Technology, Ronalds and Richardson, vol. i., p. 32.
[67] See Lyell, Elements of Geology, 477-81; Jukes, Manual of Geology, 138, 149-53; The English Cyclopædia, Natural History Department, Article, Coal; Mantell, Fossils of the British Museum, Chapter i., Part I.
[68] Page, Advanced Text-Book of Geology, n. 7, pp. 20, 21.