[29] Davis. Jour. of Geol., Vol. X, p. 87.
[30] Ibid., p. 77 et seq.
[31] In regions where canyons are common, the term is often applied to all valleys.
[32] Humphreys and Abbot. Physics and Hydraulics of the Mississippi River.
[33] From Russell’s Rivers of North America, p. 78.
[34] Alkaline carbonates considered as sodium carbonates.
[35] Carbonic acid by difference.
[36] Babb. Science, Vol. XXI, p. 343. 1893.
[37] Quoted by Mason. Water-supply, p. 204.
[38] Sot. Geog. Mag., Vol. III, p. 76. 1887.