CHAPTER IV. Babb. _science_, Vol. Xxi, P. 343. 1893.

Babb. Science, Vol. XXI, p. 343. 1893. Clarke. Data of Geo. Chemistry. Geol. Sur., U.S.A. Bull. 491. —— Smith. Misc. Collect., Vol. LVI, No. 5. 1910. Dittmar. Challenger Report, Vol. I, p. 203. 1884. Dole and Stabler. Water Supply Papers. Geol. Sur., U.S.A., Nos. 234 and 236. 1910. Geikie. Trans. Geol. Soc., Glasgow, p. 153. 1868.

Humphreys and Abbott. Physics and Hydraulics of Mississippi River, p. 148. 1876. Merrill. Rocks, Rock weathering and Soils. 1897. Murray. Scot. Geog. Mag., Vol. III, p. 65. 1887. —— Scot. Geog. Mag., Vol. IV, p. 38. 1888. Reade. Chemical Denudation in Relation to Geological Time. 1901. Russell. River Development. 1898. Schwarz. Causal Geology. 1910. Tylor. Phil. Mag., April, p. 258. 1853.