Note 164 — Chapter XIX
Reading edition
"The whole basin between the Orinoco and the Amazon is composed of granite and gneiss, slightly covered with débris. There is a total absence of sedimentary rocks. The surface is often bare and destitute of soil, the undulations being only a few feet above or below a straight line."—Evan Hopkins, in Quart. Jour. Geol. Soc., vol. vi.