Note 10 — Chapter I · THE COUNTRY—ITS FOUR DIVISIONS—THE RIVERS—THE CLIMATE

"We found the river course very tortuous, and strewed with immense fragments of various ancient slaty rocks, and of granite. The plain bordering the valley had here attained an elevation of about eleven hundred feet above the river, and its character was much altered. The well-rounded pebbles of porphyry were mingled with many immense angular fragments of basalt and of primary rocks" ("Voyage of the Beagle" chap. ix.). [10]