CHAPTER III.

ON THE PLAINS AND VALLEYS OF CHILE:—SALIFEROUS SUPERFICIAL DEPOSITS. Basin-like plains of Chile; their drainage, their marine origin.—Marks of sea-action on the eastern flanks of the Cordillera.—Sloping terrace-like fringes of stratified shingle within the valleys of the Cordillera; their marine origin.—Boulders in the valley of Cachapual.—Horizontal elevation of the Cordillera.—Formation of valleys.—Boulders moved by earthquake- waves.—Saline superficial deposits.—Bed of nitrate of soda at Iquique.— Saline incrustations.—Salt-lakes of La Plata and Patagonia; purity of the salt; its origin.