Note 50 — Chapter VII

At Paita, the most western point of South America, there is a raised beach three hundred feet high. The basal slate and sandstone rocks, dipping S. of E., are covered by conglomerate, sand, and a gypseous formation, containing shells of living species. Additional to those described by D'Orbigny we found here Cerithium læviuscula, Ostrea gallus, and Ampullina Ortoni, as determined by W.M. Gabb, Esq., of Philadelphia. Darwin found shells in Chile 1300 feet above the sea, covered with marine mud. President Loomis, of Lewisburg University, Pa., informs the writer, that in 1853, after nearly a day's ride from Iquique, he came to a former sea-beach. "It furnished abundant specimens of Patellæ and other shells, still perfect, and identical with others that I had that morning obtained at Iquique with the living animal inhabiting them." This beach is elevated 2500 feet above the Pacific. The same observer says that near Potosi there is one uninterrupted mass of lava, having a columnar structure, not less than one hundred miles in length, fifty miles wide, and eight hundred feet thick. It overlies a bed of saliferous sandstone which has been worked for salt. Fifty feet within a mine, and in the undisturbed rock which forms its roof, the doctor found fragments of dicotyledonous trees with the bark on, undecomposed, uncharred, and fibrous.