The Bermejo River in 1869-'70 became deflected from its ancient course and actually wandered about for a long time before finding a new bed. It formed for the time being an island nearly two hundred miles in length by an average of fifteen miles in width. This change of bed in our times enables us to understand the mechanical work which this and the Pilcomayo rivers have carried on for many centuries, resulting in the production of the rich alluvial lowlands of the Gran Chaco. It is an interesting fact that the Bermejo in this as in other changes of less magnitude has manifested a tendency to swerve to the eastward sufficiently marked to suggest the idea of some physical cause.
The Bermejo, like the Pilcomayo, has been the object of many expeditions to open up its waters to navigation. Between 1853 and 1858 my father. Captain Page, under the auspices of the United States Government, explored the fluvial system of the Rio de la Plata, and, with the assistance of a staff of competent officers, made extensive collections in botany and natural history, which were deposited at the Smithsonian Institution. He made track surveys of all the rivers so far as he examined them, and established wherever he went those positions which are the standards to this day used in the cartography of those countries. In' the course of these explorations he twice entered the Bermejo and once the Pilcomayo, ascending the former to a distance of nine hundred miles by river course, and turned back, paradoxical as it may seem, on account of the excess of water which had flooded the country, fearing that his steamer, in case of a sudden fall, the course of the river being unrecognizable, would be left stranded in the interior. This was the only expedition up the Bermejo undertaken with purely scientific views. Its results are embodied in the book, "The La Plata, Argentine Confederation, and Paraguay."
The author was commissioned in 1885 to examine the Bermejo and report upon its navigability. He started on the 25th of June. The way for the first three hundred miles from the mouth of the river was interrupted by obstructions caused by the wrecked vessels of former exploring expeditions; the falls of Yzo, a sharp incline of some two feet in the mile over about that extent, which causes the water to run swiftly and eddy around and look formidable to the uninitiated; and the argillaceous bars. The most formidable barrier of the last class was overcome by fixing a chain-drag with four pickaxes fastened uprightly in it, which was drawn forward and backward over the clay, marking a scratch
from Sucre, in Bolivia, to Puerto Pacheco on the Paraguay. Both projected routes proved impracticable from want of water, and M. Thouar is said to be satisfied that the only feasible route from Bolivia to the Paraguay lies by way of the Pilcomayo.—Editor, from "La Nature."