Ten or twelve leagues below the pass, the river De las Piedras, the last affluent of any consequence, falls in; thence the course of the river is easterly inclining south, as far as Pitos, the frontier fort of Salta in that direction. In the flat saline country through which it afterwards runs, its waters imbibe a brackish taste, from which it takes the name of the Salado, or the salt river, which it preserves the whole way to its junction with the Paranã, near Santa Fé. I have before stated that this river is believed to be navigable as high as Matara, in the latitude of Santiago del Estero. The Vermejo, the most important of all the affluents of the Paraguay, is formed by two considerable streams, which may be generally called the rivers of Jujuy and Tarija, from those two departments which they respectively drain. At their sources they are at no great distance from each other, but descending from opposite sides of a snow-capped range, the buttresses of which branch out far and wide to the south and east, they are soon hurried away in totally different directions; each, however, finally sweeping round the base of the stupendous platform above, describes, after a long course, the segment of a circle, which is rendered all but complete by the junction of their waters at a point about sixteen leagues below Oran, whence they flow together south in one mighty and navigable stream the whole way to the Paranã. The name of Vermejo, or the red river, is derived from the occasional discoloration of the waters by the red alluvial soil which is washed into them during the periodical floods. With respect to the many minor streams which fall into the rivers of Jujuy and Tarija, they are for the most part mere mountain torrents of little importance, except as adding to their waters, which finally become navigable below Oran.