After a long gallop, having changed horses twice, we reached the Rio Sauce: it is a deep, rapid, little stream, not above twenty-five feet wide.

The second posta on the road to Buenos Ayres stands on its banks, a little above there is a ford for horses, where the water does not reach to the horses' belly; but from that point, in its course to the sea, it is quite impassable, and hence makes a most useful barrier against the Indians.
Insignificant as this stream is, the Jesuit Falconer, whose information is generally so very correct, figures it as a considerable river, rising at the foot of the Cordillera.

With respect to its source, I do not doubt that this is the case; for the Gauchos assured me, that in the middle of the dry summer this stream, at the same time with the Colorado, has periodical floods, which can only originate in the snow melting on the Andes.

It is extremely improbable that a stream so small as the Sauce then was should traverse the entire width of the continent; and indeed, if it were the residue of a large river, its waters, as in other ascertained cases, would be saline.

During the winter we must look to the springs round the Sierra Ventana as the source of its pure and limpid stream.