For several miles we travelled along the valley of the Colorado.

The alluvial plains on the side appeared fertile, and it is supposed that they are well adapted to the growth of corn.
Turning northward from the river, we soon entered on a country, differing from the plains south of the river.

The land still continued dry and sterile: but it supported many different kinds of plants, and the grass, though brown and withered, was more abundant, as the thorny bushes were less so.

These latter in a short space entirely disappeared, and the plains were left without a thicket to cover their nakedness.

This change in the vegetation marks the commencement of the grand calcareo-argillaceous deposit, which forms the wide extent of the Pampas, and covers the granitic rocks of Banda Oriental.