Page:A narrative of travels on the Amazon and Rio Negro.djvu/332

 296 CLIMATE OF

sea, about two thousand miles long and seven or eight hundred wide.

The rivers and mountain-torrents pouring into it on every side, would gradually fill up this great basin ; and the volcanic action still visible in the scorise of the Tocantins and Tapajoz, and the shattered rocks of Montealegre, would all tend to the levelling of the vast area, and to determining the channels of the future rivers. This process, continuing for ages, would at length narrow this inland sea, almost within the limits of what is now gapo, or flooded land. Ridges, gradually elevated a few feet above the waters, would separate the tributary streams ; and then the eddies and currents would throw up sandbanks as they do now, and gradually define the limits of the river, as we now see it. And changes are yet going on. New islands are yearly forming in the stream, large tracts of flooded land are being perceptibly raised by the deposits upon them, and the numerous great lakes are becoming choked with aquatic plants, and filled up with sediment.

The large extent of flat land on the banks of the river will still continue to be flooded, till some renewed earthquakes raise it gradually above the waters ; during which time the stream will work for itself a wider and deeper bed, capable of containing its accumulated flood. In the course of ages per haps this might be produced by the action of the river itself, for at every annual inundation a deposit of sediment is formed, and these lands must therefore be rising, and would in time become permanently elevated above the highest rise of the river. This, however, would take a very long time, for as the banks rose, the river, unable to spread its waters over the adjoining country, would swell higher, and flow more rapidly than before, and so overflow a country elevated above the level of its former inundations.

The complete history of these changes, — the periods of elevation and of repose, the time when the dividing ridges first rose above the waters, and "the comparative antiquity of the tributary streams, — cannot be ascertained till the country has been more thoroughly explored, and the organic remains, which must doubtless exist, be brought forward, to give us more accurate information respecting the birth and growth of the Amazon.