THE AMAZON VALLEY. 
427 
jl to have been first raised above the water, and thus to 
I have determined the limits of the basin of the Amazon 
I on the south. The Amazon valley would then have 
formed a great inland gulf or sea, about two thousand 
‘ miles long and seven or eight hundred wide. 
I The rivers and mountain-torrents pouring into it on 
I every side, would gradually fill up this great basin ; and 
|i the volcanic action still visible in the scoriae of the To- 
I canthis and Tapajoz, and the shattered rocks of Monte- 
il alegre, would all tend to the levelling of the vast area, 
li and to determining the channels of the future rivers. 
! This process, continuing for ages, would at length nar- 
I row this inland sea, almost within the limits of what is 
now gapo, or flooded land. Ridges, gradually elevated 
I a few feet above the waters, would separate the tributary 
I; streams ; and then the eddies and currents would throw 
! up sand-banks as they do now, and gradually define the 
I limits of the river, as we now see it. And changes are 
I yet going on. New islands are yearly forming in the 
stream, large tracts of flooded land are being percep- 
j tibly raised by the deposits upon them, and the nu- 
ll merous great lakes are becoming choked with aquatic 
j plants, and filled up with sediment. 
|l The large extent of flat land on the banks of the 
I river will still continue to be flooded, till some renewed 
I 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 perhaps this might be produced 
by the action of the river itself, for at every annual in- 
undation a deposit of sediment is formed, and these lands 
