Chapter Fifty.
The Closing Chapter.
After many days of difficult navigation the balza floated upon the broad and mighty Amazon, whose yellowish-olive flood flowed yet fifteen hundred miles farther to the Atlantic Ocean.
The current was in most places over four miles an hour, and the navigation smooth and easy—so that our travellers rarely made less than fifty miles a-day. There was considerable monotony in the landscape, on account of the absence of mountains, as the Amazon, through most of its course, runs through a level plain. The numerous bends and sudden windings of the stream, however, continually opening out into new and charming vistas, and the ever-changing variety of vegetation, formed sources of delight to the travellers.
Almost every day they passed the mouth of some tributary river—many of these appearing as large as the Amazon itself. Our travellers were struck with a peculiarity in relation to these rivers—that is, their variety of colour. Some were whitish, with a tinge of olive, like the Amazon itself; others were blue and transparent; while a third kind had waters as black as ink. Of the latter class is the great river of the Rio Negro—which by means of a tributary (the Cassiquiare) joins the Amazon with the Orinoco.
Indeed, the rivers of the Amazon valley have been classed into white, blue, and black. Red rivers, such as are common in the northern division of the American continent, do not exist in the valley of the Amazon.
There appears to be no other explanation for this difference in the colour of rivers, except by supposing that they take their hue from the nature of the soil through which these channels run.
But the white rivers, as the Amazon itself, do not appear to be of this hue merely because they are “muddy.” On the contrary, they derive their colour, or most of it, from some impalpable substance held in a state of irreducible solution. This is proved from the fact, that even when these waters enter a reservoir, and the earthy matter is allowed to settle, they still retain the same tinge of yellowish olive. There are some white rivers, as the Rio Branco, whose waters are almost as white as milk itself!
The blue rivers of the Amazon valley are those with clear transparent waters, and the courses of these lie through rocky countries where there is little or no alluvium to render them turbid.
The black streams are the most remarkable of all. These, when deep, look like rivers of ink; and when the bottom can be seen, which is usually a sandy one, the sand has the appearance of gold. Even when lifted in a vessel, the water retains its inky tinge, and resembles that which may be found in the pools of peat-bogs. It is a general supposition in South America that the black-water rivers get their colour from the extract of sarsaparilla roots growing on their banks. It is possible the sarsaparilla roots may have something to do with it, in common with both the roots and leaves of many other vegetables. No other explanation has yet been found to account for the dark colour of these rivers, except the decay of vegetable substances carried in their current; and it is a fact that all the black-water streams run through the most thickly wooded regions.