Theodore Roosevelt (18581919). Through the Brazilian Wilderness. 1914.
While our course as a whole had been almost due north, and sometimes east of north, yet where there were rapids the river had generally, although not always, turned westward. This seemed to indicate that to the east of us there was a low northward projection of the central plateau across which we had travelled on muleback. This is the kind of projection that appears on the maps of this region as a sierra. Probably it sent low spurs to the west, and the farthest points of these spurs now and then caused rapids in our course (for the rapids generally came where there were hills) and for the moment deflected the river westward from its general downhill trend to the north. There was no longer any question that the Dúvida was a big river, a river of real importance. It was not a minor affluent of some other affluent. But we were still wholly in the dark as to where it came out. It was still possible, although exceedingly improbable, that it entered the Gy-Paran&á, as another river of substantially the same size, near its mouth. It was much more likely, but not probable, that it entered the Tapajos. It was probable, although far from certain, that it entered the Madeira low down, near its point of junction with the Amazon. In this event it was likely, although again far from certain, that its mouth would prove to be the Aripuanan. The Aripuanan does not appear on the maps as a river of any size; on a good standard map of South America which I had with me its name does not appear at all, although a dotted indication of a small river or creek at about the right place probably represents it. Nevertheless, from the report of one of his lieutenants who had examined its mouth, and from