126 AMAZONIA AND LA PLATA. 



The wliole region formerly constituted a level plain, whose present inequalities 

 are due to the erosion of running waters. But for a small part of its lower 

 course the Tocantins flows through the alluvial plain which forms an eastern pro- 

 longation of that of the Amazons. 



Amazoxs and Tocantins Basins. 



The absolutely unknown regions of this basin still comprise a very large por- 

 tion of its area. It is generally so inaccessible that explorers, amongst whom 

 must be mentioned Francis de Castelnau, Couto de Magalhâes, Hassler, and Ehren- 

 reich, have for the most part confined their excursions to the river and its imme- 

 diate vicinity. Goyaz has also been visited by Pohl and batterer, and during 

 the eighteenth century a few voyages of discovery were" undertaken, although 

 such expeditions were forbidden b}^ the Portuguese Government through its dread 

 of all change. Tavares Lisbao, guilty of having made the descent of the Tocan- 

 tins as far as Para, was imprisoned with his companions, and had a narrow escape 

 from capital punishment. 



Two rivers of equal length, and differing little in volume, unite to form the 

 mainstream. These are the Tocantins, j)i'operly so called, and the Araguaj^a, 

 whose mutual relations may be compared to those of the Loire and Allier in France. 

 Between the two Brazilian as between the two French watercourses there 

 stretches a line of heights sufficiently elevated to assume in some places the aspect 

 of mountains, and collectively forming a distinct geological zone. In Goyaz this 

 zone consists of metamorphic rocks encircled by sandstones. 



The farthest sources of the Tocantins or eastern branch escape from an upland 

 valley enclosed by the transverse ridge of the Pyrenees, and are collected in the 

 placid Lake Formosa. They emerge from this basin in the single channel of 

 the MaranhSo, which flows first north-west, and then trends round at a risrht ano-le 

 to the north-east. 



After its junction with a torrent from the Montes Glares, the Maranhiïo takes 

 the name of Tocantins, which it preserves for the rest of its course to the sea. 

 Its volume is doubled by the Parana (Parana-Tinga, or " White Piver "), which 

 collects all the streams descending from the western slopes of the Paranan and 

 Tabatinga Mountains. 



Below the Parana confluence the Tocantins would be accessible to laro-e 

 steamers but for the rocky ledges interrupting its course at several points. 

 Various other afifluents follow, nearly all from the eastern slope, amongst them 

 the Eio do Somno, descending from a divide 2,140 feet high, whose waters are dis- 

 charged through the Sapao to the S. Francisco basin and through the Somninho 

 to the Tocantins. On Homera de Mello's map of 1885, a lakelet on the crest of 

 the divide is even figured as discharging, besides these two emissaries, a third 

 affluent, the Novo, flowing also to the Tocantins. 



After its junction with the Manoel Alves Grande the mainstream forces its 

 way by a succession of abrupt changes through a series of rocky barriers, by the 

 northernmost of which it is at last deflected westwards to the Araguaya. 



