96 AMAZONIA AND LA PLATA. 



in an upland granitic valley of the Serra Pariraa, south of the Machiati pealc, and 

 after an easterly course of 360 miles joins the Takutu, or "Upper E,io Branco," 

 which collects the torrents from Roraima and Ca'irrit, as well as the Pirara creek 

 on the depression giving access to the Essequibo through its E,upunini affluent. 

 The Mahu (Ireng), branch of the Takutu, is famods for its falls, one of which, the 

 Corona, 160 feet high, ranks with Roraima and the Kaieteur Falls as one of the 

 " three wonders " of British Guiana. 



After receiving all these headstreams the Rio Branco trends south-westwards, 

 and like the Uaupes and Rio Negro descends through a series of rapids which inter- 

 rupt all navigation between the upper and lower reaches. Below these obstructions 

 the Rio Branco flows in an almost due southerly course between a double chain of 

 lagoons and backwaters, representing old abandoned beds, down to its confluence 

 with the Rio Negro. The Jauapiry, which joins the main stream below the Rio 

 Branco, appears to be a remnant of one of these deserted channels. 



In its lower course the Rio Negro forms, like the Canadian rivers, a succession 

 of lakes rather than a normal watercourse. In some places it expands to a width of 

 20 to 30 miles, far more than the Amazons itself, but the incline is so gentle that 

 the current is at times scarcely perceptible, and towards the confluence the Amazons 

 often sets up the Rio Negro, developing a sort of " bar," from which Manaos took 

 its old name of " Barra do Rio Negro." The rise at high water ranges from about 

 30 to 40 feet, the ordinary depth being 100 or even 160 feet. Nevertheless navi- 

 gation at low water is impeded by numerous sandbanks, and the small steamers, 

 drawing no more than four and a half feet, which ascend to Santa Izabel, 450 miles 

 above the confluence, have sometimes to stop running for one or two months in 

 the year. 



The Madeira. 



The Madeira, or " Wood " river, the Cayari (" White Water ") of the natives, 

 marks with the Rio Negro the great transverse depression of the Amazonian basin. 

 It has its farthest sources on the Bolivian uplands, and on the nearly level low- 

 lying plains, which are mostly drained by the Plate river. The Beni (Yeni), its 

 main headstream, which formerly received the overflow of Lake Titicaca, is joined 

 within the Bolivian frontier by the copious Madre de Dies (Mayu-Tata, Amaru- 

 Mayo, "Snake River"), and farther on by the Mamore ("Mother of Men"), 

 whose great tributary, the Guapore, flows entirely within Brazilian territory. 



The Guapay, or Rio Grande, that is, the upper course of the Mamore, rises in the 

 Cochabamba Andes at an altitude of over 13,000 feet, and after describing a great 

 bend round those mountains is swollen by the waters of several rivers from the 

 low-lying plains between the Bolivian and the Brazilian highlands. Its passage 

 from the southern to the northern plains is here closed by a barrier of metamorphic 

 gneiss rocks, which obstructs the current and develops a long series of falls and 

 rapids. Formed by the junction of the Beni and Mamore, the Madeira floats 

 down large quantities of drift wood, whence the name given to it by its first 

 explorer, Francisco Palheta, in 1723. Since that time it has served as the main 

 highway between the Amazonian plains and the plateaux of Bolivia, and this 



