92 



AMAZONIA AND LA PLATA. 



the Andes it plunges into the profound gorges of a sandstone plateau, where the 

 current is contracted from a width of about half a mile to some 200 feet. The 

 Araracoara rapids, followed by a cascade 100 feet bigh, mark the furtbest point 

 reached by Spix and Martins, and later by Silva Coutinho, and few travellers 

 have yet succeeded in penetrating higher up. 



The Apapuris, which joins the Japura below the rapids, is regarded by the 

 Brazilians as the political frontier between their Amazonian territory and 

 Colombia, whereas the Colombians claim as the international boundary the Avati 

 Parana creek, which branches off from the left bank of the SolimOes, and winds 

 through a half-submerged district to the right bank of the Japura. Thus, in this 

 part of its course the Amazons may be said to be a tributary of the Japura, by 

 which 125 miles lower down it is joined through numerous channels. 



Even beyond the confluence, for a space of at least 40,000 square miles, extend- 



Fig. 30 — SolimOes and Japuea Confluence. 

 Scale 1 : 8,500,000. 



125 Miles. 



ino- all the way to the Rio Negro, the region comprised between the two con- 

 verging streams is occupied by an intricate system of lagoons, creeks, and 

 backwaters, which shift their forms and channels with every inundation under 

 the alternating pressure of the Solimoes and Japura waters. If the Amazons basin 

 was at one time an inland sea, as seems probable, its former aspect is best pre- 

 served in this half- lacustrine, half-emerged inter-fluvial district. 



The Jutahy, Jurua, and Purus. 

 Between the Tea and the Japura confluences the Solimoes is joined by several 

 southern tributaries, such as the Jutahy (Hyutai) and the Jurua, which in any 

 other region would be regarded as great rivers. In 1867 Chandless ascended the 

 Jurua for a distance of 1,125 miles, including all the meanderings of its tortuous 

 channel, and at the farthest point reached by him the stream was still some 30 



