382 



AMAZONIA AND LA PLATA. 



easily forded. At this time tlie Chilian cattle-dealers, who follow its rectilinear 

 valley, often utilise the portion of its sandy bed left dry by the subsiding 

 current. The Colorado, or " Red," so named from the argillaceous sediment 



rig. 156. — Lower Colorado and Rio Xegro. 

 Scale 1 ; 3,000,000. 



vVest or ureenvvicn 



OtolO 

 Fathoms. 



Deptha. 



10 to 25 

 Fathoms. 



25 Fathoms 

 and upwards. 



75 Miles. 



contained in its waters, not only reaches the sea throughout the year, but even 

 forms a delta with two branches, both of which are navigable by small craft. 



The Rio Negko. 



The Rio Negro, largest of all the Patagonian watercourses and natural 

 i)artino--line between two distinct floras and faunas, runs parallel with the 

 Colorado throughout the whole of its eastern section, where it receives no 

 tributaries from any quarter. But its upper basin comprises a mountainous region 



