AMAZONIA. 



95 



tlie foot of tlie " Cuculiy Rock," a superb granite bluiï 1,000 feet Lig-h, visible for 

 a great distance on the surrounding plains. After its junction with the Uaupes 

 the mainstream trends eastwards between two chains of granite hills, which con- 

 stitute the true water-parting between the Orinoco and Amazons systems. The 

 rocky divide, which is con- 

 tinued north-eastwards to ^i?. 32.-Lowee Course of the Rio Beanco. 



^ 1 -r, . 1 Scale 1 : 3,500,000. 



the I'arima range, has 



been pierced at this point 

 by the waters descending 

 from the gently sloping 

 northern plains. Geolo- 

 gically speaking, the part- 

 ing line occurs, not at the 

 bifurcation of the Cassi- 

 quiare, but at the breach 

 effected by the running 

 waters along the continu- 

 ous series of cataracts, 50 

 on the Uaupes and 25 on 

 the Rio Negro, cataracts 

 which, despite their slight 

 fall, present a picturesque 

 effect with their project- 

 ing reefs, eddies, and 

 swirling waters. The Rio 

 Negro series has a total 

 incline of not more than 

 50 feet in a distance of 

 about 40 miles. 



The Rio Branco 

 ("White River"), which 

 promises to acquire great 

 importance as the most 

 direct future highway 

 between British Guiana 

 and Central Amazonia, has 

 been frequently ascended 

 by the Portuguese. Re- 

 cently a Yenezuelo-Brazi- 

 lian Frontier Commission has studied its upper valleys, but the surveys have 

 been suspended owing to the hostility of the natives. 



Like the Rio Negro, the Parima, as the Rio Branco was formerly called, has 

 for its true upper course an affluent much longer and more copious than the branch 

 commonly regarded as the chief headstream. This affluent, the TJraricoera, rises 



60 Miles. 



