340 EASIN Or 10 TAP! RA. 



march, in a country bristled with hills and rocks. The nativea 

 of San Marcellino speak of a Sierra Tunuhy, nearly thirty 

 leagues west of their village, between the Xie and the Icanna. 

 La Condamine learned also from the Indians of the Amazon, 

 that the Quiquiari comes from " a country of mountains and 

 mines." Now, the Iquiari is placed by the French astrono- 

 mer between the equator and the mouth of the Xie (Ijie), 

 which identifies it with the Iguiare that falls into the Icanna. 

 We cannot advance in the geologic knowledge of America 

 without having continually recourse to the researches of 

 comparative geography. The small system of mountains, 

 which we may provisionally call that of the sources of the 

 Rio Negro and the Uaupes, and the culminant points of 

 which are not probably more than 100 or ] 20 toises high, 

 appears to extend southward to the basin of Eio Tupura, 

 where rocky ridges form the cataracts of the Eio de los 

 Enganos and the Salto Grande de Tupura (south lat. 40' 

 to north lat. 28'), and the basin of the Upper Guaviare 

 towards the west. We find in the course of this river, from 

 CO to 70 leagues west of San Fernando del Atababo, two 

 walls of rocks bounding the strait (nearly 3 10' nor. lat. and 

 73f long.) where father Maiella terminated his excursion. 

 That missionary told me, that in going up the Guaviare, he 

 perceived near the strait (angostura), a chain of mountains 

 bounding the horizon on the south. It is not known whether 

 those mountains traverse the Guaviare more to the west, and 

 join the spurs which advance from the eastern Cordillera of 

 New Grenada, between the Bio Umadea and the Eio Ariari, 

 in the direction of the savannahs of San Juan de los Llanos. 

 I doubt the existence of this junction. If it really existed, 

 the plains of the Lower Orinoco would communicate with 

 those of the Amazon only by a very narrow land-strait, on 

 the east of the mountainous country which surrounds the 

 eource of the Eio Negro : but it is more probable that this 

 mountainous country (a small system of mountains, geognos- 

 tically dependent on the Sierra Parime) forms as it were an 



to be found in going up the Uaupes (nor. lat 40') with another gold 

 lake (south lat. 1 10') which La Condamine calls Marahi or Morachi 

 (water), and which is merely a tract often inundated between the sources of 

 the Jurubech (Urubaxi) and the Rio Marahi, a tributary stream of the 

 Caqueta. 



