HYDROGEAPHY OF PERU. 



293 



between the wooded hills and cliffs. The Moyo (Mayo), its chief affluent, rises 

 in a valley of the foothills and joins its left bank above the gorge where are 

 developed the last cataracts. The Indian boats ascend easily to this obstruction ; 

 but laden steamers have to stop during the season of low water at Laguna, some 

 25 miles below the confluence. Even here there is no lack of water, but the navi- 

 gation is endangered by abrupt windings, reefs, snags and the rapid current. 



The copious Ucayali, although even less utilised for traffic than the Huallaga, 

 owing to its greater distance from the inhabited plateaux, possesses a far more 

 extensive system of tributaries, and promises one day to become the chief high- 

 way of trade. The terra Ucayali, meaning " Confluence," belongs only to the 



Fig. 113. — Maranon and Huallaga Confluence. 

 Scale 1 : 900,000. 



12 Miles. 



lower course, and every special branch has its distinct name, the whole hydro- 

 graphic system being formerly known as the Paro, or Apo-Paro, " Great 

 Piver." 



The same Pasco group which, on its north side, gives rise to the Huallaga 

 also sends some torrents to the Ucayali basin. But these headwaters flow south- 

 wards, losing themselves in Lake Chanchay-cocha (Junin), remnant of an old 

 inland sea, and, next to Titicaca, the largest reservoir on the Andean plateau. 

 This lake, which is almost entirely surrounded by forests of reeds, is drained by 

 the Ancas-yacu, '' Blue Water," which first flows north-westwards, and then, under 

 the name of Acobamba, or Rio Jauja, descends south-east parallel with the 

 Andean axis. Beyond a narrow gorge, excavated in the thickness of the plateau, 



