290 SOUTH AMERICA— THE ANDES EEGIONS. 



paces of the source of the Pachachuca, headstream of the Ucayali affluent of the 

 Amazons. 



South of the Rimac follow several equally impoverished coast streams, mere 

 quebradas or wadies, usually with insufficient water even to irrigate the riverine 

 tracts. This description even applies to the so-called Rio Grande, which, despite 

 its name and its numerous branches, has scarcely enough water to moisten its 

 sandy bed. South of the Rio Grande some of the rivers rising in the inter- 

 Andean valleys, the Mages amongst others, have at least a very long course out 

 of all proportion to their discharge. 



In some of the apparently dry fluvial beds the natives, acquainted with the 

 nature of the soil, are able to follow the course of the current percolating below 

 the surface and utilise it for their plantations. In several of the maritime 

 districts, and especially between lea and Pisco, the hollows between the dunes are 

 moist enough for the formation of the so-called mahamaes, deep, broad trenches 

 forming little garden plots. Here are grown dates, grapes famed along the whole 

 of the Pacific seaboard, prime melons, various other fruits and vegetables, besides 

 wheat and large crops of fodder. Some of the mahamaes are A'cry extensive, while 

 the water in others is brackish, in which case the effect of the salt is neutralised 

 by thick layers of the leaves of the huarango [acacia punctata), common in the 

 country. 



The Amazonian Affluents — The Maranon. 



On the Amazonian slope the rivers, so far from running dry in their lower 

 valleys, increase continually in volume. Thanks to the abundant rainfall every 

 rivulet has here a larger volume than the most copious streams on the Pacific 

 side. The whole region is comprised in three secondary basins — those of the 

 upper Maranon, the Huallaga, and the Ucayali, all entirely within the Peruvian 

 frontier, besides a few affluents of the Purus and the Madeira, rising at the foot of 

 the Carabaya Andes on the eastern plains. 



From the standpoint of physical geography, however, these various tributaries 

 of the Amazons belong to the Andean region only in their upper courses, where 

 they are obstructed by cascades and rapids. The true periphery of the Peruvian 

 highlands is thus indicated in each fluvial basin by the zone of free navigation. 

 Hence the extreme importance taken in the economic geography of the country 

 by the various "gateways" where the Amazonian rivers escape from the Peruvian 

 uplands to the plains. These are the vital points where one day will be efi:ected 

 all the exchanges in the traffic of the Andean regions with the eastern world. 



The upper Maranon, formerly Tunguragua, is commonly regarded as the main 

 upper branch of the Amazons, not for its volume, but because it prolongs farthest 

 in the direction of the Pacific the longitudinal axis of the valley. It rises between 

 the Andes and the Western Cordillera in the little Lake Laiiri-cocha (Yauri-cocha), 

 a basin about three miles broad which floods the bed of a cirque encircled by steep 

 schistose cliffs. Escaping from this basin through narrow winding gorges spanned 



