GEOLOGY OF PERU ADAMS. 



391 



The eastern chain extends on the east of Huanta, the convent of 

 Ocopa and Tarma, the western chain passes Castrovereyna, Hnan- 

 cavelica, Hnarochari, and Yauli, inclosing a lofty table-land. In 

 latitude 10° IV the two branches unite in the knot of Huanuco and 



Pasco (Cerro de Pasco) 

 divide into three chains. 

 Pachitea (Ucayali) riv- 

 ers, the second or cen- 

 tral between the Hual- 

 laga and the Maranon, 

 while the third lies be- 

 tween the Maranon and 

 the coast. The eastern 

 range lowers to a range 

 of hills, and is lost in 

 latitude 6° 15' on the 

 west of Lamas. The 

 central, after forming 

 the rapids and cataracts 

 of the Amazon, turns to 

 the northwest and joins 

 the knot of Loja in Ecua- 

 dor. From the most cer- 

 tain information which 

 he obtained he concluded 

 that to the east of the 

 chain which passes to the 

 east of Lake Titicaca and 

 northward to Huanuco 

 a wide mountainous land 

 is situated, which is not 

 a widening of the east- 

 tern chain itself, but 

 rather that it consists 

 of heights which sur- 



From this point northward the Andes 

 The eastern lies between the Huallac^a and 



Fig. 4.- 



-Monthly variation of rainfall at Cailloma 

 during seven years. 



round the foot of the Andes like a penumbra, filling in the whole 

 space between the Beni and the Pachitea (Ucayali). 



Humboldt also made interesting comments on the direction of the 

 Andes. He noted that in Chile and Upper Peru (Bolivia), from the 

 Straits of Magellan to the parallel of Arica (18° 28' 35" S.), the 

 whole mass of the Andes runs from south to north in the direction of 

 a meridian at the most 5° NE., but from the parallel of Arica the 

 coast and the two Cordilleras east and west of the alpine lake of 

 Titicaca abruptly change their direction and incline to the northwest. 



88292— SM 1908- 



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