248 ANNALS NEW YORK ACADEMY OF SCIENCES 



In the north part of the Department of Piura, we have some unex- 

 pected topographic variations. By consulting the Eaimondi map, it will 

 be seen that the part corresponding to the West Eange has projected a 

 long spur to the southwest, known as Cerro da La Brea, or Amotape 

 Mountain. It is composed of Cretaceous shales and clioritic intrusives. 

 It is flanked on both sides by the coastal plain formations. Note also 

 the arrangement of drainage between the spur and the headwaters of the 

 Huangabamba. The rivers Chira and Catamayo represent the main line 

 of transverse drainage, while its tributaries the Suipira, Quiros and 

 Macara represent the longitudinal drainage of the somewhat depressed 

 section of the intercordilleran plain. 



EAST RANGE AND EAST SLOPE 



Concerning the East Cordillera, we have already seen in our various 

 views that it forms a prominent range of enormous altitude at various 

 points and maintains its identity throughout the entire length of the 

 Peruvian Eepublic. Its highest altitudes exceed those of the West Eange. 

 The most picturesque views may be had from the region of Lake Titicaca, 

 where, on a clear day, it may be seen passing north from Bolivian terri- 

 tory into Peru and presenting apparently an unbroken front, as far as 

 the eye can reach, to the northeast. It maintains its identity throughout 

 the departments of Puno and Cuzco, reaching enormous altitudes in the 

 Department of Junin, where it is deeply cut into serrated forms. We 

 then can follow it through the department of Huanuco and San Martin 

 and finally into the Department of Amazonas, where it apparently sep- 

 arates into two ranges and continues as such into Ecuador. While no 

 great elevations are attained in northern Peru, they assume again in 

 central Ecuador their old-time grandeur. 



Concerning the East Slope of the East Eange, I regret very much that 

 I had little opportunity to see enough of this geographic province to war- 

 rant personal description in any detail. Only in southern Peru have I 

 penetrated the East Cordillera to a point where a far-reaching view of 

 the foothills and, beyond these, the great stretch of rolling and undulat- 

 ing lowland, may be had. The foothills proper do not occupy a very wide 

 belt. They quickly descend to an elevation of not more than 4,000 feet 

 and probably less, where, from the long-distance view at least, one would 

 judge we should encounter the inland edge of the great Amazonian plains. 

 These occupy the east portion of the Department of Puno, a very large 

 part of the Department of Cuzco and nine-tenths of the Department of 

 Loreto. It is on these eastern slopes and the huge plains below that we 

 find uncivilized tribes of Indians, or the native "salvaje." 



