254 ANNALS NEW YORK ACADEMY OF SCIENCES 



To the southwest from Cora Puno, we have the West Slope extending 

 to the edge of the Coastal Plain, then follows the Coastal Plain to the 

 Cadena de la Costa, the latter now bordering the present shore line. 



If time would permit, a section passing from Mollendo through Are- 

 quipa to Puno could be shown to duplicate, in the larger phenomena, the 

 facts already brought out in the Ocona-Cora Puno section. I wish, how- 

 ever, to say just a word concerning the Titicaca region. The lake occu- 

 pies a portion only of the Intercordilleran Belt. Within this basin, Ter- 

 tiary sediments have been deposited. There is reason to believe that the 

 Titicaca basin represents an area the depression of which was associated 

 with down-faulting on a large scale. It probably extended from the 

 north end of the Tertiary Titicaca well down to La Paz. Further, the 

 Tertiary deposits rest upon limestones and shales. We are probably war- 

 ranted in correlating the latter with the limestones and shales of the 

 Cerro de Pasco lowland. To the west of the lake, we have the shales and 

 limestones extending to the divide of Cerros cle Toledo, where we again 

 come in contact with volcanic intrusives, the true core of the West Cor- 

 dillera. The belt of limestones and shales on the east slope of the West 

 Cordillera has been traced to the Cuzco section. It physiographically 

 belongs to the Intercordilleran Belt. 



The section of Forbes brings to light the same physiographic features, 

 the Coastal Plain, the West Slope and West Cordillera, followed by the 

 Intercordilleran Belt and finally the East Cordillera. 



Notes on Early Mining in Peru 



To attempt to discuss the mineral resources of Peru in detail is not my 

 intention at this time. I wish, however, to say one word relative to the 

 early history of mining, its initiation by the Incas, its subsequent devel- 

 opment during the period of Spanish rule, and finally to present a brief 

 geographical and geological correlation and distribution throughout the 

 West Cordillera and the Intercordilleran Belt. 



While the Incas as a race were decidedly agricultural and pastoral in 

 their vocations, they were, nevertheless, not ignorant of the use of the 

 precious metals. This is proved by the occurrence of gold and silver 

 vessels discovered in their notable monuments, known under the name of 

 "huacos." The huacos are large quadrangular and pyramidal earth- 

 works. They were probably used in connection with religious rites and 

 ceremonies. While these constructions, or monuments, may be counted 

 bv the score near the coast, and usually are located on the floor of the 

 broader valleys near a locality affording protection, the best preserved 



