424 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1908. 



2. The Cretaceous, principally in the western Cordillera « of Ecua- 

 dor. This rock presents three facies: (a) Toward the coast and in 

 the hills of the coastal plains, limestones, siliceous limestones, and 

 shales with variegated sandstones and quartzites; {h) in the moun- 

 tain basins, sandstones, and clay shales and slates; (c) conglomerates 

 and breccia form conglomerates, sandstones, and clay shales predomi- 

 nating in the Cordillera. 



3. With the Cretaceous are associated porphyries and greenstones, 

 some being contemporaneous and others post-Cretaceous. With these 

 igneous rocks, of which the diorites are the most common, are asso- 

 ciated the mineral deposits. 



4. The gneisses and crystalline schists of Archean age principally 

 in the eastern Cordillera. There are granites in genetic relation with 

 the gneisses and syenites in genetic relation with the schists. 



5. The volcanic rocks which are related to the still active group of 

 volcanoes of Ecuador. The volcanic tuffs contain bones of Quater- 

 nary mammals, but the volcanic activity may have commenced in the 

 Tertiary. 



6. Lacustrine Tertiary in some of the inter- Andean basins. 



SECTION FROM LIMA TO CHAUCHAMAYO, BY GUSTAV STEINMANN (1904). 



According to Steinmann there are in Peru six zones, well marked 

 by their distinct geologic com^^osition, which extend parallel to the 

 axis of the Cordilleras. These zones are designated as follows : 



1. The granitic-Tertiary zone of the coast. 



2. The first zone of Mesozoic sediments. 



3. The zone of diorites. 



4. The second zone of Mesozoic sediments with a porphyritic facies. 



5. The third zone of Mesozoic sediments with a calcareous facies. 



6. The zone of slates and granites. 



The first zone is not represented in the vicinity of Lima, but may 

 be found to the south from Pisco to Mollendo. The granitic rocks 

 are siluric or pre-siluric, cut by Mesozoic porphyries.^ The Tertiary 

 formations are probably Pliocene. 



The second zone near Lima contains sandstones and quartzites, 

 shales, and slates, with some limestones. The age of the formations 

 is Cretaceous (Neocomian) as is shown by invertebrate and plant 

 remains. The structure is in the form of an anticlinal fold. The 

 sedimentary rocks are cut by dikes of porphyry. 



" Because of the fact that the Cordilleras Oriental and Occidental in Ecuador 

 are not the equivalents of the Cordilleras Occidental and Oriental of Peru, they 

 are here spoken of as the "western " and "eastern " to avoid confusion. 



^ The writer wishes to suggest that the small Carboniferous area near Pisco 

 should be included in this zone. 



