404 ANNUAL EEPOET SMITHSONIAN INSTITUTION, 1908. 



mann, were found to be Neocomian (Wealdan) flora. The fauna 

 from San Lorenzo was also referred to the Neocomian. The fauna 

 from Huallauca, Lucha, and Chaco was found to be Albien, with the 

 Eotomagien (?) lower Cenomian also represented at Huallauca. The 

 Santonien was determined at Abra de Charata (between Oroya and 

 Tarma), and from Lucha and Huallauca and Le Quinua. The rich 

 material described increased the number of Senonian fossils from 

 Peru and contained some entirely new forms, while the Wealdan 

 flora was the first found in South America. 



It will be remembered that Steinmann (1906) has referred to the 

 Cretaceous the Puca sandstone formation, so named by him and 

 which includes the Cora-Cora copper mines of Bolivia. This has 

 already been discussed under the heading of the Permian. The Puca 

 sandstone extends into Peru. 



TERTIARY. 



Marine Tertiary of the Pacific coast. 



The marine Tertiary of the southern coastal plains was described 

 by Forbes (1860), who called it the " Tertiary and diluvial formation 

 of the coast." This formation is also shown in the section by 

 d'Orbigny (1842) and by Pissis (1856), who, however, did not de- 

 vote much attention to it. According to Forbes the Tertiary extends 

 inland from the stretch of low coast lying to the north of Arica, 

 forming gently sloping plains which show evidence of ancient sea 

 beaches. The plains are composed of sand, earth, and gravel, with 

 abundant fragments of porphyritic rocks from the mountains to the 

 east. Forbes mentions a trachytic volcanic formation seemingly con- 

 temporaneous with the plains formation, which appears to have been 

 deposited while they were still under water. This volcanic material 

 is in the form of tuffs and ashes and has subsequently been covered 

 by other deposits. 



In discussing the saline deposits of the coastal plains (especially 

 in territory that now is in Chile) Forbes advances the idea that with 

 the exception of the boracic-acid compounds, the presence of which 

 is due to volcanic causes, all the salines are such as would be left by 

 evaporating sea water or by mutual reactions of saline matters thus 

 left. This lacustrine hypothesis he applies to the nitrate deposits 

 and states that the chain of hills to the west is such as might on 

 elevation have inclosed a series of lagoons in tidal communication 

 with the sea. For the saline deposits at high elevations he includes 

 the factor of rainfall and states that they are not so characteristic of 

 the lagoon type as the lower deposits near the coast. 



The next reference to the Tertiary of the coast is concerning the 

 formations in the northern coastal plains. Among the fossils sent 



