30 ANNALS NEW YORK ACADEMY OF SCIENCES 



Percidarium (Pisces). Ethericlge has reported parts of Chara (Plantse). 

 Fossil tortoises and Mosasaurus also are said to have been found along 

 Eio Acre. These fossils are then a mixture of fresh-water, land, brackish 

 water and marine forms which lived apparently in a very special environ- 

 ment. 



In reference to the age of the above fossils, I can do no better than refer 

 to Vol. XLIV of the Bulletin of the Museum of Comparative Zoology, 

 Harvard, pp. 25-27. In this resume, Professor Branner states : 



"If we grant that the upper Amazon region from Iquitos to Tabatinga is Ter- 

 tiary, there is no evidence that the mottled sediments of the lower Amazon are 

 of the same age, to say nothing of correlating them with similar looking beds 

 on the coast of Rio Grande do Norte, Parahyba, Pernambuco and Alagoas, 2500 

 miles away. This seems also to express Professor Derby's view of the subject." 



Professor Branner also quotes Dall as saying that : 



"The Pebas fossils are unique and difficult to determine the age because the 

 characteristic forms are extinct and have no obvious relatives. They may be 

 as old as Eocene or as young as Pliocene." 



The maps of the location of the marine formations show that the entire 

 Piano Alto as herein mapped is Archean and Paleozoic ; while the Andean 

 complex has an Archean nucleus more or less covered b}^ marine deposits 

 of Mesozoic, and marine Tertiary is known to exist along both bases of 

 the Andes almost for their entire length. The trend lines of this region 

 are north and south, and they strongly indicate an extension of the East 

 Andean sea in the same directions. 



The deposits along Alto Eio Amazonas are known from Pebas, Peru, 

 down Eio Solomoes as far as Sao Paulo de Olivenca, and south along Eio 

 Javary and Eio Acre. My maps show that this region lies between the 

 Cordillera Oriental of the northern Andes and the Piano Alto. It must 

 also be remembered that nowhere east of Sao Paulo de Olivenca, which is 

 1400 miles in a straight line from the mouth of the Amazon, have similar 

 or any post-Paleozoic marine deposits been found. This fact, as well as 

 others which have already been considered, strongly indicates that the sea 

 did not invade the Amazon Valley from the east, because the Piano Alto 

 would have been a permanent barrier to such an invasion from the Per- 

 mian to comparatively recent times. 



The dip of the Piano Alto and the character of the sediment carried by 

 the Eio Negro, as well as the fact that no positive evidence exists which 

 warrants a northern extension of the East Andean Sea into Venezuela, 

 indicate a southern extension of the East Andean Sea, because as far as I 

 have been able to find, no Mesozoic and Tertiary are known to exist east 



