6 Annals of the Carnegie Museum. 



map it will be seen that in the interior the rocks exposed at the 

 surface are mostly crystalline, that is, they are granites, gneisses, and 

 crystalline schists. These rocks belong to the old rocks of the continent, 

 and their age or ages are not known. They have a strong resemblance to 

 the Archean and Algonkian rocks of North America, and it is assumed 

 that stratigraphically they belong there or thereabout. 



Resting directly on these crystalline rocks is a series of sedimentary 

 beds which are provisionally called Paleozoic. These beds are exposed at 

 many places along and near the Rio S. Francisco from about ten kilometers 

 above Penedo to the mouth of the Rio Traipu. This Paleozoic area extends 

 northward and eastward, and ends somewhere west of the town of Pilar, 

 The details of the distribution of these beds are not known at present. 

 The rocks are mostly shales, quartzites, and conglomerates. No fossils 

 have thus far been found in any of them. 



Fig. 2. Denudation of the coast sediments thirteen kilometers nortli of Jequia 

 da Praia, Alagoas. (Crandall phot.) 



Overlying these Paleozoic beds are the red sandstones on which the 

 city of Penedo is built, and which are identical in color, character, and 

 stratigraphic position with the Estancia beds which are supposed to be 

 of Triassic age. These beds have also failed thus far to yield any fossils, 

 but their stratigraphic position is remarkably constant over wide areas in 

 AlagSas, Sergipe, Bahia, and adjoining states. The area covered by the 

 Estancia beds in Alag6as is shown approximately on the map. It should 



