BRANNER-AGASSIZ EXPEDITION TO BRAZIL 20I 



rocks are gneiss and granite. The hills are about lOO meters 

 high (184 above tide) and they all appear to rise to about this 

 general level. This flatness of the hilltops continues to and 

 beyond Nicho (kil. 71), and is apparent again as one looks 

 southward and eastward from near Uniao. This seems to be 

 the region of flat-topped hills seen from Capella on the Assem- 

 blea branch of this same railway. 



About Nicho are many exposures of granite bosses, and up 

 stream from the station there are many exposures of granite in 

 the bed of the river. 



Granites and gneisses continue past Branquinha to Uniao, 

 exposed on the slopes of the mountains, in the railway cuts, and 

 in the bed of the river. 



At Uniao (kil. 88, elevation 106 meters) the Alagoas Railway 

 connects with the government road running northward to 

 Palmares and Pernambuco, and the crystalline rocks continue 

 to its junction at Glycerio with the Sul de Pernambuco line. 



CONCLUSION. 



These two sections, although nearly a thousand kilometers 

 apart, are essentially the same : a series of Mesozoic beds along 

 the coast lapping back over old crystalline rocks. 



The question of the age of the sediments cannot be discussed 

 in this place : it is too large a problem to be treated briefly. 

 Without going into detail, it is enough to say that the evidence 

 seems to point to these conclusions : 



I. The Bahia basin, formerly referred to the Cretaceous, is 

 probably either Eocene, Tertiary, or Laramie. 



II. The parti-colored beds along the coast, formerly referred 

 provisionally to the Tertiary, are the same as the Bahia Eocene. 



III. The sediments of the Alagoas section are of fresh-water 

 origin, like those of Bahia. 



IV. No fossils have been found in the section along the Bahia 

 and Minas Railway, but it seems probable that these beds are 

 the southward continuation of the Bahia beds. 



Proc. Wash. Acad. Sci., August, 1900. 



