BRANNER: THE STONE REEFS OF BRAZIL. 9 



Palaeozoic.^ They might with just as much propriety, however, be re- 

 ferred to the Jurassic or Triassic. So far as the present discussion is 

 concerned, the age of these pre- Cretaceous beds is a matter of but little 

 importance. Our present interest is chiefly with the Cretaceous and 

 with the post-Cretaceous history. 



The Cretaceous. — There are marine Cretaceous beds in the State of 

 Sergipe resting upon the Palaeozoic and crystalline rocks of the interior, 

 but how far north and south these beds extend is not known at present. 

 It is quite possible that a narrow strip of Cretaceous rocks extends up 

 and down the coast for a long distance, and it is possible, too, that the 

 bottom part of the series here set down as Eocene is really Cretaceous. 



Wliat is the age of the Bdfiia beds ? — There has been some confusion 

 in the classification of the Cretaceous and Tertiary beds of the east coast 

 of Brazil. It is necessary, therefore, to bring together the evidence 

 upon which the classification is based, and to ascertain, if possible, which 

 beds are Cretaceous and which Tertiary. Without entering into de- 

 tails it may be accepted as satisfactorily proved that the highly fossilif- 

 erous beds of the Sergipe basin are Cretaceous. The fossils from these 

 beds are described by Dr. C. A. White in his excellent monograph. ^ 

 Some of the other beds, however, have been referred to both Cretaceous 

 and Tertiary. Inasmuch as the rocks of the Bahia sedimentary basin 

 have yielded more palaeontologic evidence than any one locality outside 

 of Sergipe, the age of the beds of that region will be considered first and 

 in more detail. It is with these that we now have to deal. 



The earliest paper in which a definite geologic age is assigned the 

 coast sediments is one by J. F. M. Von Olfers, published in " Karsten's 

 Archiv fur Mineralogie, etc.," IV. 173-180, at Berlin in 1832 under the 

 title, " Ueber das niedrige Felsenriff der Kuste von Brasilien." In this 

 paper the author puts down as Tertiary the stone reefs, the sandstones 

 of the Amazon valley, the rocks of the Bahia basin, and all the sedi- 

 mentary beds from Maranhao to the Abrolhos. He makes no mention, 

 however, of any palaeontologic evidence of the ages of any of these rocks. 



In 1836 Charles Darwin touched at Bahia, and though he does not 

 give their names, he speaks of having found Tertiary fossils at the head 

 of the Bay.^ 



1 J. C. Branner, the Cretaceous and Tertiary geology of the Sergipe-Alagoas 

 Basin. Trans. Amer. Phil. Soc, XVI., p. 381-382. Philadelphia, 1889. 



2 Archives do Museu Nacional, VII. Rio de Janeiro, 1887. 



3 Charles Darwin, Geological observations, 2 ed. London, 1876, p. 193, foot- 

 note. 



