OF THE SERGIPE-ALAGOAS BASIX OF BKA7.IL. 399 



correlation of the beds deposited in such widely separated regions as Europe, South 

 Africa, India, Australia and South America. 



It is worthy of note also in connection with the discussion of the mesozoic and 

 tertiary rocks of Brazil that the fossils of Jurassic aspect are conliuod to the Sergipe- 

 Alngoas basin and to the Crato district in Cearu,* while those which have a tertiary 

 aspect are, so far as they have been worked out, entirely from the Pernambuco and 

 Piabas basins.f 



Inasmuch as the divergencies between the faunas of the Sergipe-Alagoas basin and 

 the Pernambuco basin tend to associate the former with the older and the latter with 

 the newer geological horizons, the probability is naturally suggested that the Sergipe- 

 Alagoas beds are more nearly synchronous with those of Crato in Cearu which are 

 referred by Newberry and Cope to the Jurassic, while the Pernambuco beds are similarly 

 related to those of Piabas in the province of Para. 



THE COXDITIONS ATTENDING THE DEPOSITION OF THE MESOZOIC BEDS. 



The rocks represented in the sedimentary beds of the Sergipe-Alagoas sections vary 

 from the coarse conglomerates at the base of Itabaiana and lying in contact with the 

 gneiss, through sandstones, quartzites, shales, slates and dolomitic limestones all of possi- 

 ble paleozoic age. In the mesozoic beds the rocks are sandstones, coarse, fine, and 

 often calcareous. These are variously colored from dark red through brown to cream 

 colored. The limestones are arenaceous, partially crystalline with Hint nodules, 

 oolitic and cherly. 



The nature of these mesozoic beds indicates that the changes which took place 

 during their depo.sition were not very great or ver}' sudden, l^he sandstones lie at or 

 near the base of this series, the oolitic beds follow, and the soil limestones are the 

 highest ones seen. 



The order and character of these beds appear to indicate a gradual subsidence 

 of the rejrion from the beefinnini; to the end of the cretaceous. The basal sandstones 

 often contain pebbles the size of a partridge egg, and sometimes the fossils are rolled 

 and water-worn, showing that they were deposited in tolerably strong currents and 

 near the shore. The earthy limestones and oolitic beds which follow indicate an 

 increasing depth and quieter waters, while the uppermost beds have been deposited 



•See opinions of Dr. .1. S. Newberry and Prof. E. D. Cope concerning tlie fossil fislics of Oari in Proceedings of 

 tlie .Vmerican Pliilosopliical Society, Vol. XXIII, .Ian., 1880. 



fSee Dr. C. A. While's "Contributions to the Paleontology of Brazil," p. 17, and Prof. E. I). Cope in tbe Pro- 

 ceedings of the American Philosophicil Society, ISSfi. In llic latter paper Prof Cope compares llio Pernambuco ver- 

 tebrate foasils with those of the Fox Ilills (upper cretaceous) of the United States. 



