404 THE CKETACEOUS AND TEKTIAUY GEOLOC.'T 



and crosses the Bahia and Sao Francisco railway at Pqjuca. The south end of the 

 basin has been cut away by the ocean, the island of Itaparica having been included 

 in it. 



Near Inhambupe, about thirty miles north-east of Alagoinhas, Mr. Derby found 

 disturbed beds of schists, sandstones and limestones, which he is disposed to refer to 

 the paleozoic. It is unfortunate that he does not report the dip of these supposed 

 paleoz'oic beds. While on the Rio Joannes on the east side of the basin he saw the 

 cretaceous lying inconformably against the gneiss. 



The cretaceous rocks of the basin are conglomerates, sandstones, shales and lime- 

 stones. The invertebrate fossils are described by Di*. White in his Contributions to 

 the Paleontology of Bi'azil. 



Of these fossils Dr. White remarks, that " all the types which the fauna em- 

 braces, so far as they are determinable, are represented among moUusks now living " 

 and that " a part of these types are at present known to exist or have existed only 

 upon the western hemisphei'e." 



THE PERNAMBUCO BEDS. 



The most southerly exposure of the mesozoic beds seen in the province of Per- 

 nambuco, by the writer, was near the mouth of Rio Formozo. This exposure, how- 

 ever, seems to be the northern extension, and near the end, of the Sergipe-Alagoas 

 beds, as has already been suggested. But whether it is or is not the continuation of 

 the former, these Rio Foi'mozo mesozoic beds do not pass to the northwai'd of Cabo 

 Sto. Agostinho, along the oceanward side. This cape is of quartz-porphyry,* and on 

 three sides is built against unconforraably by particolored tertiary beds of sands and 

 clays, a characteristic view of which is given in the part of this paper treating of the 

 tertiary dcposits.f Whether the mesozoic beds underlie the tertiary on the landwai-d 



"Specimens of llie crystiilline rocks from the vicinity of Cape Sto. Agostinlio, one from Estagao da Illia, collccled 

 by Professor Ilarlt, and two from the island of Sto. Aleiso, collected by the writer, were prepared for microscopic 

 examination and submitted to Dr. George H. Williams, of Johns Hopkins University, Baltimore. Concerning these 

 specimens Dr. Williams writes : " * * * They must be described as quartz porphyries or rhyolites, according as 

 they are of pre-tertiary or tertiary age. They arc quartz orthoclase aggregates with almost no bisilicate constituents, 

 but their structures are very varied. One of the specimens from Sto. Alci.\o has a granular, holocrystalline ground- 

 mass of quartz and feldspar, some chlorite, possibly representing original hornblende or mica, and considerable blue 

 tourmaline. Tlie other Sto. Alcixo specimen is a fine granophyre. Porphyritic quartz and feldspar lie in a holocrys- 

 talline groundmass whicli is filled with beautiful splierulitcs showing the black cross between crossed nicols. The 

 specimen from EstaQao da Illia bus large porphyritic sanadincs with chlorite inclusions which were once glass. The 

 groundmass is mostly composed of rectangular sanadincs with much finely disseminated chlorite and iron hydro.xide. 

 Magnetite octahedrons and beautiful zircons are abundant. There is no nephelene in any of these rocks. 



t Sec page plate of "The Uuinas de I'almyra." 



