220 J. C. BRAXXER OUTLINES OF THE GEOLOGY OF BRAZIL 



my trip on the upper Sao Francisco I have seen an impression of an oyster of 

 good size (d'assez grande taille) and remarkable not only for the thickness of 

 its shell, but also for the great prominence of the spire, which places it close 

 to the grypheas. T shall give this species the name Ostrea ahcethensis from 

 the name of the river basin in which I found it. At the same place I noted a 

 great number of impressions of the same species. 



"In the mac-igno sandstones I have likewise seen less well preserved impres- 

 sions of divers polyps and fragments of undeterminable univalve shells of 

 considerable size. . . . 



"Everything shows, therefore, that the metamorphic limestones of the prov- 

 ince of Minas Geraes and belonging to the stage of which we speak are not 

 older than the Cretaceous."' 



Mr. Derby, in referring to these statements, expresses the opinion that 

 Mr. Liais erred in the identification of the fossils."*^ 



Whether Liais erred or not, his notes and those of Claussen clearly 

 point out the region in which fossils may be sought and to which field 

 geologists shoiild give their careful attention. If Liais is correct in the 

 identification of his fossils, there is an area of Cretaceous rocks in the 

 region where he found them, but it does not necessarily follow that there 

 are no Permian beds beneath them. 



Economic geology of the Fermian. — The coal beds of Parana, Santa 

 Catharina, and Eio Grande do Sul are among the important economic 

 products of the Permian in Brazil. Here, too, belong the Iraty bitumi- 

 nous shales of the southern states. The Permian limestones aTe wide- 

 spread and are likely to be a source of national importance for the manu- 

 facture of Portland cement. 



It seems quite possible that some of the important occurrences of 

 diamonds in Brazil are in the glacial beds at the base of the Permian. 



TRIASSIC 



The Triassic rocks, so far as they have been recognized in Brazil, are 

 known as the Botucatu. a name given them by Gonzaga de Campos for 

 the Serra de Botucatu. in the State of Sao Paulo. They are soft reddish 

 sandstones, usually horizontal, but more or less faulted, and associated 

 with sheets and dikes of diabase eruptives. These beds attain a maximum 

 thickness of 500 meters or more, but averaging from 100 to 300 meters. 

 They cover large areas in the States of Sao Paulo. Parana, Santa Cath- 

 arina. Eio Grande do Sul, Matto Grosso, and Goyaz, and probably also in 

 Piauhy and Maranhao. 



The only fossils thus far reported from the Triassic of Brazil were 



*3 Reconhecimento geologrico do Valle de Sao Francisco. For O. A. Derby. Pagina 9 

 do annexo ao Relatorio de W. Milnor Roberts sobre o Rio Sao Francisco. Rio de Janeiro. 



1880. 



