STRATIGRAPHIC GEOLOGY 211 



The opinion prevails in the diamond region of Bahia that the coarse 

 conglomerates yield the largest diamonds and carbonados, while the fine 

 grained sandstones yield only small ones. 



It has been hoped that coal might be found associated yith the Upper 

 Carboniferous rocks of the Amazonas region, but thns far no snch beds 

 have been discovered, and the fact that the beds known are of marine 

 origin does not encourage the hope of coal being found there. 



Limestone is common in the Carboniferous rocks of the Amazonas 

 region. 



PERMIAN 



General ol serrations. — The Permian is par excellence the Brazilian 

 series; rocks of Permian age cover large areas in Maranhao, Piauhy, 

 Ceara, Bahia, Goyaz, Minas Geraes, Sao Paulo, Parana, Santa Catharina, 

 Rio Grande do Sul, and Matto Grosso, making an enormous total. Fos- 

 sils from the Brazilian Permian are described by linger, Brongniart, 

 Carruthers, Cope, Derby, Lisboa, MacGregor, Osborn, Eenault, Z. H. 

 Scott, Seward, Solms-Laubach, David White, and Woodward. 



The division of the Permian into Upper and Lower Permian on the 

 geological map is based on what appears to be a clearly defined and easily 

 recognized distinction. In northern Brazil, Small shows a well marked 

 unconformity between the Upper Permian, which is exposed over most of 

 eastern Piauhy, and the Lower Permian in the Serra Grande that lies 

 along the boundary between Piauhy and Ceara. The only uncertainty 

 about this classification — and it is a serious one — is that the Serra Grande 

 series has never yielded any fossils, and its reference to the Lower Per- 

 mian is therefore in doubt. In southern Brazil the Upper Permian is 

 characterized by the fossils Stereosiernum and Mesosaurus and by sili- 

 ceous beds and concretions, while the Lower Permian contains the Glos- 

 sopteris flora, the coal beds, and in some places in Sao Paulo and Parana 

 it contains well marked evidences of glaciation. The evidences of glacia- 

 tion are best described by Woodworth, the title of whose book is given in 

 the bibliographic list under Sao Paulo. Thus far, unquestioned ej-idences 

 have been found only in the States of Santa Catharina, Parana, and Sao 

 Paulo ; but Dr. Lisboa found in Minas Geraes what seem to be evidences 

 of glaciation in the region between Rio Borrachudo and Rio Abaete.^^ 

 In Sao Paulo and from there southward the Permian beds dip gently 

 westward, while characteristic Permian fossils, notably Stereosiernum 

 tumidum,^^ found near Villa Rica, Paraguay, and Productus and Spirifer 



*5 M. A. R. Lisboa : The occurrence of faceted pebbles on the central plateau of Brazil. 

 Am. .Tour. Sci., January, 1907, vol. xxlll, pp. 9-19. 

 i« Freeh in Lethea Geognostica, Th. I, 2 Bd., Lief 3, p. 460. 



