236 J. C. BRANNER OUTLINES OF THE GEOLOGY OF BRAZIL 



on the east side of the Almas Valley. These shales have been referred to 

 the Devonian, but without paleontologic evidence. 



Eesting on the Caboclo shales are the Lavras quartzites and sandstones 

 from which the diamonds and carbonados are obtained in the State of 

 Bahia. These quartzites and sandstones are sometimes "yellowish brown, 

 white, or gray, but they are more frequently pinkish and are almost every- 

 where strongly false-bedded. Over most of the area they are folded, and 

 in some places they are much faulted. They are represented on the map 

 as doubtful Carboniferous, for here again no paleontologic evidence has 

 yet been found of their age. 



The Lavras beds have a total thickness of two hundred to two hundred 

 and fifty meters near Lengoes. ( Crandall. ) 



I am of the opinion that the Lavras quartzites of Bahia are to be corre- 

 lated with the diamond-bearing quartzites of Grao Mogol, in the State of 

 Minas Geraes. ITnfortunately the structural connection between the two 

 regions has never been worked out. See also page 265. 



Overlying the diamond-bearing quartzites of the Chapada diamantina 

 is a series of limestones with interbedded shales that I have hitherto re- 

 ferred with doubt to the Jurassic and Triassic.^^ The accumulated evi- 

 dence leads me to conclude that the limestones called by me the Salitre 

 are simply the northward extension of the Lower Permian limestones of 

 the Eio das Velhas, Eio Verde, and of the upper Eio Sao Francisco. 



The maximum thickness of these limestones in Bahia is not known, 

 but it is at least 100 meters. They are mostly horizontal and thin bedded, 

 but in some places they are highly folded. It is not at all improbable 

 that there are limestones in the Chapada diamantina older than 'the Per- 

 mian, but data for distinguishing them are entirely lacking at present. 



At Jacu, a few kilometers east of the town of Aracy, which is 40 kilo- 

 meters north of Serrinha, a station on the Bahia Sao Francisca Eailway, 

 fossils of Permian age have been fouitd in dark gray shales. Permian 



TcrtraryTZaUat/, 



I E. 



Figure 9. — Section from the ArcJiean near Aracy to the Tertiary Tadle-lands to the East 



fossils have also been found 12 kilometers south of the town of Bom 

 Conselho, in eastern Bahia. The Permian beds at these two places under- 

 lie the tablelands that form the belt shown on the map as Cretaceous and 



«Am. Jour. Sci., vol. xxxi, p. 481. Bui. Geol. Soc. Amer., vol. 22, p. 188. 



