'1-yl J. C. BRAXXER OUTLIXES OF THE GEOLOGY OF BRAZIL 



rocks or of the area covered by them. Castelnau speaks of them as much 

 contorted argillaceous schists dipping south and southeast.^^ 



The summit of the divide in the new federal district northeast of 

 Pyrenopolis and west of Formosa is capped by sedimentary rocks that I 

 have referred provisionally to the I'pper Permian. Tliese rocks extend 

 southward along the divide between Eio Sao Marcos and Eio Sao Bar- 

 tholomeo and appear to connect with the Upper Permian in Minas Geraes 

 near Patrocinio. To the north of Formosa these same sedimentary beds 

 form the great i^lateau along the watershed to the north, between the 

 States of Goyaz and Bahia. to and beyond the frontier with Maranhao 

 and Piauhy. 



In the vicinit}' of Pyrenopolis these Permian sediments are a mere 

 remnant, but farther north they spread out until they have a width of 

 600 kilometers or more in the northern part of the State of Goyaz. 



The notes of George Gardner show that the rocks are about horizontal, 

 and that they are mostly sandstones and limestones. 



Inasmuch as there are cavernous limestones in the Serra do Eoncador 

 in northeast Matto Grosso. it seems probable that these beds extend quite 

 across northern Goyaz into the States of Para and Matto Grosso. 



The map shows an area of Triassic rocks in the southwestern part of 

 the State of Goyaz. Triassic rocks are known in the adjoining States of 

 Sao Paulo and Minas Geraes. and it is inferred that the similar beds on 

 the northwest side of Eio Paranagua are also Triassic. The precise loca- 

 tions of the margins of the Triassic rocks in the State of Goyaz. however, 

 are not known at present. 



Overlying the Triassic rocks in the southwest corner of the State is a 

 later series of sediments supposed to be of Cretaceous age. The only 

 notes we have of this series are those of Castelnau, who crossed them on 

 the road leading from Goyaz to Cuyaba. in the State of Matto Grosso. 

 The drawings and photographs given by Henry Savage-Landor at pages 

 253, 256, and 352 of his "Across Unknown South America." Boston, 

 1913, give a vivid idea of the topography and structure. ^^ 



Economic geology. — Goyaz has produced notable quantities of gold, 

 chiefly from placer deposits where it is derived from schists. Diamonds 

 and other precious stones have also been mined, especially along Eio 

 Claro, an affluent of the upper Eio Araguaya. Iron, both magnetic ore 

 and hematite, is reported from many places in the State, but very little 

 is known as yet about the quantity available. Hussak mentions one bed. 



*» Expedition . . . histoire du voyage, vol. ii. p. 248. Paris. ISoO. 



30 Unfortunately that author's statements about lavas are not to be trusted. The rock 

 so named by him is mostly the well known canfja or limonite iron ore. while the "lava 

 over giant volcanic dome" at page 270 is an exfoliated mass of sandstone. 



