308 J. C. BKAXXER OUTLINES OF THE GEOLOGY OP BRAZIL 



part of a great sheet or of a number of flows that are widely exposed over 

 the Brazilian states of Matto Grosso, Sao Panlo, Parana, Santa Catha- 

 rina, Eio Grande do Sul, and over parts of Urngnay, Paragnay, and the 

 Argentine Republic. The rocks are mostly diabase porphyrite. often 

 amygdaloidal. They appear sometimes as dikes and sometimes as sheets 

 whose margins form steep mountain escarpments. 



Siemiradski thinks there are faults with large dislocations through 

 the northern part of the state, but as yet they have not been precisely 

 located. 



Economic geology. — The chief mineral products of Eio Grande do Sul 

 is coal, which is found only in the Lower Permian areas. Copper and 

 gold have been mined from the older Paleozoic rocks near Lavras, and 

 large quantities of agates that weather from the trap rocks or are shipped 

 from the plateau region south of Passo Fundo. Marble is reported from 

 several i^laces within the area of the crystalline rocks, and zinc is said to 

 occur, but not in workable quantities (Scott). Magnesite is reported 

 from Eio Pardo and from Eio Capivary, where it occtirs in Archean 

 rocks, probably in the form of crystalline marble. It is popularly known 

 at these places as pedra moura, marmore amarello, and ollio de hoi 

 hranco. Molybdenum is said to occur with copper at Palmas (Oliveira). 



Geologic Maps of Eio Grande do Sid 



Hettner, 1891. — An article on southern Brazil published by Dr. Alfred 

 Hettner in the Zeltschrift der Gesellschaft fiir Erdkimde zu Berlin. Band 

 XXYI, Berlin, 1891, contains a sketch-map of the general geology of the 

 State of Eio Grande do Sul. It is on a scale of 1 to T, 500. 000 and shows 

 one structural section and five subdivisions of the geology, one of which, 

 the red sandstone, is said to be of undetermined age. 



Branner, 1906. — In the first edition of his Geologia Elementar, Eio, 

 1906, Branner published, at page 238, a sketch-map of the geology of 

 most of Eio Grande do Sul and part of Santa Catharina. The data for 

 it were taken chiefly from Hettner's paper. It is on a scale of 1 to 

 4,300,000 and five subdivisions of the geology are shown. The same map 

 is given at page 319 of the second edition of Branner's Geologia Ele- 

 mentar, Eio, 1915. 



I. C. ^liite, 1908. — In his final report on the coal measures ... of 

 south Brazil, Dr. I. C, AVliite gives a map of the State of Parana to show 

 the general distribution of the Permian coal horizon and of the overlying 

 rocks. The distribution of these beds in Eio Grande do Sul is included 

 in the map. Only two geologic divisions are shown, the Tubarao, or coal- 

 boarino: beds, and the overlvincr- beds, thouo^h not in detail. The scale is 



