GENERAL AND ECONOMIC GEOLOGY 317 



Mar and pass over the divide and extend westward to the base of the 

 Lower Permian sediments. In the southwest corner of the state a small 

 exposure (70 kilometers long) of Devonian rocks rests against the 

 Archean and dips gently toward the northwest. On top of the Devonian 

 rocks are Lower Permian beds — sandstones and shales — which rest on the 

 Archean from near Faxina to the Minas frontier just north of Mococa, 

 Sao Panlo. These Lower Permian beds contain well marked evidences of 

 glaciation. The next higher beds are the Upper Permian, which contain 

 the fossils Ster-eosternum and Mesosaurus and characteristic siliceous con- 

 cretions and beds. The Permian beds are followed by the Triassic red 

 beds called the Botncatu. They form the mass of the Serra de Botucatn 

 and extend sonthwestward into the State of Parana and northward to and 

 be3^ond Eifaina^ where they cross into the State of Minas. Still farther 

 west, and forming the highlands of a large part of the state, are the 

 Baurii beds, which are Lower Cretaceous. These sedimentary beds dip 

 gently toward the northwest. All beds below the Bauru (Cretaceous) are 

 cut by eruptive dikes, and the Triassic sediments are interbedded with 

 sheets of lava. In showing the areas of the eruptive rock on the Sao 

 Paulo part of the geologic map no attempt is made to give the details of 

 the areas, partly because the areas have not been outlined and partly be- 

 cause the scale of the map does not admit of such details. The red lands 

 of Sao Paulo, famous for their fertility, are formed by the decomposition 

 of the eruptive rocks, and the areas of the red lands are really much 

 larger than the map might lead one to suppose. 



From 30 kilometers west of the city of Sao Paulo and following down 

 the Eio Parahyba to Bocaina, there are bituminous shales and sandstones 

 marking the sites of Tertiary lakes within the Archean area. 



Economic geology. — The mineral resources of Sao Paulo now known 

 are iron, marble, bituminous shales, building stones, limestones, and 

 ceramic clays. 



The first iron manufactured in Brazil, and probably the first made in 

 America, was produced about the year 1600, at Ipanema, in the State of 

 Sao Paulo. The manufacture of iron at that place was not kept up, and 

 though it was attempted several times afterwards, it has thus far never 

 been commercially successful.^^ The Ipanema iron ores are in an isolated 

 Archean area, a little more than a hundred kilometers west of the city of 

 Sao Paulo. 



The bituminous shales at the base of the Upper Permian are exposed 

 at many places in Sao Paulo and could easily be located along nearly all 



^^1 Leandro Dupre : Memoria sobre a fabrica de ferro de Sao Joao de Ipanema. Annaes 

 da Escola de Minas, no. 4, pp. 49-90. Rio, 1885. 



XXII — Bull. Geol. Soc. A^r., Vol. 30, 1918 



