238 



J. C. BRANNER OUTLINES OF THE GEOLOGY OF BRAZIL 



of the Brazilian coast. The Tertiary beds are mostly horizontal sands 

 and clays. 



In some parts of the interior of Bahia ant-hills of enormous size cover 

 the surface of the ground so completely that they seriously interfere with 

 its cultivation and produce a peculiar and striking minor topography. 



Economic geology. — The minerals and rocks of economic importance 

 in the State of Bahia are gold, diamonds, carbonados, amethysts, mona- 

 zite sands, manganese, bituminous shales, marbles, limestones, and pot- 

 tery clays. These materials have all been worked in Bahia except possibly 



Figure 10. — Ant-hills on Rio Utinga 



Tlie view is taken near the village of Pegas, State of Bahia. From a photograph by 



R. Crandall, 1907. 



the marbles. Bituminous shales were worked at Marahii for a while, but 

 the enterprise was soon abandoned. There are, however, other mineral 

 resources in the state that have not yet been developed; such are iron, 

 considerable bodies of which occur below Chique-Chique ; copper, found 

 at Carahyba; mica, talc, graphite, grindstones, whetstones. Nitrate of 

 potash and salt are found in the interior of the state, but the nitrate 

 occurs only as cave deposits, while the salt is manufactured by leaching 

 the surface earth from dry lake beds, mostly in or near the limestone 

 areas. The limestones and clays so abundant in the state might be used 

 for the manufacture of Portland cement, but they have never been 

 utilized. 



Those who seek information in regard to the geology of the diamond 



