GENERAL AND ECONOMIC GEOLOGY 305 



width from about tliirtv kilometers in the vicinity of Xatal and south of 

 there to a width of 130 kilometers about Mossoro. A few remnants of 

 the coastal sediments cap the mountains south of Mossoro, known as 

 Porto Alegre, Martins, and Joao do Yalle. 



The Archean rocks are cut by dikes and by quartz veins, and there are 

 patches of old Paleozoic quartzites let down into the Archean rocks by 

 faults. 



Economic geology. — The sedimentary belt contains limestones, and 

 there are also occasional crystalline limestones in the Archean areas. 



Mica and asbestos are reported from the Archean area, and clays for 

 the manufacture of bricks, tiles, and common pottery are abundant in the 

 coastal sedimentary belt. Sands for the manufacture of common glass 

 are abundant. 



Geologic Maps of Rio Grande do Norte 



Branner, 1901. — A sketch-map showing the geology of the southern 

 coastal region of Eio Grande do Xorte was published, as plate 15 of 

 Branner's paper on the geology of the northeast coast of Brazil, in the 

 Bulletin of the Geological Society of America, volume 13, opposite page 

 93, 1901. The details of Branner's map at and north of Xatal were cor- 

 rected by Jenkins' map, published in 1913. 



E. H. Soper, 1913. — A report made to the Inspectoria do Obras Contra 

 as Seccas by E. H. Soper in 1913, under the title ^^Geologia e suppri- 

 mento d'agua subterranea no Eio Grande do Norte e Parahyba" (publi- 

 cation number 26), is accompanied by a geologic map of Eio Grande do 

 Norte. It is on a scale of 1 to 1,000,000 and show^s four subdivisions, 

 namely: (1) gneisses, granites, and schists, (2) sandstones, (3) lime- 

 stone, and (4) sands and clays. 



E. H. Soper, 1916.— A paper by E. H. Soper, entitled ''The geology of 

 Parahyba and Eio Grande do Korte, Brazil," and published in volume 

 LV of the Proceedings of the American Philosophical Society in 1916, 

 contains a small map showing the geology of that State. It is on a scale 

 of 1 to 2,941,176 and shows four geologic subdivisions, namely: Paleo- 

 zoic, late Cretaceous to early Tertiary sandstones, late Cretaceous to early 

 Tertiary limestones, and Eecent to Tertiary sands and clays. 



Bibliography of the Geology of Rio Grande do Norte 



J. C. Branner : Geology of the northeast coast of Brazil. Bulletin of the Geo- 

 logical Society of America, 1901, volume 13, pages 41-98. Rochester, 1902. 



Frederico Leopoldo Cesar Burlamaque : Notieia acerca dos animaes de ragas 

 extinctas, descobertos em varios pontos do Brazil. Bibliotheca Guana- 



