234 



J. C. BRAXXEE OUTLINES OF THE GEOLOGY OF BRAZIL 



BAHIA 



Previous investigations. — The base map of the State of Bahia has been 

 prepared partly from the original map of Branner, Crandall. and Wil- 

 liams, partly from the maps of Dr. Theodoro Sampaio, and partly from 

 those of the Inspectoria de Obras Contra as Seccas made under the direc- 

 tion of Dr. M. A. E. Lisboa. 



The geology of Bahia as given on the maj) has been prejoared chiefly 

 from the author's o^m obserrations and notes^ supplemented by the notes 

 of his assistants. Eoderic Crandall and Horace E. AVilliams. The notes 

 on the geology made by Dr. Theodoro Sampaio on a trij) from Carandahy 

 to Bahia form a valuable contribution to our knowledge, while the notes 

 of Sir Richard Burton and of Halfeld on the geology along the Eio Sao 

 Francisco, though fragmentary, have been very helpful. The region 

 north of Eio Sao Francisco was crossed by George Gardner and by J. W. 

 Wells, who give useful notes on the geology. 



The coast region is described by Eathbun on Itaparica. by Gonzaga de 

 Campos on Marahii. by Branner on the whole coast, while the fossils are 

 described by Jones. Krasser. C. A. White, and A. Smith Woodward. 



The great Bemdigo meteorite found in the interior of Bahia and re- 

 moved to Eio de Janeiro in 1888 is described by Carvalho. Daubre, and 

 Derby. 



General geology. — The geology of the State of Bahia is remarkably 

 varied and interesting. The rocks of the Brazilian complex — the Archean 



Figure 5. — Section 10 Kilometers long across the Serra de Jacohina at Jaguarary. 



State of Bahia 



The old Paleozoic beds are faulted and thrust beneath the Archean on the east. The 

 location of the manganese beds is near east base of the mountains. 



granites, gneisses, and schists — are exposed over large areas; into these 

 oldest rocks have been faulted and folded here and there an old series of 

 quartzites and other metamorphosed rocks that appear in the topography 

 as isolated peaks and ridges, usually with their beds standing on end or 

 at high angles. These rocks are shown on the map as early Paleozoic, 

 and are typified in Bahia by the Serra de Jacobina, Serra de Angico. and 

 by the long isolated ridges of quartzite west of Eio Sao Francisco between 

 Barra and Urubii. Xo paleontologic evidence of the age of these beds 

 has yet been found. 



Extendino- alono- the east side of the Eio Sao Francisco from near 



