J. C. Branner — The Tonibador Escarpment. 335 



Art. XXXVII. — The Tomhador Escarpment in the State of 

 Bahia, Brazil ; by J ohn C. Branner. 



In a preceding article I have described the geology of the 

 Serra do Mulato near Joazeiro, state of Bahia ;'''■ in that article 

 mention was made of the Tombador beds of quartzite that cap 

 many of the mountains along the liio Sao Francisco above 

 Joazeiro. The present article describes briefly the geology of 

 the Serra do Tombador near the city of Jacobina, from which 

 that series of rocks was named, and the relations of those beds 

 to older and newer rocks througli the diamond regions of 

 Bahia. 



The southern extremity of the Serra do Tombadorf is known 

 locally as the Serra da Gamelleira, and is about twenty kilo- 

 meters southeast of the mining town of Yentura. This 

 southern or Gamelleira portion is cut off from the main Tom- 

 bador range by Rio Jacuipe about fifty kilometers southwest 

 of the city of Jacobina. From the Jacuipe water-gap the 

 Tombador range runs a little east of north, always parallel 

 with but entirely distinct from the Jacobina range, and form- 

 ing the eastern rim of the Salitre Yalley drainage, to the falls 

 of Rio Salitre, some thirty-five kilometers south of the city 

 of Joazeiro. It has, therefore, a total length of nearly three 

 hundred kilometers on an air line. 



The geology of the Serra do Tombador has long been a veri- 

 table stumbling-block in Brazilian geology. The difficulties 

 it has created, however, are not due to the nature of its geol- 

 ogy, but rather to the fact that it is in a distant part of the 

 interior difficult of access, and because the information regard- 

 ing its geology is scanty and consequently liable to misinter- 

 pretation. 



The earliest notes, and indeed the only ones, on the geology 

 of the Serra do Tombador proper were written by Dr. J. A. 

 Allen, about 1868 and published in 1870 in Hartt's Geology 

 and Physical Geography of Brazil at pages 809-313. Mr. 

 Allen explains in his paper, however, that his trip across this 

 region was made hastily, " the geology of the country being 

 to me at the time a matter of secondary interest " (p. 309). 

 Many of his observations and notes are remarkably clear and 



* This Journal, Oct., 1910, pp. 256-263. 



f The Portuguese word tombador means tumble-down or roll-down. It is 

 often applied to precipitous places on the side of a hill or mountain, and 

 also to mountains themselves. In the state of Bahia alone there are two 

 prominent ranges bearing this name. One of them is on the southeast side 

 of the Eio SSo Francisco just south of Eemanso, the other— the one here 

 described — is thirty kilometers west of the city of Jacobina. 



