J. G. Branner — The I'ombador Escarpment. 343 



Against the theory of the geologic identity of the two 

 ranges are the following facts : 



First, the difference in tlie characters of the rocks them- 

 selves. The rocks of the Jacobina range are mostly quartz- 

 ites of the kinds known in Minas Geraes as itacolumites, 

 while those of the Torabador range are mostly ordinary sand- 

 stones. Though the Tombador beds are also sometimes quartz- 

 ites, the quartzitic nature of the series is not nearly so pro- 

 nounced or so nniversal as in the case of the Jacobina range. 



Second, the absence from the Tombador range of the soft 

 beds so characteristic of the Jacobina i-ange. These soft beds 

 are talcose schists or slates that break down readily and form 

 the valleys. No such beds have yet been found-in the Tom- 

 bador series. In view of the fact that such soft beds make up 

 about half of the total thickness of the Jacobina series, it 

 seems highly improbable that they would completely disappear 

 in the few kilometers that separate the two ranges from each 

 other. 



Conclusions: — The Cretaceous fossils reported by Liais as 

 having been found at fazenda Engenho on the northwestern 

 slopes of the Serra do Tombador are misleading. The fossils, 

 if found where reported, were not in place. 



The escarpment of the Tombador range is formed by a 

 thick, horizontal series of false-bedded sandstones and quartz- 

 ites, that rest unconformably upon a very old series of granites 

 and other crystalline rocks. The sedimentary beds of the 

 Tombador series have thus far yielded no fossils, but they are 

 supposed to be Paleozoic, and are provisionally referred to the 

 Silurian. They are the same as tlie sandstones that cap the 

 Serra do Mulato and the Serra da Cruz, and they occur over a 

 Avide area in the interior, of Bahia and along the upper valley 

 of the Sao Francisco. 



Overlying the Tombador beds are the Jacuipe flints, and 

 these are followed by the Lavras sandstones and qnartzites, 

 the series of sediments in which the diamonds and carbonados 

 of Bahia are found. 



