394 ORVILLE A. DERBY 



merit of mica, giving the rock an appearance so similar to that of the 

 quartzite members of the underlying metamorphic series that the two 

 have been very generally confounded under the name of ''itacolu- 

 mite." In these sections, however, outcrops occur, as in the neigh- 

 borhood of Diamantina, in which the rock is a typical unmetamor- 

 phosed sandstone or conglomerate; and it is now clear that meta- 

 morphism, when it exists, is a local, not a general, characteristic. 



Regarding the age of the Espinhafo uplift, and of the beds affected 

 by it, no satisfactory evidence is at hand, as thus far no fossils have 

 been found in these beds, or in others whose relations to them have 

 been clearly established. Up to the present all writers who have 

 treated of the region, myself included, have considered it to be 

 very ancient, Archean or early Palaeozoic. This opinion was based 

 largely on the metamorphism of the rocks in the Diamantina and 

 Ouro Preto districts, and, in my own case, partly on the fact that 

 in other parts of Brazil the epoch of folding and metamorphism on 

 a large scale could be proven by fossil evidence to be pre-Devonian. 

 Both of these arguments are evidently weak, and must now be put 

 aside in view of the unmetamorphosed and comparatively modern 

 aspect of the folded rocks of the Bahia section of the Serra do Espin- 

 hafo, and of the possibility of local disturbances affecting rock of 

 Devonian or later age. In the coast regions of the states of Bahia, 

 Sergipe, and Alagoas there are evidences of such disturbances which 

 have some bearing on the question here considered. 



On the lower Rio Pardo, Hartt (6) found a series of inclined con- 

 glomerates, sandstones, and shales, with obscure plant remains which 

 he referred to the Devonian, and noted indications of the presence 

 of the same series on the lower Jequetinhonha as well. In a recent 

 excursion in this region I found that this series occupies a zone several 

 kilometers wide, and was informed that to the westward there is a 

 considerable zone of limestone (marble). Owing to the high state 

 of the river, I missed seeing the fossil locality. The conglomerate 

 also occurs at Salobro, about a league distant from the margin of 

 the Rio Pardo, and here it is diamond-bearing (the so-called Canna- 

 vieiras diamond district), presenting considerable resemblance to 

 the diamantiferous conglomerate of the upper Paraguassu region. 

 The occurrence of this series on the Jequetinhonha was confirmed 



