SERRA DO ESPINHAQO, BRAZIL 395 



by Dr. Joaquim Bahiana, a competent geological observer, and it 

 evidently occupies a considerable belt along the eastern margin of 

 the gneiss plateau. Branner (17) has described a similar fringe 

 of presumably Palaeozoic strata in the states of Sergipe and Alagoas, 

 and I have seen traces of it to the northward of the city of Bahia in 

 the neighborhood of Inhambupe. The fossils reported by Hartt 

 were fragmentary and unsatisfactory, and his reference of them to 

 the Devonian can only be considered as provisional. It is highly 

 probable, however, that the series is Palaeozoic, and certainly not 

 older than the Devonian. On the other hand, the uplifted strata 

 (consisting of conglomerates, sandstones, shales, and limestones) of 

 Sergipe and Alagoas are certainly pre- Cretaceous. 



The limestones of the upper Sao Francisco basin appear to repre- 

 sent, as Eschwege (2) has already indicated, two distinct geological 

 formations which have not yet been discriminated. A part of them 

 is certainly included in a disturbed series of sandstones and shales 

 which is almost certain early Palaeozoic and presumably older than 

 the Espinhafo uplift ; another part lies horizontally, at least in places, 

 and is presumably newer. At Bom Jesus da Lapa, on the right bank 

 of the Sao Francisco and almost due west from Rio de Contas, I 

 found, in 1880 (8, 9, 10), badly preserved fossil corals of the genera 

 Favosites and Chaetetes ( ?), which indicate middle or upper Palaeo- 

 zoic age (Upper Silurian to Permian). Possibly this limestone can 

 be correlated with that above described to the east of the serra, but 

 nothing definite can be said on this head. If, as above suggested 

 as possible, the sandstone of the Jacobina region proves to be folded 

 and of Cretaceous age, the question of the age of the uplift would 

 be decided as Cretaceous or post-Cretaceous; but it hardly seems 

 probable that this will prove to be the case. 



The rocks entering into the composition of the Serra do Espinhafo 

 fall naturally into three groups, each of which will probably eventually 

 have to be subdivided into two or more. These are: (i) the gneisses 

 and micaschists; (2) the schists, quartzites, and limestones of the 

 auriferous regions; and (3) the quartzites and sandstones of the 

 diamantiferous regions. With these are associated granites and other 

 eruptives which apparently have not penetrated into the upper series 

 and presumably antedate it. 



