OP THE SEHGU'K-ALACioAS BASIN 0¥ liUA/AL. 



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scarcely be a doiiht. Looking norlli-uast lioin llic liio Sao Franci.sco, a shoil tlis- 

 tance below Piopiia one sees the Maraba as shown in the foUowinii- cut ; the inhmd 



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Serra dc ^laiaba from near Propria, Kio Sao Francisco. 



or north-west side of the hills presenting abrupt faces, the south-east slope having a 

 gentle dip toward the sea, suggesting that, if composed of sedimentary rocks, they 

 must di]) beneath the horizontal tertiary beds which cover the greater part of the 

 region in the immediate vicinity of the mountain. 



An examination of the country between Penodo and the serra shows that this 

 impression is tlu' correct one. Leaving out of account the sandstones underlying the 

 eit}- of Penedo, in going from this place to Maraba, one traverses a wide belt of low, 

 flat, fertile country which borders the river, and which is more or less flooded by the 

 enchentes or "freshets" of the Kio Sao Francisco. Prom this low country he rises 

 gradually and almost imperceptibly upon the taboleiros or plateaux, which are com- 

 posed of the horizontally bedded clays and sandstones of the tertiary. These 

 beds continue high up the south-cast face of the Serra de Maruba and end uncon- 



Section through the Serra de Maraba. 



formably against it. They (the tertiary beds) are cut through by the ordinary pro- 

 cesses of subaerial erosion, and, if careful seai-ch could be made, it is pi-obablc liiat 

 exposures of the cretaceous, or at least of rocks higher than those seen on the sum- 

 mit and face of Maraba and lower than the tertiary could be found. At Igreja Nova, 

 a hamlet near the south-east base of the mountain, several loose fragments of com- 

 pact limestone wei'e found .strongly resembling that which occurs near the top of the 

 Itabaiana series, but the rock was not seen in place. 



The serra itself, as seen in the few expo.sures on the top, is composed of li;;ht-colored 

 sandstones dipping at an angle of about 40° to the S. E.* These roeks are much jointed, 

 and in niiiny places changed to quartzites. The contact between the paleozoic and 



• The alope of the liill where it was seen to correspond with that of the rocks is here given ns the dip. The rocks 

 are so metamorphosed that it is difficult or impossible, to obtain the di|) dirceUy. 



