200 J. C. BRANNER AGGRADED LIMESTONE PLAINS, BAHIA, BRAZIL 



tally bedded. The region seems very fiat nearly to the station of Jnrema, 

 the soil is snuff colored, and the forests rather sparse catingas. At kilo- 

 meter 401 -|- 200 the limestone seems much harder and more compact 

 than it is farther south. Blocks a meter in diameter are exposed in the 

 ditches up to kilometer 402. A photograph taken from the handcar at 

 this place gives a clear idea of the character of the region and of the 

 exposure of the Catinga limestone along this portion of the railway. 



Nothing noteworthy is recorded up to kilometer 412 -\- '75 -\- 400 

 meters, where the cut beside the track is as much as 2 meters deep. The 

 lumps of hard limestone thrown from the ditch have water-worn quartz 

 boulders mixed with them. 



Jurema station, at kilometer 413.5, is on the side of a shallow valley 

 cut in crystalline rocks. An excavation opposite the station-house shows 

 the Catinga limestone filling crevices in schists, shales, and crystalline 

 rocks. Just north of the yard switch there is a cut 2^/2 meters deep, in 

 which lumps of granite and other old rocks are mingled with the soft 

 Catinga limestone. About Jurema station the limestone seems to be 

 spread down over the slopes of the hills, so that it appears to have a 

 greater thickness than it really has. The snuff-colored soil, with a thin 

 layer of lumpy limestone beneath, continues to where the railway crosses 

 the channel of Eiacho do Tourao, about kilometer 419, Here, again, the 

 limestone covers the flat high ground, while the stream channel at the 

 bridge is in decomposed granites, gneisses, and schists. From where the 

 railway again strikes the higher ground, at about kilometer 421, the lime- 

 stone seems to be continuous nearly to kilometer 430, which is just south 

 of Carnahyba station. It is on this portion of the line also that the 

 limestone seems to reach its greatest thickness. The land slopes so gently 

 northward that to the eye it seems as flat as a floor. The soil is of the 

 greenish snuff color, and during the rainy season it is said to form such 

 a pasty mass that the railway sinks into it, and material for the roadbed 

 had to be brought from elsewhere. Over the top of it is a thin covering 

 of quartz gravels. The vegetation is an open catinga, with very little 

 undergrowth among the scrubby, sprawling trees. 



In the vicinity of Carnahyba station (kilometer 430.87) the limestone 

 reaches its greatest thickness, which is about 7 meters, and does not ex- 

 ceed 10. In the accompanying photograph (plate 17, figure 2) one man 

 stands at the top of the limestone beds and the other at the contact of the 

 limestone with the underlying decomposed gneiss. 



Where the Eio Solidade crosses the line of the railway at Carnahyba 

 station, the stream channel cuts deep into the crystalline rocks that under- 

 lie the limestones. 



