GEOLOGY OF EASTERN BRAZIL. 313 



Janeiro. This is the Rio Parahyba do Sul, not to be 

 confounded with the Rio Parahyba north of Per- 

 nambuco, nor yet with the more important river 

 Paranahyba in the province of Piauhy. 



For the greater part of the way to Rio the railway 

 runs parallel with the river. As laid down on the 

 maps, the valley lies between a mountain range called 

 the Serra da Mantiqueira on the left, and a minor 

 range, which divides the upper course of the river 

 from the middle part, where it flows in the opposite 

 direction. The appearance of the country through 

 which I now passed forcibly suggested to me views 

 respecting its geological history, which were confirmed 

 and extended by what I afterwards saw in the neigh- 

 bourhood of Rio, and by all that I have since been 

 able to learn on the subject. 



I had already been struck by what little I had seen 

 of the plateau region of the province of San Paulo. 

 Beneath the superficial crust of vegetable soil, the 

 plateau appears to be formed of more or less red 

 arenaceous deposits, such as would result from the 

 erosion and decomposition of the gneiss or granite 

 which is the only rock I had seen in the country. In 

 the valley of the Parahyba, the connection was un- 

 mistakable. Every section in the valley showed 

 thick beds of the same coarse-grained, red arenaceous 

 deposits, and on the slopes the same material lay at 

 the base of whatever masses of granite we approached." 

 But what especially struck me were the forms and 

 appearance of the mountains on either hand, if that 

 designation could properly be given to them. I saw 

 nothing that would elsewhere be called a mountain 



