432 A JOURNEY IN BRAZIL. 



longitudinal channel of the Amazons itself, but also the 

 lateral furrows through which its tributaries reach the 

 main stream, and the network of anastomosing branches 

 flowing between them ; the whole forming the most ex 

 traordinary river system in the world. 



My assumption that the sea has produced very extensive 

 changes in the coast of Brazil changes more than suffi- 

 cient to account for the disappearance of the glacial wall 

 which I suppose to have closed the Amazonian Valley in the 

 ice period is by no means hypothetical. This action is 

 still going on to a remarkable degree, and is even now rapid- 

 ly modifying the outline of the shore. When I first arrived 

 at Pard, I was struck with the fact that the Amazons, the 

 largest river in the world, has no delta. All the other riv- 

 ers which we call great, though some of them are insignifi- 

 cant as compared with the Amazons, the Mississippi, 

 the Nile, the Ganges, and the Danube, deposit extensive 

 deltas, and the smaller rivers also, with few exceptions, are 

 constantly building up the land at their mouths by the ma- 

 terials they bring along with them. Even the little river 

 Kander, emptying into the lake of Thun, is not without its 

 delta. Since my return from the Upper Amazons to Para, 

 I have made an examination of some of the harbor islands, 

 and also of parts of the coast, and have satisfied myself that, 

 with the exception of a few small, low islands, never rising 

 above the sea-level, and composed of alluvial deposit, they 

 are portions of the main-land detached from it, partly by the 

 action of the river itself, and partly by the encroachment of 

 the ocean. In fact, the sea is eating away the land much 

 faster than the river can build it up. The great island of 

 Marajo was originally a continuation of the valley of the 

 Amazons, and is identical with it in every detail of its geo- 



