CHAPTER XIV.
the physical geography and geology of the amazon valley.
The basin of the Amazon surpasses in dimensions that of any Other river in the world. It is entirely situated in the Tropics, on both sides of the Equator, and receives over its whole extent the most abundant rains. The body of fresh water emptied by it into the ocean, is therefore far greater than that of any other river; not only absolutely, but probably also relatively to its area, for as it is almost entirely covered by dense virgin forests, the heavy rains which penetrate them do not suffer so much evaporation as when they fall on the scorched Llanos of the Orinooko or the treeless Pampas of La Plata. Tor richness of vegetable productions and universal fertility of soil it is unequalled on the globe, and offers to our notice a natural region capable of supporting a greater population, and supplying it more completely with the necessaries and luxuries of life, than any other of equal extent. Of this wonderful district we will now describe the principal physical peculiarities.
From about 4° north latitude to 20° south, every stream that flows down the eastern slope of the Andes is a tributary of the Amazon. This is as if every river, from St. Petersburg to Madrid, united their waters into one mighty flood.
The Marañon, which is generally considered the main stream of the Amazon, deserves that title on several accounts. It rises to the westward of all the other great tributaries, and it receives all the waters which flow nearest to the Pacific, and most remote in a direct line from the mouth of the river. It flows for a considerable distance in the most westerly valley of the Andes, separated by one range only from the Pacific, and at the point where it breaks through the eastern chain of the
