The Trombetes. On the north side of the Amazon there are fewer important rivers, the Trombetes, the first from the east, which is navigable 135 miles, comes from the Guiana Highlands.
The Negro, 900 miles from Pará, 1500 miles long, is navigable for 450 miles forming midway a succession of lagoons, and overflowing its banks, often for a width of 20 miles. The rivers farther west have been sufficiently described.
The average depth of the Amazon is 50 feet, the current is three miles an hour. Beginning to rise in November the river is fullest in June, then falling to November. The Madeira, which rises and falls two months earlier, is in places 4-6 miles wide. The width of the Amazon is 20-60 miles, while in periods of inundation the forest is partly submerged for a width of 400 miles.
The Plata Basin
A much smaller portion of Brazil lies in the basin of La Plata; this, at least for the moment, is the best and richest part of the entire country, containing the greatest population outside of the coastal fringe.
The Uruguay. At the south the several rivers forming the Uruguay, which rise in the Serra do Mar, drain Rio Grande do Sul and part of Santa Catharina, while from there up to the north end of São Paulo and into Goyaz only a narrow coast region is outside the Paraná Basin.
The Paraná. The most remote source of the Paraná, that of the branch Paranahyba, is in the Serra Pyreneos in Goyaz, while the Rio Grande branch rises in the Serra da Mantiqueira near the peak Itatiaiá, so to say, in sight of Rio. Many affluents are received from the States of São Paulo and Paraná, these generally flowing northwest or west; the Paraná itself flows southwest forming the western boundary of those States. A branch, the Tiété, in São Paulo, 700 miles long, is broken by 54 rapids and two falls. The Paranapanema in Paraná, 600 miles long, is navigable for 30 miles. The Iguassú, rising in the Serra do Mar in Santa Catharina and flowing west is hardly navigable for canoes.
Twenty-eight miles above the mouth of the Tiété the course of the Paraná is interrupted by the Falls of Urubupungá. From here to the Guaira or Sete Quedas Falls, 400 miles, there is unobstructed navigation. At this point the river forms a lake 4¹⁄₂ miles long and 2¹⁄₂ wide before cutting through the Serra de Maracajú. Then after rushing through a deep and narrow gorge for two miles, it plunges down a long cañon hardly 200 feet wide in a series of rapids or falls called the Sete Quedas, Seven Falls. It is reported as able to supply over a million horse power, probably the most of any cataract in the world. Again the river is navigable from a little below the falls, and with regular service it forms an outlet for the State of Paraná to the ocean.
The Paraguay. The River Paraguay rises near Diamantino in Matto Grosso receiving a number of tributaries from that State, one of which, the Cuyabá, called the São Lourenço lower down, has its source close to that of the Tapajós branch of the Amazon.