The Amazon Basin

During this season of rising temperatures, increasing humidity, heavy rain and swollen rivers, we get a small taste of the Amazon Basin. Covering almost 2.75 million square miles (nearly the size of our lower 48 States), this geophysical province is bordered by the Guiana Highlands on the north, the Andes of southern Colombia, Ecuador, Peru and northern Bolivia on the west and the Brazilian Plateau on the south. Its vast tropical rainforest, representing 60% of that ecosystem on Earth, has spread across the Basin since the mid Cretaceous, 100 million years ago.

The Amazon River, the largest (by volume) on our planet, winds for more than 4000 miles, taking in flow from countless tributaries; the most prominent of these are the Rio Negro of northern Brazil, the Rio Madiera, which flows northeastward from Bolivia, and the Rio Tapajos, draining the northern edge of the Brazilian Plateau. The vast watershed of the Amazon transports 20% of Earth's river water and, at its mouth, discharges more than 11 times the flow of the Mississippi. Spread across 250 miles of coastline, this pulse of fresh water, which generally peaks in late May, produces brackish conditions up to 100 miles from shore.

The Amazon Basin and its magnificent rainforest support a tremendous diversity of plant and animal life, much of which remains unknown to modern science. Yet, it is increasingly threatened by the forces of industry and development; logging, agriculture and pollution all take a significant toll. Your support for the Nature Conservancy, the Wilderness Society and other international conservation organizations will help to protect what remains of this vast tropical ecoystem.