The first European to discover the Amazon was the Spanish explorer Vicente Yafiez Pinzon, onetime captain aboard Christopher Columbus’s ship the Nina. Cruising the coast of Brazil in 1500, he sailed into at least one of the mouths of the Amazon and realized that he had found a very large river indeed.
But real exploration did not begin until 1541, when Francisco de Orellana, another Spaniard, set out on an adventure down one of the Amazon’s tributaries in eastern Ecuador. Drifting with the current into ever-larger streams, Orellana and his band of soldiers reached the Atlantic nearly a year and a half later. Along the way they battled with tall, fierce female warriors whom Orellana likened to the Amazons, the legendary female warriors of Greek mythology. And so the river got its name.
The name is appropriate, for the Amazon is a giant among rivers. Only the Nile is longer—and only slightly longer. But the Amazon’s total length (almost 4,000 miles, or 6,500 kilometers) is still impressive: it is equal to about 1% times the distance from San Francisco to New York.
Its drainage basin is the largest of any river in the world. Fed by more than 1,000 tributaries, including 7 that are themselves more than 1,000 miles (1,600 kilometers) long, it drains more than half of Brazil as well as parts of Bolivia, Peru, Ecuador, Colombia, and Venezuela. Its total drainage basin of some 2722,000 square miles (7,050,000 square kilometers) encompasses about one-third of South America—an area more than 10 times the size of Texas and nearly as large as the entire contiguous United States.
Over most of this vast region the climate is very warm and humid. Rain falls about 200 days each year, and total rainfall exceeds 80 inches (2,030 millimeters) per year. One result of so much rain is that Amazonia, as the central region is known, is covered by the largest tropical rain forest in the world. Another result is that the river carries by far the largest volume of water of any river in the world. On the average, some 28 billion gallons (105 trillion liters) per minute flow into the sea—about 10 times the flow of the Mississippi. The discharge is so great, in fact, that it noticeably dilutes the salinity of the Atlantic’s waters for more than 100 miles (160 kilometers) offshore.
The great river begins as hundreds of tiny streams high in the Peruvian Andes, some of them within 100 miles (160 kilometers) of the Pacific Ocean. Rushing down the slopes, stream after stream continues to merge to form larger and larger rivers. Near Iquitos in eastern Peru, the northeastward-flowing Ucayali and the Rio Maranon, the two main headwaters of the Amazon, unite to form a truly major river. Iquitos is the point farthest upstream that shallow-draft freighters and passenger vessels can penetrate (deepwater ships can reach as far as Manaus in central Brazil).
Beyond Iquitos the river changes both its character and course. Turning abruptly eastward, it more or less parallels the equator as it meanders over lowland plains. At Iquitos the river also changes its name. Locally it is known as the Solimnes from Iquitos to its junction with the Rio Negro at Manaus and is called the Amazon only from Manaus to the sea.
Crossing the low interior basin of Brazil, the Amazon flows along a very gentle gradient—only about 11/4 inches per mile (20 millimeters per kilometer). Sluggish now, it branches into numerous secondary channels, which are separated by very densely forested islands. Beyond the riverbanks are broad, swampy floodplains dotted with lakes (varzeas) and covered with lush, periodically flooded forests.
All along the course of the river there are seasonal floods. Tributaries flowing from the south tend to reach their highest stages from February to April, while those coming from the north tend to crest in June or July.
On its long journey to the sea the Amazon also varies in color. Some of its tributaries are called Rios Blancos (white rivers), though their color is oftener a murky yellow or tan. Others are known as Rios Negros (black rivers), their waters dark but crystal clear. The white rivers rise in the Andes, and their turbidity results from the heavy loads of mud and silt they carry. The black rivers, in contrast, rise in areas of ancient basement rock where little sediment remains to be washed away; only dissolved organic matter stains their clarity.
Clearly the most dramatic union of a black-water stream and a white one occurs at Manaus, where the Rio Negro flows into the muddy Amazon. For many miles the black and white waters flow side by side in separate, clearly defined streams before they finally intermingle.
About 600 miles, (965 kilometers) from the coast, at Obidos, the ocean begins to affect the river. Tides are able to penetrate this far upstream because of the extremely gentle slope of the land.
Beyond the point where the Xingu flows in from the south, the Amazon splits up into a maze of channels clogged by larger and larger islands. (Maray), the biggest island in the delta, is about the size of Vermont and New Hampshire combined.) Finally, beyond its several mouths, the river merges with the sea.
Although there are a few sizable cities along the river’s banks and scattered settlements inland, Amazonia is largely uninhabited. Here and there plantations have been cleared in the jungles, and natives ply the streams in search of latex and Brazil nuts. But mostly the great green luxuriant rain forest is still pristine wilderness, one of the few large areas left on earth where nature’s creation remains more or less unspoiled and intact.
Leslie writes for travel sites and is planning on the West Highland Way.
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