Amazon Basin

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Amazon Basin


or Amazonia, in South America; the largest lowland on earth, with an area of more than 5 million sq. km.

The basin extends from the Andes to the Atlantic Ocean, between the Guiana and Brazilian plateaus in the basin of the Amazon, the largest river in the world in volume. It is situated in the geosyncline of the South American craton, which is mainly filled with Paleozoic marine and Mesozoic-Cenozoic continental deposits. The climate is hot (mean monthly temperatures 24–28° C) and moist (precipitation 1,500–3,000 mm and more per year).

Western Amazonia is a very broad (up to 1,600 km), level, and low-lying plain. The climate is equatorial and constantly moist. The rivers flow slowly in weakly incised broad valleys; these rivers are meandering and turbid (Rio Branco). The flat surfaces of the stream divides—the so-called terra firme (“hard earth”)—are covered by rain forests (selva, or hylea) on podzolic lateritic soils. In the river valleys, flood plains (várzea) and intermittently drowned and low delta (igapó) landscapes are distinguished; the latter are regularly submerged for several months. The várzea vegetation is similar to the eté and includes an especially large number of palms; rubber trees, or Hevea; kapok, or sumaúma (Ceiba); and cacao. The igapó vegetation is very sparse; imbaubal Cecropia is characteristic. Animals adapted to an arboreal life—including New World monkeys, sloths, and anteaters—are typical of the Western Amazon hylea. The land animals include giant armadillos, tapirs, and peccaries. There are also many birds, reptiles, amphibians, fishes, insects, and ants.

Eastern Amazonia (east of the mouth of the Rio Negro and Tapajós) is considerably narrower (up to 350 km). Marine Paleozoic and crystalline Precambrian rocks outcrop along the margins while the central portion has undergone recent subsidence, as a result of which the surface is intensely dissected, with buttes up to 350 m high; the rivers are straighter and deeper, with estuary-like mouths, many rapids, and transparent water that is darkened by decomposing vegetation (the Rio Negro). The climate is sub-equatorial. From June to September trade winds blow southeastward from the Brazilian plateau and cause droughts. This causes a considerable number of barren spots and savanna patches on red soils in the deciduous forests. Only bands of várzea and igapó on alluvial soils remain evergreen. Animals typical of open spaces make their appearance: these include brockets, anteaters, small armadillos, many rodents, and termites.

The Amazon lowland is very sparsely populated. Rivers are the basic paths of communication; along them are small settlements and two large cities—Manaus at the mouth of the Rio Negro, and Belém at the mouth of the Para River; a highway has been built between Belém and Brasilia. Manganese ore, discovered in 1945 (Serra do Navio in Amapa), nearby iron deposits, and oil fields in the lower Madeira valley (at Nova Olinda) are being developed.


Lukashova, E. N. Iuzhnaia Amerika. Moscow, 1958.


References in periodicals archive ?
Project implementation: Catch Amazon river dolphins throughout the Amazon basin to examine and GPS-tag them, gather data to determine how threatened they are, develop strategies to protect them
Diversity and Distribution of Rainforest Communities in the Amazon basin
Dubai's annual rainfall averages 10mm; rainfall in the Amazon Basin averages 2000mm annually.
The black ghost knifefish hunts at night in the murky rivers of the Amazon basin using closely integrated sensing and movement systems.
In 2003, Peru began construction on an interoceanic highway through the southern Amazon Basin in the Peruvian administrative regions of Madre de Dios and Puno; the highway is intended to link Amazon sites with Pacific ports (Figure 1).
Although an Ecuadoran court has upheld a decision that US oil giant Chevron was responsible for environmental damage in its Amazon basin region by sister concern Texaco, the court has asked the company to pay a reduced $9.
agency cites heat waves in Europe and Russia, droughts in the Amazon Basin, Australia and East Africa, and huge storms like Tropical Cyclone Nargis and Hurricane Katrina.
The Amazon rainforest, also known as Amazonia or the Amazon jungle, is a moist broadleaf forest that covers most of the Amazon Basin of South America.
Scientists have used tree rings from eight cedar trees in Bolivia to unlock a 100-year history of rainfall across the entire Amazon basin.
The Amazon Jungle is a broadleaf forest that covers most of the Amazon Basin of South America.
Everett, an anthropological linguist known for his work with the Piraha tribe of the Amazon basin, views language as a tool invented by human groups to address specific biological, cultural, and social needs.
The entire Amazon basin is a supplier of fresh water for many other parts of Brazil and the northern parts of Argentina, so it is important for the climate and economy of Brazil," he added.