:''This article is about the river. For other uses, see
Amazon (disambiguation)''
The 'Amazon River' or 'River Amazon' (; ) of
South America is the largest
river in the world by volume, with greater total
river flow than the next eight largest rivers combined, and with the largest
drainage basin in the world. Because of its vast dimensions it is sometimes called ''The River Sea'' (''o rio-mar'' in Portuguese), and at no point is it crossed by bridges.
[1] Debate as to whether the Amazon or the
Nile is the world's longest river has gone on for many years, with the consensus during the 20th century being that, by possibly only a few kilometers, the Nile is the longer of the two (see
below).
The area covered by the water of the River and its tributaries more than triples over the course of a year. In an average dry season
110,000 square kilometres (42,000 sq mi) of land are water-covered, while in the wet season the flooded area of the Amazon Basin rises to
350,000 square kilometres (135,000 sq mi). At its widest point the Amazon River can be
11 kilometres (7 mi) wide during the dry season, but during the rainy season when the Amazon floods the surrounding plains it can be up to
45 kilometres (28 mi) wide.
A satellite image of the mouth of the Amazon River, looking south
The quantity of fresh water released by the Amazon to the
Atlantic Ocean is enormous: up to 300,000 m³ per second in the rainy season. The Amazon is responsible for a fifth of the total volume of
fresh water entering the oceans worldwide. Offshore of the mouth of the Amazon,
potable water can be drawn from the ocean while still out of sight of the coastline, and the salinity of the ocean is notably lower a hundred miles out to sea. In 1500, Vicente Yañez Pinzón was the first European to sail into the river. Pinzón called the river flow "río Santa María de la Mar Dulce", finally the name was shortened to "Mar Dulce" (sweet sea).
The Amazon
estuary is over
325 kilometres (202 mi) wide. The main river (which is between approximately one and six miles wide) is navigable for large ocean steamers to
Manaus,
1,500 kilometres (930 mi) upriver from the mouth. Smaller ocean vessels of 3,000 tons
[2] and
5.5 metres (18 ft) draft can reach as far as
Iquitos, Peru,
3,600 kilometres (2,240 mi) from the sea. Smaller riverboats can reach
780 kilometres (485 mi) higher as far as
Achual Point. Beyond that, small boats frequently ascend to the
Pongo de Manseriche, just above Achual Point.
The Amazon drains an area of some
6,915,000 square kilometres (2,670,000 sq mi), or some 40 percent of South America. It gathers its waters from 5 degrees north latitude to 20 degrees south
latitude. Its most remote sources are found on the inter-
Andean plateau, just a short distance from the
Pacific Ocean.
The Amazon has changed its course several times. In early
Cenozoic times, before the uplifting of the
Andes, it flowed westward.
[3]
The Amazon originates from the Apacheta cliff in Arequipa at the
Nevado Mismi, with a sole sign of a wooden cross.
The Upper Amazon has a series of major river systems in
Peru (many of which are alike in
Ecuador) that flow North and South into the
Marañón and
Amazon River. Among others, these include the following rivers:
Morona,
Pastaza,
Nucuray,
Urituyacu,
Chambira,
Tigre,
Nanay,
Napo,
Huallaga, and
Ucayali. The same as in the snow-crested
Andes high above Lake Lauricocha in central Peru, the headstream of the Marañón River rises in the glaciers in what is known as the Nevado de Yarupa. Rushing through waterfalls and gorges in an area of the high jungle called the ''
pongos'', the Marañón River flows about
1,000 miles (1,600 km) from west-central to northeast Peru before it combines with the
Ucayali River, just below the provincial town of
Nauta, to form the mighty Amazon River. The primary tributaries of the Marañón River are--from south to north--the Crisnejas, Chamayo, Urtcubamba, Cenepa, Santiago, Moroña, Pastaza, Huallaga, and Tiger Rivers (Cavero-Egusquiza 1941:49-51).The most distant source of the Amazon was firmly established in 1996
[4], 2001
[5] and 2007
[6] as a glacial stream on a snowcapped
5,597 m (18,363 ft) peak called
Nevado Mismi in the Peruvian
Andes, roughly
160 km (100 mi) west of Lake
Titicaca and
700 km (430 mi) southeast of
Lima. The waters from Nevado Mismi flow into the Quebradas
Carhuasanta and Apacheta, which flow into the
Río Apurímac which is a tributary of the
Ucayali which later joins the
Marañón to form the Amazon proper. Formally, though, the union of the Ucayali and the Marañón form the
Río Amazonas, which changes its name to
Solimões on the triple frontier between
Peru,
Colombia and
Brazil, and later changes its name back to the Amazon only after it meets the
Rio Negro near
Manaus.
After the confluence of
Río Apurímac and
Ucayali, the river leaves Andean terrain and is instead surrounded by
flood plain. From this point to the
Marañón, some
1,600 km (990 mi), the forested banks are just out of water, and are inundated long before the river attains its maximum flood-line. The low river banks are interrupted by only a few hills, and the river enters the enormous
Amazon Rainforest.
The river systems and flood plains in Brazil, Peru, Ecuador, Colombia and Venezuela whose waters drain into the ''Solimões'' and its tributaries are called the "Upper Amazon".
Amazonian Rainforest
Main articles: Amazon Rainforest
The Amazon
Rainforest begins from the eastern edge of the
Andes. It is the largest rainforest in the world and is of great
ecological significance, as its biomass is capable of absorbing enormous amounts of
carbon dioxide.
Conservation of the Amazon Rainforest has been a major issue in recent years.
The rainforest is supported by the extremely wet climate of the Amazon basin. The Amazon, and its hundreds of tributaries, flow slowly across the landscape, with an extremely shallow gradient sending them towards the sea:
Manaus,
1,600 km (1,000 mi) from the
Atlantic, is only
44 m (144 ft) above sea level.
The
biodiversity within the rainforest is extraordinary: the region is home to at least 2.5 million insect species, tens of thousands of plants, and some 2,000 birds and mammals. One fifth of all the world's species of birds can be found in the Amazon rainforest.
The diversity of plant species in the Amazon basin is the highest on Earth. Some experts estimate that one square kilometre may contain over 75,000 types of trees and 150,000 species of higher plants. One square kilometre of Amazon rainforest can contain about 90,000 tons of living plants.
Flooding
A
NASA satellite image of a flooded portion of the river.
The average depth of the river in the height of the rainy season is
40 m (131 ft) and the average width can be nearly
40 km (25 mi). It starts to rise in November, and increases in volume until June, then falls until the end of October. The rise of the Negro branch is not synchronous; the rainy season does not commence in its valley until February or March. By June it is full, and then it begins to fall with the Amazon. The Madeira rises and falls two months earlier than the Amazon.
Towards the sea
The breadth of the Amazon in some places is as much as
6 km (4 mi) to
10 km (6 mi) from one bank to the other. At some points, for long distances, the river divides into two main streams with inland and lateral
channels, all connected by a complicated system of natural
canals, cutting the low, flat igapo lands, which are never more than
5 m (16 ft) above low river, into many islands.
From the village of Canaria at the great bend of the Amazon to the Negro 1,000 km (600 mi) downstream, only very low land is found, resembling that at the mouth of the river. Vast areas of land in this region are submerged at high water, above which only the upper part of the trees of the sombre forests appear. Near the mouth of the Rio Negro to Serpa, nearly opposite the river Madeira, the banks of the Amazon are low, until approaching Manaus, they rise to become rolling hills. At Óbidos, a bluff
17 m (56 ft) above the river is backed by low hills. The lower Amazon seems to have once been a
gulf of the
Atlantic Ocean, the waters of which washed the cliffs near Óbidos.
Only about 10% of the water discharged by the Amazon enters the mighty stream downstream of Óbidos, very little of which is from the northern slope of the valley. The drainage area of the Amazon basin above Óbidos is about 5 million km² (2 million mile²), and, below, only about 1 million km² (400,000 mile²), or around 20%, exclusive of the 1.4 million km² (600,000 mile²) of the Tocantins basin.
In the lower reaches of the river, the north bank consists of a series of steep, table-topped
hills extending for about
240 km (149 mi) from opposite the mouth of the Xingu as far as
Monte Alegre. These hills are cut down to a kind of
terrace which lies between them and the river yeah.
Monte Alegre reaches an altitude of several hundred feet. On the south bank, above the Xingu, an almost-unbroken line of low
bluffs bordering the flood-plain extends nearly to Santarem, in a series of gentle curves before they bend to the south-west, and, abutting upon the lower Tapajos, merge into the bluffs which form the terrace margin of the Tapajos river valley.
Mouth of the river
Mouth of the Amazon River
The width of the mouth of the river is usually measured from
Cabo do Norte to
Punto Patijoca, a distance of some 330 km (207 mi); but this includes the ocean outlet, 60 km (40 mi) wide, of the Para river, which should be deducted, as this stream is only the lower reach of the Tocantins. It also includes the ocean frontage of
Marajó, an island lying in the mouth of the Amazon. This means that the Amazon is wider at its mouth than the entire length of the
Thames in
England.
Tidal bore
Following the coast, a little to the north of Cabo do Norte, and for
160 kilometres (99 mi) along its Guiana margin up the Amazon, is a belt of half-submerged islands and shallow sandbanks. Here the tidal phenomenon called the
bore, or ''
pororoca'', occurs, where the depths are not over
7 metres (23 ft). The tidal bore starts with a roar, constantly increasing, and advances at the rate of from
15 km/h (9 mph) to
25 km/h (16 mph), with a breaking wall of water from
1.5 m (5 ft) to
4 m (13 ft) high. The bore is the reason the Amazon does not have a
delta; the ocean rapidly carries away the vast volume of
silt carried by the Amazon, making it impossible for a delta to grow. It also has a very large tide sometimes reaching
20 feet (6 m) and has become a popular spot for
river surfing.
[1]
Amazon River at dawn
Wildlife
More than one third of all species in the world live in the
Amazon Rainforest, a giant tropical forest and river basin with an area that stretches more than 2.1 million square miles and is among the richest tropical forests in the world. Amazon river has over 3,000 recognized species of
fish and that number is still growing. Some estimates go as high as 5,000.
The waters of the Amazon support a diverse range of wildlife. Along with the
Orinoco, the river is one of the main habitats of the
Boto, also known as the Amazon River Dolphin. The largest species of river dolphin, it can grow to lengths of up to
2.6 metres (9 ft).
Also present in large numbers are the notorious
Piranha, carnivorous fish which congregate in large schools, and may attack livestock and even humans. Although many experts believe their reputation for ferocity is unwarranted, a school of piranha was apparently responsible for the deaths of up to 300 people when their boat capsized near
Óbidos in 1981. However, only a few species attack humans, and many are solely fish-eaters, and do not school.
The
Bull Shark has been reported 2,220 miles (4000 km) up the Amazon River at
Iquitos in
Peru. The
Arapaima, or pirarucu (Arapaima gigas) is a South American tropical
freshwater fish. It is one of the largest freshwater fish in the world, reportedly with a maximum length in excess of 3 m (9.8 ft.) and weight up to 200 kg (440 lb.).
The
Anaconda snake is found in shallow waters in the Amazon basin. One of the world's largest species of snake, the Anaconda spends most of its time in the water, with just its nostrils above the surface. Anacondas have been known to occasionally attack fishermen .
The river supports thousands of species of fish, as well as crabs, algea, and turtles.'
The Colonial Encounter and Amazonia
During what many
archaeologists call the ''formative period'', Amazonian societies were deeply implicated in the emergence of South America's highland
agrarian systems, and possibly contributed directly to the social and religious fabric constitutive of the
Andean civilizational orders
[2].
For 350 years after the European ''discovery'' of the mighty Amazon by
Vicente Yáñez Pinzón, the Portuguese portion of the basin remained a virtually undisturbed ''wilderness'', occupied by
Indigenous peoples. While there is ample evidence for large-scale, pre-Columbian social formations, including
chiefdoms, in many areas of Amazonia (particularly the inter-fluvial regions) the former indigenous inhabitants probably had relatively low population densities.
In what is currently
Brazil,
Ecuador,
Bolivia,
Colombia,
Peru, and
Venezuela a number of
colonial and
religious settlements were established along the banks of primary rivers and tributaries for the purpose of trade, slaving and evangelization among the putatively
savage indigenous peoples of the vast rain forest.
The total population of the Brazilian portion of the Amazon basin in 1850 was perhaps 300,000, of whom about two-thirds comprised by Europeans and slaves, the slaves amounting to about 25,000. In Brazil, the principal commercial city, Para (now
Belém), had from 10,000 to 12,000 inhabitants, including slaves. The town of Manáos, now
Manaus, at the mouth of the Rio Negro, had from 1,000 to 1,500 population. All the remaining villages, as far up as
Tabatinga, on the Brazilian frontier of Peru, were relatively small.
On
September 6 1850, the emperor,
Dom Pedro II, sanctioned a law authorizing steam navigation on the Amazon, and gave Barão de Mauá (
Irineu Evangilista de Sousa) the task of putting it into effect. He organized the "Compania de Navigacao e Commercio do Amazonas" at Rio de Janeiro in 1852; and in the following year it commenced operations with three small steamers, the ''Monarch'', the ''Marajó'' and ''Rio Negro''.
At first, navigation was principally confined to the main river; and even in 1857 a modification of the government contract only obliged the company to a monthly service between Pará and Manaus, with steamers of 200 tons cargo capacity, a second line to make six round voyages a year between Manaus and Tabatinga, and a third, two trips a month between Para and Cameta. This was the first step in opening up the vast interior.
The success of the venture called attention to the opportunities for economic exploitation of the Amazon, and a second company soon opened commerce on the Madeira, Purus and Negro; a third established a line between Pará and Manaus; and a fourth found it profitable to navigate some of the smaller streams. In that same period, the Amazonas Company was increasing its fleet. Meanwhile, private individuals were building and running small steam craft of their own on the main river as well as on many of its tributaries.
On
July 31 1867 the government of Brazil, constantly pressed by the maritime powers and by the countries encircling the
upper Amazon basin, especially
Peru, decreed the opening of the Amazon to all flags; but limited this to certain defined points: Tabatinga—on the Amazon; Cameta—on the Tocantins; Santarem—on the Tapajos; Borba—on the Madeira and Manáos—on the Rio Negro. The Brazilian decree took effect on
7 September 1867.
Thanks in part to the
mercantile development associated with
steam boat navigation, coupled with the internationally driven demand for natural
rubber (1880-1920), Manáos (now Manaus), Para (
Brasil), and
Iquitos,
Peru became thriving, cosmopolitan centers of commerce and spectular—albeit illusory—''modern'' "urban growth". This was particularly the case for
Iquitos during its late 19th and early 20th century ''Rubber Bonanza'' zenith when this dynamic boom-town was known abroad as the
St. Louis of the Amazon.
The first direct foreign trade with Manáos was commenced around 1874. Local trade along the river was carried on by the English successors to the Amazonas Company—the Amazon Steam Navigation Company—as well as numerous small
steamboats, belonging to companies and firms engaged in the rubber trade, navigating the Negro, Madeira, Purfis and many other tributaries, such as the Marañón to ports as distant as
Nauta,
Peru.
By the turn of the 20th century, the principal exports of the Amazon Basin were
india-rubber,
cacao,
Brazil nuts and a few other products of minor importance, such as
pelts and ''exotic'' forest produce (
resins, barks, woven
hammocks, prized bird
feathers, live
animals, etc.) and extracted goods (
lumber,
gold, etc.).
20th century concerns
Four centuries after the European discovery of the Amazon river, the total cultivated area in its basin was probably less than
25 square miles (65 km²), excluding the limited and crudely cultivated areas among the mountains at its extreme headwaters. This situation changed dramatically during the 20th century.
Manaus, the largest city on the Amazon, as seen from a
NASA satellite image, surrounded by the muddy Amazon River and the dark
Negro River.
Wary of foreign exploitation of the nation's resources, Brazilian governments in the 1940s set out to develop the interior, away from the seaboard where foreigners owned large tracts of land. The original architect of this expansion was President
Getúlio Vargas, the demand for rubber from the Allied forces in
World War II providing funding for the drive.
The construction of the new capital
Brasilia in the interior in 1960 also contributed to the opening up of the Amazon basin. A large scale colonization program saw families from north-eastern Brazil relocated to the forests, encouraged by promises of cheap land. Many settlements grew along the road from Brasilia to
Belém, but rainforest soil proved difficult to cultivate.
Still, long-term development plans continued. Roads were cut through the forests, and in 1970, the work on Trans-Amazon highway network began. The network's three pioneering highways were completed within ten years, connecting all the major cities of the Brazilian Amazon interior.
The Amazon River system
Dispute regarding length
As stated earlier, the historic consensus of geographic authorities has been to regard the Amazon as the second longest river in the world, with the
Nile being the longest. However, the Amazon has been measured by different geographers as being anywhere between
6,259 kilometres (3,889 mi) and
6,800 kilometres (4,225 mi) long. The
Nile River in Africa is reported to be anywhere from
5,499 kilometres (3,417 mi) to
6,690 kilometres (4,157 mi). The differences in these measurements often result from the use of different definitions.
A recent study by Brazilian scientists claims that the Amazon is actually longer than the Nile. Using
Nevado Mismi, which was labeled by the
National Geographic Society as the Amazon's source back in
2001, these scientists have made new calculations of the Amazon's length. They now estimate that the Amazon is 65 miles longer than the Nile.
[7]
Guido Gelli, director of science at the Brazilian Institute of Geography and Statistics (
IBGE), told the Brazilian TV network
Globo in June 2007 that it could be considered as a fact that the Amazon was the longest river in the world. However, other geographers have had access to the same data since 2001, and a consensus has yet to emerge to support the claims of these Brazilian scientists.
Major tributaries
The Amazon has over 1,000
tributaries in total. Some of the more notable:
Longest rivers in the Amazon system
#
6,387 km (3,969 mi) - Amazon,
South America
#
3,379 km (2,100 mi) -
Purus,
Peru /
Brazil, (2,948 km) (3,210 km)
#
3,239 km (2,013 mi) -
Madeira,
Bolivia /
Brazil
#
2,820 km (1,752 mi) -
Yapura,
Colombia /
Brazil
#
2,750 km (1,709 mi) -
Tocantins,
Brazil, (2,416 km) (2,640 km)
#
2,575 km (1,600 mi) -
Araguaia,
Brazil (tributary of Tocantins)
#
2,410 km (1,498 mi) -
Juruá,
Peru /
Brazil
#
2,250 km (1,398 mi) -
Negro,
South America
#
2,100 km (1,305 mi) -
Xingu,
Brazil
#
1,900 km (1,181 mi) -
Tapajós,
Brazil
#
1,749 km (1,087 mi) -
Guaporé,
Brazil /
Bolivia (tributary of Madeira)
#
1,575 km (979 mi) -
Içá (Putumayo),
South America
#
1,415 km (879 mi) -
Marañón,
Peru
#
1,300 km (808 mi) -
Iriri,
Brazil (tributary of Xingu)
#
1,240 km (771 mi) -
Juruena,
Brazil (tributary of Tapajós)
#
1,200 km (746 mi) -
Tapajós,
Brazil
#
1,130 km (702 mi) -
Madre de Dios,
Peru /
Bolivia (tributary of Madeira)
#
1,100 km (684 mi) -
Huallaga,
Peru (tributary of
Marañón)
References
1. "Amazon (river)," Microsoft® Encarta® Online Encyclopedia 2007
http://encarta.msn.com. Retrieved August 18, 2007
2. Amazon uk.encarta.msn.com. Retrieved 1 October 2006.
3. "Amazon river 'switched direction'." Published 24 October 2006. Retrieved 25 October 2006.
4. Source of the Amazon River Identificated (Jacek Palkiewicz)
5. Explorers Pinpoint Source of the Amazon (National Geographic News)
6. Amazon river 'longer than Nile' (BBC news) (2007-06-16)
7. http://news.nationalgeographic.com/news/2007/06/070619-amazon-river.html
★
External links
★
Amazon dries up Youtube (July 31, 2006)
★
Bibliography on Water Resources and International Law See 'Amazon River'. Peace Palace Library
★
Amazon River and Amazon Rainforest virtual tour
★
Information on the Amazon from Extreme Science
★
Fundación Gaia Amazonas
★
Pictures of the Amazon River
★
Amazon River and Amazon rainforest information
★
An Amazon River web site
★
Information and a map of the Amazon's watershed
★
Expedition to the source 1996
★
Expedition to the source 2001
★
Amazon river 'longer than Nile' (BBC News)
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