The Amazon River (US /ËÃ¦mÉzÉ'n/ or UK /ËÃ¦mÉzÉn/; Spanish and Portuguese: Amazonas) in South America is the largest river by discharge of water in the world, averaging a discharge of about 209,000 cubic meters per second (7,381,000 cu ft/s), (209,000,000 liters or 55,211,960 gallons/sec) greater than the next seven largest independent rivers combined. The Amazon basin is the largest drainage basin in the world, about 7,050,000 square kilometres (2,720,000Â sqÂ mi), and accounts for approximately one-fifth of the world's total river flow. The portion of the river's drainage basin in Brazil alone is larger than any other river's basin. The Amazon enters Brazil with only one-fifth of the flow it finally discharges into the Atlantic Ocean, yet already has a greater flow at this point than the discharge of any other river.
In its upper stretches, above its confluence with the Rio Negro, the Amazon is called SolimÃµes in Brazil; however, in Peru, Colombia and Ecuador, as well as the rest of the Spanish-speaking world, the river is generally called the Amazon downstream from the confluence of the MaraÃ±Ã³n and Ucayali rivers in Peru. Although the ApurÃmac river had been considered the most distant source of the Amazon river for nearly a century, a study published in 2014 clearly showed that the Cordillera Rumi Cruz in the Mantaro river drainage extended ~80Â km farther upstream compared to Mt. Mismi in the ApurÃmac drainage and thus the Mantaro River is the actual most distant source of the Amazon river. Although the Mantaro-Ucayali river can be considered the "most distant" source of the Amazon, the MaraÃ±Ã³n contributes far more water than the Ucayali where they join, and therefore the MaraÃ±Ã³n river is still the mainstem source of the Amazon.
The width of the Amazon is between 1.6 and 10 kilometres (1.0 and 6.2Â mi) at low stage, but expands during the wet season to 48 kilometres (30Â mi) or more. The river enters the Atlantic Ocean in a broad estuary about 240 kilometres (150Â mi) wide. The mouth of the main stem is 80 kilometres (50Â mi). Because of its vast dimensions, it is sometimes called "The River Sea".
The total volume of water discharging from the Amazon river in a year is about 6,591 cubic kilometers.
The largest city along the Amazon River is Manaus. Located in Brazil it is home to over 1.7 million people.
The Amazon basin, the largest in the world, covers about 40% of South America, an area of approximately 7,050,000 square kilometres (2,720,000Â sqÂ mi). It drains from west to east, from Iquitos in Peru, across Brazil to the Atlantic. 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 locals often refer to it as "El Jefe Negro", referring to an ancient god of fertility.
The Amazon River and its tributaries are characterized by extensive forested areas that become flooded every rainy season. Every year, the river rises more than 9 metres (30Â ft), flooding the surrounding forests, known as vÃ¡rzea ("flooded forests"). The Amazon's flooded forests are the most extensive example of this habitat type in the world. In an average dry season, 110,000 square kilometres (42,000Â sqÂ mi) of land are water-covered, while in the wet season, the flooded area of the Amazon basin rises to 350,000 square kilometres (140,000Â sqÂ mi).
The quantity of water released by the Amazon to the Atlantic Ocean is enormous: up to 300,000 cubic metres per second (11,000,000Â cuÂ ft/s) in the rainy season, with an average of 209,000 cubic metres per second (7,400,000Â cuÂ ft/s) from 1973 to 1990. The Amazon is responsible for about 20% of the Earth's fresh water entering the ocean. The river pushes a vast plume of fresh water into the ocean. The plume is about 400 kilometres (250Â mi) long and between 100 and 200 kilometres (62 and 124Â mi) wide. The fresh water, being lighter, flows on top of the seawater, diluting the salinity and altering the color of the ocean surface over an area up to 1,000,000 square miles (2,600,000Â km2) in extent. For centuries ships have reported fresh water near the Amazon's mouth yet well out of sight of land in what otherwise seemed to be the open ocean.
The Atlantic has sufficient wave and tidal energy to carry most of the Amazon's sediments out to sea, thus the Amazon does not form a true delta. The great deltas of the world are all in relatively protected bodies of water, while the Amazon empties directly into the turbulent Atlantic.
There is a natural water union between the Amazon and the Orinoco basins, the so-called Casiquiare canal. The Casiquiare is a river distributary of the upper Orinoco, which flows southward into the Rio Negro, which in turn flows into the Amazon. The Casiquiare is the largest river on earth that links two major river systems, a so-called bifurcation.
The Amazon river has a series of major river systems in Colombia, Ecuador and Peru, some of which flow into the MaraÃ±Ã³n and Ucayali, others directly into the Amazon proper. Among others, these include the following rivers: Putumayo, CaquetÃ¡, VaupÃ©s, GuainÃa, Morona, Pastaza, Nucuray, Urituyacu, Chambira, Tigre, Nanay, Napo, and Huallaga.
The most distant source of the Amazon was erroneously thought to be in the ApurÃmac river drainage for nearly a century. Such studies continued to be published even recently, such as in 1996, 2001, 2007, and 2008, where various authors showed that the snowcapped 5,597Â m (18,363Â ft) Nevado Mismi peak was the most distant source of the river (located roughly 160Â km (99Â mi) west of Lake Titicaca and 700Â km (430Â mi) southeast of Lima). Quebrada Carhuasanta emerges from Nevado Mismi, joins Quebrada Apacheta and soon forms RÃo Lloqueta which becomes RÃo Hornillos and eventually joins the RÃo ApurÃmac. After ~700Â km the ApurÃmac then joins RÃo Mantaro to form the Ene, which joins the Perene to form the Tambo, which joins the Urubamba to form the Ucayali, which later joins RÃo MaraÃ±Ã³n to form what most people subsequently call the Amazon River.
However, the ApurÃmac drainage is not the most distant source of the Amazon river after all. In 2014 a study published in a peer-reviewed journal of the Royal Geographic Society by two American scientists (James Contos and Nicolas Tripcevich) showed that the most distant source of the Amazon is actually in the RÃo Mantaro drainage. A variety of methods were used to compare the lengths of the Mantaro river vs. the Apurimac river from their most distant source points to their confluence, clearly showing the longer length of the Mantaro. Then distances from Lago JunÃn to several potential source points in the uppermost Mantaro river were measured and it was determined that the Cordillera Rumi Cruz was the most distant source of water in the Mantaro basin (and therefore in the entire Amazon basin). The most accurate measurement method was direct GPS measurement obtained by kayak descent of each of the rivers from their source points to their confluence (performed by Contos). Obtaining these measurements was remarkable feat given the difficult class IV/V nature of each of these rivers, especially in their lower "Abyss" sections. In the end, it was determined that the most distant point in the Mantaro drainage is nearly 80Â km farther upstream compared to Mt. Mismi in the ApurÃmac drainage. This fact means the maximal length of the Amazon river is ~80Â km longer than previously thought. Contos continued downstream to the ocean and finished the first complete descent of the Amazon river from its newly identified source (finishing November 2012), a journey repeated by two groups after the news spread.
While the Ucayaliâ"MaraÃ±Ã³n confluence is the point at which most geographers place the beginning of the Amazon proper, in Brazil the river is known at this point as the SolimÃµes das Ãguas. Further downriver from that confluence, the darkly colored waters of the Rio Negro meet the sandy colored Rio SolimÃµes, and for over 6Â km (4Â mi) these waters run side by side without mixing.
After the confluence of ApurÃmac and Ucayali, the river leaves Andean terrain and is surrounded by floodplain. From this point to the MaraÃ±Ã³n, some 1,600Â km (990Â mi), the forested banks are just out of water and are inundated long before the river attains its maximum flood stage. 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 SolimÃµes and its tributaries, are called the "Upper Amazon". The Amazon River proper runs mostly through Brazil and Peru. It is part of the border between Colombia and PerÃº, and it has tributaries reaching into Venezuela, Colombia, Ecuador, and Bolivia.
Not all of the Amazon's tributaries flood at the same time of the year. Many branches begin flooding in November and may continue to rise until June. The rise of the Rio Negro starts in February or March and begins to recede in June. The Madeira River rises and falls two months earlier than most of the rest of the Amazon.
The depth of the Amazon between Manacapuru and Ã"bidos has been calculated as between 20 to 26 metres (66 to 85Â ft). At Manacapuru, the Amazon's water level is only about 24 metres (79Â ft) above mean sea level. More than half of the water in the Amazon downstream of Manacapuru is below sea level. In its lowermost section, the Amazon's depth averages 20 to 50 metres (66 to 164Â ft), in some places as much as 100 metres (330Â ft).
The main river is navigable for large ocean steamers to Manaus, 1,500 kilometres (930Â mi) upriver from the mouth. Smaller ocean vessels of 3,000 tons or 9,000 tons and 5.5 metres (18Â ft) draft can reach as far as Iquitos, Peru, 3,600 kilometres (2,200Â mi) from the sea. Smaller riverboats can reach 780 kilometres (480Â mi) higher as far as Achual Point. Beyond that, small boats frequently ascend to the Pongo de Manseriche, just above Achual Point.
Annual flooding is caused by tidal waves called "pororoca", which occur in late winter at high tide, when the Atlantic Ocean overlaps into the river. The resulting waves can be up to 4 meters high and travel 13 kilometers inland.
At some points the river divides into anabranches, or multiple channels, often very long, with inland and lateral channels, all connected by a complicated system of natural canals, cutting the low, flat igapÃ³ lands, which are never more than 5 metres (16Â ft) above low river, into many islands.
From the town of Canaria at the great bend of the Amazon to the Negro, vast areas of land 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 Ã"bidos, a bluff 17Â m (56Â 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 Ã"bidos.
Only about ten percent of the Amazon's water enters downstream of Ã"bidos, very little of which is from the northern slope of the valley. The drainage area of the Amazon basin above Ã"bidos city is about 5,000,000 square kilometres (1,900,000Â sqÂ mi), and, below, only about 1,000,000 square kilometres (390,000Â sqÂ mi) (around 20%), exclusive of the 1,400,000 square kilometres (540,000Â sqÂ mi) of the Tocantins basin. The Tocantins River enters the southern portion of the Amazon delta.
In the lower reaches of the river, the north bank consists of a series of steep, table-topped hills extending for about 240 kilometres (150Â 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.
On the south bank, above the Xingu, a line of low bluffs bordering the floodplain extends nearly to SantarÃ©m in a series of gentle curves before they bend to the southwest, and, abutting upon the lower TapajÃ³s, merge into the bluffs which form the terrace margin of the TapajÃ³s river valley.
The definition of where exactly the mouth of the Amazon is located, and how wide it is, is a matter of dispute, because of the area's peculiar geography. The ParÃ¡ and the Amazon are connected by a series of river channels called furos near the town of Breves; between them lies MarajÃ³, the world's largest combined river/sea island.
If the ParÃ¡ river and the MarajÃ³ island ocean frontage are included, the Amazon estuary is some 325 kilometres (202Â mi) wide. In this case, the width of the mouth of the river is usually measured from Cabo Norte, the cape located straight east of PracuÃºba in the Brazilian state of AmapÃ¡, to Ponta da Tijoca near the town of CuruÃ§Ã¡, in the state of ParÃ¡.
A more conservative measurement excluding the ParÃ¡ river estuary, from the mouth of the Araguari River to Ponta do Navio on the northern coast of MarajÃ³, would still give the mouth of the Amazon a width of over 180 kilometres (110Â mi). If only the river's main channel is considered, between the islands of CuruÃ¡ (state of AmapÃ¡) and Jurupari (state of ParÃ¡), the width falls to about 15 kilometres (9.3Â mi).
More than one-third of all known species in the world live in the Amazon rainforest, a giant tropical forest and river basin with an area that stretches more than 5,400,000 square kilometres (2,100,000Â sqÂ mi). It is the richest tropical forest in the world in terms of biodiversity. There are over 3,000 species of fish currently recognized in the Amazon basin, with more being discovered every year. In addition to the thousands of species of fish, the river supports crabs, algae, and turtles.
Along with the Orinoco, the Amazon is one of the main habitats of the boto, also known as the Amazon river dolphin (Inia geoffrensis). It is the largest species of river dolphin, and it can grow to lengths of up to 2.6 metres (8Â ft 6Â in). The color of its skin changes with age; young animals are gray, but become pink nd then white as they mature. The dolphins use echolocation to navigate and hunt in the river's tricky depths. The boto is the subject of a legend in Brazil about a dolphin that turns into a man and seduces maidens by the riverside.
The tucuxi (Sotalia fluviatilis), also a dolphin species, is found both in the rivers of the Amazon basin and in the coastal waters of South America. The Amazonian manatee (Trichechus inunguis), also known as "seacow", is found in the northern Amazon River Basin and its tributaries. It is a mammal and an herbivore. Its population is limited to fresh water habitats, and, unlike other manatees, it does not venture into salt water. It is classified as vulnerable by the International Union for Conservation of Nature.
The Amazon and its tributaries are the main habitat of the giant otter (Pteronura brasiliensis). It is a member of the weasel family and is the largest of its kind. Because of habitat destruction and hunting, its population has dramatically decreased.
The anaconda 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. The caiman, which is related to alligators and other crocodilians, also inhabits the Amazon as do varieties of turtles.
The Amazonian fish fauna is the center of diversity for Neotropical fishes, of which more than 5,600 species are currently known. The bull shark (Carcharhinus leucas) has been reported 4,000 kilometres (2,500Â mi) up the Amazon River at Iquitos in Peru. The arapaima, known in Brazil as the 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 of 3 metres (9.8Â ft) and weight up to 200 kilograms (440Â lb). Another Amazonian freshwater fish is the arowana (or aruanÃ£ in Portuguese), such as the silver arowana (Osteoglossum bicirrhosum), which is a predator and very similar to the arapaima, but only reaches a length of 120 centimetres (47Â in). Also present in large numbers is the notorious piranha, an omnivorous fish that congregates in large schools and may attack livestock and even humans. There are approximately 30 to 60 species of piranha. However, only a few of its species are known to attack humans, most notably Pygocentrus nattereri, the red-bellied piranha. The candirÃº, native to the Amazon River, is a species of parasitic fresh water catfish in the family Trichomycteridae. The electric eel (Electrophorus electricus) and more than 100 species of electric fishes (Gymnotiformes) inhabit the Amazon basin. River stingrays (Potamotrygonidae) are also known.
Freshwater microbes are generally not very well known, even less so for a pristine ecosystem like the Amazon. Recently, metagenomics has provided answers to what kind of microbes inhabit the river. The most important microbes in the Amazon River are Actinobacteria, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria and Crenarchaeota.
The Amazon River originated as a transcontinental river in the Miocene Epoch between 11.8 million and 11.3 million years ago and took its present shape approximately 2.4 million years ago.
The Amazon once flowed west as part of a proto-Amazon-Congo river system, from the interior of present day Africa when the continents were joined as western Gondwana. Fifteen million years ago, the Andes were formed by the collision of the South American plate with the Nazca plate. The rise of the Andes and the linkage of the Brazilian and Guyana bedrock shields, blocked the river and caused the Amazon to become a vast inland sea. Gradually this inland sea became a massive swampy, freshwater lake and the marine inhabitants adapted to life in freshwater. For example, over 20 species of stingray, most closely related to those found in the Pacific Ocean, can be found today in the freshwaters of the Amazon.
Ten to eleven million years ago, waters worked through the sandstone from the west and the Amazon began to flow eastward, leading to the emergence of the Amazon rainforest. During Ice Ages, sea levels dropped and the great Amazon lake rapidly drained and became a river, which would eventually become the world's largest, draining the most extensive expanse of rainforest on the planet.
During what many archaeologists call the formative period, Amazonian societies were deeply involved 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.
Mounds of the Amazon
Early human settlements were typically based on low-lying hills or mounds.
Five types of archaeological mound have been noted in the Amazon region: shell refuse and artificial mounds, artificial earth platforms for entire villages, earth mounds and ridges for cultivation, causeways and canals, and figurative mounds, both geometric and biomorphic.
Shell mounds were the earliest; they represent piles of human refuse and are mainly dated between 7500 and 4000 BP. They all represent pottery age cultures; no preceramic shell mounds have been documented so far by archaeologists.
Figurative mounds are the latest chronologically.
Artificial earth platforms for entire villages are the second type of mounds. They are best represented by the Marajoara culture.
There is ample evidence for complex large-scale, pre-Columbian social formations, including chiefdoms, in many areas of Amazonia (particularly the inter-fluvial regions) and even large towns and cities. For instance the pre-Columbian culture on the island of MarajÃ³ may have developed social stratification and supported a population of 100,000 people. The Native Americans of the Amazon rain forest may have used Terra preta to make the land suitable for the large-scale agriculture needed to support large populations and complex social formations such as chiefdoms.
Many indigenous tribes engaged in constant warfare. James Stuart Olson wrote: "The Munduruku expansion dislocated and displaced the KawahÃb, breaking the tribe down into much smaller groups... [Munduruku] first came to the attention of Europeans in 1770 when they began a series of widespread attacks on Brazilian settlements along the Amazon River."
In March 1500, Spanish conquistador Vicente YÃ¡Ã±ez PinzÃ³n was the first documented European to sail into the river. PinzÃ³n called the river flow RÃo Santa MarÃa del Mar Dulce, later shortened to Mar Dulce (literally, sweet sea, because of its fresh water pushing out into the ocean). Another Spanish explorer, Francisco de Orellana, was the first European man to travel from the founts situated in the Andes to the end of the river. In this travel, Orellana bapthized some of the affluents of the amazonas like Rio Negro, Napo or Jurua. The name Amazonas came from the natives warriors that attacked this expedition, mostly women, that reminded Orellana of the woman warriors the Amazonas from the Hellenic culture.
Gonzalo Pizarro set off in 1541 to explore east of Quito into the South American interior in search of El Dorado, the "city of gold" and La Canela, the "valley of cinnamon". He was accompanied by his second-in-command Francisco de Orellana. After 170Â km, the Coca River joined the Napo River (at a point now known as Puerto Francisco de Orellana); the party stopped for a few weeks to build a boat just upriver from this confluence. They continued downriver through an uninhabited area, where they could not find food. Orellana offered and was ordered to follow the Napo River, then known as RÃo de la Canela ("Cinnamon River") and return with food for the party. Based on intelligence received from a captive native chief named Delicola, they expected to find food within a few days downriver by ascending another river to the north.
Orellana took about 57 men, the boat, and some canoes and left Pizarro's party on 26 December 1541. However, Orellana apparently missed the confluence (probably with the Aguarico) where he was to look for food. By the time he and his men reached another village many of them were sick from hunger and eating "noxious plants", and near death. Seven men died at that village. His men threatened to mutiny if he followed his orders and the expedition turned back to join Pizarro's larger party. He accepted to change the purpose of the expedition to discover new lands in the name of the King of Spain, and the men built a larger boat in which to navigate downstream. After a journey of 600Â km down the Napo River they reached a further major confluence, at a point near modern Iquitos, and then followed the upper Amazon, now known as the SolimÃµes, for a further 1,200Â km to its confluence with the Rio Negro (near modern Manaus), which they reached on 3 June 1542. On the Nhamunda River, a tributary of the Amazon downstream from Manaus, Orellana's party had a fierce battle with warriors who, they reported, were led by fierce female warriors who beat the men to death with clubs if they tried to retreat. Orellana's men began referring to the women as Amazons, a reference to the women of Greek Mythology. The river was initially known as the MaraÃ±Ã³n (the name by which the Peruvian part of the river is still known today) or Rio de Orellana. It later became known as the Rio Amazonas, the name by which it is still known in both Spanish and Portuguese.
Regarding the initial mission of finding cinnamon, Pizarro reported to the King that they had found cinnamon trees, but that they could not be profitably harvested. In fact, true cinnamon (Cinnamomum verum) is not native to South America. Other related cinnamon-containing plants (of the family Lauraceae) are fairly common in that part of the Amazon and Pizarro probably saw some of these. The expedition reached the mouth of the Amazon on 24 August 1542, demonstrating the practical navigability of the Great River.
In 1560, another Spanish conquistador, Lope de Aguirre, may have made the second descent of the Amazon. Historians are uncertain whether the river he descended was the Amazon or the Orinoco River, which runs more or less parallel to the Amazon further north.
Portuguese explorer Pedro Teixeira was the first European to travel up the entire river. He arrived in Quito in 1637, and then returned via the same route.
From 1648 to 1652, Portuguese Brazilian bandeirante AntÃ³nio Raposo Tavares led an expedition from SÃ£o Paulo overland to the mouth of the Amazon, investigating many of its tributaries, including the Rio Negro, and covering a distance of more than 10,000Â km (6,214Â mi).
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 indigenous peoples of the vast rain forest, such as the Urarina. In the late 1600s, Spanish Jesuit Father Samuel Fritz, apostle of the Omaguas, established some forty mission villages.
Early scientific, zoological and botanical exploration of the Amazon River and basin occurred in the second half of 18th century through the first half of the 19th century.
- Charles Marie de La Condamine explored the river in 1743.
- Alexander von Humboldt 1799-1804
- Johann Baptiste von Spix and Phillip von Martius, 1817-1820
- William Henry Bates and Alfred Russell Wallace, 1848-1859
Post-colonial exploitation and settlement
The Cabanagem revolt (1835-1840) was directed against the white ruling class. It is estimated that from 30 to 40% of the population of GrÃ£o-ParÃ¡, estimated at 100,000 people, died.
The total population of the Brazilian portion of the Amazon basin in 1850 was perhaps 300,000, of whom about two-thirds were Europeans and slaves, the slaves amounting to about 25,000. The Brazilian Amazon's principal commercial city, ParÃ¡ (now BelÃ©m), had from 10,000 to 12,000 inhabitants, including slaves. The town of ManÃ¡os, now Manaus, at the mouth of the Rio Negro, had a population between 1,000 to 1,500. All the remaining villages, as far up as Tabatinga, on the Brazilian frontier of Peru, were relatively small.
On 6 September 1850, Emperor Pedro II of Brazil sanctioned a law authorizing steam navigation on the Amazon and gave the Viscount of MauÃ¡ (Irineu Evangelista de Sousa) the task of putting it into effect. He organized the "Companhia de NavegaÃ§Ã£o e ComÃ©rcio do Amazonas" in Rio de Janeiro in 1852; in the following year it commenced operations with three small steamers, the Monarch, the MarajÃ³ 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 ParÃ¡ 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 ParÃ¡ and CametÃ¡. 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, PurÃºs and Negro; a third established a line between ParÃ¡ 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 31 July 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 countries, but they limited this to certain defined points: Tabatinga â" on the Amazon; CametÃ¡ â" on the Tocantins; SantarÃ©m â" on the TapajÃ³s; Borba â" on the Madeira, and Manaus â" on the Rio Negro. The Brazilian decree took effect on 7 September 1867.
Thanks in part to the mercantile development associated with steamboat navigation coupled with the internationally driven demand for natural rubber, the Peruvian city of Iquitos became a thriving, cosmopolitan center of commerce. Foreign companies settled in Iquitos, from whence they controlled the extraction of rubber. In 1851, Iquitos had a population of 200, and by 1900 its population reached 20,000. In the 1860s, approximately 3,000 tons of rubber was being exported annually, and by 1911 annual exports had grown to 44,000 tons, representing 9.3% of Peru's exports. During the rubber boom it is estimated that diseases brought by immigrants, such as typhus and malaria, killed 40,000 native Amazonians.
The first direct foreign trade with Manaus commenced around 1874. Local trade along the river was carried on by the English successors to the Amazonas Companyâ"the Amazon Steam Navigation Companyâ"as well as numerous small steamboats, belonging to companies and firms engaged in the rubber trade, navigating the Negro, Madeira, PurÃºs and many other tributaries, such as the MaraÃ±Ã³n, to ports as distant as Nauta, Peru.
By the turn of the 20th century, the exports of the Amazon basin were India-rubber, cacao beans, 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) and extracted goods, such as lumber and gold.
For 350 years after the first European encounter of the Amazon by PinzÃ³n, the Portuguese portion of the basin remained an untended former food gathering and planned agricultural landscape occupied by the indigenous peoples who survived the arrival of European diseases.
Four centuries after the European discovery of the Amazon river, the total cultivated area in its basin was probably less than 65 square kilometres (25Â sqÂ mi), excluding the limited and crudely cultivated areas among the mountains at its extreme headwaters. This situation changed dramatically during the 20th century.
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 GetÃºlio Vargas, with the demand for rubber from the Allied forces in World War II providing funding for the drive.
In 1960, the construction of the new capital city of BrasÃlia in the interior also contributed to the opening up of the Amazon basin. A large-scale colonization program saw families from northeastern Brazil relocated to the forests, encouraged by promises of cheap land. Many settlements grew along the road from BrasÃlia to BelÃ©m, 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 the Trans-Amazonian Highway (TransamazÃ´nica) network began. The network's three pioneering highways were completed within ten years but never fulfilled their promise. Large portions of the Trans-Amazonian and its accessory roads, such as BR-319 (Manaus-Porto Velho), are derelict and impassable in the rainy season. Small towns and villages are scattered across the forest, and because its vegetation is so dense, some remote areas are still unexplored.
With a population of 1.9 million people in 2014, Manaus is the largest city on the Amazon. Manaus alone makes up approximately 50% of the population of the Brazilian state of Amazonas, which is the largest state. The racial makeup of the city is 64% Pardo (Mulatto and mestizo) and 32% White.
Dispute regarding length
While debate as to whether the Amazon or the Nile is the world's longest river has gone on for many years, 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 and 6,800 kilometres (3,889 and 4,225Â mi) long. It is often said to be "at least" 6,400 kilometres (4,000Â mi) long. The Nile is reported to be anywhere from 5,499 to 6,690 kilometres (3,417 to 4,157Â mi). Often it is said to be "about" 6,650 kilometres (4,130Â mi) long. There are many factors that can affect these measurements.
A study by Brazilian scientists concluded that the Amazon is actually longer than the Nile. Using Nevado Mismi, which in 2001 was labeled by the National Geographic Society as the Amazon's source, these scientists made new calculations of the Amazon's length. They calculated the Amazon's length as 6,992 kilometres (4,345Â mi). Using the same techniques, they calculated the length of the Nile as 6,853 kilometres (4,258Â mi), which is longer than previous estimates but still shorter than the Amazon. They made it possible by measuring the Amazon downstream to the beginning of the tidal estuary of Canal do Sul and then, after a sharp turn back, following tidal canals surrounding the isle of MarajÃ³ and finally including the marine waters of the RÃo ParÃ¡ bay in its entire length. 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. The length of both the Amazon and the Nile remains open to interpretation and continued debate.
Scientists have discovered the longest underground "river" (actually a saline water aquifer) in the world, in Brazil. Water in the aquifer flows a distance of 6,000 kilometres (3,700Â mi) at a depth of nearly 4,000 metres (13,000Â ft). It flows from the Andean foothills to the Atlantic coast in a nearly west-to-east direction like the Amazon River. The discovery was made public in August 2011 meeting of the Brazilian Geophysical Society in Rio de Janeiro. The "river", named Hamza after the discoverer, an Indian-born scientist Valiya Hamza who is working with the National Observatory at Rio, makes it the first and geologically unusual instance of a twin-river system flowing at different levels of the earth's crust in Brazil. A combination of seismic data and anomalous temperature variation with depth measured in 241 inactive oil wells helped locate the aquifer. Except for the flow direction, the Amazon and the Hamza have very different characteristics. The most obvious ones are their width and flow speed. While the Amazon is 1 kilometre (0.62Â mi) to 100 kilometres (62Â mi) wide, the Hamza is 200 kilometres (120Â mi) to 400 kilometres (250Â mi) in width. But the flow speed is 5 metres per second (16Â ft/s) in the Amazon and less than 1 millimetre per second (0.039Â in/s) speed in the Hamza.
Several geological factors have played a vital role in the formation and existence of these subterranean water bodies. The large deep aquifer formed when the plate carrying the Pacific Ocean bottom was dragged and ends up under the continental plate. Water at such depths would normally escape upwards but the unusual conditions that exist along the eastern Pacific Rim allow the moisture to remain intact. In the case of the Hamza, the porous and permeable sedimentary rocks behave as conduits for the water to sink to greater depths. East-west trending faults and the karst topography present along the northern border of the Amazon basin may have some role in supplying water to the "river". If the impermeable rocks stop the vertical flow, the west to east gradient of the topography directs it to flow towards the Atlantic Ocean.
Unlike the Hamza, the 153Â km-long underground river in Mexico's YucatÃ¡n Peninsula and the 8.2Â km-long Cabayugan River in the Puerto Princesa Subterranean River National Park in the Philippines have come into being thanks to the karst topography. Water in these places has dissolved the carbonate rock to form extensive underground river systems.
The Amazon has over 1,100 tributaries, 17 of which are over 1,500 kilometres (930Â mi) long. Some of the more notable ones are:
List by length
- 6,259Â km (3,889Â mi) to 6,712Â km (4,171Â mi) â" Amazon, South America
- 3,250Â km (2,020Â mi) â" Madeira, Bolivia/Brazil
- 3,211Â km (1,995Â mi) â" PurÃºs, Peru/Brazil
- 2,820Â km (1,750Â mi) â" Yapura, Colombia/Brazil
- 2,639Â km (1,640Â mi) â" Tocantins, Brazil
- 2,627Â km (1,632Â mi) â" Araguaia, Brazil (tributary of Tocantins)
- 2,400Â km (1,500Â mi) â" JuruÃ¡, Peru/Brazil
- 2,250Â km (1,400Â mi) â" Rio Negro, Brazil/Venezuela/Colombia
- 1,992Â km (1,238Â mi) â" TapajÃ³s, Brazil
- 1,979Â km (1,230Â mi) â" Xingu, Brazil
- 1,900Â km (1,200Â mi) â" Ucayali River, Peru
- 1,749Â km (1,087Â mi) â" GuaporÃ©, Brazil/Bolivia (tributary of Madeira)
- 1,575Â km (979Â mi) â" IÃ§Ã¡ (Putumayo), South America
- 1,415Â km (879Â mi) â" MaraÃ±Ã³n, Peru
- 1,370Â km (850Â mi) â" Teles Pires, Brazil (tributary of TapajÃ³s)
- 1,300Â km (810Â mi) â" Iriri, Brazil (tributary of Xingu)
- 1,240Â km (770Â mi) â" Juruena, Brazil (tributary of TapajÃ³s)
- 1,130Â km (700Â mi) â" Madre de Dios, Peru/Bolivia (tributary of Madeira)
- 1,100Â km (680Â mi) â" Huallaga, Peru (tributary of MaraÃ±Ã³n)
- Peruvian Amazon
- Â This articleÂ incorporates text from a publication now in the public domain:Â George Earl Church (1911). "Amazon". In Chisholm, Hugh. EncyclopÃ¦dia Britannica (11th ed.). Cambridge University Press.Â
- Bibliography on Water Resources and International Law Peace Palace Library
- Information on the Amazon from Extreme Science
- A photographic journey up the Amazon River from its mouth to its source
- Amazon Alive: Light & Shadow documentary film about the Amazon river
- Amazon River Ecosystem
- Research on the influence of the Amazon River on the Atlantic Ocean at the University of Southern California
- Geographic data related to Amazon River at OpenStreetMap