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Amazon River

Amazon River

Overview
The Amazon of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

 is the second longest river in the world and by far the largest by waterflow with an average discharge
Discharge (hydrology)
In hydrology, discharge is the volume rate of water flow, including any suspended solids , dissolved chemical species and/or biologic material , which is transported through a given cross-sectional area...

 greater than the next seven largest rivers combined (not including Madeira and Rio Negro, which are tributuaries of the Amazon). The Amazon, which has the largest drainage basin
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 in the world, about 7050000 square kilometres (2,722,020.2 sq mi), accounts for approximately one-fifth of the world's total river flow.

In its upper stretches, above the confluence of the Negro River, the Amazon is called Solimões
Solimões
Solimões is the name often given to early stretches of the Amazon River from the border of Brazil and Peru to its confluence with the Rio Negro.Further upstream from the border, the name of the river seems to depend on the speaker...

 in Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

; however, in Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....

, Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

 and Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...

, as well as the rest of the Spanish-speaking world, the river is generally called the Amazon downstream from the confluence of the Marañón
Marañón
Marañón may refer to:* Marañón, Navarre, a town and municipality in Spain* Marañón River, in Peru* Marañón Province, in Peru* Valle del Marañón, a valley in Peru* Gregorio Marañón , Spanish physician, historian, writer and philosopher...

 and Ucayali
Ucayali
The Ucayali River arises about north of Lake Titicaca, in the Arequipa region of South America. The Amazon River takes its name close to Nauta city , in the confluence among Ucayali and Marañón rivers....

 rivers in Peru.
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Encyclopedia
The Amazon of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

 is the second longest river in the world and by far the largest by waterflow with an average discharge
Discharge (hydrology)
In hydrology, discharge is the volume rate of water flow, including any suspended solids , dissolved chemical species and/or biologic material , which is transported through a given cross-sectional area...

 greater than the next seven largest rivers combined (not including Madeira and Rio Negro, which are tributuaries of the Amazon). The Amazon, which has the largest drainage basin
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 in the world, about 7050000 square kilometres (2,722,020.2 sq mi), accounts for approximately one-fifth of the world's total river flow.

In its upper stretches, above the confluence of the Negro River, the Amazon is called Solimões
Solimões
Solimões is the name often given to early stretches of the Amazon River from the border of Brazil and Peru to its confluence with the Rio Negro.Further upstream from the border, the name of the river seems to depend on the speaker...

 in Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

; however, in Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....

, Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

 and Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...

, as well as the rest of the Spanish-speaking world, the river is generally called the Amazon downstream from the confluence of the Marañón
Marañón
Marañón may refer to:* Marañón, Navarre, a town and municipality in Spain* Marañón River, in Peru* Marañón Province, in Peru* Valle del Marañón, a valley in Peru* Gregorio Marañón , Spanish physician, historian, writer and philosopher...

 and Ucayali
Ucayali
The Ucayali River arises about north of Lake Titicaca, in the Arequipa region of South America. The Amazon River takes its name close to Nauta city , in the confluence among Ucayali and Marañón rivers....

 rivers in Peru. The Ucayali-Apurímac
Apurímac
Apurímac is the name of:*Apurímac River - a river in the south-eastern parts of central Perú*Apurímac Region - a region in the south-eastern parts of central Perú*Apurimac - an album by the German cross-cultural new age band Cusco....

 river system is considered the main source of the Amazon.

The width of the Amazon varies between 1.6 and 10 km (0.994196378639691 and 6.2 mi) at low stage, but expands during the wet season to 48 kilometres (30 mi) or more. The river enters the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 in a broad estuary
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....

 about 240 kilometres (149.1 mi) wide. The mouth of the main stem
Main Stem
"Main Stem" is 1942 instrumental by Duke Ellington and His Famous Orchestra. Although recorded in 1942, the single would not be released until 1944 where it was Duke Ellington's last of four number one's on the Harlem Hit Parade. "Main Stem" would also peak at number twenty on the pop chart"Main...

 is 80 kilometres (49.7 mi). Because of its vast dimensions, it is sometimes called The River Sea. At no point is the Amazon crossed by a bridge. This is not because of its huge dimensions; in fact, for most of its length, the Amazon's width is well within the capability of modern engineers to bridge. However, the bulk of the river flows through tropical rainforest, where there are few roads or cities, limiting the need for crossings.

Drainage area



The Amazon Basin, the largest drainage basin in the world, covers about 30 % of South America, an area of approximately 7050000 square kilometres (2,722,020.2 sq mi). It gathers its waters from 5 degrees north latitude
5th parallel north
The 5th parallel north is a circle of latitude that is 5 degrees north of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Southeast Asia, the Pacific Ocean and South America....

 to 20 degrees south latitude
20th parallel south
The 20th parallel south is a circle of latitude that is 20 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Australasia, the Pacific Ocean and South America....

. Its most remote sources are found on the inter-Andean
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...

 plateau, just a short distance from the Pacific Ocean.

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 (29.5 ft), flooding the surrounding forests, known as várzea
Freshwater swamp forest
Freshwater swamp forests, or flooded forests, are forests which are inundated with freshwater, either permanently or seasonally. They normally occur along the lower reaches of rivers and around freshwater lakes...

("flooded forests"). The Amazon's flooded forests are the most extensive example of this habitat type in the world. In an average dry season
Dry season
The dry season is a term commonly used when describing the weather in the tropics. The weather in the tropics is dominated by the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year...

, 110000 square kilometres (42,471.2 sq mi) of land are water-covered, while in the wet season
Wet season
The the wet season, or rainy season, is the time of year, covering one or more months, when most of the average annual rainfall in a region occurs. The term green season is also sometimes used as a euphemism by tourist authorities. Areas with wet seasons are dispersed across portions of the...

, the flooded area of the Amazon Basin rises to 350000 square kilometres (135,135.8 sq mi).

The quantity of water released by the Amazon to the Atlantic Ocean is enormous: up to 300000 m3/s in the rainy season, with an average of 209000 m3/s from 1973 to 1990. The Amazon is responsible for about 20% of the Earth's fresh water
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 entering the ocean. The river pushes a vast plume of fresh water into the ocean. The plume is about 400 kilometres (248.5 mi) long and between 100 and 200 km (62.1 and 124.3 mi) wide. The fresh water, being lighter, overrides the salty ocean, diluting the salinity and altering the color of the ocean surface over an area up to 1000000 square miles (2,589,988.1 km²) large. 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.

The tidal bore
Tidal bore
A tidal bore is a tidal phenomenon in which the leading edge of the incoming tide forms a wave of water that travel up a river or narrow bay against the direction of the river or bay's current...

 is the reason the Amazon does not have a protruding delta
River delta
A delta is a landform that is formed at the mouth of a river where that river flows into an ocean, sea, estuary, lake, reservoir, flat arid area, or another river. Deltas are formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river...

; the ocean rapidly carries away the vast volume of silt
Silt
Silt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar. Silt may occur as a soil or as suspended sediment in a surface water body...

 carried by the Amazon, making it impossible for a delta to grow past the shoreline.

There is a natural water union between the Amazon and the Orinoco
Orinoco
The Orinoco is one of the longest rivers in South America at . Its drainage basin, sometimes called the Orinoquia, covers , with 76.3% of it in Venezuela and the remainder in Colombia...

 basins, the so-called Casiquiare canal
Casiquiare canal
The Casiquiare river is a distributary of the upper Orinoco flowing southward into the Rio Negro, in Venezuela, South America. As such, it forms a unique natural canal between the Orinoco and Amazon river systems. It is the largest river on the planet that links two major river systems, a...

. The Casiquiare is a river distributary
Distributary
A distributary, or a distributary channel, is a stream that branches off and flows away from a main stream channel. They are a common feature of river deltas. The phenomenon is known as river bifurcation. The opposite of a distributary is a tributary...

 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 the planet that links two major river systems, a so called bifurcation.

Origins



has a series of major river systems in Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

, Ecuador and Peru, some of which flow into the Marañón
Marañón River
The Marañón River rises about 160 km to the northeast of Lima, Peru, flows through a deeply-eroded Andean valley in a northwesterly direction, along the eastern base of the Cordillera of the Andes, as far as 5 degrees 36' southern latitude; then it makes a great bend to the northeast, and...

 and Ucayali, others directly into the Amazon proper. Among others, these include the following rivers: Putumayo
Putumayo River
The Içá or Putumayo River is one of the tributaries of the Amazon River, west of and parallel to the Yapura. It forms part of Colombia's border with Ecuador, as well as most of the frontier with Peru...

, Caquetá
Caquetá
Caquetá may refer to:* Caquetá River, a river in Colombia* Caquetá Territory, a former territory of Colombia* Caquetá Department, a department of Colombia...

, Vaupés
Vaupés River
Vaupés River is a tributary of the Rio Negro in South America. It arises in the Guaviare Department of Colombia, flowing east through Guaviare and Vaupés Departments. It forms part of the international border between Colombia and the Amazonas state of Brazil. On the border it merges with the...

, Guainía, Morona
Morona
The Morona is a tributary to the Amazon River, and flows parallel to the Pastaza River and immediately to the west of it, and is the last stream of any importance on the northern side of the Amazon before reaching the Pongo de Manseriche....

, Pastaza
Pastaza River
The Pastaza is a large tributary to the Amazon River.It has its headwaters in the province of Tungurahua, where the Tambo River joins the Latacunga River, near the foot of the Volcano Tungurahua, flowing south-east towards the Amazon Basin...

, Nucuray, Urituyacu, Chambira, Tigre
Tigre River
The Tigre River is a Peruvian tributary of the Amazon River west of the Nanay, and is navigable for 125 miles from its confluence with the Amazon. It forms from the confluence of the Ecuadorian rivers Cunambo and Pintoyacu at the Peruvian border. Like the Nanay, it flows entirely on the plains. ...

, Nanay, Napo
Napo River
The Napo is a tributary to the Amazon River that rises in Ecuador on the flanks of the volcanoes of Antisana, Sincholagua and Cotopaxi.The total length of 1075 km. Catchment area of ​​100,518 square kilometers...

, and Huallaga
Huallaga River
The Huallaga River is a tributary of the Marañón River, part of the Amazon Basin. Old names for this river include Guallaga and Rio de los Motilones. The Huallaga is born on the slopes of the Andes in central Peru and joins the Marañón before the latter reaches the Ucayali River to form the Amazon....

.

The most distant source of the Amazon was established in 1996, 2001, 2007, and 2008, as a glacial stream on a snowcapped 5597 m (18,362.9 ft) peak called Nevado Mismi
Nevado Mismi
Nevado Mismi is a mountain peak of volcanic origin located in the Andes mountain range of Peru. A glacial stream on the Mismi was firmly identified as the most distant source of the Amazon River in 1996; this finding was confirmed in 2001 and again in 2007....

 in the Peruvian Andes
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...

, roughly 160 km (99.4 mi) west of Lake Titicaca
Lake Titicaca
Lake Titicaca is a lake located on the border of Peru and Bolivia. It sits 3,811 m above sea level, making it the highest commercially navigable lake in the world...

 and 700 km (435 mi) southeast of Lima
Lima
Lima is the capital and the largest city of Peru. It is located in the valleys of the Chillón, Rímac and Lurín rivers, in the central part of the country, on a desert coast overlooking the Pacific Ocean. Together with the seaport of Callao, it forms a contiguous urban area known as the Lima...

. The waters from Nevado Mismi flow into the Quebradas Carhuasanta
Carhuasanta
The Quebrada Carhuasanta is located in the Apurímac Region of Peru. It is known as the headwaters of the Amazon River. The brook is fed by the winter snows of Nevado Mismi, , some 6,400 kilometres from the Atlantic Ocean...

 and Apacheta, which flow into the Río Apurímac
Apurímac River
The Apurímac River rises from glacial meltwater of the ridge of Nevado Mismi, a mountain in the Arequipa Province in southern Peru.The Apurímac is the source of the world's largest river system, the Amazon River...

 which is a tributary of the Ucayali which later joins the Marañón
Marañón River
The Marañón River rises about 160 km to the northeast of Lima, Peru, flows through a deeply-eroded Andean valley in a northwesterly direction, along the eastern base of the Cordillera of the Andes, as far as 5 degrees 36' southern latitude; then it makes a great bend to the northeast, and...

 to form the Amazon proper. While the Ucayali–Marañón 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 Solimões
Solimões
Solimões is the name often given to early stretches of the Amazon River from the border of Brazil and Peru to its confluence with the Rio Negro.Further upstream from the border, the name of the river seems to depend on the speaker...

 das Águas
. Further downriver from that confluence the darkly colored waters of the Rio Negro meet the sandy colored Rio Solimões
Solimões
Solimões is the name often given to early stretches of the Amazon River from the border of Brazil and Peru to its confluence with the Rio Negro.Further upstream from the border, the name of the river seems to depend on the speaker...

, and for over 6 km (4 mi) these waters run side by side without mixing.

After the confluence of Río Apurímac
Apurímac River
The Apurímac River rises from glacial meltwater of the ridge of Nevado Mismi, a mountain in the Arequipa Province in southern Peru.The Apurímac is the source of the world's largest river system, the Amazon River...

 and Ucayali, the river leaves Andean terrain and is instead surrounded by floodplain
Floodplain
A floodplain, or flood plain, is a flat or nearly flat land adjacent a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge...

. From this point to the Marañón
Marañón River
The Marañón River rises about 160 km to the northeast of Lima, Peru, flows through a deeply-eroded Andean valley in a northwesterly direction, along the eastern base of the Cordillera of the Andes, as far as 5 degrees 36' southern latitude; then it makes a great bend to the northeast, and...

, some 1600 km (994.2 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
Amazon Rainforest
The Amazon Rainforest , also known in English as Amazonia or the Amazon Jungle, is a moist broadleaf forest that covers most of the Amazon Basin of South America...

.

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".
The Amazon River proper runs mostly through Brazil and Peru, it is part of the border between Colombia and Perú, and it has tributaries reaching into Venezuela, Colombia, Ecuador, and Bolivia.

Flooding


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 average depth of the Amazon between Manacapuru
Manacapuru
Manacapuru is a municipality located in the Brazilian state of Amazonas. Its population was 85,144 and its area is 7,329 km². It is also one of the biggest cities of the state, and shares its name with Rio Manacapuru, a tributary to the Amazon River....

 and Óbidos has been calculated as between 20 to 26 m (65.6 to 85.3 ft). At Manacapuru the Amazon's water level is only about 24 metres (78.7 ft) above mean sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...

. 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 m (65.6 to 164 ft), in some places as much as 100 metres (328.1 ft).

The main river is navigable for large ocean steamers to Manaus
Manaus
Manaus is a city in Brazil, the capital of the state of Amazonas. It is situated at the confluence of the Negro and Solimões rivers. It is the most populous city of Amazonas, according to the statistics of Brazilian Institute of Geography and Statistics, and is a popular ecotourist destination....

, 1500 kilometres (932.1 mi) upriver from the mouth. Smaller ocean vessels of 3,000 tons or 9,000 tons and 5.5 metres (18 ft) draft
Draft (hull)
The draft of a ship's hull is the vertical distance between the waterline and the bottom of the hull , with the thickness of the hull included; in the case of not being included the draft outline would be obtained...

 can reach as far as Iquitos
Iquitos
Iquitos is the largest city in the Peruvian rainforest, with a population of 370,962. It is the capital of Loreto Region and Maynas Province.Located on the Amazon River, it is only above sea level, although it is more than from the mouth of the Amazon at Belém on the Atlantic Ocean...

, Peru, 3600 kilometres (2,236.9 mi) from the sea. Smaller riverboats can reach 780 kilometres (484.7 mi) higher as far as Achual Point. Beyond that, small boats frequently ascend to the Pongo de Manseriche
Pongo de Manseriche
The Pongo de Manseriche is a gorge in northwest Peru. The Marañón River runs through this gorge before it reaches the Amazon Basin.The Pongo de Manseriche is 3 miles long, located at 4° 27' 30" south latitude and 77° 34' 51" west longitude, just below the mouth of the Rio Santiago, and between it...

, just above Achual Point.

Geography


At some points the river divides into anabranch
Anabranch
An anabranch is a section of a river or stream that diverts from the main channel or stem of the watercourse and rejoins the main stem downstream. Local anabranches can be the result of small islands in the watercourse...

s, or multiple channels, often very long, with inland and lateral channels
Stream channel
Stream channel is the physical confine of a stream consisting of a bed and stream banks.Stream channels exist in a variety of geometries. The stream channel development is controlled by both water and sediment movement. There is a difference between low gradient streams and high gradient streams...

, all connected by a complicated system of natural canals, cutting the low, flat igapó lands, which are never more than 5 metres (16.4 ft) above low river, into many islands.

From the town of Canaria at the great bend of the Amazon to the Negro, 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 (55.8 ft) above the river is backed by low hills. The lower Amazon seems to have once been a gulf
Headlands and bays
Headlands and bays are two related features of the coastal environment.- Geology and geography :Headlands and bays are often found on the same coastline. A bay is surrounded by land on three sides, whereas a headland is surrounded by water on three sides. Headlands are characterized by high,...

 of the Atlantic Ocean, the waters of which washed the cliffs near Óbidos.

Only about ten percent of the Amazon's water enters downstream of Óbidos, very little of which is from the northern slope of the valley. The drainage area of the Amazon Basin above Óbidos city is about 5000000 square kilometres (1,930,510.8 sq mi), and, below, only about 1000000 square kilometres (386,102.2 sq mi) (around 20%), exclusive of the 1400000 square kilometres (540,543 sq mi) of the Tocantins basin. The Tocantins River
Tocantins River
The Tocantins is a river in Brazil, the central fluvial artery of the country. In the Tupi language, its name means "toucan's beak" . It runs from south to north for about 2,640 km. It is not really a branch of the Amazon River, although usually so considered, since its waters flow into the...

 enters the Amazon very close to its mouth.

In the lower reaches of the river, the north bank consists of a series of steep, table-topped hills extending for about 240 kilometres (149.1 mi) from opposite the mouth of the Xingu as far as Monte Alegre
Monte Alegre, Pará
Monte Alegre, Pará is a town and municipality in the state of Pará in the Northern region of Brazil.-References:...

. These hills are cut down to a kind of terrace
Terrace (agriculture)
Terraces are used in farming to cultivate sloped land. Graduated terrace steps are commonly used to farm on hilly or mountainous terrain. Terraced fields decrease erosion and surface runoff, and are effective for growing crops requiring much water, such as rice...

 which lies between them and the river.

On the south bank, above the Xingu, an almost-unbroken line of low bluffs bordering the floodplain extends nearly to Santarém in a series of gentle curves before they bend to the southwest, and, abutting upon the lower Tapajós, merge into the bluffs which form the terrace margin of the Tapajós river valley.

Mouth



The definition of where exactly the mouth of the Amazon is located, and how wide it is, a matter of dispute, because of the area's peculiar geography. The Pará and the Amazon are connected by a series of river channels called furos near the town of Breves
Breves, Brazil
Breves is a Brazilian municipality located in the state of Pará. Its population as of 2008 is estimated to be 99,223 people. The area of the municipality is 9,550.454km². The city belongs to the mesoregion Marajó and to the microregion of Furos de Breves....

; between them lies Marajó
Marajó
Marajó is an island located at the mouth of the Amazon River in Brazil. It is part of the state of Pará.- Geography :With a land area of 40,100 km² , which compares to the size of Switzerland, it is the largest island to be completely surrounded by freshwater in the world...

, an island almost the size of Switzerland that is the world's largest combined river/sea island.

If the Pará river and the Marajó island ocean frontage are included, the Amazon estuary
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....

 is some 325 kilometres (201.9 mi) wide. In this case, the width of the mouth of the river is usually measured from Cable Note, in the Brazilian state of Amapá
Amapá
Amapá is one of the states of Brazil, located in the extreme north, bordering French Guiana and Suriname to the north. To the east is the Atlantic Ocean, and to the south and west is the Brazilian state of Pará. Perhaps one of the main features of the state is the River Oiapoque, as it was once...

, to Ponta da Tijoca near the town of Curuçá
Curuçá
Curuçá is a town and municipality in the state of Pará in the Northern region of Brazil.-See also:* Curuçá River* Vila Curuçá * List of municipalities in Pará-References:...

, in the state of Pará
Pará
Pará is a state in the north of Brazil. It borders the Brazilian states of Amapá, Maranhão, Tocantins, Mato Grosso, Amazonas and Roraima. To the northwest it also borders Guyana and Suriname, and to the northeast it borders the Atlantic Ocean. The capital is Belém.Pará is the most populous state...

. By this criterion, the Amazon is wider at its mouth than the entire length of the River Thames
River Thames
The River Thames flows through southern England. It is the longest river entirely in England and the second longest in the United Kingdom. While it is best known because its lower reaches flow through central London, the river flows alongside several other towns and cities, including Oxford,...

 in England.

A more conservative measurement excluding the Pará river estuary, from the mouth of the Araguari River
Araguari River (Amapá)
Araguari River is the primary river of Amapá state in north-eastern Brazil.Araguari River is the primary river of Amapá state in north Brazil.-References:*...

 to Ponta do Navio on the northern coast of Marajó, would still give the mouth of the Amazon a width of over 180 kilometres (111.8 mi). If only the river's main channel is considered, between the islands of Curuá (state of Amapá) and Jurupari (state of Pará), the width falls to about 15 kilometres (9.3 mi).

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 5400000 square kilometres (2,084,951.7 sq mi). It is the richest tropical forest in the world in terms of biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...

. There are over 2,100 species of fish currently recognized in the Amazon Basin, with more being discovered every year

Mammals. Along with the Orinoco
Orinoco
The Orinoco is one of the longest rivers in South America at . Its drainage basin, sometimes called the Orinoquia, covers , with 76.3% of it in Venezuela and the remainder in Colombia...

, the Amazon is one of the main habitats of the boto
Boto
The Amazon river dolphin, alternatively Bufeo, Bufeo Colorado, Boto Cor de Rosa, Boutu, Nay, Tonina, or Pink Dolphin , is a freshwater river dolphin endemic to the Orinoco, Amazon and Araguaia/Tocantins River systems of Brazil, Bolivia, Peru, Ecuador, Colombia and Venezuela...

, 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 (8.5 ft). The color of its skin changes with age. It varies from gray when it is young, to pink and white as it matures. The dolphins use sonar to navigate and hunt in the river's tricky depths. The boto is the subject of a very famous legend in Brazil about a dolphin that turns into a man and seduces maidens by the riverside. The tucuxi
Tucuxi
The Tucuxi , alternately bufeo gris or bufeo negro is a dolphin found in the rivers of the Amazon Basin. The word "tucuxi" is derived from the Tupi language word tuchuchi-ana and has now been adopted as the species' common name...

 (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
Amazonian Manatee
The Amazonian Manatee is a species of manatee that lives in the freshwater habitats of the Amazon basin. They are found in Brazil, Peru, Colombia, Ecuador, Guyana and Venezuela. Amazonian manatees are aquatic animals of the Sirenia order and are also known as "seacows". Their colour is grey but...

 (Trichechus inunguis) also known as “seacow” is found in the northern Amazon River Basin and its tributaries. It is a mammal and a herbivore. Its population is limited to fresh water habitats and unlike other manatees, they do not venture into salt water. It is classified as vulnerable by the IUCN. The Amazon and its tributaries are the main habitat of the Giant Otter
Giant Otter
The giant otter is a South American carnivorous mammal. It is the longest member of the Mustelidae, or weasel family, a globally successful group of predators. Unusually for a mustelid, the giant otter is a social species, with family groups typically supporting three to eight members...

 (Pteronura brasiliensis). The giant otter 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.

Reptiles. The anaconda
Anaconda
An anaconda is a large, non-venomous snake found in tropical South America. Although the name actually applies to a group of snakes, it is often used to refer only to one species in particular, the common or green anaconda, Eunectes murinus, which is one of the largest snakes in the world.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. In addition to the thousands of species of fish, the river supports crabs, algae, and turtles.

Fish. The Amazonian fish fauna is the center of diversity for Neotropical fishes
Neotropical fishes
The freshwater fishes of tropical South and Central America represent one of the most diverse aquatic ecosystems on Earth, with more than 5,600 species, representing about 10% all living vertebrate species...

, of which more than 5,600 species are currently known (Albert and Reis, 2011). The bull shark
Bull shark
The bull shark, Carcharhinus leucas, also known as Zambezi shark or unofficially known as Zambi in Africa and Nicaragua shark in Nicaragua, is a shark common worldwide in warm, shallow waters along coasts and in rivers...

 (Carcharhinus leucas) has been reported 4000 kilometres (2,485.5 mi) up the Amazon River at Iquitos
Iquitos
Iquitos is the largest city in the Peruvian rainforest, with a population of 370,962. It is the capital of Loreto Region and Maynas Province.Located on the Amazon River, it is only above sea level, although it is more than from the mouth of the Amazon at Belém on the Atlantic Ocean...

 in Peru. The arapaima
Arapaima
The arapaima, pirarucu, or paiche is a South American tropical freshwater fish. It is a living fossil and one of the largest freshwater fishes in the world.-Anatomy and morphology:...

, known in Brazil as the pirarucu (Arapaima gigas), is a South American tropical freshwater fish
Freshwater fish
Freshwater fish are fish that spend some or all of their lives in freshwater, such as rivers and lakes, with a salinity of less than 0.05%. These environments differ from marine conditions in many ways, the most obvious being the difference in levels of salinity...

. It is one of the largest fresh water fish in the world, reportedly with a maximum length in excess of 4.5 metres (14.8 ft) and weight up to 200 kilograms (440.9 lb). Another Amazonian fresh water fish is the arowana
Arowana
Arowanas are freshwater bony fish of the family Osteoglossidae, also known as bonytongues. In this family of fishes, the head is bony and the elongate body is covered by large, heavy scales, with a mosaic pattern of canals. The dorsal and the anal fins have soft rays and are long based, while the...

 (or aruanã in Portuguese), such as the Silver arowana
Silver arowana
The silver arowana, Osteoglossum bicirrhosum, sometimes spelled arawana, is a freshwater bony fish of the family Osteoglossidae, commonly kept in aquaria...

 (Osteoglossum bicirrhosum), which is also a predator and very similar to the arapaima, but only reaches a length of maximum 120 centimetres (47.2 in). Also present in large numbers is the notorious piranha
Piranha
A piranha or piraña is a member of family Characidae in order Characiformes, an omnivorous freshwater fish that inhabits South American rivers. In Venezuela, they are called caribes...

, a carnivorous fish which congregates in large schools, and may attack livestock and even humans. There are approximately from 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 candirú
Candirú
‎Candiru or candirú , also known as cañero, toothpick fish, or vampire fish, are a number of genera of parasitic freshwater catfish in the family Trichomycteridae; all are native to the Amazon River...

 are a number of general parasitic, fresh water catfish
Catfish
Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...

 in the family Trichomycteridae
Trichomycteridae
Trichomycteridae is a family of catfishes commonly known as the pencil or parasitic catfishes. This family includes the infamous candiru fish, feared by some people for its alleged habit of entering into the urethra of humans....

; all are native to the Amazon River. The strongly electric electric eel
Electric eel
The electric eel , is an electric fish, and the only species of the genus Electrophorus. It is capable of generating powerful electric shocks, of up to six hundred volts, which it uses for both hunting and self-defense. It is an apex predator in its South American range...

 (Electrophorus electricus) and more than 100 species of weakly-electric fishes Gymnotiformes
Gymnotiformes
The Gymnotiformes are a group of teleost bony fishes commonly known as the Neotropical or South American knifefishes. They have long bodies and swim using undulations of their elongated anal fin...

 also inhabit the Amazon Basin.

Colonial encounters



During what many archaeologists call the formative period, Amazonian societies were deeply involved in the emergence of South America's highland agrarian
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

 systems, and possibly contributed directly to the social and religious fabric constitutive of the Andean civilizational orders.

In 1500, Vicente Yáñez Pinzón
Vicente Yáñez Pinzón
Vicente Yáñez Pinzón was a Spanish navigator, explorer, and conquistador, the youngest of the Pinzón brothers...

 was the first European to sail into the river. Pinzón called the river flow Río Santa María del Mar Dulce, later shortened to Mar Dulce (literally, sweet sea, because of its fresh water pushing out into the ocean). For 350 years after the first European encounter of the Amazon by Pinzón, the Portuguese portion of the basin remained an untended former food gathering and planned agricultural landscape occupied by the indigenous peoples
Indigenous peoples
Indigenous peoples are ethnic groups that are defined as indigenous according to one of the various definitions of the term, there is no universally accepted definition but most of which carry connotations of being the "original inhabitants" of a territory....

 who survived the arrival of European diseases. There is ample evidence for complex large-scale, pre-Columbian social formations, including chiefdom
Chiefdom
A chiefdom is a political economy that organizes regional populations through a hierarchy of the chief.In anthropological theory, one model of human social development rooted in ideas of cultural evolution describes a chiefdom as a form of social organization more complex than a tribe or a band...

s, 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 Marajó
Marajó
Marajó is an island located at the mouth of the Amazon River in Brazil. It is part of the state of Pará.- Geography :With a land area of 40,100 km² , which compares to the size of Switzerland, it is the largest island to be completely surrounded by freshwater in the world...

 may have developed social stratification
Social stratification
In sociology the social stratification is a concept of class, involving the "classification of persons into groups based on shared socio-economic conditions ... a relational set of inequalities with economic, social, political and ideological dimensions."...

 and supported a population of 100,000 people. The Native Americans of the Amazon rain forest may have used Terra preta
Terra preta
Terra preta is a type of very dark, fertile anthropogenic soil found in the Amazon Basin. Terra preta owes its name to its very high charcoal content, and was indeed made by adding a mixture of charcoal, bone, and manure to the otherwise relatively infertile Amazonian soil, and stays there for...

 to make the land suitable for the large scale agriculture needed to support large populations and complex social formations such as chiefdoms.

One of Gonzalo Pizarro
Gonzalo Pizarro
Gonzalo Pizarro y Alonso was a Spanish conquistador and younger paternal half-brother of Francisco Pizarro, the conqueror of the Inca Empire...

's lieutenants, Francisco de Orellana
Francisco de Orellana
Francisco de Orellana was a Spanish explorer and conquistador. He completed the first known navigation of the length of the Amazon River, which was originally named for him...

, set off in 1541 to explore east of Quito
Quito
San Francisco de Quito, most often called Quito , is the capital city of Ecuador in northwestern South America. It is located in north-central Ecuador in the Guayllabamba river basin, on the eastern slopes of Pichincha, an active stratovolcano in the Andes mountains...

 into the South American interior in search of El Dorado
El Dorado
El Dorado is the name of a Muisca tribal chief who covered himself with gold dust and, as an initiation rite, dived into a highland lake.Later it became the name of a legendary "Lost City of Gold" that has fascinated – and so far eluded – explorers since the days of the Spanish Conquistadors...

 and the "Country of Cinnamon
Cinnamon
Cinnamon is a spice obtained from the inner bark of several trees from the genus Cinnamomum that is used in both sweet and savoury foods...

". He was ordered to follow the Coca River
Coca River
The Coca River is a river in eastern Ecuador. It is a tributary of the Napo River. The two rivers join in Puerto Francisco de Orellana....

 and return when the river reached its confluence. After 170 km, the Coca River joined the Napo River
Napo River
The Napo is a tributary to the Amazon River that rises in Ecuador on the flanks of the volcanoes of Antisana, Sincholagua and Cotopaxi.The total length of 1075 km. Catchment area of ​​100,518 square kilometers...

 (at a point now known as Puerto Francisco de Orellana), and his men threatened to mutiny if he followed his orders and the expedition turned back. On 26 December 1541, he accepted to change the purpose of the expedition to the conquest of new lands in the name of the King of Spain, and the 49 men built a larger boat in which to navigate downstream. After a journey of 600 km down the Napo River, constantly threatened by the Omaguas, they reached a further major confluence, at a point near modern Iquitos
Iquitos
Iquitos is the largest city in the Peruvian rainforest, with a population of 370,962. It is the capital of Loreto Region and Maynas Province.Located on the Amazon River, it is only above sea level, although it is more than from the mouth of the Amazon at Belém on the Atlantic Ocean...

, and then followed what is now known as the Amazon River for a further 1200 km to its confluence with the Rio Negro (near modern Manaus
Manaus
Manaus is a city in Brazil, the capital of the state of Amazonas. It is situated at the confluence of the Negro and Solimões rivers. It is the most populous city of Amazonas, according to the statistics of Brazilian Institute of Geography and Statistics, and is a popular ecotourist destination....

), which they reached on 3 June 1542. This area around the Amazon was dominated by the Icamiaba natives, who were mistaken for fierce female warriors by the members of the expedition. Orellana later narrated the belligerent victory of the Icamiaba “women” over the Spanish invaders to Charles V, Holy Roman Emperor
Charles V, Holy Roman Emperor
Charles V was ruler of the Holy Roman Empire from 1519 and, as Charles I, of the Spanish Empire from 1516 until his voluntary retirement and abdication in favor of his younger brother Ferdinand I and his son Philip II in 1556.As...

, who, recalling the Amazons
Amazons
The Amazons are a nation of all-female warriors in Greek mythology and Classical antiquity. Herodotus placed them in a region bordering Scythia in Sarmatia...

 of Greek mythology, baptized the river Amazonas, the name by which it is still known in both Spanish and Portuguese. At the time, however, the river was referred to by the expedition as Grande Río ("Great River"), Mar Dulce ("Fresh Water Sea") or Río de la Canela ("Cinnamon River"). Orellana claimed that he had found great cinnamon trees there, in other words a source of one of the most important spices reaching Europe from the East. In fact, true cinnamon (Cinnamomum verum) is not native to South America. Other related cinnamon-containing plants (of the family Lauraceae) do occur and Orellana must have observed some of these. The expedition continued a further 1200 km to the mouth of the Amazon, which it reached on 24 August 1542, demonstrating the practical navigability of the Great River. This was surely one of the most improbably successful voyages in known history.

In 1560 another Spanish conquistador
Conquistador
Conquistadors were Spanish soldiers, explorers, and adventurers who brought much of the Americas under the control of Spain in the 15th to 16th centuries, following Europe's discovery of the New World by Christopher Columbus in 1492...

, Lope de Aguirre
Lope de Aguirre
Lope de Aguirre was a Basque Spanish conquistador in South America. Nicknamed El Loco, 'the Madman', Aguirre is best known for his final expedition, down the Amazon river, in search of the mythical El Dorado...

, made the second descent of the Amazon.

In 1637–47 the Portuguese explorer Pedro Teixeira
Pedro Teixeira
Pedro Teixeira was a Portuguese explorer who became, in 1637, the first European to travel up the entire length of the Amazon River....

 was the first European to ascend the river from Belém, near the mouth, to Quito
Quito
San Francisco de Quito, most often called Quito , is the capital city of Ecuador in northwestern South America. It is located in north-central Ecuador in the Guayllabamba river basin, on the eastern slopes of Pichincha, an active stratovolcano in the Andes mountains...

, part of the Spanish Viceroyalty of Peru
Viceroyalty of Peru
Created in 1542, the Viceroyalty of Peru was a Spanish colonial administrative district that originally contained most of Spanish-ruled South America, governed from the capital of Lima...

, and then to return the same way. Teixeira's expedition was massive—some 2000 people in 37 large canoes. From 1648 to 1652, António Raposo Tavares
Antonio Raposo Tavares
António Raposo Tavares o Velho was a Portuguese colonial bandeirante who explored mainland eastern South America and claimed it for Portugal, extending the territory of the colony beyond the limits imposed by the treaty of Tordesillas...

 lead one of the longest known expeditions from São Paulo
São Paulo
São Paulo is the largest city in Brazil, the largest city in the southern hemisphere and South America, and the world's seventh largest city by population. The metropolis is anchor to the São Paulo metropolitan area, ranked as the second-most populous metropolitan area in the Americas and among...

 to the mouth of the Amazon, investigating many of its tributaries, including the Rio Negro, and covering a distance of more than 10000 km (6,214 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
Urarina
The Urarina are an indigenous people of the Peruvian Amazon Basin who inhabit the Chambira, Urituyacu, and Corrientes Rivers. According to both archaeological and historical sources, they have resided in the Chambira Basin of contemporary northeastern Peru for centuries. The Urarina refer to...

. Father Fritz
Samuel Fritz
Samuel Fritz was a Czech Jesuit missionary, noted for his exploration of the Amazon River and its basin.-Life:Fritz was born at Trautenau, Bohemia. He joined the Society of Jesus in 1673. In 1684 he was sent to Quito as a missionary. For forty-two years Fritz acted in this capacity among the...

, apostle of the Omaguas, established some forty mission villages. Charles Marie de La Condamine
Charles Marie de La Condamine
Charles Marie de La Condamine was a French explorer, geographer, and mathematician. He spent ten years in present-day Ecuador measuring the length of a degree latitude at the equator and preparing the first map of the Amazon region based on astronomical observations.-Biography:Charles Marie de La...

 accomplished the first scientific exploration of the Amazon River.

Many indigenous tribes engaged in constant warfare. According to James Stuart Olson, "The Munduruku
Munduruku
The Munduruku are an indigenous people of Brazil living in the Amazon River basin. Some Mundurucu communities are part of the Coatá-Laranjal Indigenous Land. They had an estimated population in 2010 of 11,640.-History:...

 expansion dislocated and displaced the Kawahib, 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."

The Cabanagem
Cabanagem
The Cabanagem was a social revolt that occurred in the then-province of Grão-Pará, Brazil.Among the causes for this revolt were the extreme poverty of the Paraense people and the political irrelevance to which the province was relegated after the independence of Brazil.The name "Cabanagem" refers...

, one of the bloodiest regional wars ever in Brazil, which was chiefly directed against the white ruling class, reduced the population of Pará
Pará
Pará is a state in the north of Brazil. It borders the Brazilian states of Amapá, Maranhão, Tocantins, Mato Grosso, Amazonas and Roraima. To the northwest it also borders Guyana and Suriname, and to the northeast it borders the Atlantic Ocean. The capital is Belém.Pará is the most populous state...

 from about 100,000 to 60,000.

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. The Brazilian Amazon's principal commercial city, Pará (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 a population between 1,000 to 1,500. All the remaining villages, as far up as Tabatinga
Tabatinga
Tabatinga is a municipality in the Três Fronteiras area of Northwestern Brazil. It is located in the Brazilian state of Amazonas. Its population was 45,293...

, on the Brazilian frontier of Peru, were relatively small.

Post-colonial history


On 6 September 1850 the emperor, Pedro II
Pedro II of Brazil
Dom Pedro II , nicknamed "the Magnanimous", was the second and last ruler of the Empire of Brazil, reigning for over 58 years. Born in Rio de Janeiro, he was the seventh child of Emperor Dom Pedro I of Brazil and Empress Dona Maria Leopoldina and thus a member of the Brazilian branch of...

, sanctioned a law authorizing steam navigation on the Amazon, and gave the Viscount of Mauá (Irineu Evangelista de Sousa
Irineu Evangelista de Sousa
Irineu Evangelista de Sousa, the Viscount of Mauá was a Brazilian entrepreneur, industrialist, banker and politician. He was called the Rothschild of the South American continent by the New York Times in 1871. He received the titles of baron and visconde com grandeza of Mauá...

) the task of putting it into effect. He organized the "Companhia de Navegação e Comércio do Amazonas" in 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 Pará and Cametá. 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 31 July 1867 the government of Brazil, constantly pressed by the maritime powers and by the countries encircling the upper Amazon basin, especially Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....

, decreed the opening of the Amazon to all flags; but limited this to certain defined points: Tabatinga – on the Amazon; Cametá – on the Tocantins; Santarém – on the Tapajós; Borba – on the Madeira, and Manaus – on the Rio Negro. The Brazilian decree took effect on 7 September 1867.

Thanks in part to the mercantile development associated with steamboat
Steamboat
A steamboat or steamship, sometimes called a steamer, is a ship in which the primary method of propulsion is steam power, typically driving propellers or paddlewheels...

 navigation, coupled with the internationally driven demand for natural rubber (1880–1920), Manáos (now Manaus) and Pará (now Belém) in (Brazil), and Iquitos
Iquitos
Iquitos is the largest city in the Peruvian rainforest, with a population of 370,962. It is the capital of Loreto Region and Maynas Province.Located on the Amazon River, it is only above sea level, although it is more than from the mouth of the Amazon at Belém on the Atlantic Ocean...

, Peru became thriving, cosmopolitan centers of commerce and spectacular—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 boomtown was known abroad as the St. Louis
St. Louis, Missouri
St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...

 of the Amazon. Foreign companies settled in this city, from where 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
Rubber boom
The rubber boom was an important part of the economic and social history of Brazil and Amazonian regions of neighboring countries, being related with the extraction and commercialization of rubber...

 it is estimated that diseases brought by immigrants such as typhus
Typhus
Epidemic typhus is a form of typhus so named because the disease often causes epidemics following wars and natural disasters...

 or malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...

 killed 40,000 native Amazonians.

The first direct foreign trade with Manaus 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, Purus and many other tributaries, such as the Marañón to ports as distant as Nauta
Nauta
Nauta is a bustling small town situated in the northeastern area of the Peruvian Amazon roughly 100 km south of the Province's capital, Iquitos...

, Peru. The Amazon Steam Navigation Company had 38 vessels.

By the turn of the 20th century, the principal exports of the Amazon Basin were India-rubber, cacao beans, Brazil nut
Brazil Nut
The Brazil nut is a South American tree in the family Lecythidaceae, and also the name of the tree's commercially harvested edible seed.- Order :...

s and a few other products of minor importance, such as pelts
Fur
Fur is a synonym for hair, used more in reference to non-human animals, usually mammals; particularly those with extensives body hair coverage. The term is sometimes used to refer to the body hair of an animal as a complete coat, also known as the "pelage". Fur is also used to refer to animal...

 and exotic forest produce (resin
Resin
Resin in the most specific use of the term is a hydrocarbon secretion of many plants, particularly coniferous trees. Resins are valued for their chemical properties and associated uses, such as the production of varnishes, adhesives, and food glazing agents; as an important source of raw materials...

s, barks, woven hammock
Hammock
A hammock is a sling made of fabric, rope, or netting, suspended between two points, used for swinging, sleeping, or resting. It normally consists of one or more cloth panels, or a woven network of twine or thin rope stretched with ropes between two firm anchor points such as trees or posts....

s, prized bird feather
Feather
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...

s, live animals, etc.) and extracted goods (lumber
Lumber
Lumber or timber is wood in any of its stages from felling through readiness for use as structural material for construction, or wood pulp for paper production....

, gold, etc.).

20th and 21st century concerns


Four centuries after the European discovery of the Amazon river, the total cultivated area in its basin was probably less than 65 square kilometres (25.1 sq 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 Getúlio Vargas
Getúlio Vargas
Getúlio Dornelles Vargas served as President of Brazil, first as dictator, from 1930 to 1945, and in a democratically elected term from 1951 until his suicide in 1954. Vargas led Brazil for 18 years, the most for any President, and second in Brazilian history to Emperor Pedro II...

, 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 Brasília
Brasília
Brasília is the capital city of Brazil. The name is commonly spelled Brasilia in English. The city and its District are located in the Central-West region of the country, along a plateau known as Planalto Central. It has a population of about 2,557,000 as of the 2008 IBGE estimate, making it the...

 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 Brasília 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 the Trans-Amazonian highway
Trans-Amazonian highway
The Trans-Amazonian Highway , was inaugurated on August 30, 1972. It is 5,300 km long, making it the third longest highway in Brazil...

 (Transamazônica) 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
Porto Velho
Porto Velho is the capital of the Brazilian state of Rondônia, in the upper Amazon River basin. The population is estimated to be 426,558 people...

), 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 current population of 1.8 million people, Manaus is the Amazon’s largest city. Manaus alone represents 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
Pardo
In Brazil, Pardo is a race/colour category used by the Brazilian Institute of Geography and Statistics in Brazilian censuses. It is a Portuguese word that encompasses various shades of brown, but is usually translated as "grayish-brown"...

 (Mulatto and mestizo) and 32% White
White Brazilian
White Brazilians make up 48.4% of Brazil's population, or around 92 million people, according to the IBGE's 2008 PNAD . Whites are present in the entire territory of Brazil, although the main concentrations are found in the South and Southeastern parts of the country...

.

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 6259 and 6800 km (3,889.2 and 4,225.3 mi) long. It is often said to be "at least" 6400 kilometres (3,976.8 mi) long. The Nile is reported to be anywhere from 5499 to 6690 km (3,416.9 to 4,157 mi). Often it is said to be "about" 6650 kilometres (4,132.1 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
Nevado Mismi
Nevado Mismi is a mountain peak of volcanic origin located in the Andes mountain range of Peru. A glacial stream on the Mismi was firmly identified as the most distant source of the Amazon River in 1996; this finding was confirmed in 2001 and again in 2007....

, which in 2001 was labeled by the National Geographic Society
National Geographic Society
The National Geographic Society , headquartered in Washington, D.C. in the United States, is one of the largest non-profit scientific and educational institutions in the world. Its interests include geography, archaeology and natural science, the promotion of environmental and historical...

 as the Amazon's source, these scientists made new calculations of the Amazon's length. They calculated the Amazon's length as 6992 kilometres (4,344.6 mi). Using the same techniques they calculated the length of the Nile as 6853 kilometres (4,258.3 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 Marajó and finally including the marine Waters of the Río Pará 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
Rede Globo
Rede Globo , or simply Globo, is a Brazilian television network, launched by media mogul Roberto Marinho on April 26, 1965. It is owned by media conglomerate Organizações Globo, being by far the largest of its holdings...

 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. As of 2010 the length of both the Amazon and the Nile remains open to interpretation and continued debate.

Scientists have discovered the longest underground river in the world, in Brazil, running for a length of 6,000 km at a depth of nearly 4 km. 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 at a recent meeting of the Brazilian Geophysical Society in Rio de Janeiro
Rio de Janeiro
Rio de Janeiro , commonly referred to simply as Rio, is the capital city of the State of Rio de Janeiro, the second largest city of Brazil, and the third largest metropolitan area and agglomeration in South America, boasting approximately 6.3 million people within the city proper, making it the 6th...

. The river ‘Hamza,' named after the discoverer, an Indian-born scientist Valiya Mannathal 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. If the slowing down of certain seismic waves caused by the damp spot helped uncover the underground ocean, the unusual temperature variation with depth measured in 241 inactive oil wells helped locate the subterranean river. 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 former is 1 km to 100 km wide, the latter is 200 km to 400 km in width. But the flow speed is five meters per second in the Amazon and less than a millimeter per second speed in the Hamza.

Several geological factors have played a vital role in the formation and existence of these subterranean water bodies. The underground ocean, discovered in 2007, has been formed when the plate carrying the Pacific Ocean bottom gets 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 153 km-long underground river in Mexico's Yucatán Peninsula and the 8.2 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 drills its way downward by dissolving the carbonate rock to form an extensive underground river system.

Major tributaries


The Amazon has over 1,100 tributaries
Tributary
A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

, 17 of which are over 1500 kilometres (932.1 mi) long. Some of the more notable ones are:
  • Branco
    Branco River
    The Rio Branco is the principal affluent of the Rio Negro from the north; it is enriched by many streams from the sierras which separate Venezuela and Guyana from Brazil. Its two upper main tributaries are the Urariquira and the Takutu...

  • Casiquiare canal
    Casiquiare canal
    The Casiquiare river is a distributary of the upper Orinoco flowing southward into the Rio Negro, in Venezuela, South America. As such, it forms a unique natural canal between the Orinoco and Amazon river systems. It is the largest river on the planet that links two major river systems, a...

  • Caqueta River
  • Huallaga
    Huallaga River
    The Huallaga River is a tributary of the Marañón River, part of the Amazon Basin. Old names for this river include Guallaga and Rio de los Motilones. The Huallaga is born on the slopes of the Andes in central Peru and joins the Marañón before the latter reaches the Ucayali River to form the Amazon....

  • Putumayo (or Içá River)
    Putumayo River
    The Içá or Putumayo River is one of the tributaries of the Amazon River, west of and parallel to the Yapura. It forms part of Colombia's border with Ecuador, as well as most of the frontier with Peru...

  • Javary
 
  • Jurua
  • Madeira
    Madeira River
    The Madeira River is a major waterway in South America, approximately 3,250 km miles long The Madeira is the biggest tributary of the Amazon...

  • Marañón
    Marañón River
    The Marañón River rises about 160 km to the northeast of Lima, Peru, flows through a deeply-eroded Andean valley in a northwesterly direction, along the eastern base of the Cordillera of the Andes, as far as 5 degrees 36' southern latitude; then it makes a great bend to the northeast, and...

  • Morona
    Morona
    The Morona is a tributary to the Amazon River, and flows parallel to the Pastaza River and immediately to the west of it, and is the last stream of any importance on the northern side of the Amazon before reaching the Pongo de Manseriche....

  • Nanay
  • Napo
    Napo River
    The Napo is a tributary to the Amazon River that rises in Ecuador on the flanks of the volcanoes of Antisana, Sincholagua and Cotopaxi.The total length of 1075 km. Catchment area of ​​100,518 square kilometers...

  •  
  • Negro
  • Pastaza
    Pastaza River
    The Pastaza is a large tributary to the Amazon River.It has its headwaters in the province of Tungurahua, where the Tambo River joins the Latacunga River, near the foot of the Volcano Tungurahua, flowing south-east towards the Amazon Basin...

  • Purus
  • Tambo
  • Tapajós
    Tapajós
    The Tapajós, a Brazilian river running through a humid and hot valley, pours into the Amazon River 500 miles above Pará and is about 1200 miles long.It rises on the lofty Brazilian plateau near Diamantino in 14 degrees 25' south latitude...

  • Tigre
    Tigre River
    The Tigre River is a Peruvian tributary of the Amazon River west of the Nanay, and is navigable for 125 miles from its confluence with the Amazon. It forms from the confluence of the Ecuadorian rivers Cunambo and Pintoyacu at the Peruvian border. Like the Nanay, it flows entirely on the plains. ...

  •  
  • Tocantins
    Tocantins River
    The Tocantins is a river in Brazil, the central fluvial artery of the country. In the Tupi language, its name means "toucan's beak" . It runs from south to north for about 2,640 km. It is not really a branch of the Amazon River, although usually so considered, since its waters flow into the...

  • Trombetas
    Trombetas
    The Trombetas is a river on the northern side of the Amazon River. Its confluence with the Amazon is just north of the town of Óbidos, Pará in Brazil. It has its sources in the Guyana highlands, but its long course is frequently interrupted by violent currents, rocky barriers, and rapids...

  • Ucayali
  • Xingu
    Xingu River
    The Xingu River , also called Rio Xingu, is a 1,230-mile long, river in north Brazil; it is a southeast tributary of the Amazon River.-Description and history:...

  • Yapura
    Japurá River
    The Japurá River or Caquetá River is a river about long rising as the Caquetá River in the Andes in the Southwest of Colombia. It flows southeast into Brazil, where it is called the Japurá. The Japurá enters the Amazon River through a network of channels...


  • List by length

    1. 6259.2 km (3,889.3 mi) to 6712 km (4,170.7 mi) – Amazon, South America
    2. 3250 km (2,019.5 mi) – Madeira
      Madeira River
      The Madeira River is a major waterway in South America, approximately 3,250 km miles long The Madeira is the biggest tributary of the Amazon...

      , Bolivia/Brazil
    3. 3211 km (1,995.2 mi) – Purus, Peru/Brazil
    4. 2820 km (1,752.3 mi) – Yapura
      Japurá River
      The Japurá River or Caquetá River is a river about long rising as the Caquetá River in the Andes in the Southwest of Colombia. It flows southeast into Brazil, where it is called the Japurá. The Japurá enters the Amazon River through a network of channels...

      , Colombia/Brazil
    5. 2639 km (1,639.8 mi) – Tocantins
      Tocantins River
      The Tocantins is a river in Brazil, the central fluvial artery of the country. In the Tupi language, its name means "toucan's beak" . It runs from south to north for about 2,640 km. It is not really a branch of the Amazon River, although usually so considered, since its waters flow into the...

      , Brazil
    6. 2627 km (1,632.3 mi) – Araguaia
      Araguaia River
      The Araguaia River or, in Portuguese, Rio Araguaia is one of the major rivers of Brazil, and the principal tributary of the Tocantins. It has a total length of approximately 2,627 km. Araguaia means "river of macaws" in the Tupi language....

      , Brazil (tributary of Tocantins)
    7. 2400 km (1,491.3 mi) – Juruá, Peru/Brazil
    8. 2250 km (1,398.1 mi) – Rio Negro, Brazil/Venezuela/Colombia
    9. 1992 km (1,237.8 mi) – Tapajós
      Tapajós
      The Tapajós, a Brazilian river running through a humid and hot valley, pours into the Amazon River 500 miles above Pará and is about 1200 miles long.It rises on the lofty Brazilian plateau near Diamantino in 14 degrees 25' south latitude...

      , Brazil
    10. 1979 km (1,229.7 mi) – Xingu
      Xingu River
      The Xingu River , also called Rio Xingu, is a 1,230-mile long, river in north Brazil; it is a southeast tributary of the Amazon River.-Description and history:...

      , Brazil
    11. 1900 km (1,180.6 mi) – Ucayali River, Peru
    12. 1749 km (1,086.8 mi) – Guaporé
      Guaporé River
      Rio Guaporé is the name of a river in western Brazil along the Bolivian border. Its Bolivian name is Río Iténez.The river has its source in the Brazilian Mato Grosso circa 150 km northeast of Pontes e Lacerda. From this town on it flows in a westerly direction for about 120 km, where at...

      , Brazil/Bolivia (tributary of Madeira)
    13. 1575 km (978.7 mi) – Içá (Putumayo)
      Putumayo River
      The Içá or Putumayo River is one of the tributaries of the Amazon River, west of and parallel to the Yapura. It forms part of Colombia's border with Ecuador, as well as most of the frontier with Peru...

      , South America
    14. 1415 km (879.2 mi) – Marañón
      Marañón River
      The Marañón River rises about 160 km to the northeast of Lima, Peru, flows through a deeply-eroded Andean valley in a northwesterly direction, along the eastern base of the Cordillera of the Andes, as far as 5 degrees 36' southern latitude; then it makes a great bend to the northeast, and...

      , Peru
    15. 1370 km (851.3 mi) – Teles Pires
      Teles Pires
      The Teles Pires or Rio São Manuel is a 1370 km long river in Brasil.The river flows through the state of Mato Grosso and its lower part is border between states Mato Grosso and Pará...

      , Brazil (tributary of Tapajós)
    16. 1300 km (807.8 mi) – Iriri
      Iriri River
      The Iriri River is a tributary of the Xingu River in Brazil, in the state of Pará. It is long making it the 116th longest river in the world and the 15th longest in the Amazon Basin. The headwaters are the traditional home of the Panará people....

      , Brazil (tributary of Xingu)
    17. 1240 km (770.5 mi) – Juruena
      Juruena River
      The Juruena River is a 1240 km long river in west-central Brazil, in the state of Mato Grosso. For the last 190 km of its lower part the river becomes the border between the states Mato Grosso and Amazonas...

      , Brazil (tributary of Tapajós)
    18. 1130 km (702.2 mi) – Madre de Dios
      Madre de Dios River
      The Madre de Dios River, homonymous to the Peruvian region it runs through, then becomes the Beni River in Bolivia and then turns northward into Brazil, where it is called the Madeira River...

      , Peru/Bolivia (tributary of Madeira)
    19. 1100 km (683.5 mi) – Huallaga
      Huallaga River
      The Huallaga River is a tributary of the Marañón River, part of the Amazon Basin. Old names for this river include Guallaga and Rio de los Motilones. The Huallaga is born on the slopes of the Andes in central Peru and joins the Marañón before the latter reaches the Ucayali River to form the Amazon....

      , Peru (tributary of Marañón)

    External links