Solimões () is the name often given to the upper stretch of the Amazon River in Brazil, from its confluence with the Rio Negro near Manaus upstream to the tri-border area shared by Brazil, Peru, and Colombia. The Solimões flows for about through a floodplain that reaches roughly wide in places.

Use of the name Solimões for the upper Amazon is mostly confined to Brazilian speakers of Portuguese; the rest of the world refers to both the upper and lower portions of the river simply as the Amazon.

Etymology

The name Solimões derives from an Amazonian Indigenous people whom Spanish and Portuguese chroniclers encountered during the era of European exploration; lacking detailed knowledge of the river, chroniclers used local names to distinguish its stretches. This people, recorded as living along the river between the present-day municipalities of Coari and Anamã, were called the Yurimaguas by 16th-century chroniclers; the Jesuit missionary Samuel Fritz undertook their conversion in that period. Their name appears in a number of variant spellings across chroniclers' accounts, including Soriman, Joriman, Sorimão, and Sorimões. In Portuguese these forms were further rendered as Solimão and Soliemoens, giving rise to the modern name of the river and of the region it drains.

The precise reasoning behind the name remains uncertain. One proposed derivation traces Sorimão, Sorimões, and Solimões to the Latin word sublimatum, in reference to a poison the Yurimaguas were said to apply to the tips of arrows and darts. Seventeenth-century chroniclers, including Cristóbal de Acuña in 1641, described the Yurimaguas as one of the more warlike peoples along the river, with densely populated settlements along its banks, and their poisoned arrowheads have been cited as a possible source of the river's name.

Geography The Amazon/Solimões river just above its confluence with the Rio Negro is already by far the largest river in the world, even though its two largest tributaries — the Negro and the Madeira River — have not yet contributed to its flow volume.

The Solimões portion of the Amazon River lies entirely within the Brazilian state of Amazonas, and part of the state is often referred to as the "Solimões region." Along its course the river passes the municipalities of Tabatinga, São Paulo de Olivença, Amaturá, Santo Antônio do Içá, Tonantins, Jutaí, Fonte Boa, Tefé, Coari, Codajás, Anamã, Anori, and Manacapuru before reaching Manaus, where its confluence with the Rio Negro marks the point at which the river again takes the name Amazon. The ecoregion of the Solimões River drainage basin is entirely tropical rainforest.

Course and hydrology The Solimões is an anastomosed river, meaning it is divided into long, relatively stable channels that rejoin farther downstream. The course of the river and the extent of its floodplains are largely controlled by tectonic lineaments, with northwest–southeast and southwest–northeast trends predominating, alongside less common north–south and west–east trends. Where these lineaments intersect, they form low-lying, roughly diamond-shaped depressions that are occupied by floodplains, in places reaching up to wide. The elevated terrain surrounding the river corresponds geologically to the Cretaceous-age Alter do Chão sedimentary formation.

Studies of the river's Quaternary history indicate that a landscape of terra firme interspersed with extensive várzea forest already existed around the Solimões roughly 250,000 years ago. A newer generation of terra firme is thought to have formed approximately 35,000 to 45,000 years ago as river channels cut down through the landscape, considerably reducing the extent of várzea forest.

Tributaries Going downstream from Tabatinga to Manaus, the Solimões receives numerous tributaries, several of which are themselves major Amazonian rivers.

+ Solimões River and its principal tributaries Tributary Receiving river Country/countries Length Source coordinates Javari River Solimões (right bank) Peru – Brazil Curuçá River Javari Brazil Ituí River Javari Brazil Jandiatuba River Solimões (right bank) Brazil Putumayo River (Içá) Solimões (right bank) Colombia – Ecuador – Peru – Brazil Igara Paraná River Putumayo Colombia Jutaí River Solimões (right bank) Brazil Zinho River Jutaí Brazil Bia River Jutaí Brazil Mutum River Jutaí Brazil Juruá River Solimões (right bank) Peru – Brazil Gregório River Juruá Brazil Japurá River (Caquetá) Solimões (left bank) Colombia – Brazil Apaporis River Japurá-Caquetá Colombia – Brazil Cahuinari River Japurá-Caquetá Colombia Yarí River Japurá-Caquetá Colombia Caguán River Japurá-Caquetá Colombia Tefé River Solimões (right bank) Brazil Coari River/Lake Coari Solimões (right bank) Brazil Badajós River Solimões Brazil Purus River Solimões (right bank) Peru – Brazil Ipixuna River Purus Brazil Tapauá River Purus Brazil Mucuim River Purus Brazil Ituxi River Purus Brazil Sepatini River Purus Brazil — Pauini River Purus Brazil Acre River Purus Peru – Brazil – Bolivia Iaco River Purus Peru – Brazil Chandless River Purus Peru – Brazil Manacapuru River Solimões (left bank) Brazil

See also Amazon basin Marañón River List of rivers of Amazonas

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