<P> 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 . </P> <P> Portuguese explorer Pedro Teixeira was the first European to travel up the entire river . He arrived in Quito in 1637, and returned via the same route . </P> <P> From 1648 to 1652, Portuguese Brazilian bandeirante António Raposo Tavares led an expedition from São Paulo overland to the mouth of the Amazon, investigating many of its tributaries, including the Rio Negro, and covering a distance of more than 10,000 km (6,214 mi). </P> <P> 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 evangelisation among the indigenous peoples of the vast rainforest, such as the Urarina . In the late 1600s Spanish Jesuit Father Samuel Fritz, apostle of the Omaguas, established some forty mission villages . </P>

Where does the sediment in the amazon river come from