is found in the middle and upper Amazon within the Purus river basin. Most of the central and lower sections of the river flow through the Purus várzea ecoregion. In the municipality of Tapauá, Amazonas, the river flows through the Abufari Biological Reserve, a strictly protected area. Earthworks discovery In 2008, a previously unknown pre-Columbian civilization was discovered in the upper region of the river close to the Bolivian border. After much of the forest in the region was cleared for agricultural use, satellite pictures revealed the remains of large geometric earthworks. See also Amazon rainforest Esperanza, Ucayali Brazilian Amazon Peruvian Amazon River basin Catauxi References Purus River. (2010). In Encyclopædia Britannica. Retrieved January 12, 2010, from Encyclopædia Britannica Online. External links Map of Amazon State with Purus River, Brazilian Ministry of Transport Tributaries of the Amazon River Rivers of Acre (state) Rivers of Amazonas (Brazilian state) Rivers of Peru International rivers of South America Brazil–Peru border Rivers of Ucayali Region Border rivers