So far, more than 250 large geometric earthworks, forming a network of avenues, ditches and enclosures, have been identified, and the scientists who mapped them believe that as many as 2,000 further structures may be hidden beneath the jungle canopy.

The earthworks take the form of ditches up to 11 metres wide and one to two metres deep, lined by banks up to a metre high. The civilisation that built them appears to have spanned a period beginning around 2,000 years ago and ending in the 13th century and may have been represented by a population of around 60,000 people. Excavations have unearthed a range of artefacts, including ceramics and grinding stones, from some of the sites but not others, suggesting that some may have played a ceremonial role.

The discovery, details of which have been published in the journal Antiquity, overturns the long-held belief that the soils of the upper Amazon were too infertile to support extensive agriculture and hence a large civilisation. They also lend weight to the supposedly mythical tales of lost cities in the Amazon jungle, from El Dorado to Percy Fawcett’s City of Z.

March 2010