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Amazon Geoglyphs: Pre-Columbian Cities Hidden in Acre's Forest

The deforestation of Acre revealed thousands of geoglyphs — large geometric earthworks of pre-Columbian origin — proving that the Amazon was home to complex civilisations long before European contact

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1
The Discovery of the Geoglyphs
As deforestation cleared Acre's forest in the 1980s-2000s, satellite images revealed hundreds of large geometric earthworks – circles, squares and polygons up to 300 meters across – proving pre-Columbian civilization in the Amazon
2
Amazonian Dark Earth (Terra Preta)
The geoglyphs coincide with patches of terra preta - extraordinarily fertile black soil created by human habitation over centuries; the combination proves that the pre-Columbian Amazon was intensively cultivated and densely populated
3
Lidar Survey Revelations
The application of lidar (light detection and ranging) surveys to the Amazon in recent years has revealed entire ancient settlement systems invisible beneath the treetops — the extent of pre-Columbian Amazonian civilization is being rewritten
4
Population Estimates Revised
Scientists now estimate that 8-10 million people lived in the Amazon prior to European contact – the population collapse from disease after 1492 allowed the forest to regrow over abandoned farmland, creating the "pristine" Amazonian Europeans described
5
Scientific Significance
The Acre geoglyphs have been studied by Brazilian, British and American archaeologists - their findings challenge the assumption that the Amazon could not support complex civilizations and fundamentally change our understanding of pre-Columbian America
6
Potential for cultural tourism
Several geoglyph sites in Acre are accessible from the Rio Branco - the earthworks visible from the air or from elevated positions give physical form to the extraordinary civilization whose people and culture were almost completely erased