Geoglyphs of Acre

The Geoglyphs of Acre represent one of the most significant archaeological discoveries in the Amazon, revealing that pre-Columbian societies built monumental geometric earthworks across a vast area for at least two millennia. Built within anthropogenic forests that had been managed through agroforestry for ten thousand years, the geoglyphs overturned the assumption that the Amazon was an untouched wilderness and demonstrated the presence of complex, organized societies in western Amazonia.

The builders' specific narratives have not survived. No oral traditions directly describing the construction or purpose of the geoglyphs have been recorded, and the European contact that might have captured such accounts arrived too late — or too destructively — to preserve them.

What archaeology reveals instead is a story of deep continuity. Charcoal and palm phytolith records at geoglyph sites show human land management beginning approximately ten thousand years ago. For millennia, people selectively burned, planted palms, transplanted saplings, and cultivated bamboo forests — practicing a form of agroforestry so sophisticated that the resulting landscape appeared natural to later observers. The forest that twentieth-century colonists cleared was not pristine. It was a garden, tended across hundreds of human generations.

The geoglyphs themselves emerged from this tradition of landscape shaping, with the earliest construction dating to approximately 3500 BP. Over the following two millennia, communities carved increasingly elaborate geometric forms — circles, squares, U-shapes, ellipses, octagons — into the managed forest floor. The Tequinho site, with its radiating road system and central enclosure, appears to have served as a regional ceremonial hub. Construction continued until approximately 650 BP, then ceased for reasons that remain unclear.