Terra Preta (Amazonian Dark Earths)

Assembled from 17 blocks · 1 evidence · 18 related

1. Story
2. Patches of deep, dark, exceptionally fertile soil scattered across the Amazon, generally on bluffs above major rivers, in a landscape whose natural soils are among the most weathered and nutrient-poor on Earth. They are not natural. They are the accumulated residue of long-term human settlement - hearth charcoal, bone, fish and turtle remains, food waste and broken pottery - built up over centuries and, critically, still fertile today. The charcoal is the reason: pyrogenic carbon resists decomposition for millennia and provides a structure that holds nutrients against the tropical rain that leaches them out of ordinary soil. Formation is generally placed between roughly two and a half thousand and five hundred years before the present and stops abruptly, which is what one would expect if the populations that made it collapsed at European contact. How much of the basin they cover is genuinely disputed, with published estimates spanning more than an order of magnitude, and the dispute matters because it is a proxy for how densely the pre-Columbian Amazon was populated.
3. Knowledge
4. Indigenous Peoples and Demarcated Territories of the Amazon
5. Terra Preta (Amazonian Dark Earths)
6. Connections
7. Indigenous Peoples and Demarcated Territories of the Amazon
8. Dark earths accumulate under long-term settlement
9. Brazil Nut Tree (Bertholletia excelsa)
10. Amazon Deforestation
11. Xingu Indigenous Territory
12. Terra Preta (Amazonian Dark Earths)
13. Dark earths accumulate under long-term settlement
14. Orellana descends the river to the Atlantic
15. Brazil's constitution recognises indigenous land rights as original
16. Evidence
17. Supports the finding that domesticated tree species are disproportionately abundant in the modern Amazon and that their abundance and richness increase near archaeological sites, indicating a persistent pre-Columbian human signature in present forest composition. V55 verification basis: not retrieved in this session; the magnitude of the enrichment is deliberately not quoted.