Location
Terra preta soils are found mainly in Brazilian Amazonia, where Sombroek et al. estimate that they cover at least 0.1 to 0.3%, or 6,300 to 18,900 square kilometres (2,400 to 7,300 sq mi) of low forested Amazonia); but others estimate this surface at 10.0% or more (twice the area of Great Britain).
Plots of terra preta exist in small plots averaging 20 hectares (49 acres), but areas of almost 900 acres (360 ha) have also been reported. They are found among various climatic, geological, and topographical situations. Their distributions either follow main water courses, from East Amazonia to the central basin, or are located on interfluvial sites (mainly of circular or lenticular shape and of a smaller size averaging some 1.4 hectares (3.5 acres), see also distribution map of terra preta sites in Amazon basin. The spreads of tropical forest between the savannas could be mainly anthropogenic — a notion with dramatic implications worldwide for agriculture and conservation.
Terra preta sites are also known in Ecuador, Peru, French Guiana, in Benin, Liberia, and on the South African savannas. Similar dark earth was found in late Roman Britain.
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