Dark earths and the human built landscape in Amazonia: a widespread pattern of anthrosol formation

Ancient anthrosols known as Amazonian dark earths or terra preta are part of the human built landscape and often represent valuable landscape capital for modern Amazonian populations in the form of fertile agricultural soils. The fertility, resilience, and large stocks of carbon in terra preta have inspired research on their possible role in soil fertility management and also serve as an example for a growing biochar industry it is claimed will sequester carbon for climate change mitigation. Although there is considerable scientific and public interest in terra preta, there is still much debate and little concrete knowledge of the specific processes and contexts of its formation. Research indicates that the formation of terra preta occurred mainly in midden deposits, themselves patterned around habitation areas, public areas, and routes of movement. Data from topographic mapping, soil analyses, and excavations in three regions of Amazonia demonstrate a widespread pattern of anthrosol formation in ring-shaped mounds surrounding flat terraces that extend across large areas of prehistoric settlements. It is hypothesized that there is a widespread type or types of occupation where the terraces were domestic areas (houses or yards) surrounded by refuse disposal areas in middens which built up into mounds over time, forming large deposits of terra preta and creating what could be called a ‘middenscape’. Initial results support the hypotheses, showing the interrelationship of residential and public areas, anthrosols, routes of movement, and natural resources. The patterning of anthrosols in ancient settlements indicates the use of space and can therefore serve as a basis for comparison of community spatial organization between sites and regions.