The Amazonian black soils at these and other such sites are deep, stratified, deposits rich in pottery, stone artifacts, human skeletons, plant and animal food remains and ecofacts, house structural traces, facilities such as adobe stoves or hearths, plazas, mounds, cemeteries, and other indisputable cultural features. What makes the soils black is mainly charcoal from human

burning of plant materials, including carbonized seeds, pods, husks, flowers, leaves, bark, and roots. In addition, large amounts of unburned plant material were discarded at these sites, as evidenced by unburned wood, phytoliths, plant organic matter, and abundant potassium. Large amounts of human excrement, human bones, fish bones, and animal bones discarded SCH727965 solubility dmso in the refuse selleck compound raise phosphorus, calcium, and lipid levels (Glaser and Birk, 2011 and Smith, 1980:556, 561–562). All these materials arguably were produced by ordinary daily activities in settlements.

The clear and repetitive stratigraphy and contents show that the black soils accrued at and around settlements (Evans and Meggers, 1968:33–34; Morais and Neves, 2012 and Neves, 2012:137–245; Nimuendaju, 2004:118–164, Plates 184–5; Roosevelt, 1991a, Roosevelt, 1991b, Roosevelt, 1997 and Roosevelt, 2014). There are intact features that would not be there if the deposit were not in situ, including post-holes, hearths, structure floors and platforms, burials, and pockets and lenses of primary and secondary refuse. There is no evidence that vegetation was brought to the sites specifically to be burned to create the black soils for purposes of cultivation. Nor do the dark soils give evidence of being thoroughly disturbed deposits of settlement refuse that was moved wholesale for use in cultivation, though the refuse was sometimes recycled for building mounds, as described above. Communities could have taken

all their refuse and placed it in certain locations to use for cultivation, Niclosamide but the aforementioned intact domestic and ritual features and the dating show that they did not do this (Arroyo-Kalin, 2012). People disposed of refuse as was convenient while they lived at the settlement and cultivated it either outside structures or in their ruins. Archeological research at current settlements show that refuse is regularly swept from houses to heaps outdoors (Siegel, 1990 and Siegel and Roe, 1986). Black soil deposits have all the values for plant cultivation that composted household refuse is well-known to have (Glaser and Birk, 2011). Both the charcoal and the organic matter from decayed plant and animal matter yield and absorb nutrients and moisture and make them available to plant roots.