Cultivars, anthropic soils, and stability : a preliminary report of archaeological research in Araracuara, Colombian Amazonia = Plantas cultivadas, suelos antrópicos y estabilidad : informe preliminar sobre la arqueología de Araracuara, Amazonia Colombiana - Mora Camargo, Santiago (Programa Tropenbos--Colombia ; University of Pittsburgh, Dept. of Anthropology, 1991)