Lapa das boleiras rockshelter: stratigraphy and formation processes at a paleoamerican site in Central Brazil

Lapa das Boleiras rockshelter, a Paleoamerican archaeological site in Central Brazil, was intensely occupied by humans from 10,000 14C BP (11.8 cal kyr BP), until approximately 7500 14C BP (8.4 cal kyr BP). In this paper we present some interpretations about the formation processes operating on the site. One of our main conclusions is that the bulk of accumulated sediments at the site is of anthropogenic origin: they are constituted by volumetrically significant quantities of plant ash remains, what is somewhat unexpectedly in view of prevailing models about the lifestyle of Paleoamerican hunter–gatherers in South America. The evidence we discuss below is also consistent with paleoenvironmental data that suggest a dry period during the mid-Holocene in the region, probably leading to a decrease in human occupation [Araujo, A.G.M., Neves, W., Piló, L.B., Atui, J.P., 2005. Holocene dryness and human occupation in Brazil during the ‘Archaic Gap’. Quaternary Research 64, 298–307]. We surmise that both factors underpin a surprising reduction in sediment accumulation at the site during the mid-Holocene.