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Ocupação neolítica e pedogénese médio-holocénica na Encosta de Sant'Ana (Lisboa): considerações geoarqueológicas

2004; Volume: 7; Issue: 2 Linguagem: Inglês

0874-2782

Cláudia Costa, João Muralha Cardoso, Diego E. Angelucci,

Maritime and Coastal Archaeology

The archaeological site at Encosta de Sant'Ana (Martim Moniz) is situated in the downtown area of Lisbon, near the so-called Baixa Pombalina. Encosta de Sant'Ana is located along to the left slope of a small valley (Ribeiro de Arroios), close to its outlet into the Baixa area, which is an alluvial plain derived from a small bay of the river, entering landwards (the Esteiro da Baixa). An excavation campaign was undertaken at the site in 2002. Salvage archaeological fieldwork was needed to guarantee the study of the local heritage, in advance of construction works. The site revealed a thick, multiphase, archaeological succession, spanning the Neolithic to the present, through Bronze Age, Roman, Islamic, Medieval and Modern times, scattered discontinuously through different excavations sectors. The stratification is organised in three main complexes: (a) an upper slope waste complex (unit 1, complex CLR), dating to historical times; (b) a lower slope waste group of sediments (units 2 and 3, complex CLA), featuring Bronze Age layers; (c) a palaeosoil developed from alluvial fine sediment (unit 4, complex AL), detected in sectors C and E, and containing Neolithic finds. Neolithic occupation layers are formed of in situ living floors with archaeological features (hearths and pits) and an abundant archaeological collection of lithic and ceramic artefacts, and faunal remains. Two conventional radiocarbon dates were obtained from charcoal fragments collected from this layer, thus dating the Neolithic occupation to the last phases of the 5th millennium cal BC. The Neolithic layer lays over an alluvial palaeosoil, whose formation may be attributed, thanks to the available dating, to the Atlantic chronozone. Micromorphological observation was performed on thin sections collected from the soil and showed that the Neolithic occupants settled on a stable surface, featuring a relatively deep A soil horizon. The archaeological and geoarchaeological data presented here are discussed in order to understand the relationships between the Neolithic settlement system and the mid-Holocene soil formation phase, emphasizing the close link between them, as already recorded in other southern European sites.