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Geoarchaeology of Pleistocene open-air sites in the Vila Nova da Barquinha-Santa Cita area (Lower Tejo River basin, central Portugal) |
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| Authors: | António A Martins Pedro P Cunha Luiz Osterbeek Stefano Grimaldi Jan-Pieter Buylaert João Matos |
| Institution: | a Centro de Geofísica, Dep. Geociências University Évora, Portugal b Dep. of Earth Sciences, Marine and Environmental Research Centre, Univ. Coimbra, Portugal c Instituto Politécnico de Tomar, Centro de Geociências Univ. Coimbra, Portugal d Museu de Arte Pré-Histórica de Mação, Centro de Geociências Univ. Coimbra, Portugal e Universitá degli Studi di Trento, Centro de Geociências Univ. Coimbra, Portugal f Centro de Interpretação de Arqueologia do Alto Ribatejo, Centro de Geociências Univ. Coimbra, Portugal g Nordic Laboratory for Luminescence Dating, Aarhus Univ., Risø DTU, Denmark h Bolseiro BIC (proj. POCI/CTE-GEX/58120/2004), Dep. Geociências Univ. Évora, Portugal |
| Abstract: | This paper aims to provide insight into human occupation and landscape change during the Pleistocene in a central area of the Lower Tejo basin (Portugal). Detailed geomorphological mapping, coupled with lithostratigraphy, sedimentology and luminescence dating, supports the identification of a complete terrace staircase sequence. It consists of six gravely terraces located below the culminant (Pliocene) basin unit. A chronological framework for the sedimentary sequences and associated human industries is proposed and correlated with marine oxygen isotope stages (MIS): T1 terrace, not dated; T2, not dated; T3, >300 ka; T4, ∼300-160 ka (MIS8, MIS7 and MIS6); T5, ∼136-75 ka (MIS5); T6, ∼62-30 ka (MIS3); colluvium and aeolian sands, ∼30-14 ka (MIS2); valley fill deposits, ∼14 ka to present (MIS1). The oldest artefacts were found at the base of the T4 terrace, with the local stratigraphic level dated to ≥175 ± 6 ka (Middle Pleistocene). The lithic assemblages collected from distinct stratigraphic levels (T4, T5 top, T6 terraces and colluvium) are characterized by the predominance of opportunistic technological choices, a feature that can be attributed partly to the preferential exploitation of the available raw material, dominated by local-sourced quartzites and quartz pebbles. The adaptation to local raw material (texture and volume), together with subsistence patterns and behaviours, could explain the rarity of Acheulian types (handaxes and cleavers) and picks in the T4 terraces of the Tejo tributaries; this is in contrast to the same terrace of the Tejo valley, in which these types are found. Interpretation of the environmental conditions (controlled by climate and glacio-eustatic sea-level changes) affecting the hunter-gatherer human groups is also presented. |
| Keywords: | Palaeolithic Pleistocene Luminescence dating Terraces Tejo River Iberia |
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