Geoarchaeology of Pleistocene open-air sites in the Vila Nova da Barquinha-Santa Cita area (Lower Tejo River basin, central 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 AE 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.

Fluvial archives as a framework for the Lower and Middle Palaeolithic: patterns of British artefact distribution and potential chronological implications

“…5C, D). These finds are from sandy and sometimes organic beds within a complex sequence forming Terrace 4 of the Tagus in its lower Portuguese reach, regarded as Late Pleistocene by Mozzi et al but now shown to be significantly older by subsequent research, including optically stimulated luminescence dating (Martins et al 2010). This is, of course, an isolated point of comparison and is floated here as an indication of the type of evaluation of artefact assemblages that might be fruitful in future.…”

New data on the chronology of the Vale do Forno sedimentary sequence (Lower Tejo River terrace staircase) and its relevance as a fluvial archive of the Middle Pleistocene in western Iberia

“…In reach III, the Tejo is routed EeW, crossing three structural depressions with a Tertiary cover (Martins et al, 2009). In reach IV, the Tejo changes to a NNEeSSW trend, with valley sides displaying different degrees of terrace staircase development (Martins et al, 2010a(Martins et al, , 2010b (Figs. 1 and 2).…”

“…The high amplitude sea-level changes that characterized the Middle and Late Pleistocene controlled the episodic down-cutting phases of the river during sea-level lowstands; these alternated with flooding and agradation phases in the incised valley during highstands . Such climate related eustatic oscillations are superimposed onto a long-term uplift pattern, both phenomena having controlled the river terrace staircase development (Cunha et al, 2005(Cunha et al, , 2008Martins et al, 2010aMartins et al, , 2010b.…”

Geocronología de los yacimientos achelenses de Pinedo y Cien Fanegas (Valle del Tajo) e implicaciones en la evolución fluvial en el entorno de Toledo (España)

“…En el curso bajo del río Tajo (Portugal), las dataciones OSL disponibles (Cunha et al, 2008(Cunha et al, , 2012Martins et al, 2009Martins et al, , 2010 indican que las terrazas de c. +30−48 m, con edades de c. 260-340 ka, poseen industrias achelenses (Monte do Famaco), mientras que la terraza inmediatamente inferior (+16−28 m) posee industrias claramente musterienses con fechas comprendidas entre 135 ka (base) y 73 ka (techo), dentro del tránsito Pleistoceno Medio-Superior (MIS 6 -MIS 5). Estas cronologías más recientes son también características de las unidades superiores de las terrazas complejas a +18-20 m en los valles del Jarama y Manzanares (Panera et al, 2011;Pérez-González et al, 2013;Silva et al, 2013).…”