In the uppermost reach of the Lower Tejo River (eastern central Portugal), where the river crosses two quartzite ridges that separate the Ródão (upstream) and Arneiro (downstream) depressions, Palaeolithic artefacts have been recovered from three lower river terrace levels and a cover unit of aeolian sands. This paper presents data on the discovery of archaeological artefacts from the terrace levels and the aeolian sands that can be linked to Middle and Upper Palaeolithic industries from new field sites at Tapada do Montinho and Castelejo. The archaeological data when placed in a geomorphological, sedimentary and chronological framework, contribute new information on the understanding of human occupation in western Iberia during coldclimate episodes of the last 62 to 12 ka; and especially during the cooler and driest conditions that occurred between 32 and 12 ka, when the climate favoured aeolian sediment transport. In the Lower Tejo River, the integration of absolute age datasets with archaeological, geomorphological and sedimentary data indicate that in westernmost Iberia the first appearance of artefacts in river terrace sediments suggests that the earliest marker for human occupation dates from the lower Acheulian (Lower Palaeolithic), probably corresponding to an age of~340 ka. Data also suggest, for the first time, that Acheulian lithic industries were replaced by Middle Palaeolithic ones (namely the Levallois stone knapping technique) by~160 ka (~MIS6). Middle Palaeolithic industries were later replaced by Upper Palaeolithic industries at 32 ka. The post 32 ka period, dominated by aeolian sediment transport, is related to the onset of cold-dry climate conditions which resulted in low river flow discharges, floodplain exposure and reworking by NW winds. This colddry period is coeval with the disappearance of Megafauna and associated Neanderthal communities, and the replacement of the Middle Palaeolithic industries by Upper Palaeolithic ones in this westernmost part of Europe.

. 2012 (July): Optically stimulated luminescence (OSL) dating of quartzite cobbles from the Tapada do Montinho archaeological site (east-central Portugal). Boreas, Vol. 41, pp. 452-462. 10.1111/j.1502-3885.2012.00249.x. ISSN 0300-9483.The burial age of an alluvially deposited cobble pavement at the Tapada do Montinho archaeological site (east-central Portugal) is investigated using optically stimulated luminescence (OSL) dating. Measurements on the cobbles (quartzite clasts) were carried out on intact slices and large aliquots (~8 mm) of quartz grains (63-300 mm), both recovered from the outer 1.5-mm surface of the cobbles. The recycling ratio, recuperation and dose-recovery tests show that the single-aliquot regenerative-dose (SAR) protocol is applicable to both rock slices and quartz grains; both have similar luminescence characteristics. The variation in the natural OSL signal with depth below the cobble surface using intact slices from two different cobbles shows that both were bleached to a depth of at least~2 mm before deposition. A model of the variation of dose with depth fitted to data from one of the cobbles gives a burial age of~19 ka and also predicts the dose-depth variation at the time of deposition. Ages based on rock slices suggest that one cobble surface, and the inner parts of two other cobbles experienced a resetting event at~45 ka, consistent with the age control. However, the surfaces of the other cobbles all record light-exposure events in the range 26 to 14 ka, suggesting that some of the cobbles were exposed to daylight perhaps more than once in this period. Given the shallow burial depth and unexpectedly young ages of the surrounding and overlying finer-grained sediment, it is suggested that phases of light exposure following surficial erosion are probably responsible for this underestimate. Nevertheless, it is remarkable that we can identify and quantify four events (two light exposures of different durations and two sequential burial periods) in the dose record contained within a single clast, and this suggests that the luminescence dating of rock surfaces may prove, in the future, to be at least as important as sand/silt sediment dating.