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Optically stimulated luminescence (OSL) techniques have been applied to investigate the potential for dating the deposition of upcast mounds associated with qanat ventilation shafts at the site of a medieval qanat located in Aragón, Spain. Coarse quartz grains, extracted from sediment samples taken from excavated sections of several mounds, possessed sufficiently strong OSL to enable an evaluation of equivalent dose by applying the single aliquot regenerative procedure to small aliquots, each containing an individual bright grain. The OSL dates for both palaeosol and overlying upcast indicate that a chronostratigraphic record has been preserved within the mounds investigated, and micromorphological analysis of thin sections of sediment blocks taken from the mounds is shown to provide an essential means of verifying the characteristics of the strata, in particular, the critical interface of upcast and the ancient ground surface. The earliest OSL dates for basal deposits taken from two separate sections of the same mound are in agreement, placing the mound construction during the first half of the 13th century A.D. However, in two other mounds the OSL dates for the deposition of upcast are internally consistent with the stratigraphy but significantly later, dating to the 16th and 17th centuries A.D. We interpret the differences between the dates for the upcast deposition to be the result of partial erosion of the upper shaft and later repair of the mounds, and this finding underlines the importance of both examining multiple mounds in the same qanat system and the internal structure of each sampled mound. This exploratory work demonstrates the potential for wider application of OSL for dating this important type of subterranean irrigation feature in the study of both the archaeology of human settlement and palaeoenvironmental change in arid regions. [ABSTRACT FROM AUTHOR]

Abstract: Optically stimulated luminescence (OSL) dating has been applied to determine the burial age of sediment horizons within a sequence containing Lower Palaeolithic artefacts on an upland site associated with a solution feature (doline) at West Cliffe, located on the North Downs in Kent, UK. The study makes use of a novel extension of the single aliquot OSL measurement procedure to investigate the nature of significant overdispersion in equivalent dose values with very small aliquots of quartz inclusions, enabling single grain resolution to be approached with ∼90 μm diameter quartz extracted from the relatively fine-grained brickearth. A detailed examination of the uniformity of the distribution of radionuclide sources in the sampled volumes was also performed and this included the application of a spatially-resolved technique for beta dose rate measurement. The OSL ages, obtained for the burial of brickearth positioned stratigraphically below and above a clay and flint clast layer containing the artefacts and debitage, place the deposition of the artefacts to between ca 140 and 80 ka ago. This is significantly later than indicated by the artefact typology (>300 ka) and contrary to the expectation of in situ burial indicated by earlier research in this region. If displacement occurred on other upland sites this finding has important implications for establishing the timing of hominin use of the upland areas which, beyond broad attribution to Lower or Middle Palaeolithic origin, is uncertain and similar doubts apply to the interpretation of the environments that prevailed. [Copyright &y& Elsevier]

The feasibility of applying optically stimulated luminescence (OSL) techniques to obtain estimates of the burial age of lithic clasts in the form of pebbles of quartzose lithology is investigated in this study. We applied OSL measurement procedures to vein-quartz and quartzite pebbles from contexts at five sites with fluvial and coastal beach contexts of depositional age ranging from 500 ka to the mid Holocene. As in previous OSL studies with lithics, measured depth-dose profiles were interpreted to identify regions associated with key stages in the burial history of the pebbles, including the extent of pre-burial optical resetting, primary burial and any subsequent secondary stages of exposure to sunlight. While some of the pebbles had not been fully optically reset before burial, none were in field saturation, as commonly encountered with larger lithic clasts such as cobbles. The relatively low concentrations of radionuclides within vein-quartz and quartzite pebbles simplified the assessment of the radiation dose rate. OSL age estimates consistent with independent dating evidence were obtained for the three sites sampled in the UK (Langford Quarry, Leet Hill Quarry, Swanscombe Skull Site and Barnfield Pit) and one of two sites tested in Portugal (Forte Cão), whereas evidence of secondary optical bleaching detected in pebbles from a second site (Vale de Atela) underestimated the independent age for primary burial. The oldest depositional age of the contexts tested was ~500 ka (Leet Hill Quarry), and for some of the pebbles tested there was the capacity to extend the potential dating range further as the age equivalence of the limiting value of D e was in excess of 1 Ma. The advantages of working with smaller, portable, clasts in the form of pebbles and with a lithology of higher transparency opens up a wide range of potential applications, whether the depositional processes are environmental or anthropogenic in origin or modification. • New approach to the dating of Quaternary sediments containing vein-quartz and quartzite pebbles. • OSL techniques applied to sliced pebble cores produce depth-dose profiles that are related to optical exposure history. • Successful comparison of OSL ages with independently dated MIS 12, MIS 11, MIS 5 and Holocene depositional contexts. • Low dose rates for vein-quartz and quartzite pebbles potentially enable further extension of the dating range. [ABSTRACT FROM AUTHOR]