Molina G.,Polytechnic University of Catalonia |
Tite M.S.,Research Laboratory for Archaeology and the History of Art |
Molera J.,University of Vic |
Climent-Font A.,Autonomous University of Madrid |
Pradell T.,Polytechnic University of Catalonia
Journal of the European Ceramic Society | Year: 2014
Lustre is a decoration consisting of a few hundreds of nanometres thick surface layer of silver and copper metal nanoparticles incorporated into the glaze. Polychrome lustreware with several combinations of colours and shines was produced in Abbasid Iraq in the 9th century AD. Three colour combinations, black plus red, white-silvery plus red-coppery and yellow-golden plus red-coppery, have been studied, and the materials and methods of production determined. Two separated firings the first for the copper and the second for the silver lustre were performed. The black, white, yellow and green colours of the silver lustres are associated with the different sizes of the nanoparticles and to their distribution in the layer. Although the addition of lead and tin in the initial mixture is demonstrated, their incorporation in the glaze has been found to be the key factor in the production of the red-coppery and yellow-golden lustre. © 2014 Elsevier Ltd.
Foote A.D.,Copenhagen University |
Kaschner K.,Albert Ludwigs University of Freiburg |
Schultze S.E.,Copenhagen University |
Garilao C.,Leibniz Institute of Marine Science |
And 11 more authors.
Nature Communications | Year: 2013
The climatic changes of the glacial cycles are thought to have been a major driver of population declines and species extinctions. However, studies to date have focused on terrestrial fauna and there is little understanding of how marine species responded to past climate change. Here we show that a true Arctic species, the bowhead whale (Balaena mysticetus), shifted its range and tracked its core suitable habitat northwards during the rapid climate change of the Pleistocene-Holocene transition. Late Pleistocene lineages survived into the Holocene and effective female population size increased rapidly, concurrent with a threefold increase in core suitable habitat. This study highlights that responses to climate change are likely to be species specific and difficult to predict. We estimate that the core suitable habitat of bowhead whales will be almost halved by the end of this century, potentially influencing future population dynamics. © 2013 Macmillan Publishers Limited. All rights reserved.
Brown A.G.,University of Southampton |
Basell L.S.,Research Laboratory for Archaeology and the History of Art |
Toms P.S.,University of Gloucestershire |
Bennett J.A.,University of Exeter |
And 2 more authors.
Quaternary Science Reviews | Year: 2010
This paper presents the first systematic chronostratigraphic study of the river terraces of the Exe catchment in South West England and a new conceptual model for terrace formation in unglaciated basins with applicability to terrace staircase sequences elsewhere. The Exe catchment lay beyond the maximum extent of Pleistocene ice sheets and the drainage pattern evolved from the Tertiary to the Middle Pleistocene, by which time the major valley systems were in place and downcutting began to create a staircase of strath terraces. The higher terraces (8-6) typically exhibit altitudinal overlap or appear to be draped over the landscape, whilst the middle terraces show greater altitudinal separation and the lowest terraces are of a cut and fill form. The terrace deposits investigated in this study were deposited in cold phases of the glacial-interglacial Milankovitch climatic cycles with the lowest four being deposited in the Devensian Marine Isotope Stages (MIS) 4-2. A new cascade process-response model is proposed of basin terrace evolution in the Exe valley, which emphasises the role of lateral erosion in the creation of strath terraces and the reworking of inherited resistant lithological components down through the staircase. The resultant emergent valley topography and the reworking of artefacts along with gravel clasts, have important implications for the dating of hominin presence and the local landscapes they inhabited. Whilst the terrace chronology suggested here is still not as detailed as that for the Thames or the Solent System it does indicate a Middle Palaeolithic hominin presence in the region, probably prior to the late Wolstonian Complex or MIS 6. This supports existing data from cave sites in South West England. © 2009 Elsevier Ltd. All rights reserved.
Bonneau A.,Bordeaux Montaigne University |
Bonneau A.,Laval University |
Bonneau A.,Research Laboratory for Archaeology and the History of Art |
Brock F.,Research Laboratory for Archaeology and the History of Art |
And 3 more authors.
Radiocarbon | Year: 2011
The dating of South African rock art using radiocarbon is a considerable challenge and only 1 direct date has so far been obtained, on black pigments from Sonia's Cave Upper, Boontjieskloof. The main problem with direct dating these paintings is the presence of calcium oxalates behind, on, and within the pigment layers. Calcium oxalates are formed through lichen and bacterial action on the rock face. These reactions can sometimes take place over long periods and can incorporate carbon of a younger age into the pigments. This study aims to date black pigments from a rockshelter, RSA TYN2 (Eastern Cape, South Africa), by removing the calcium oxalate contamination. Two different protocols were tried: density separation and acidification. The latter successfully removed calcium oxalates and was therefore applied to 3 black pigment samples from the rockshelter. After acid pretreatment, accelerator mass spectrometry (AMS) dating was undertaken on the remaining residues. Three results were obtained (2072 ± 28 BP, 2100 ± 40 BP, and 2083 ± 32 BP), which constitute the oldest results so far obtained for direct dates on South African rock art. The most likely calibrated date range for the painting at this site is between 2120 and 1890 cal BP. The ages are in close agreement with each other and this consistency suggests that our preparation protocol has successfully removed the majority of the carbon contaminants. © 2011 by the Arizona Board of Regents on behalf of the University of Arizona.
Guerin G.,French National Center for Scientific Research |
Mercier N.,French National Center for Scientific Research |
Nathan R.,Research Laboratory for Archaeology and the History of Art |
Adamiec G.,Silesian University of Technology |
Lefrais Y.,French National Center for Scientific Research
Radiation Measurements | Year: 2012
The infinite matrix assumption is commonly used to derive dose rates in the field of paleodosimetric dating methods. The update of nuclear data allowed calculating new dose rate conversion factors and attenuation factors for taking account of grain size. The relevance of the infinite matrix assumption was found to be limited to specific cases and a discussion of potential errors in estimating dose rates to natural dosimeters in sedimentary media is proposed. A new set of geometric features is shown to be of paramount importance for estimating dose rates in sedimentary media. To quantify these effects, Monte Carlo modelling was applied and the architecture of the programmes is described. It is also shown that proper characterization of sediment samples, coupled to the modelling of radioactivity in these sediments may provide more accurate dose rates to quartz grains, down to the single grain scale. © 2012 Elsevier Ltd. All rights reserved.
Raghavan M.,Research Laboratory for Archaeology and the History of Art |
Raghavan M.,Copenhagen University |
McCullagh J.S.O.,Chemistry Research Laboratory |
Lynnerup N.,Copenhagen University |
Hedges R.E.M.,Research Laboratory for Archaeology and the History of Art
Rapid Communications in Mass Spectrometry | Year: 2010
We report a novel method for the chromatographic separation and measurement of stable carbon isotope ratios (δ13C) of individual amino acids in hair proteins and bone collagen using the LCIsoLink system, which interfaces liquid chromatography (LC) with isotope ratio mass spectrometry (IRMS). This paper provides baseline separation of 15 and 13 of the 18 amino acids in bone collagen and hair proteins, respectively. We also describe an approach to analysing small hair samples for compound-specific analysis of segmental hair sections. The LC/IRMS method is applied in a historical context by the δ13C analysis of hair proteins and bone collagen recovered from six individuals from Uummannaq in Greenland. The analysis of hair and bone amino acids from the same individual, compared for the first time in this study, is of importance in palaeodietary reconstruction. If hair proteins can be used as a proxy for bone collagen at the amino acid level, this validates compound-specific isotope studies using hair as a model for palaeodietary reconstruction. Our results suggest that a small offset observed in the bulk δ13C values of the hair and bone samples may be attributed to two factors: (i) amino acid compositional differences between hair and bone proteins, and (ii) differential turnover rates of the tissues and the amino acid pools contributing to their synthesis. This application proposes that hair may be a useful complementary or alternative source of compound-specific paleodietary information. © 2010 John Wiley & Sons, Ltd.
Tomlinson E.L.,Royal Holloway, University of London |
Thordarson T.,University of Edinburgh |
Lane C.S.,Research Laboratory for Archaeology and the History of Art |
Smith V.C.,Research Laboratory for Archaeology and the History of Art |
And 3 more authors.
Geochimica et Cosmochimica Acta | Year: 2012
The Sólheimar ignimbrite was one of the largest eruptions from the Katla caldera (Iceland) and is important for tephra studies in the North Atlantic because of its possible linkage with the Vedde Ash, a compositionally bimodal tephra layer used for correlation of sedimentary records in the North Atlantic and Northern Europe. The composition of the Sólheimar ignimbrite extends from rhyolite to basaltic-icelandite, a trend that defines a coherent magma mixing line. Mixing is evident both in mingled textures seen in hand specimens and thin sections and as binary mixing trends in major and trace element and 87Sr/ 86Sr isotopes of the volcanic glasses. The Sólheimar rhyolite is slightly more radiogenic than the basaltic-icelandite in terms of Sr isotopes, which is inconsistent with generation of the rhyolite by fractionation of the basaltic-icelandite. Alternatively, the Sólheimar rhyolite may have been produced by partial melting of Icelandic crust. Major and trace element modelling indicates that partial melting of Icelandic tholeiite does not replicate the observed rhyolite composition, in particular K 2O is significantly lower in the modelled melt. However, partial melting of Katla alkali basalt does produce a comparable melt. We suggest a two-stage model in which 30-40% melting of basalt generated a dacitic magma which underwent subsequent ~30% fractionation of the observed phenocryst phases (feldspar, clinopyroxene, spinel and FeTi oxide) form rhyolite. The eruption of the Sólheimar ignimbrite was triggered by the intrusion of basaltic-icelandite magma, which mixed with resident rhyolite magma during eruption.The Sólheimar ignimbrite has been linked to the Vedde Ash (. Lacasse et al., 1995), a compositionally bimodal tephra layer used to link sedimentary records in the North Atlantic and Northern Europe. Despite the importance of the Vedde Ash in late Quaternary studies, its provenance remains equivocal. We demonstrate that Vedde rhyolite glasses share the same major and trace element chemistry as the Sólheimar rhyolite, carrying the implication that these deposits may be produced by the same eruption. However, the Sólheimar ignimbrite lacks the basaltic component that is sometimes associated with rhyolitic shards of the Vedde Ash at far distal locations, therefore this correlation cannot be confirmed. © 2012 Elsevier Ltd.
Parker A.G.,Oxford Brookes University |
Lee-Thorp J.,Research Laboratory for Archaeology and the History of Art |
Mitchell P.J.,University of Oxford
Proceedings of the Geologists' Association | Year: 2011
The late Holocene environmental history of the Lesotho highlands, southern Africa, is poorly understood with few detailed studies to date. At Likoaeng, Senqu Valley, Lesotho, a 3m stratified sedimentary sequence from an open-air archaeological site records vegetation development for the period 3400-1070cal.BP. Phytolith analyses and bulk sediment organic matter δ 13C indicate that C 4 grassland dominated the lower part of the sequence until approximately 2960cal.BP when there was a switch to C 3 Pooid grassland (2960-2160cal.BP). Also noted was a change from hunting mainly bovids to a dominance of fishing at the site. The change in grassland type and archaeological subsistence strategies corresponds with an episode of neoglacial cooling and the expansion of Alpine sourgrasses into lower altitudes. From 2160 to 1600cal.BP grassland became a mix of C 3 and C 4 types and by 1600-1070cal.BP there was a return to C 4 dominated grassland. During this latter phase there was a reversal from fishing to hunting again (and eventually some keeping of domestic livestock) at the site. These data outline the vegetation response to latitudinal shifts of frontal systems, and relatively strong atmospheric circulation variability, perhaps underpinned by variations of polar water into the Benguela Current during the late Holocene. © 2010 The Geologists' Association.
Canti M.,English Heritage |
Bronk-Ramsey C.,Research Laboratory for Archaeology and the History of Art |
Hua Q.,Australian Nuclear Science and Technology Organisation |
Marshall P.,English Heritage
Quaternary Geochronology | Year: 2015
Dating phases of pedogenesis, soil carbonate deposition or even the burial of whole soil profiles using 14C is a valuable goal in archaeology and pedology, but one that has been consistently hampered by the presence of old carbon skewing the measurements to produce apparent dates older than the true formation date. Calcite produced by earthworms could be a useful alternative source of datable carbon. Since earthworms both inhabit and ingest soils with an old carbon content, however, the granules could yield a 14C date older than the date of their formation. In this study, by examining granules from two sites of known-age stratigraphy, we show that the radiocarbon date derived from the granules' calcite closely reflects their true formation date, opening up the possibility of using the granules either individually or as distributions of dates to understand soil processes and date sealed archaeological layers. © 2015 Elsevier B.V.
Ramsey C.B.,Research Laboratory for Archaeology and the History of Art |
Dee M.,Research Laboratory for Archaeology and the History of Art |
Lee S.,Research Laboratory for Archaeology and the History of Art |
Nakagawa T.,Northumbria University |
Staff R.A.,Research Laboratory for Archaeology and the History of Art
Radiocarbon | Year: 2010
Calibration is a core element of radiocarbon dating and is undergoing rapid development on a number of different fronts. This is most obvious in the area of 14C archives suitable for calibration purposes, which are now demonstrating much greater coherence over the earlier age range of the technique. Of particular significance to this end is the development of purely terrestrial archives such as those from the Lake Suigetsu sedimentary profile and Kauri tree rings from New Zealand, in addition to the groundwater records from speleothems. Equally important, however, is the development of statistical tools that can be used with, and help develop, such calibration data. In the context of sedimentary deposition, age-depth modeling provides a very useful way to analyze series of measurements from cores, with or without the presence of additional varve information. New methods are under development, making use of model averaging, that generate more robust age models. In addition, all calibration requires a coherent approach to outliers, for both single samples and where entire data sets might be offset relative to the calibration curve. This paper looks at current developments in these areas. © 2010 by the Arizona Board of Regents on behalf of the University of Arizona.