166 research outputs found

    Integrated chronological control on an archaeologically significant Pleistocene river terrace sequence: the Thames-Medway, eastern Essex, England

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    Late Middle Pleistocene Thames-Medway deposits in eastern Essex comprise both large expanses of Palaeolithic artefact-bearing river sands/gravels and deep channels infilled with thick sequences of fossiliferous fine-grained estuarine sediments that yield valuable palaeoenvironmental information. Until recently, chronological control on these deposits was limited to terrace stratigraphy and limited amino-acid racemisation (AAR) determinations. Recent developments in both this and optically stimulated luminescence (OSL) dating make them potentially powerful tools for improving the chronological control on such sequences. This paper reports new AAR analyses and initial OSL dating from the deposits in this region. These results will help with ongoing investigation of patterns of early human settlement. Using AAR, the attribution by previous workers of the interglacial channel deposits to both MIS 11 (Tillingham Clay) and MIS 9 (Rochford and Shoeburyness Clays) is reinforced. Where there are direct stratigraphic relationships between AAR and OSL as with the Cudmore Grove and Rochford Clays and associated gravels, they agree well. Where OSL dating is the only technique available, it seems to replicate well, but must be treated with caution since there are relatively few aliquots. It is suggested on the basis of this initial OSL dating that the gravel deposits date from MIS 8 (Rochford and Cudmore Grove Gravels) and potentially also MIS 6 (Dammer Wick and Barling Gravels). However, the archaeological evidence from the Barling Gravel and the suggested correlations between this sequence and upstream Thames terraces conflict with this latter age estimate and suggest that it may need more investigation

    Development of new imaging techniques for the study and interpretation of late Rembrandt paintings

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    Recent macro-XRF scanning of Rembrandt’s Selfportrait from 1669 in the Mauritshuis – as part of the ReVisRembrandt project – has revealed significant new information about the pigments and build-up of the painting. The elemental distribution maps make clear that the umber-rich ground plays a very important role in the final appearance of this painting, information that is highly relevant for the study of this self-portrait, as well as many other late Rembrandt paintings. It was also possible to image the presence of organic lakes (by means of the potassium map) and bone black (by means of the calcium and phosphorus maps) in the upper paint layers. In addition to conventional investigative techniques, such as x-radiography and infrared imaging, it is anticipated macro-XRF scanning will become an important diagnostic tool for conservators and art historians alike

    An aminostratigraphy for the British Quaternary based on Bithynia opercula

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    Aminostratigraphies of Quaternary non-marine deposits in Europe have been previously based on the racemization of a single amino acid in aragonitic shells from land and freshwater molluscs. The value of analysing multiple amino acids from the opercula of the freshwater gastropod Bithynia, which are composed of calcite, has been demonstrated. The protocol used for the isolation of intra-crystalline proteins from shells has been applied to these calcitic opercula, which have been shown to more closely approximate a closed system for indigenous protein residues. Original amino acids are even preserved in bithyniid opercula from the Eocene, showing persistence of indigenous organics for over 30 million years. Geochronological data from opercula are superior to those from shells in two respects: first, in showing less natural variability, and second, in the far better preservation of the intra-crystalline proteins, possibly resulting from the greater stability of calcite. These features allow greater temporal resolution and an extension of the dating range beyond the early Middle Pleistocene. Here we provide full details of the analyses for 480 samples from 100 horizons (75 sites), ranging from Late Pliocene to modern. These show that the dating technique is applicable to the entire Quaternary. Data are provided from all the stratotypes from British stages to have yielded opercula, which are shown to be clearly separable using this revised method. Further checks on the data are provided by reference to other type-sites for different stages (including some not formally defined). Additional tests are provided by sites with independent geochronology, or which can be associated with a terrace stratigraphy or biostratigraphy. This new aminostratigraphy for the non-marine Quaternary deposits of southern Britain provides a framework for understanding the regional geological and archaeological record. Comparison with reference to sites yielding independent geochronology, in combination with other lines of evidence, allows tentative correlation with the marine oxygen isotope record

    The River Orontes in Syria and Turkey: downstream variation of fluvial archives in different crustal blocks

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    The geomorphology and Quaternary history of the River Orontes in western Syria and south-central Turkey have been studied using a combination of methods: field survey, differential GPS, satellite imagery, analysis of sediments to determine provenance, flow direction and fluvial environment, incorporation of evidence from fossils for both palaeoenvironments and biostratigraphy, uranium-series dating of calcrete cement, reconciliation of Palaeolithic archaeological contents, and uplift modelling based on terrace height distribution. The results underline the contrasting nature of different reaches of the Orontes, in part reflecting different crustal blocks, with different histories of landscape evolution. Upstream from Homs the Orontes has a system of calcreted terraces that form a staircase extending to ~200 m above the river. New U-series dating provides an age constraint within the lower part of the sequence that suggests underestimation of terrace ages in previous reviews. This upper valley is separated from another terraced reach, in the Middle Orontes, by a gorge cut through the Late Miocene–Early Pliocene Homs Basalt. The Middle Orontes terraces have long been recognized as a source of mammalian fossils and Palaeolithic artefacts, particularly from Latamneh, near the downstream end of the reach. This terraced section of the valley ends at a fault scarp, marking the edge of the subsiding Ghab Basin (a segment of the Dead Sea Fault Zone), which has been filled to a depth of ~ 1 km by dominantly lacustrine sediments of Pliocene–Quaternary age. Review of the fauna from Latamneh suggests that its age is 1.2–0.9 Ma, significantly older than previously supposed, and commensurate with less uplift in this reach than both the Upper and Lower Orontes. Two localities near the downstream end of the Ghab have provided molluscan and ostracod assemblages that record somewhat saline environments, perhaps caused by desiccation within the former lacustrine basin, although they include fluvial elements. The Ghab is separated from another subsiding and formerly lacustrine depocentre, the Amik Basin of Hatay Province, Turkey, by a second gorge, implicit of uplift, this time cut through Palaeogene limestone. The NE–SW oriented lowermost reach of the Orontes is again terraced, with a third and most dramatic gorge through the northern edge of the Ziyaret Dağı mountains, which are known to have experienced rapid uplift, probably again enhanced by movement on an active fault. Indeed, a conclusion of the research, in which these various reaches are compared, is that the crust in the Hatay region is significantly more dynamic than that further upstream, where uplift has been less rapid and less continuous

    The use of uplift modelling in the reconstruction of drainage development and landscape evolution in the repeatedly glaciated Trent catchment, English Midlands, UK

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    Denudation of the continental shelf between Britain and France at the glacial-interglacial timescale

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    The erosional morphology preserved at the sea bed in the eastern English Channel dominantly records denudation of the continental shelf by fluvial processes over multiple glacial-interglacial sea-level cycles rather than by catastrophic flooding through the Straits of Dover during the mid-Quaternary. Here, through the integration of multibeam bathymetry and shallow sub-bottom 2D seismic reflection profiles calibrated with vibrocore records, the first stratigraphic model of erosion and deposition on the eastern English Channel continental shelf is presented. Published Optical Stimulated Luminescence (OSL) and C ages were used to chronometrically constrain the stratigraphy and allow correlation of the continental shelf record with major climatic/sea-level periods. Five major erosion surfaces overlain by discrete sediment packages have been identified. The continental shelf in the eastern English Channel preserves a record of processes operating from Marine Isotope Stage (MIS) 6 to MIS 1. Planar and channelised erosion surfaces were formed by fluvial incision during lowstands or relative sea-level fall. The depth and lateral extent of incision was partly conditioned by underlying geology (rock type and tectonic structure), climatic conditions and changes in water and sediment discharge coupled to ice sheet dynamics and the drainage configuration of major rivers in Northwest Europe. Evidence for major erosion during or prior to MIS 6 is preserved. Fluvial sediments of MIS 2 age were identified within the Northern Palaeovalley, providing insights into the scale of erosion by normal fluvial regimes. Seismic and sedimentary facies indicate that deposition predominantly occurred during transgression when accommodation was created in palaeovalleys to allow discrete sediment bodies to form. Sediment reworking over multiple sea-level cycles (Saalian-Eemian-early Weichselian) by fluvial, coastal and marine processes created a multi-lateral, multi-storey succession of palaeovalley-fills that are preserved as a strath terrace. The data presented here reveal a composite erosional and depositional record that has undergone a high degree of reworking over multiple sea-level cycles leading to the preferential preservation of sediments associated with the most recent glacial-interglacial period

    A review of simulation modelling approaches used for the spread of zoonotic influenza viruses in animal and human populations

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    Increasing incidences of emerging and re-emerging diseases that are mostly zoonotic (e.g. severe acute respiratory syndrome, avian influenza H5N1, pandemic influenza) has led to the need for a multidisciplinary approach to tackling these threats to public and animal health. Accordingly, a global movement of 'One-Health/One-Medicine' has been launched to foster collaborative efforts amongst animal and human health officials and researchers to address these problems. Historical evidence points to the fact that pandemics caused by influenza A viruses remain a major zoonotic threat to mankind. Recently, a range of mathematical and computer simulation modelling methods and tools have increasingly been applied to improve our understanding of disease transmission dynamics, contingency planning and to support policy decisions on disease outbreak management. This review provides an overview of methods, approaches and software used for modelling the spread of zoonotic influenza viruses in animals and humans, particularly those related to the animal-human interface. Modelling parameters used in these studies are summarized to provide references for future work. This review highlights the limited application of modelling research to influenza in animals and at the animal-human interface, in marked contrast to the large volume of its research in human populations. Although swine are widely recognized as a potential host for generating novel influenza viruses, and that some of these viruses, including pandemic influenza A/H1N1 2009, have been shown to be readily transmissible between humans and swine, only one study was found related to the modelling of influenza spread at the swine-human interface. Significant gaps in the knowledge of frequency of novel viral strains evolution in pigs, farm-level natural history of influenza infection, incidences of influenza transmission between farms and between swine and humans are clearly evident. Therefore, there is a need to direct additional research to the study of influenza transmission dynamics in animals and at the animal-human interface
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