1,155 research outputs found
Provenancing the stones:Mapping the Stonehenge Bluestones using mineralogy
No full textWhere did the Stonehenge bluestones come from? Scientific advances are allowingus to pinpoint the outcrops that they were quarried from with ever-greater accuracy.Rob Ixer, Richard Bevins, and Duncan Pirrie describe some of the latest thinking
The West Kennet grus: how far?
No full textStones from West Kennet had no obvious practical use, yet they must have been carried to the site from some distance. Rob Ixer, Richard Bevins & Duncan Pirrie are hoping to pin down exactly where they came from
Mineralization of La Salvadora deposit, Province of Mendoza, Argentina
No full textLa Salvadora ore deposit (35°21′16″S; 68°23′22″W), located in the Province of Mendoza, Argentina, is part of a group of polymetallic veins linked to a porphyry copper that shows a crude temperature zonation away from the potassic centre. This porphyry deposit is genetically related to Lower Permian volcanic rocks from a subduction tectonic setting. La Salvadora is a quartz and carbonate vein deposit hosted by a sericitized, silicified and carbonatized rhyolite. The ore paragenesis is composed of galena, chalcocite, native silver, chalcopyrite, and bornite, along with minor stromeyerite, tetrahedrite, sphalerite and hematite. Myrmekitic intergrowths of galena - rhombic chalcocite, with irregular stromeyerite inclusions in the rhombic chalcocite, are present. Ore mineral analyses show: (i) that the galena is free of silver and copper; (ii) the heterogeneities observed in Pb-free chalcocite are produced by variable contents of silver; (iii) stromeyerite has a very homogeneous composition despite its differences in origins; and, (iv) little copper is observed either in the native silver or in sphalerite. The myrmekitic intergrowths and the stromeyerite inclusions in the chalcocite suggest that they precipitated from fluids at temperatures between 150° and 67°C, which is supported by the morphology of the fluid inclusions which suggest temperatures of formation below 120°C, typical of epithermal systems.Fil: Rubinstein, Nora Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Bevins, Richard. National Museums; Reino Unid
Exotic granodiorite lithics from Structure 5 at West Kennet, Avebury World Heritage Site, Wiltshire, UK
No full textReconstructing extraction techniques at Stonehenge’s bluestone megalith quarries in the Preseli hills of west Wales
No full textExcavations at two of the sources of Stonehenge’s bluestones in Mynydd Preseli, west Wales, have led to the discovery of stone tools associated with megalith quarrying in the final centuries of the fourth millennium BC, shortly before the suspected date of the bluestones’ erection at Stonehenge, 240 km away. Among the most plentiful of these tools are stone wedges, three of which were found in situ at the rhyolite bluestone quarry of Craig Rhos-y-felin. Two of these were positioned in the joints of a rhyolite pillar adjacent to a recess left by a removed pillar. Geochemical analysis reveals that these and the third wedge are of compositions different to the rock on either side of the cracks into which they had been driven, confirming their identification as quarrying tools. This research sheds new light on the methods used to extract the stones for Stonehenge
Object histories in prehistoric Britain: a stone macehead from the West Kennet Avenue occupation site, southern Britain
No full textMaceheads are distinctive perforated stone objects that occur in Neolithic and Bronze Age sites across Europe. Maceheads of different forms have been found across Britain, but with a marked concentration in Scotland and especially in Orkney. Widely regarded as ceremonial objects, they have been invariably interpreted as weapons, or symbols of power and political authority. Such interpretations, however, do not generally rely on detailed technological studies. For the most part, the way maceheads were used or treated in different contexts remains rather elusive. Recent excavations at the West Kennet Avenue occupation site, located a few hundred meters from the massive henge at Avebury, Southern Britain, brought to light a stone macehead. The site represents a significant episode of Middle Neolithic occupation, a period for which settlement evidence is generally scarce, and is located in a region in which maceheads are uncommon. Previous research on British prehistoric maceheads has demonstrated a strong association between stone maceheads and Grooved Ware sites dating to the later Neolithic, whilst earlier Middle Neolithic examples made from antler are often associated with burials. Therefore, the occurrence of a stone macehead on a Middle Neolithic settlement site is intriguing. The all-over polished ovoid macehead is grey to reddish brown in colour and, like many other examples across Britain and Europe, is broken. Inspired by Annelou van Gijn’s rigorous attention to object biographies, this paper will attempt to bring to life the biographical associations of the macehead. Questions about the making, use and breaking (intentional or not) of the macehead will be addressed through detailed technological and microwear analysis
Subgreenschist facies metamorphism of metabasites from the Precordillera terrane of western Argentina; constraints on the later stages of accretion onto Gondwana
No full textThe metamorphic character of metabasites of the Precordillera terrane of western Argentina provides constraints which help to distinguish between contrasting models for the tectonic settings during the late stages of the accretion of this terrane onto the margin of Gondwana in late Lower Palaeozoic times. Metamorphic conditions are constrained to a low-temperature/low-pressure setting at ca. 250-350°C and 2-3 kbar, with geothermal gradients of between 30-35°C km -1 . The metamorphic character of the rocks and the derived P-T conditions demonstrate that the metamorphism did not develop in an ocean-floor setting as has been previously proposed. Neither is the metamorphic character compatible with being derived from enhanced heat flow in an extensional setting at the western edge of the Precordillera in the mid-Ordovician following docking against Gondwana. The most compatible model is one in which the metamorphism developed as a result of collision between the Chilenia and Precordillera terranes in early Devonian times. In addition, the metamorphism constrains the subduction depth to < ca. 15 km had the leading western edge of the Precordillera been subducted westwards beneath Chilenia. However, the metamorphic character is perhaps better linked to subduction of the leading edge of Chilenia eastwards against the Precordillera.Fil: Robinson, Doug. University of Bristol; Reino UnidoFil: Bevins, Richard E.. National Museums and Galleries of Wales; Reino UnidoFil: Rubinstein, Nora Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentin
Undergraduates' personal constructs : Classroom teaching and the role of the teacher.
No full textThis in-depth study shows how Personal Construct Theory (PCT) can be used to investigate the bipolar constructs of teaching and the role of the teacher held by five university undergraduates from a range of subject disciplines. The approach adopted was developed from that devised by George Kelly (1905 -1967) which was originally applied to psychotherapy. As a phenomenological approach, PCT draws out the perceptions that individuals hold about the world rather than trying to impose a pre-existing theory or psychological framework.In this study, the participants' constructs of teaching and the role of the teacher originally derived from their experiences as pupils in school were elicited. The contention is that when 'real-world' classroom experiences are offered, prior to making career decisions, undergraduates have the opportunity to develop or change their views related to teaching. The study employed PCT pre and postexperience conversations which were analysed for changes in these views and reported as individual case studies. PCT pre and post-experience conversations provide evidence that time spent in a classroom does change the views of undergraduates about teaching and the role of the teacher. In this case, all five participants agreed that teaching was a career they would be pursuing either immediately or in the near future, which represents a significant change for two of the participants who had not previously planned to pursue a teaching career. The study provides evidence that a practical classroom experience (practicum) changes an individual's views of the teaching from a previously held view that teaching was not a career option to teaching becoming a career choice. This study argues that this type of practicum should precede a full-time teacher training course to allow any candidate unsure about embarking on the training to 'try-out' teaching first. This detailed study provides evidence for the validity of the PCT conversation as an effective approach for eliciting personal constructs and identifying any changes around the issues of teaching and the role of a teacher as a result of a school placement
A Scottish provenance for the Altar Stone of Stonehenge
No full textPublished online: 14 August 2024Understanding the provenance of megaliths used in the Neolithic stone circle at Stonehenge, southern England, gives insight into the culture and connectivity of prehistoric Britain. The source of the Altar Stone, the central recumbent sandstone megalith, has remained unknown, with recent work discounting an Anglo-Welsh Basin origin1,2. Here we present the age and chemistry of detrital zircon, apatite and rutile grains from within fragments of the Altar Stone. The detrital zircon load largely comprises Mesoproterozoic and Archaean sources, whereas rutile and apatite are dominated by a mid-Ordovician source. The ages of these grains indicate derivation from an ultimate Laurentian crystalline source region that was overprinted by Grampian (around 460 million years ago) magmatism. Detrital age comparisons to sedimentary packages throughout Britain and Ireland reveal a remarkable similarity to the Old Red Sandstone of the Orcadian Basin in northeast Scotland. Such a provenance implies that the Altar Stone, a 6 tonne shaped block, was sourced at least 750 km from its current location. The difficulty of long-distance overland transport of such massive cargo from Scotland, navigating topographic barriers, suggests that it was transported by sea. Such routing demonstrates a high level of societal organization with intra-Britain transport during the Neolithic period.Anthony J. I. Clarke, Christopher L. Kirkland, Richard E. Bevins, Nick J. G. Pearce, Stijn Glorie and Rob A. Ixe
- …
