Quality in Bayesian chronological models in archaeology

Bayesian chronological modelling is fast becoming the method of choice for the interpretation of radiocarbon dates in archaeological and palaeoenvironmental studies around the world. Although software enabling the routine application of the method has been available for more than twenty years, more than half of published models have appeared in the past fiveyears. Unfortunately, the pace of development in statistical methodology has not been matched by the increased care in sample selection and reporting that is required for robust modelling. Barely half the applications considered in this article provide the information necessary to assess the models presented critically. This article discusses what information is required to allow the quality of Bayesian chronological models to be assessed, and provides check-lists for authors, editors and referees, in the hope of improving current practice

Confessions of a serial polygamist: the reality of radiocarbon reproducibility in archaeological samples

Since 1993 Historic England (and its predecessor English Heritage) has commissioned 9,074 radiocarbon measurements on archaeological samples. Over 80% of these have been interpreted within formal Bayesian statistical models. The multiple strands of reinforcing evidence incorporated in these models provide precise chronologies that make stringent demands on the accuracy of the radiocarbon results included in the analysis. Inter-laboratory replication is consequently a routine part of model construction and validation. We report an analysis of replicate measurements on 1,089 archaeological samples. It is clear that laboratory reproducibility accounts for only part of the observed variation. The type of material dated is also critical to the reproducibility of measurements, with some sample types proving particularly problematic

The Resettlement of the British Landscape: Towards a chronology of Early Mesolithic lithic assemblage types

During the Upper Palaeolithic Britain was visited intermittently, perhaps only on a seasonal basis, by groups often operating at the margins of their range. The Early Mesolithic, by contrast, witnessed the start of the permanent occupation of the British landscape, with certain key sites showing evidence for long-lasting occupation from the very start of the period. However, currently our understanding of the timing and tempo of the Mesolithic colonisation and infilling of the landscape is limited because of the paucity of precise radiocarbon measurements. In this article we assess and model existing radiocarbon measurements to refine current typochronological models for the first two millennia of the Holocene. This is a necessary first step towards understanding the Mesolithic resettlement of the British Isles. Our results throw new light on the relationship between the last Upper Palaeolithic 'Long Blade' industries and early Mesolithic assemblages, as well as refining our understanding of the chronology of early Mesolithic assemblage types. Our data also suggest regional patterning to the timing of Mesolithic settlement and throw new light on issues of population movement and adoption of new technologies

The Resettlement of the British Landscape: Towards a chronology of Early Mesolithic lithic assemblage types

During the Upper Palaeolithic Britain was visited intermittently, perhaps only on a seasonal basis, by groups often operating at the margins of their range. The Early Mesolithic, by contrast, witnessed the start of the permanent occupation of the British landscape, with certain key sites showing evidence for long-lasting occupation from the very start of the period. However, currently our understanding of the timing and tempo of the Mesolithic colonisation and infilling of the landscape is limited because of the paucity of precise radiocarbon measurements. In this article we assess and model existing radiocarbon measurements to refine current typochronological models for the first two millennia of the Holocene. This is a necessary first step towards understanding the Mesolithic resettlement of the British Isles. Our results throw new light on the relationship between the last Upper Palaeolithic 'Long Blade' industries and early Mesolithic assemblages, as well as refining our understanding of the chronology of early Mesolithic assemblage types. Our data also suggest regional patterning to the timing of Mesolithic settlement and throw new light on issues of population movement and adoption of new technologies

Islands of history: the Late Neolithic timescape of Orkney

Orkney is internationally recognised for its exceptionally well-preserved Neolithic archaeology. The chronology of the Orcadian Neolithic is, however, relatively poorly defined. The authors analysed a large body of radiocarbon and luminescence dates, formally modelled in a Bayesian framework, to address the timescape of Orkney's Late Neolithic. The resultant chronology for the period suggests differences in the trajectory of social change between the ‘core’ (defined broadly as the World Heritage site) and the ‘periphery’ beyond. Activity in the core appears to have declined markedly fromc.2800 cal BC, which, the authors suggest, resulted from unsustainable local political tensions and social concerns

Histories of Deposition: Creating Chronologies for the Late Bronze Age-Early Iron Age transition in southern Britain

The Late Bronze Age–Early Iron Age midden sites of Southern Britain are amongst the richest archaeological sites in the country. The organic accumulations contain substantial quantities of animal bone, decorated ceramics, metalwork and other objects; the often deep stratigraphy allows for changes in material culture and depositional practices, food production and consumption, and shifts in social identities, to be traced through time. The well-stratified assemblages also provide useful materials for dating the deposits. This has been problematic, however, as the majority of samples produce unhelpfully broad calibrated radiocarbon dates, due to the effects of the earlier Iron Age plateau in the calibration curve, which spans c. 800–400 BC. Interpretation has relied on current understandings of the associated pottery and metalwork, which placed most midden sites somewhere between the tenth and the seventh/mid-sixth centuries cal BC (c. 1000–600/550 cal BC), but the end-date of these traditions is particularly uncertain. This article addresses this issue by presenting the results of a new dating programme for East Chisenbury in Wiltshire, southern England. Twenty-eight radiocarbon determinations were obtained and combined with the site stratigraphy in a Bayesian chronological model. The results have transformed the chronology of the site, with the end of the occupation sequence being pulled forward some one-hundred years, to the mid-to-late fifth century cal BC. These new chronologies have significant implications for our understanding of the Late Bronze Age–Early Iron Age transition and require a revision of the currently accepted chronology of post-Deverel Rimbury decorated wares in south-central England

A1_1 Tick, tick, tick... GRBoom!

This paper considers the possibility that a gamma ray burst (GRB) will cause a mass extinction on our planet. The distance over which a low energy GRB would expose a human to a lethal amount of radiation is calculated and found to be approximately 73 kiloparsecs. This indicates that we only need to consider GRBs occurring within the Milky Way galaxy. GRBs are also highly directional; the probability of a GRB striking the Earth is calculated to be 0.06%. From these calculations it is found that a lethal GRB is likely to impact on the Earth once every 328 million years

A1_6 Do you want to hang out?

This paper addresses the simple question: how much time will it take for wet clothes to dry, if they are hung up on a washing line, based on the current weather conditions? The metric form of the Penman equation is used to calculate the evaporation rate of water from a plane surface, which is dependent on the meteorological conditions of ambient temperature, wind speed, relative humidity, and the various properties of air and water at said ambient temperature. Empirically measuring the surface area of, and the mass of water contained in, a wet piece of clothing enables the time taken t for total evaporation to be determined. This paper concludes with an equation for t, provided the above factors are known, and gives example results for different items of clothing

A1_7 The Neutrino Problem

This report examines the premise from the movie "2012" (2009) that solar neutrinos start interacting with the core of the Earth, causing it to melt. A lower energy limit required for this interaction is found to be 9.55*10^4 GeV  and it is shown that the source of such energetic neutrinos is unlikely to be from within the solar system