The impact of Bayesian chronologies on the British Iron Age

William Derek Hamilton,Colin Haselgrove,Chris Gosden

doi:10.1080/00438243.2015.1053976

William Derek Hamilton, Colin Haselgrove + Show 1 more

Open Access

https://doi.org/10.1080/00438243.2015.1053976

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Abstract

Radiocarbon dating was long neglected in Iron Age research, with dates on the ‘Hallstatt plateau’ (800–400 bc) considered too broad to be useful compared to artefact typo-chronologies. Such views are now untenable. Around fifty British Iron Age settlements and cemeteries have been dated using Bayesian methodologies, yielding two important general results: (1) typological dating produces sequences that are regularly too late; and (2) many phenomena, from chariot burials to settlement shifts, represent brief horizons, rather than being long lived. Drawing on a selection of studies, this article explores the impact of Bayesian modelling on British Iron Age studies. It highlights potential pitfalls and issues that must be considered when dating the period, illustrates some major successes and looks to the future.

Highlights

For close on a century, complex chronologies have been constructed for Iron Age Britain based largely on artefact typologies
Bayesian modelling on British Iron Age sites has been, more or less, one site at a time, thereby lacking a coherent research design aimed at using site chronologies to explore how society operated and interacted across a landscape
Iron Age settlements in north-east England show a surge in enclosure c. 200 cal

Summary

Introduction

For close on a century, complex chronologies have been constructed for Iron Age Britain based largely on artefact typologies. The case for avoidance Foremost among the reasons behind the historical ‘failure’ of Iron Age radiocarbon chronologies is the well-documented problem with calibrating dates (Haselgrove et al 2001; Cunliffe 2005, 652–4) This is a direct result of a major plateau in the calibration curve (‘Hallstatt plateau’) between approximately 800 and 400 BC (Fig. 1). Nowadays the 1-sigma errors on individual Accelerator Mass Spectrometry (AMS) measurements from samples of first-millennium BC date are routinely as low as 25–35 radiocarbon years With this precision or better, many earlier Iron Age results will calibrate to an approximate two-century span covering the first or second half of the Hallstatt plateau.

Impact of Bayesian chronologies on the British Iron Age

Findings

Conclusion