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Scientific Dating of Pleistocene Sites: Guidelines for Best Practice Contents

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Scientific Dating of Pleistocene Sites: Guidelines for Best Practice Contents Consultation Draft Scientific Dating of Pleistocene Sites: Guidelines for Best Practice Contents Foreword............................................................................................................................. 3 PART 1 - OVERVIEW .............................................................................................................. 3 1. Introduction .............................................................................................................. 3 The Quaternary stratigraphical framework ........................................................................ 4 Palaeogeography ........................................................................................................... 6 Fitting the archaeological record into this dynamic landscape .............................................. 6 Shorter-timescale division of the Late Pleistocene .............................................................. 7 2. Scientific Dating methods for the Pleistocene ................................................................. 8 Radiometric methods ..................................................................................................... 8 Trapped Charge Methods................................................................................................ 9 Other scientific dating methods ......................................................................................10 Relative dating methods ................................................................................................10 3. Bayesian Chronological Modelling................................................................................11 PART 2 – SCIENTIFIC DATING METHODS ..................................................................................13 4. Radiocarbon Dating ...................................................................................................13 5. Uranium-Thorium dating ............................................................................................14 6. Luminescence dating in the Pleistocene ........................................................................16 7. Amino acid racemization (AAR)....................................................................................18 8. Palaeomagnetism ......................................................................................................19 9. Tephrochronology .....................................................................................................21 10. The ’Vole Clock’ .....................................................................................................23 PART 3 – CASE STUDIES ........................................................................................................25 11. Happisburgh Site 3, Norfolk .....................................................................................25 12. Boxgrove ..............................................................................................................26 13. The Axe Valley at Broom – OSL dating Middle Pleistocene fluvial sediments ...................28 14. Seeing beneath the sea – Palaeolithic finds from Aggregate Area 240 ............................29 15. Uranium-series dating – constraining the age of the Middle Palaeolithic tools and fauna from Pin Hole, Creswell, Derbyshire ....................................................................................30 16. Neanderthals in Norfolk: Lynford Quarry ...................................................................30 17. Gransmoor, East Yorkshire – a precise chronology for environmental records.................31 PART 4 – PRACTICALITIES ......................................................................................................33 Consultation Draft 18. Project Organisation and Planning ............................................................................33 18.1 Specifications/briefs ...............................................................................................33 18.2 Desk-top assessment ..............................................................................................34 18.3 Watching briefs .....................................................................................................34 18.4 Evaluation.............................................................................................................34 18.5 Excavation ............................................................................................................34 18.6 Assessment ...........................................................................................................34 18.7 Post-excavation Analysis .........................................................................................35 18.8 Dissemination and archiving ....................................................................................35 19. Laboratories ..........................................................................................................36 Radiocarbon Dating.......................................................................................................36 Uranium-Thorium Dating ...............................................................................................36 Luminescence Dating ....................................................................................................36 Amino acid racemization (AAR) .......................................................................................37 Tephrochronology ........................................................................................................38 Palaeomagnetism .........................................................................................................38 20. Advice and Information...........................................................................................39 A: Historic England ........................................................................................................39 B. Scientific Dating Laboratories ......................................................................................40 C. On-line Resources .....................................................................................................40 21. Glossary................................................................................................................44 22. References ............................................................................................................48 23. Acknowledgements ................................................................................................61 24. Text Boxes ............................................................................................................62 25. Tables ..................................................................................................................64 26. Figures .................................................................................................................76 Consultation Draft 1 Foreword 2 Alex Bayliss, Historic England 3 These guidelines provide advice on best practice for the effective use of scientific dating on 4 Pleistocene sites. They are applicable to all archaeological projects, but are aimed primarily at those 5 undertaken as part of the planning process. Pleistocene sites typically produce limited material that 6 is suitable for dating. Some of the methods that can be employed are familiar to those working in 7 later periods (eg Radiocarbon Dating), although special considerations for their effective use may 8 apply. Other methods (eg the ’Vole Clock‘) are only used in the Pleistocene. The selection of 9 appropriate techniques, given the available types of datable material, its taphonomic relationship to 10 the archaeological objectives of the project, and the expected time-range of the site, is key. Different 11 strands of evidence can be explicitly combined using Bayesian statistical modelling, and the resultant 12 chronologies can be validated, not only by comparison to relative dating from stratigraphy, but also 13 by employing multiple scientific dating techniques. Above all, seek expert advice. All laboratories will 14 be happy to advise on applying their technique to Pleistocene deposits, and will welcome the 15 opportunity to discuss sample selection and potential methods of cross-checking their results with 16 you. It is by working together with a range of specialists that you will provide the best dating 17 possible for your site. 18 PART 1 - OVERVIEW 19 1. Introduction 20 David R Bridgland, Durham University 21 The Pleistocene is the geological period during which multiple ice ages, or glacials, occurred, the last 22 of which ended only c 11,700 years ago, at the beginning of the Holocene, or the post-glacial. The 23 Pleistocene and Holocene together are termed the Quaternary. The Pleistocene began 2.58 million 24 years ago, and we now know that there were numerous ice ages during this period, although those 25 of the Middle and Late Pleistocene (together accounting for the last c 0.8 million years) were more 26 severe than those occurring earlier. The Pleistocene was not continuously cold; instead there were 27 periodic warmer episodes, termed interglacials, during which conditions were similar to those of the 28 Holocene, which is generally regarded as merely the latest of numerous interglacials. This glacial– 29 interglacial oscillation is a principal characteristic of the Pleistocene and has been used as a 30 framework for dividing the Quaternary into
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