Waterlogged Wood
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Waterlogged Wood On 1st April 2015 the Historic Buildings and Monuments Commission for England changed its common name from English Heritage to Historic England. We are now re-branding all our documents. Although this document refers to English Heritage, it is still the Commission's current advice and guidance and will in due course be re-branded as Historic England. Please see our website for up to date contact information, and further advice. We welcome feedback to help improve this document, which will be periodically revised. Please email comments to [email protected] We are the government's expert advisory service for England's historic environment. We give constructive advice to local authorities, owners and the public. We champion historic places helping people to understand, value and care for them, now and for the future. HistoricEngland.org.uk/advice 2010 Waterlogged Wood Guidelines on the recording, sampling, conservation and curation of waterlogged wood 1 Preface Contents Waterlogged wood comprises a rare and significant part of the archaeological 1 Introduction ....................................................... 3 resource. It can occur in extensive wetlands 1.1 Why is waterlogged wood important?................................... 3 or in small features, such as pits or wells, 1.2 Who are these guidelines for? ......................................... 4 on otherwise dry sites. Its comparative rarity means that most archaeologists 2 Project planning and evaluation .................................... 4 have little experience of dealing with the 2.1 Briefs, specifications, project designs and written schemes of investigation .... 4 material. Waterlogged sites are usually more 2.2 Desk-based assessments .............................................. 5 complex and costly to investigate than dry 2.3 Evaluations ......................................................... 5 sites, a fact that can often put pressure 2.4 Preservation in situ or excavation ....................................... 6 on archaeological curators, contractors 2.5 Unexpected discovery ................................................ 7 and consultants. It is hoped that these guidelines will help archaeologists make 3 Excavation, recording, sampling and temporary storage.............. 7 the best possible decisions in the face of 3.1 Excavation ......................................................... 7 such pressures. 3.2 Recording in situ..................................................... 9 The Monuments At Risk in England’s 3.3 Lifting, packaging and transportation .................................. 10 Wetlands (MAREW) report demonstrated 3.4 Assessment ........................................................ 11 the enormous destruction of waterlogged 3.5 Recording after lifting ............................................... 14 deposits that has taken place across 3.6 Sampling.......................................................... 17 England, with 2020 sites lost over the 3.7 Maritime excavation ................................................ 19 last 50 years (Van De Noort et al 2001). 3.8 Temporary storage.................................................. 20 The associated loss of waterlogged wood is likely to increase over the next 100 4 Analysis and dating ............................................... 20 years as summers become hotter and 4.1 Woodworking information ........................................... 21 drier (UKCP09). As this finite resource 4.2 Woodland management ............................................. 22 inexorably diminishes, the need for well- 4.3 Dendrochronology.................................................. 23 conducted excavation, curation and in situ 4.4 Other dating methods . 24 management increases. 4.5 Other forms of analysis .............................................. 25 This document is the third edition of Waterlogged Wood Guidelines issued by 5 Site monitoring and reburial ...................................... 25 English Heritage, previous editions being 5.1 Assessing wood condition ............................................ 25 produced in 1990 (Coles (ed) 1990) and 5.2 Reburial........................................................... 25 in 1995 (Brunning 1995). Since then some 5.3 Site monitoring .................................................... 26 new techniques have been developed and others have been modified, although many 6 Conservation, curation and display ................................ 26 of the most important techniques and 6.1 Condition assessment ............................................... 27 issues remain unchanged. 6.2 Conservation methods (for large-scale wooden structures) ................ 29 Sites that produce waterlogged wood 6.3 Storage and display ................................................. 30 are also likely to preserve other organic materials and palaeoenvironmental 7 Final report and archiving......................................... 30 remains. For such projects the English Heritage guidelines on dendrochronology 8 References ....................................................... 31 (English Heritage 1998, new edition forthcoming), environmental archaeology 9 Where to get advice ............................................... 34 (English Heritage 2002), leather and textile (English Heritage 2009), investigative conservation (English Heritage 2008a) and piling (English Heritage 2007) may also prove useful. Some advice on how to deal with wood from inter-tidal and sub-tidal environments is included within these guidelines, but more detailed advice and guidance for underwater archaeology is available from other sources (eg Green 1990 and Bowens 2008). 2 1 Introduction significant information about material Six things to remember culture, economy, industry and buildings. 1.1 Why is waterlogged wood important? Wood can be analysed in combination Many archaeologists live busy lives and Wooden remains are important because with other palaeoenvironmental data may not have time to read innumer- they provide evidence for the main raw sources to increase understanding of the able professional guidelines from cover material used for structures, artefacts wider landscape. It gives direct evidence to cover, no matter how useful they and fuel throughout most of human for the character of the local treescape may be. If you go no further than this existence. Clarke (1968) thought that and how this changed over time. It can page here are six things to remember. a typical dry archaeological site might also provide information on woodland preserve about 15% of what was actually management and on the selection of raw 1 Wet site excavation justifiably used by its inhabitants, but more recent materials, and can be used to identify costs more. estimates, based on archaeological and imported products. Archaeological costs rise where pres- anthropological evidence, suggest that Waterlogged wood is also valuable ervation of the record is best. Make perishable organic materials comprise 90– for scientific dating. It can provide sure this is recognised in project plan- 95% of the potential archaeological record samples for radiocarbon dating, like other ning, briefs, specs, WSIs and Project (eg Soffer et al 2001; Purdy 1988). Analysis organic materials, but several species Designs. of wooden remains provides unique and can also be used for tree-ring dating 2 Get specialist advice early. The involvement of wood specialists at an early stage will save time and mon- ey. The EH Regional Science Advisors should be able to supply contacts and provide good advice themselves. 3 Preservation in situ of water- logged sites is a big risk. Don’t condemn waterlogged deposits to possible gradual unseen destruction merely as a more convenient alterna- tive to excavation. All preservation in situ entails a potential risk of failure. Specialist advice should be sought through the EH Regional Science Advisors. 4 Keep temporary storage short term. The longer waterlogged wood is kept in temporary storage the worse its Figs 1 and 2 (above) Medieval wicker fish basket from Hicklin’s Land, Hemington (Leicestershire); and basket shown partly condition will become and the more dismantled to show internal funnels (scale rod = 1m) (© University of Leicester Archaeological Services). likely it will end up in a skip. Try Fig 3 (below left) Oak piles, woodchips and charred debris from a Bronze Age site at Must Farm, Cambridgeshire. Numerous and implement a rapid timetable for domestic organic artefacts were also present (© Cambridge Archaeological Unit). Fig 4 (below right) The ‘God Dolly’ from the early Neolithic Bell Track, Somerset. The earliest known human figurine in the UK. recording, sampling and selection for (© Somerset Levels Project). conservation. 5 Expect to conserve some wood. Sites that produce significant quan- tities of waterlogged wood should expect that at least a proportion of the assemblage warrants conservation and curation. 6 Don’t panic. Many archaeologists will be unfamiliar with dealing with waterlogged wood. It is rare and important, and its appear- ance can cause stress to tight budgets. Get specialist advice before the fear takes hold, so that good decisions can be made. 3 (dendrochronology), which can produce sections 3.1.1 and 3.6 so the advice given below will attempt to be extremely precise dates. The use of some 5 Who will help me sort this out? see realistic, rather than idealistic. imported species can also help to date section 9 Funding in blocks associated