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Marine Geophysical Researches

, Volume 26, Issue 2–4, pp 135–144 | Cite as

Imaging of Buried Archaeological Materials: The Reflection Properties of Archaeological Wood

  • Stephanie H.L. Arnott
  • Justin K. DixEmail author
  • Angus I. Best
  • David J. Gregory
Article

Abstract

Effective marine archaeological site management demands detailed information on not only the spatial distribution of artefacts but also the degradation state of the materials present. Although sonar methods have frequently been used in an attempt to detect buried wooden shipwrecks they are currently unable to indicate their degradation state. To assess the sensitivity of acoustic measurements to changes in the degradation state of such material, and hence the potential for sonars to quantify degradation, laboratory measurements of compressional wave velocity, as well as bulk density for oak and pine samples, in varying states of decay, were undertaken. These data enabled the calculation of theoretical reflection coefficients for such materials buried in various marine sediments. As wood degrades, the reflection coefficients become more negative, resulting in the hypothesis that the more degraded wood becomes, the easier it should be to detect. Typical reflection coefficients of the order of −0.43 and −0.52 for the most degraded oak and pine samples in sand are predicted. Conversely, for wood exposed to seawater the predicted reflection coefficients are large and positive for undegraded material (0.35 for oak, 0.18 for pine) and decrease to zero or slightly below for the most degraded samples. This indicates that exposed timbers, when heavily degraded, can be acoustically transparent and so undetectable by acoustic methods. Corroboration of these experimental results was provided through comparison with high resolution seismic reflection data that has been acquired over two shipwrecks.

Keywords

acoustics archaeology Chirp compressional wave velocity reflection coefficient shipwreck sonar sub-bottom profiler 

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References

  1. Adams, J.R., Black, J. 2004From rescue to research: Medieval ship finds in St Peter Port, GuernseyInt. J. Nautical Archaeol.33230252Google Scholar
  2. Arnott, S.H.L. 2004 Ultrasonic evaluation of the degradation state of marine archaeological woodUniversity of SouthamptonSouthamptonPh.D., thesisGoogle Scholar
  3. Arnott, S., Best, A.I., Dix, J.K., Gregory, D. 2002aAcoustical properties of waterlogged woodStepnowski, A. eds. Proceedings of the Sixth European Conference on Underwater Acoustics, Gdansk, Poland, 24–27 June 2002Technical University of GdanskPoland345350Google Scholar
  4. Arnott, S., Dix, J.K., Best, A.I., Gregory, D. 2002bAcoustic propagation in waterlogged woodActa Acustica united with Acustica88699702Google Scholar
  5. Biot, M.A. 1956aTheory of propagation of elastic waves in a fluid saturated porous solid, I. Low frequency rangeJ. Acoust. Soc. Am.28168178Google Scholar
  6. Biot, M.A. 1956bTheory of propagation of elastic waves in a fluid saturated porous solid, II. High frequency rangeJ. Acoust. Soc. Am.28179191Google Scholar
  7. Björdal, C.G., Nilsson, T., Daniel, G. 1999Microbial decay of waterlogged archaeological wood found in Sweden. Applicable to archaeology and conservationInt. Biodeteriorat. Biodegrad.436373Google Scholar
  8. Bucur, V. 1988Wood structural anisotropy estimated by acoustic invariantsInt. Assoc. Wood Anatomists Bull.96774(new series)Google Scholar
  9. Buglass, J. 2000Ships timber recovered from Humberside fieldNautical Archaeol. (Nautical Archaeol. Soc. Newslett.)48Google Scholar
  10. Bull, J.M., Quinn, R., Dix, J.K. 1998Reflection coefficient calculation from marine high resolution seismic reflection (Chirp) data and application to an archaeological case studyMar. Geophys. Res.20111CrossRefGoogle Scholar
  11. Dinwoodie, J.M. 1981Timber, its nature and behaviourVan Nostrand ReinholdWokinghamGoogle Scholar
  12. Dix, J.K., Arnott, S., Best, A.I., Gregory, D. 2001The acoustic characteristics of marine archaeological woodLeighton, T.G.Heald, G.J.Griffiths, H.D.Griffiths, G. eds. Proceedings of the Institute of Acoustics Conference on Acoustical Oceanography, Southampton, 9–12 April 2001Institute of AcousticsBath299305Google Scholar
  13. Gregory, D. 1998Re-burial of timbers in the marine environment as a means of their long-term storage: experimental studies in Lynæs Sands, DenmarkInt. J. Nautical Archaeol.27343358Google Scholar
  14. Hearmon, R.F.S. 1948The Elasticity of Wood and PlywoodHMSOLondonGoogle Scholar
  15. Hoffmann, P. 1981Chemical wood analysis as a means of characterizing archaeological woodGrattan, D.W.McCawley, J.C. eds. ICOM Waterlogged Wood Working Group ConferenceICOMOttawa7383Google Scholar
  16. Kaye, G.W.C., Laby, T.H. 1986Tables of Physical and Chemical Constants 15LongmanNew YorkGoogle Scholar
  17. Lavery, B., 1988, The Royal Navy’s first Invincible. Portsmouth.Google Scholar
  18. Mathewson, C.C., Gonzalez, T. 1988Protection and preservation of archaeological sites through burialMarinos, P.G.Koukis, G.C. eds. The Engineering Geology of Ancient Works, Monuments and Historical SitesEngineering Geology and the Protection of Historical Sites and Monuments. Proceedings of the International Symposium of the International Association of Engineering GeologyRotterdam9061918529Google Scholar
  19. McCarthy, M. 1986Protection of Australia’s underwater sitesMelucco, A. eds. Preventive Measures During Excavation and Site ProtectionICCROMRome133146Google Scholar
  20. McGrail, S. 1974The Building and Trials of the Replica of an Ancient Boat: The Gokstad Faering, Part 1 Building the ReplicaNational Maritime MuseumGreenwichGoogle Scholar
  21. McGrail, S. 1998Ancient Boats in North-West Europe: The archaeology of water transport to AD 1500Cunliffe, B eds. Longman Archaeology SeriesLongmanLondonGoogle Scholar
  22. Powell, K.L., Pedley, S., Daniel, G., Corfield, M. 2001Ultrastructural observations of microbial succession and decay of wood buried at a Bronze Age archaeological siteInt. Biodeteriorat. Biodegrad.47165173Google Scholar
  23. Orsi, T.H., Dunn, D.A. 1991Correlations between sound velocity and related properties of glacio-marine sediments: Barents SeaGeo-Mar. Lett.117983Google Scholar
  24. Oxley, I. 1998The environment of historic shipwreck sites: a review of the preservation of materials, site formation and site environmental assessmentUniversity of St AndrewsSt AndrewsM.Sc., thesisGoogle Scholar
  25. Quinn, R., Adams, J.R., Dix, J.K., Bull, J.M. 1998The Invincible (1758) site – an integrated geophysical assessmentInt. J. Nautical Archaeol.27126138Google Scholar
  26. Quinn, R., Breen, C., Forsythe, W., Barton, K., Rooney, S., O’Hara, D. 2002Integrated geophysical surveys of the French frigate La Surveillante (1797), Bantry Bay, Co., Cork, IrelandJ. Archaeol. Sci.29413422Google Scholar
  27. Quinn, R., Bull, J.M., Dix, J.K. 1997Imaging wooden artefacts using Chirp sourcesArchaeol. Prospect.42535CrossRefGoogle Scholar
  28. Richardson, M.D., Briggs, K.B. 1993On the use of acoustic impedance values to determine sediment propertiesProc. Institute Acoust.151524Google Scholar
  29. Schniewind, A.P. 1990Physical and mechanical properties of archaeological woodRowell, R.M.Barbour, R.J. eds. Archaeological Wood: Properties, Chemistry and PreservationAmerican Chemical SocietyWashington87109Google Scholar
  30. Sheriff, R.E., Geldart, L.P. 1995Exploration Seismology 2Cambridge University PressCambridgeGoogle Scholar
  31. Tsoumis, G.T. 1991Science and Technology of Wood: Structure, Properties, UtilizationVan Nostrand ReinholdNew YorkGoogle Scholar
  32. Zabel, R.A., Morrell, J.J. 1992 Wood Microbiology: Decay and its PreventionAcademic PressLondonGoogle Scholar

Copyright information

© Springer 2005

Authors and Affiliations

  • Stephanie H.L. Arnott
    • 1
  • Justin K. Dix
    • 1
    Email author
  • Angus I. Best
    • 1
  • David J. Gregory
    • 2
  1. 1.National Oceanography Centre, SouthamptonSouthamptonUK
  2. 2.Department of Conservation (Archaeology)National Museum of DenmarkBredeDenmark

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