The acoustic characteristics of marine archaeological wood

National and International Governmental Organisations have recently recognised the necessity for the in situ preservation and management of our underwater cultural heritage. These bodies consider it essential that this is achieved through non-destructive, non- intrusive survey rather than excavation. In response to this demand we aim to develop a non-intrusive technique capable of both identifying wooden materials buried in the marine environment and assessing their state of preservation.In order to achieve this goal the geoacoustic characteristics (principally compressional velocity and density) of archaeological wooden material have been systematically investigated by an extensive series of laboratory based experiments. This has included quantifying the affect of varying states of saturation and more importantly macrofaunal and microfaunal degradation, on measured velocities and densities. These data have been used to calculate predicted reflection coefficients for such materials buried in typical estuarine sediments.Further, these values have been compared both with experimentally derived coefficients calculated for 14th and 17th Century oak samples in varying states of preservation and actual values calculated from high-resolution seismic imagery of buried wreck sites. Preliminary results suggest that impedance variability maybe sufficient for high-frequency acoustic sources to detect the change in preservation state over a site.