RASSE Methodology

Seabed character studies

The presence of exposed and/or buried archaeological material will affect the physical and acoustic properties of sediment. By adopting rapid remote geophysical survey techniques that yield quantitative information, not only can the archaeological potential and condition of sites over large areas of seabed be assessed, but provision can also be made for monitoring sites repeatedly, and for measuring change.

A definitive archaeological site investigation agenda requires a multi-disciplinary approach to provide for the effective management of any form of submerged cultural heritage.

The RASSE project aims to integrate geophysical (remote surveying), physical (sedimentological & engineering), biological, chemical, geographical and historical applications to fully understand factors affecting submerged archaeological material, levels of preservation and site stability, using the investigation methods outlined below.

Data gathering will take place over a three year cycle on each of three test sites. Each site will be recorded three times during the research project, and this will enable the project team to identify optimum equipment configurations, and to measure (any) change to sites in an accurate and quantitative way.

Following publication of the Year One report, the RASSE team will be constructing and trialling a towable multibeam platform a new towable multibeam sonar platform. This platform will enable the team to reduce the distance between the sonar head and the seabed, and so to increase resolution of the sonar footprint.

Site overviews and results.

Above: A remote sensing image of a wreck site in the Goodwin Sands.

Above: Table of remote sensing methods selected for use in this project, what environmental factors these methods address, and how the accuracy of these measurements will be assessed.

Enhanced Geophysical Tool Evaluation

Pattern recognition techniques that have been applied for the automatic classification of sonar data (sidescan sonar, bathymetric sidescan and multibeam sonar) include those produced by Quester Tangent and Applied Acoustics.

Dr Louis Atallah (British University in Dubai, and School of Informatics, University of Edinburgh) and colleagues have successfully processed sidescan data gathered by the Universities of Ulster and St Andrews in Belfast Lough, using algorithms based on scale-saliency methods. These algorithms will be tested on data acquired during this project from both multibeam and sidescan sonar systems.

In addition, combining bathymetric and sidescan data can aid development of automated seabed classification and object discrimination and such procedures will be tested on project datasets, with the aim of improving the classification of artefacts. The overall objective of this work will be to produce useful documentation that will advise curators on the best algorithms and processing methodologies for use on remote sensing datasets in the future.

Bottom right: photograph of a towed side-scan sonar 'fish', which records seabed topography.

Outreach

This website will provide a portal for public access to the RASSE project, and will be updated regularly. The site includes a copy of the project design (see our Library page) while annual reports and advisory publications will be added in due course.

Copies of reports, the project database, ArcGIS shapefiles, and other digital file types are to be submitted to English Heritage and the National Monuments Record (NMR), and to the relevant County Archaeology Services.

The intention is to publish key results for academic purposes in archaeologically orientated journals such as the Journal of Archaeological Science and the International Journal of Nautical Archaeology.

The project team are also willing to present papers on the RASSE project at local seminars and conferences. Interested parties should contact Philip Robertson.