High resolution acoustic imagery from a shallow archaeological site: The Grace Dieu - a case study


Plets, Ruth M.K., Dix, Justin K., Adams, Jon R., Best, Angus I. and Mindell, David A. (2005) High resolution acoustic imagery from a shallow archaeological site: The Grace Dieu - a case study. In, Papadakis, J. and Bjorno, L. (eds.) Proceedings of the 8th European Conference on Underwater Acoustics, 12-15 Jun 2006. 1st International Conference on Underwater Acoustic Measurements: Technologies and Results Heraklion, Greece, Foundation for Research & Technology - Hellas.

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Description/Abstract

Shallow water (< 5 m) archaeological shipwreck sites present unique challenges to geophysical investigation. Retrieval of reliable data is very difficult due to issues of water column bubble turbulence and the restricted acoustic geometry of the system. This paper will present an acquisition method that tackles these problems through the combination of a high resolution sub-bottom system, DGPS navigation and a non-motorised deployment method.

The test site for this system was the Grace Dieu (1418), the ‘great ship’ of Henry V’s fleet, which was scuttled at its berth in the Hamble River (UK). The site is typically covered by 2-5 m of water, and is partially buried within muddy inter-tidal sediments. At exceptionally low tides, during the spring equinox, a few of the marginal timbers are exposed.
Close survey line spacing (< 2.5 m), accurate navigation and decimetre resolution acoustic data enable a full 2D and pseudo-3D interpretation, including amplitude analysis, of the site to be undertaken. This data has identified the true plan form and dimensions of the remaining segments of this historic vessel supporting the assertion that it was the most significant naval design for over two centuries. It has also been possible to identify the presence of a horizon of incoherent timbers associated with the scuttling of the vessel. Through an archaeological case study the potential of imaging buried objects in extremely shallow environments has been effectively demonstrated.

Item Type: Book Section
Keywords: chirp, maritime archaeology, shipwreck sites, shallow water, geophysics
Subjects: C Auxiliary Sciences of History > CC Archaeology
Q Science > QE Geology
G Geography. Anthropology. Recreation > GC Oceanography
Divisions: University Structure - Pre August 2011 > School of Humanities > Archaeology
University Structure - Pre August 2011 > School of Ocean & Earth Science (SOC/SOES)
University Structure - Pre August 2011 > National Oceanography Centre (NERC)
ePrint ID: 40834
Date Deposited: 11 Jul 2006
Last Modified: 27 Mar 2014 18:25
URI: http://eprints.soton.ac.uk/id/eprint/40834

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