Acoustic archaeology: A sound approach
- Published: May 15, 2013
- Author: David Bradley
- Channels: Chemometrics & Informatics
Crumble to the sea
Researchers in the UK have carried out the most detailed analysis ever of the archaeological remains of the lost medieval town of Dunwich on England's Suffolk coast. The study analysed data obtained via acoustic spectroscopy to see the ruins through the murky depths of the North Sea.
Coastlines are ever shifting, heavy seas, pounding tides, wind and rain beating against shoreline cliffs take their toll over time. But, where humans settle and build on coastal margins, storms can shatter lives as cliffs crumble. One such place is at Dunwich on the east coast of the England where a combination of storms as well as planning decisions by the towns inhabitants caused the mediaeval village to crumble into the sea. Dunwich with its 8 churches and two friaries, once stood proudly staring out to sea 5 kilometres south of Southwold and about 4 km North of Leiston the village that now serves Sizewell nuclear power station.
"Our coastlines have always been changing, and communities have struggled to live with this change," says David Sear of the department of Geography and Environment at Southampton University. "Dunwich reminds us that it is not only the big storms and their frequency - coming one after another, that drives erosion and flooding, but also the social and economic decisions communities make at the coast. In the end, with the harbour silting up, the town partly destroyed, and falling market incomes, many people simply gave up on Dunwich."
Dunwich was once a thriving port of a similar size to 14th Century London, but seven centuries of storms, coastal erosion, flooding and other factors have all but wiped it off the map, but for the submerged remnants and a few fragmentary buildings. The loss of Dunwich began in 1286 when a huge storm swept much of the settlement into the sea and silted up the Dunwich River. This storm was followed by a succession of others that silted up the harbour and squeezed the economic life out of the town, leading to its eventual demise as a major international port in the 15th Century.
In work supported by English Heritage, Sear and his colleagues have used advanced underwater imaging techniques to plot a precise map of the lost streets and major buildings of Dunwich to reveal previously unmarked ruins on the seabed. Sear worked alongside the University's GeoData Institute, the National Oceanography Centre, Southampton, Wessex Archaeology and local divers from North Sea Recovery and Learn Scuba.
Sounding out murky waters
"Visibility under the water at Dunwich is very poor due to the muddy water," Sear explains. This somewhat limited visual exploration of the site by divers, so he and his colleagues turned to high-resolution DIDSON acoustic imaging. This is the first time the technology has been used in such a context as it is more commonly used to explore ship wrecks and such like. "The data produced by DIDSON technology helps us to not only see the ruins, but also understand more about how they interact with the tidal currents and sea bed," Sear adds.
"Whilst we cannot stop the forces of nature, we can ensure what is significant is recorded and our knowledge and memory of a place doesn't get lost forever," Sear says. The project was started in 2008 and has now confirmed the town limits, revealing Dunwich to have been approximately 1.8 square kilometres, almost as big as the present City of London. The study also shows that there was a smaller, central enclosed area of 1 square kilometre that may have been Saxon earthworks.
Current global climate change and concern for rising sea levels affecting coastal habitations around the world have made coastal erosion a topical issue in the 21st Century, but Dunwich shows that it has been with us a long time. It is perhaps no coincidence that the severe storms of the 13th and 14th Centuries were also a period of climate change as the warmer mediaeval climatic optimum chilled to the infamous Little Ice Age.
Article by David Bradley
The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.