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Last Updated: Tuesday, 23 September, 2003, 16:21 GMT 17:21 UK
Hi-tech could reveal 'drowned city'
Divers in lake
Could divers help locate secrets uncovered by bathymetry?
New underwater technology could be used to unearth secrets of drowned landscapes around the Welsh coastline.

British scientists have unveiled a revolutionary scanning technique that can create a map of sea beds to identify where people might have lived thousands of years ago.

Legends relating to the Welsh coast abound, including the "lost city" of Cantre'r Gwaelod in Cardigan Bay.

A sonar technique known as bathymetry developed by scientists at Imperial College, London, could give an insight into where people could have lived in the sea off the current Welsh coastline up to 8,000 years ago.

Parts of Cardigan Bay and the Bristol Channel were once dry land and we could look at areas such as these to see if they are of archaeological interest
Sian Rees, Cadw

Cadw, the agency responsible for Wales' ancient monuments, could liaise with other bodies such as universities to look into the lost heritage that lies off the Welsh coast.

The Imperial College team has already conducted an initial survey of an river running into the English Channel.

Ice age

The research in the Channel showed the river bed that had been created several thousands of years ago, as well as the bays and cliffs along its valley.

According to Dr David Miles, English Heritage's chief archaeologist, the technique could also be useful for study in Welsh waters.

Cardigan Bay at Borth
Cardigan Bay could be one site that is investigated
"This technique could also be applied to study areas of the Irish sea and the Severn estuary," said Dr Miles.

At the end of the last ice age about 10,000 years ago sea levels were much lower than now.

But when the ice melted, previously dry areas were drowned by the waters over a number of years.

According to Dr Miles, bathymetry could also be used to study the Wentloog levels which had been colonised and drained by the Romans on the Severn estuary.

Sian Rees, a Cadw inspector of ancient monuments with responsibility for maritime archaeology, said: "Bathymetry has already been used to study protected wrecks off the Welsh coastline but this new technique can obviously be used on a much wider scale," she said.

"Parts of Cardigan Bay and the Bristol Channel were once dry land and we could look at areas such as these to see if they are of archaeological interest.

Severn Bridge
The Severn estuary was once colonised by the Romans

The Imperial College team used sonar equipment tied to the hull of a survey to sweep across the sea bed.

The new technique, using satellite positioning equipment, computers and software allows the creation of a three-dimensional image of the landscape beneath the boat.

Archaeologists can then use this information to identify the most likely places where humans lived.

"These areas could be studied in more detail with the possibility of finding archaeological material from sedimentary deposits," said Dr Sanjeev Gupta, who led the Imperial College research team.

"The technique allows us to use valleys from the last ice age and use seismic profiling to look at ancient river systems."

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