In programme 6 we featured a pamphlet dating from 1607 which described the ‘great flood’ – which has now been shown to have probably been a tsunami – that hit the Bristol Channel coast line on 30th January that year.
A total of 570km of coastline was affected, from northern Devon to Gloucestershire and from Monmouthshire to Glamorgan. Indeed, less devastating effects were suffered along the west Wales coast to Cardigan Bay.
The disaster is commemorated on plaques on the walls of several churches in Somerset and Monmouthshire. One such plaque in the church of Kingston Seymour reads – “An inundation of the sea water by overflowing and breaking down the Sea banks; happened in this Parish of Kingstone-Seamore, and many others adjoining; by reason whereof many Persons were drown’d and much Cattle and Goods, were lost: the water in the Church was five feet high and the greatest part lay on the ground about ten days. WILLIAM BOWER”
It is estimated that 2,000 people lost their lives in the disaster and that some communities were completely devastated, never to recover, having literally been swept out of existence. Tsunamis were an unknown phenomena in Britain at the time, and for centuries the disaster was thought to have been caused by a great storm flood.
However, the idea that the area was hit by a tsunami was put forward in 2002 by Dr Simon Haslett, Head of Geography at Bath Spa University College, author of Coastal Systems and Dr Ted Bryant, School of Geosciences at the University of Wollongong, Australia, author of Tsunami: the Underrated Hazard, in their scientific paper Archaeology in the Severn Estuary.
The two scientists’ initial suspicions had been raised while reading historical documents from the flood-hit areas, which contained some revealing reports and testimonies pointing to the suddenness of the flood, its characteristics and its devastating effects. Many documents report that the weather was fine, dry and sunny, and that people were going about their daily business as normal. At Appledore harbour in Devon, a 60-ton ship was fully laden and about to set sail when she was carried inland by the flood and left lying in marshland way beyond the high tide mark.
Other telling accounts of the speed and ferocity of the flood – many from Monmouthshire – include individual cases of people caught and drowned as they fled upstairs, a child surviving after being hoisted onto the beams of a house, people clinging to treetops and flotsam, bolted doors smashed by the water, houses swept away with their inhabitants, properties hit 4 miles inland, and the wave advancing faster than a greyhound could outrun it. Most telling of all are the accounts of the sea being “driven back” from the beaches seconds before the wave hitting – which describes how a tsunami sucks the water from the coast prior to hitting land. Other telling testimonies describing the ‘rolling hills of water’ and what looked like a ‘wall of fog’ rushing in at great speed match eyewitness accounts of more recent tsunamis of modern times. These testimonies and many more examples can be found by following this link to a more detailed account of the disaster.
Drs Haslett and Bryant returned to the Severn estuary in 2004 to conduct archeological research. They found many areas where the erosion of rocks and land had been caused by water rushing at high velocity. They included two areas of farmland that had simply been swept away – one to the north of Bristol by the foundations of the new Severn Crossing, and another which is now the reservoir for Oldbury nuclear power station. They also found huge rocks that had been carried inland way past the high water mark and left stacked like dominoes. Furthermore, after drilling boreholes over an area from north Devon and Gloucesterchire to the Gower, the scientists found that the area had been covered by a layer of sand at a time corresponding with when the disaster struck.
All this evidence enabled Haslett and Bryant to calculate the height of the wave, its speed, the size of the area affected and the extent of the damage it would have caused. Again, these findings can be found by following the above link.
By the way, next time you’re in the Prince of Wales pub at the bottom of St Mary’s Street in Cardiff, take a look at the outside of its western wall. You will see the outline of the belltower end of the old St Mary’s Church which once stood on the site, and which is believed to have been destroyed by the tsunami of 1607.