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Scientists find new evidence of massive tsunami that devastated ancient Britain in 6200BC

Scientists led by the University of Bradford have made a major breakthrough in the hunt for confirmation of a historic mega tsunami that is thought to have raged across the North Sea some 8,150 years ago.

Scientists find new evidence of massive tsunami that devastated ancient Britain in 6200BC
The North Sea, Storegga underwater landslide event run-out, associated deposit locations
and core ELF001A [Credit: Gaffney et al. 2020]
Evidence of the catastrophic event has already been found in onshore sediments in Western Scandinavia, the Faroe Isles, northeast Britain, Denmark and Greenland but now for the first time confirmation of the event has been found on the UK’s southern coasts.

The giant tsunami, known as the Storegga Slide, was caused when an area of seabed the size of Scotland (measuring some 80,000sq km and around 3,200 cubic km) shifted suddenly.

This triggered huge waves that would have brought devastation to an inhabited ancient land bridge, which once existed between the UK and mainland Europe - an area known as Doggerland - that is now submerged beneath the North Sea.

Professor Vince Gaffney from the School of Archaeological and Forensic Sciences in the Faculty of Life Sciences at the University of Bradford said: “Exploring Doggerland, the lost landscape underneath the North Sea, is one of the last great archaeological challenges in Europe. This work demonstrates that an interdisciplinary team of archaeologists and scientists can bring this landscape back to life and even throw new light on one of prehistory’s great natural disasters, the Storegga Tsunami. The events leading up to the Storegga tsunami have many similarities to those of today. Climate is changing and this impacts on many aspects of society, especially in coastal locations.”

Scientists find new evidence of massive tsunami that devastated ancient Britain in 6200BC
The sediment of which the sedaDNA was studied [Credit: Dr Martin Bates, UWTSD]
Details of the discoveries, carried out by the Europe’s Lost Frontiers European Research Council-funded research consortium, have been published in the journal Geosciences. The research was led by the University of Bradford and involved Universities of Warwick, Wales St Trinity David, St Andrews, Cork, Aberystwyth, Tartu as well as the Smithsonian and Natural History Museum.

It is thought the tsunami, the largest to hit Northern Europe since the end of the last ice age, happened following a period of global climate change. Until now no clear trace of the tsunami had been found across the southern North Sea and importantly no trace had been found on Doggerland, which was gradually swallowed by rising sea levels after the end of the last glacial maximum. Indeed, scientists now think the tsunami may even have led to the final inundation of Doggerland.

Cores from an area south of a marine trough named the Outer Dowsing Deep provided nearly half a metre of tsunami-like deposits, stones and broken shells sandwiched between laminated estuarine sediments.

Dating indicated they were contemporary with the Storegga event, while analysis including geochemical, sedimentological, palaeomagnetic, isotopic, palaeobotany and ‘sedaDNA’ (sedentary DNA) techniques showed the deposits could be readily interpreted as resulting from a tsunami.

Scientists find new evidence of massive tsunami that devastated ancient Britain in 6200BC
Coastline reconstruction at 8.2 ka cal BP and inferred direction of tsunami advance
[Credit: Gaffney et al. 2020]
The multi-proxy characterisation was necessary as the signatures of tsunamis are often difficult to identify in comparison to those from periodic storm activity. Key to understanding the sequence was the interpretation of geochemical signatures of three major waves hitting and retreating from the land.

A number of innovative sedaDNA breakthroughs were achieved by the University of Warwick scientists - for the first time they were able to see how biomass changes with large natural events.

In addition a new ‘metagenomic assessment methodology’ was developed for authenticating the sedaDNA damaged, whilst under the sea for thousands of years. These innovations, together with assessment of the stratigraphic integrity of samples and refinement in algorithms to define ancient fragmented molecules of DNA, helped establish the sediment provenance.

Professor Robin Allaby from the School of Life Sciences at the University of Warwick said: “This study represents an exciting milestone for sedimentary ancient DNA studies establishing a number of breakthrough methods to reconstruct an 8,150 year old environmental catastrophe in the lands that existed before the North Sea flooded them away into history.”

Scientists find new evidence of massive tsunami that devastated ancient Britain in 6200BC
3D rendering of the area from northern and southern perspectives before and after inundation
(arrow represents north direction) [Credit: Gaffney et al. 2020]
Dr Richard Bayes from the School of Earth and Environmental Sciences, University of St Andrews, said: “The multi-proxy approach has paid off dividends here, in particular the geochemical analysis combined with the geophysics is allowing us to see and interpret data in a way never previously possible.”

At the time the tsunami hit Doggerland, a Mesolithic hunter-gather people could have been using the remaining archipelago and for those unfortunate enough to be caught within the tsunami runup zone, it would have been devastating. However, the palaeo-topography and environmental modelling suggest that much of the landscape may have survived reasonably intact to rapidly return to pre-tsunami conditions. The longer term fate of these lands was to be submerged as sea level rose to those of the present day.

Source: University of Bradford [July 15, 2020]


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