The Storegga Slide
The three ancient Storegga Slides are considered to be amongst the largest ever known landslides. They occurred underwater, at the edge of Norway’s continental shelf, and involved an estimated 290 km length of the coastal shelf with a total volume of 3,500 km3. This catastrophic landslide would have caused an enormous wave, or tsunami, in the north Atlantic which swept southwards.
In Scotland, traces of the tsunami have been recorded, with deposited sediment being discovered in Montrose Basin, the Firth of Forth, up to 80 km inland and 4m above current normal tide levels.
Based on radiocarbon dating of plant material recovered from sediment deposited by the tsunami the landslides occurred around 6225–6170 BC.
At the time of the last Storegga Slide, a land bridge as Doggerland existed, linking the area of Great Britain, Denmark and the Netherlands across what is now the southern North Sea. This area is believed to have included a coastline of lagoons, marshes, mudflats, and beaches, and to have been a rich hunting ground populated by Mesolithic people.
Doggerland would have been inundated by a tsunami triggered by the Storegga Slide. This event would have had a catastrophic impact on the contemporary Mesolithic population, and separated cultures in Britain from those on the European mainland.
To look for evidence of the tsunami at Howick a number of core samples were taken. This virtually non-invasive technique allows a relatively large area to be quickly surveyed.
Evidence at Howick
There is compelling evidence for the impact of this ancient tsunami at Howick. The photograph shows Dr Ian Boomer holding one of the core samples from the Howick Burn Valley. There is an obvious change in the texture of the core with rocky material on the left-hand side. This is the lower layer of sand and pebbles deposited by the tsunami.