A Tsunami Devastated Stone-age Britain. Could it happen again? (Patreon)

[This is a transcript with links to references.]

A new study by a group of British geologists suggests that a huge tsunami devastated the populations of Stone Age Britain, about 8200 years ago. Cool! Disaster! Extinction! Could it happen again? Let’s have a look.

This new research is about a fantastically destructive series of disasters known as the three Storegga slides. Sounds like a ride at an amusement park, but it was far from that.

The Storegga slides where massive landslides, underwater, west of Norway. Let’s have a look at a map. Norway is here and Great Britian is southwest of this. The three slides happened around here . Geologists believe that they happened in a relatively short period of maybe days or weeks.

They Storegga slides are among the largest known submarine landslides in history. An estimated three thousand five hundred cubic kilometres of sediment suddenly slipped under water. The slides left still visible erosion marks on the seafloor that span 95 thousand square kilometres.

 Scientists still debate the exact cause of the slides. One hypothesis says it was related to an earthquake. Another is that it was a sudden influx of meltwater from glaciers that destabilized the sea floor. A third that it was a sudden release of methane from underneath the ocean. And science being what science is, there are probably a few dozen more ideas for what happened, but I think I’ll leave it at that.

Whatever the cause, the consequences would have been devastating for people living in the coastal regions of Norway and the Eastern part of the UK. This is because one of those three slides must have caused a massive tsunami. Here is a recent simulation for how that tsunami would have impacted in Northern Scotland near Aberdeen close to a place called Tarty Burn.  Note how the water retreats before hitting and then filling up this little stream. This is not a real time simulation. In reality this flood wave would have taken about 8 hours to roll in and out.

 There’s evidence that this indeed happened in sedimentary deposits that can be found way inland in the Eastern Parts of Great Britain, and that contain debris from the seafloor. The time at which these deposits have been dated is consistent with the time of the slides.

Computer simulations have found that the wave could have reached a height of about 20 meters and in some regions of Great Britain it would have reaches as much as 80 kilometres into the land.

Maybe not so coincidentally, archaeological studies have found that some prehistoric coastal settlements in the affected parts of Great Britain were abandoned around that time. They measure this in terms of dating any kinds of events such as new buildings or changes in land use, and they saw a sharp decline following the Storegga slides.

And that brings me to the new paper, which is about the impact that this tsunami wave would have had of the people who lived in that region at the time.

The people back then were what’s called Mesolithic hunter-gatherers. Mesolithic means that it was a period in the middle of the stone age that was a transition between nomadic and settled lifestyles. At this time it was still possible to cross over from Europe to Great Britain by land through a region called Doggerland. This region once allowed people to walk over from Great Britain to what is now the Netherlands. Doggerland is today at the bottom of the North Sea, and the Dutch are trying very hard to not join them there. Doggerland should not be confused with diggerland which google helpfully suggested.

 The authors of the new paper now say that archeological findings indicate that many of these stone age people in Great Britain lived near the coast where they harvested and farmed seaweed and shellfish. And in the winter, they ate a lot of hazelnuts. Because, as the squirrels have also figured out, nuts are very durable and very nourishing, so they make great winter food.

Unfortunately, the tsunami would have devastated the hazelnut bushes.  So, the lucky people who survived the tsunami would have had nothing left to eat for the winter. They would have forced them to leave.

They authors also point out that the impact of the tsunami would have been particularly devastating in this region of the world because the stone age people living there wouldn’t ever have seen anything like it before and had zero warning. This is different to, say, Japan, where they have frequent earthquakes that sometimes cause tsunamis, so they’d learned to move settlements further inlands. Not so in the UK. They were literally rolled over by this freak event.

Could it happen again? Experts say it’s very unlikely that another big underwater landslide happens in that region.  The sea floor off the coast of Norway was thoroughly investigated 20 years ago because Shell is extracting gas from down there. They found that the reason the sea floor slipped is that during an earlier ice age the reason was covered with glaciers. When the glaciers melted, they left behind a layer of loose dirt that later caused the slip. A similar event could only happen if there was another ice age.

That said, it isn’t entirely possible that other regions will see similar slips or that tsunamis are caused by other events such as earthquakes. This is why every once in a while you hear scientists say that the UK needs a tsunami warning system. But the way these things go, people will only listen to scientists after it happened.