New research proposes that Stone Age mass graves on Scotland's Orkney and Shetland islands could be linked to a devastating tsunami that struck around 5,500 years ago. The study, led by Genevieve Cain of the University of Oxford, suggests that the mass burial sites, known as cairns, may have been hastily constructed to bury victims of the Garth tsunami, which caused sea levels to rise by nearly 10 metres.
The Orkney islands contain at least 72 stone tombs dating back up to 6,000 years. Traditionally, archaeologists have interpreted these mass burials as reflecting social and spiritual practices. However, the new study argues that the timing and location of these sites coincide with the catastrophic event, which would have resulted in high death tolls and rapid burials.
Evidence for the Garth tsunami was originally found in deposits at Sullum Voe in Shetland, with further evidence in Loch Garth and Loch of Benston on the Scottish mainland. The researchers point to sandy deposits overlaying Neolithic settlements on the island of Sanday, previously attributed to wind, but now interpreted as tsunami debris due to the presence of stones.
Similar findings occur around the Bay of Skaill and Brodgar Isthmus, where palaeoenvironmental records indicate significant woodland loss around 5,500 years ago, associated with sand influx. The study, published in the Journal of Archaeological Method and Theory, acknowledges that the tsunami theory is controversial and has met scepticism from some researchers who note that previous archaeological evidence does not suggest the tombs were built in haste.
