In the Bay of Mecklenburg, researchers have discovered an almost one kilometer long stone wall at the bottom of the Baltic Sea. It was probably created by hunters and gatherers more than 10,000 years ago. At that time, the area was not yet flooded, as the group led by Jacob Geersen from the Leibniz Institute for Baltic Sea Research Warnemünde (IOW) and Marcel Bradtmöller from the University of Rostock write. The so-called blinker wall could have helped people capture reindeer, the research team suspects in the specialist magazine “PNAS”.

The wall is located around ten kilometers northwest of the town of Rerik at a depth of around 21 meters. It consists of almost 1,700 stones, is 971 meters long, up to two meters wide and usually less than a meter high. The structure was flooded by the Baltic Sea about 8,500 years ago. There is nothing comparable in Europe, the group writes.

The Blinkerwall was discovered by chance during mapping in September 2021. The 1,673 stones of the wall have a volume of almost 53 cubic meters and together weigh more than 142 tons. Most weigh well under 100 kilograms.

The team considers natural causes for the system – such as a tsunami, retreating glaciers or underwater currents – to be extremely unlikely. Other human interventions as a cause are also implausible.

The team believes that groups of foragers used the facility to hunt reindeer. The structure has not been dated directly, but from 9,800 years ago the region was forested and reindeer passed by less often – such a structure would no longer have made sense.