A Stone Age wall found at the bottom of the Baltic Sea "may be Europe's oldest megastructure". The structure stretches almost a kilometer from the coast of Germany and may have once stood on the shore of a lake.
A Stone Age wall discovered beneath the waves off Germany's Baltic coast may be the oldest known megastructure built by humans in Europe, researchers say.
The wall, which stretches for nearly a kilometer along the seafloor in Mecklenburg Bight, was discovered by accident when scientists were operating a multi-beam sonar system from a research vessel during a student trip about 10 km (six miles) offshore, The Guardian writes.
Closer inspection of the structure revealed about 1,400 smaller stones that appeared to be arranged to connect nearly 300 larger boulders, many of which were too heavy for groups of people to move.
The underwater wall, described as a “breathtaking discovery”, is covered by 21 meters of water, but researchers believe it was built by hunter-gatherers on land next to a lake or swamp more than 10,000 years ago.
Although the purpose of the wall is difficult to prove, scientists suspect that it served as a roadway for hunters pursuing herds of reindeer.
“When you chase animals, they follow these structures, they don't try to jump over them,” says Jakob Giersen of the Leibniz Institute for Baltic Sea Research in Warnemünde, a German port city on the Baltic Sea coast.
“The idea would be to create an artificial bottleneck with a second wall or lake shore,” he added.
The second wall, which ran adjacent to the barrier wall, may be buried in seafloor sediments, the researchers write in the Proceedings of the National Academy of Sciences.
On the other hand, the wall may have helped drive animals into the nearby lake, slowing them down and making them easy prey for men lying in ambush in canoes armed with spears or bows and arrows.
Based on the size and shape of the 971-meter-long wall, Jakob Geersen and his colleagues believe it is unlikely that it was formed by natural processes, such as a huge tsunami pushing rocks into place, or rocks left behind by a moving glacier.
The angle of the wall, which is mostly less than 1 meter high, changes direction when it collides with larger boulders, suggesting that the smaller piles of stones were placed deliberately to connect them. In total, the stones of the wall are believed to weigh more than 142 tons.
If the wall was an ancient hunting trail, it was likely built more than 10,000 years ago and submerged as sea levels rose about 8,500 years ago.
“This places the wall among the oldest known examples of hunting architecture in the world and potentially makes it the oldest man-made megastructure in Europe,” the researchers say.
Now Geersen aims to return to the site to reconstruct the ancient landscape and look for animal bones and human artifacts, such as hunting shells, that may be buried in the sediments around the wall.