Massive Undersea Wall Discovered Off Brittany Coast Dates Back To 5000 BC

French marine archaeologists have uncovered a vast underwater wall near Brittany, dating back to around 5,000 BC, according to BBC. This discovery might relate to a stone age society that vanished due to rising sea levels, possibly inspiring local myths of a submerged city. The wall, measuring 120 metres in length, is the largest underwater structure found in France.

The wall's original purpose remains uncertain. Archaeologists suggest it could have been a fish-trap or a dyke against rising waters. Initially built on the Ile de Sein's shoreline, it now lies nine metres underwater as the island has significantly reduced in size over time.

The structure averages 20 metres in width and two metres in height. Divers discovered large granite monoliths protruding from the wall at regular intervals. These stones were likely placed on bedrock first, with the wall constructed around them using slabs and smaller stones.

The wall's construction required significant effort from a settled community, weighing approximately 3,300 tonnes. Its durability over 7,000 years indicates it was robustly built. "It was built by a very structured society of hunter-gatherers," stated archaeologist Yvan Pailler.

Pailler noted that these monoliths predate Brittany's famous menhirs linked to Neolithic culture. There might have been knowledge transfer between Mesolithic hunter-gatherers and Neolithic agriculturists regarding stone extraction and transport techniques.

Discovery and Exploration

Local geologist Yves Fouquet identified the wall after examining undersea depth charts created with advanced radar technology. "Just off Sein I saw this 120-metre line blocking off an undersea valley. It couldn't be natural," he told Le Monde newspaper.

Archaeologists began exploring the site in summer 2022 but waited until winter when seaweed receded to map it accurately. Their findings were published in the International Journal of Nautical Archaeology.

Connection to Local Legends

The paper suggests such sites may have inspired Breton legends of sunken cities like Ys, believed to be in the Bay of Douarnenez nearby. "It is likely that the abandonment of a territory developed by a highly structured society has become deeply rooted in people's memories," it states.

The rapid rise in sea levels led to abandoning fishing structures and habitation sites, leaving a lasting impression on local folklore. This historical event might explain tales of lost cities passed down through generations.

With inputs from WAM