An underwater archaeological expedition in the Brittany region of western France has led to the discovery of a unique stone wall that is approximately 7,000 years old. According to scientists, the length of this structure reaches 120 meters, and it has already been recognized as the largest underwater construction found in France.
This is reported by Finway
Ancient Wall on the Seabed: Scale and Purpose
Currently, this massive wall is located underwater at a depth of about nine meters. However, archaeologists have established that when it was built, it was situated right on the coastline of Saint Island. Radiocarbon dating indicates that the structure was constructed around 5000 BC, when sea levels were significantly lower than they are today.
The dimensions of the construction are also impressive: the total mass of the stone blocks is around 3,300 tons. This indicates a high level of organization within the ancient community capable of executing large-scale engineering projects. As noted by archaeologist Ivan Payler, the construction could have been carried out by settled hunter-gatherers or the first Neolithic communities that emerged in the region.
The wall is about 20 meters wide and approximately two meters high. Along it are large granite monoliths arranged in parallel rows. Researchers suggest that these stones were initially placed on bedrock, and then the main part of the structure was formed around them.
Hypotheses About Its Purpose and Connection to Legends
The purpose of this structure remains a subject of debate among scientists. One theory suggests that it could have been a fish trap: the stone projections were used to hold woven barriers that trapped fish during low tide. Another hypothesis is that the wall served as a dam or protective structure designed to hold back the advancing sea. It is believed that the gradual rise in water levels could have led to the flooding of nearby settlements.
“Scientists also do not rule out that the structure was part of an ancient Stone Age settlement, the disappearance of which may have inspired local legends about sunken cities.”
Researchers emphasize the similarity of the construction techniques of this wall to the well-known Breton menhirs, although the new find is several centuries older than the first megalithic monuments in the region.
The discovery of the ancient structure was made possible thanks to modern technologies. Geologist Yves Fouquet noticed a perfectly straight line on the radar maps of the seabed that crossed an underwater valley. Following dives that began in 2022, researchers confirmed the artificial origin of the object.
Complete mapping was only possible in winter when dead algae revealed the stone surface. A detailed description of the discovery has been published in the International Journal of Maritime Archaeology. There, scientists also suggested that the structure might be related to Breton legends about the sunken city of Ys, which, according to tradition, was located nearby in the Douarnenez Bay.
According to scientists, the sudden rise in sea levels and the forced abandonment of coastal settlements may have left a deep mark on collective memory, transforming into myths that have persisted to this day.