The megalithic alignments of Carnac, in southern Brittany, are one of the most spectacular prehistoric remains in Europe. Arranged over more than 10 kilometers between the towns of Carnac, La Trinité-sur-Mer and Erdeven, these groups of thousands of driven stones form a spectacular landscape of inexhaustible interest. Until recently, however, their exact dating remained imprecise, largely due to the absence of datable organic materials in the acidic soils of the Morbihan.
Now, a recent archaeological study at the site of Le Plasker, a few kilometers from the main core of Carnac, sheds light on this unknown. The acquisition of 49 radiocarbon dates has made it possible to establish a new refined chronology that places the construction of the first monumental elements around 4720 B.C., i.e. at the beginning of the fifth millennium B.C. Carnac could thus become the oldest megalithic monument in Europe.
Le Plasker: a decisive discovery
The excavations at Le Plasker began in 2020 under the direction of Audrey Blanchard, as part of an archaeological rescue project prior to the development of a business park. The discovery exceeded all expectations. A previously unknown section of the Carnac megalithic complex was uncovered, with structures including a monumental tomb, stone alignments and large stone hearths with evidence of combustion.
The archaeological study, supported by geoarchaeological, micromorphological and anthracological analyses, revealed that the site was intermittently occupied from the Late Mesolithic (ca. 5700-5100 cal BC) to the mid-Neolithic (ca. 4050 cal BC). However, it was the dating of the burial mound and surrounding alignments that provided the most revolutionary piece of information: the monumentalization of the landscape at Carnac began much earlier than previously thought.
A monumental tomb before megalithism
One of the most important finds was a monumental pre-megalithic tomb, radiocarbon dated between 4791 and 4686 cal BC. It is a small circular mound, about 3.3 meters in diameter, covering a stone cist with a quadrangular plan, built above ground level and oriented northwest to southeast. These dates make the tumulus of Le Plasker one of the oldest funerary monuments in Western Europe, contemporary or even earlier than the first phases of the famous Carnatic tumuli of Saint-Michel or Tumiac.
Although neither skeletal remains nor grave goods have been preserved due to the acidity of the soil, micromorphological analysis revealed that the cist was originally covered with organic matter, perhaps a wooden roof. In addition, 46 horizontally arranged monoliths were identified around the mound, perhaps with a symbolic or landscape function. This tomb is located in the center of a complex that seems to have been planned from the beginning with a clear monumental intention.