The Carnac stone alignments, stretching impressively across the Brittany coast of France, stand as one of Europe’s most iconic and enigmatic megalithic landscapes. These rows of standing stones have puzzled archaeologists for centuries, their origins, precise age, and purpose shrouded in mystery. Recent breakthroughs from a pioneering French-Swedish research collaboration have now shed unprecedented light on these ancient monuments, bringing us closer than ever to understanding their construction timeline and cultural significance. This new insight emerges from advanced radiocarbon dating combined with innovative statistical methods, redefining the Carnac alignments as some of the earliest monumental structures of their kind in Europe.
For decades, the Carnac region has captivated scholars and enthusiasts alike, boasting more than 3,000 standing stones spread over a staggering 10-kilometer coastal landscape, ranging from Carnac and La Trinité-sur-Mer to Erdeven. Despite their grandeur, establishing firm dates for these megaliths has proved remarkably challenging. Organic remains suitable for radiocarbon analysis rarely survive the region’s acidic soils, and alternative dating techniques, such as Optically Stimulated Luminescence (OSL), have provided results too imprecise for conclusive interpretations. Addressing these obstacles, the NEOSEA project, an ERC-funded initiative led by the University of Gothenburg in Sweden and involving French partners including Archeodunum and the University of Nantes, has deployed an innovative multi-method approach to unravel the telltale signs embedded within this prehistoric landscape.
Central to this research is the excavation of a previously unexplored section of the Carnac complex known as Le Plasker, located bordering the town of Plouharnel. This rescue excavation, prompted by planned commercial development of a 7,000-square-meter business park, provided a rare opportunity for systematic archaeological investigation. Under the expert leadership of Audrey Blanchard, excavation director and researcher with the NEOSEA project, the team employed advanced excavation techniques along with meticulous sampling strategies. These methods allowed for the recovery of numerous archaeological features, including stone foundation pits associated with hearths and cooking pits, which had been difficult to date with precision until now.
One of the study’s landmark achievements lies in its application of Bayesian statistical modeling to nearly 50 new radiocarbon dates obtained from charcoal and sediment samples linked stratigraphically and contextually with the construction phases of the megalithic structures. This statistical framework enabled the researchers to refine chronological estimates far beyond previous capabilities, reconstructing a detailed sequence of monument construction dating back to between 4600 and 4300 calibrated BC. As a result, the Carnac alignments now emerge as among the earliest known megalithic constructions in Europe, reaffirming Brittany’s Bay of Morbihan as the continent’s earliest epicenter for such monumental architecture.
Importantly, while the massive standing stones themselves have largely disappeared—often removed or repurposed during prehistoric or historic periods—their foundation pits remain intact. These pits offer critical clues about the original placement and construction techniques of the stones. Their direct association with hearths and cooking pits suggests a ritualized or communal function involving fire, though whether these hearths provided illumination, cooking facilities, or feasting venues during the erection of the monoliths remains an open question. Ongoing sedimentary and lithic analyses aim to clarify these aspects and provide further context about the social and ceremonial practices of the builders.
Perhaps even more remarkable is the discovery of a monumental tomb dating to approximately 4700 calibrated BC uncovered at Le Plasker. This tomb was constructed directly atop the remnants of a Mesolithic hunter-gatherer hut, marking a striking temporal and cultural transition at the site. This stratigraphic superimposition reveals complex interactions between Mesolithic foragers and incoming Neolithic communities, illustrating how the revolutionary transformation to farming and monument building unfolded in this part of Western Europe. The tomb’s scale and construction sophistication further emphasize the developing social hierarchies and ritual behaviors emerging at the dawn of Europe’s megalithic era.
The innovative combination of excavation, radiocarbon dating, and Bayesian modeling employed by the NEOSEA project truly marks a methodological breakthrough. Acidic soil conditions in the Morbihan region are notorious for exponential degradation of organic material, severely limiting opportunities for absolute dating and challenging interpretations of the archaeological record. However, the use of a large and well-contextualized sample set, integrated within a Bayesian framework, allowed researchers to overcome these limitations and articulate a much more confident chronological framework during one of Europe’s most revolutionary periods.
Moreover, this work opens new perspectives on the nature and function of megalithic monuments. The association with hearths and pyrotechnical features prompts fresh hypotheses regarding the role of fire in the ritual landscape of early Neolithic communities. This suggests that these alignments were more than simply architectural or territorial markers; they might also have served as focal points for communal activities involving cooking, feasting, or ceremonial fire use—a hypothesis warranting further targeted investigation.
The broader implications of these findings echo beyond Brittany, contributing significantly to debates about the origins and spread of megalithic cultures throughout Europe. By placing the Bay of Morbihan firmly at the forefront of early megalithic development, this study challenges previous assumptions that regions like the British Isles or the Mediterranean held earlier dominance and stresses the crucial complexity and diversity of Neolithic monumentality across different geographical contexts.
Published in the prestigious journal Antiquity, this cutting-edge research underscores the power of interdisciplinary collaboration and advanced analytical approaches in archaeology. It highlights how the integration of high-precision dating techniques and robust statistical methods can unlock new historical narratives from landscapes once considered archaeologically impenetrable. The Carnac region, with its remarkable stone rows now precisely dated to the mid-fifth millennium BCE, stands testament to the ingenuity and cultural dynamism of Neolithic communities shaping the prehistoric world.
As further sediment and lithic analyses continue, the research community eagerly awaits deeper insights into the construction phases, social functions, and symbolic meanings embedded within the Carnac megaliths. This study represents a milestone toward decoding one of Europe’s most monumental and mysterious prehistoric legacies, offering not only a clearer timeline but also prompting reassessment of the ritual, social, and technological innovations that defined early prehistoric societies.
Ultimately, this breakthrough shines a spotlight on the Bay of Morbihan’s immense archaeological significance and reaffirms its status as a cradle of European megalithic tradition. It invites a new generation of researchers and enthusiasts to renew their fascination with the monumental landscapes carved by our ancestors more than six millennia ago, inspiring fresh explorations into the enigma of megalithic Europe.
Subject of Research: Not applicable
Article Title: Le Plasker in Plouharnel (fifth millennium cal BC): a newly discovered section of the megalithic complex of Carnac
News Publication Date: 23-Jun-2025
Web References: http://dx.doi.org/10.15184/aqy.2025.10123
Image Credits: Bettina Schultz Paulsson
Keywords: Carnac alignments, megalithic monuments, Bayesian modeling, radiocarbon dating, Neolithic Europe, prehistoric archaeology, Brittany, stone rows, early tomb, Mesolithic-Neolithic transition
