An immense dry-stone cairn at Barnenez in the Finestère region of Brittany, France, contains eleven passage graves and ranks among the most important prehistoric monuments of western Europe (fig. 1). It overlooks the Morlaix inlet in the commune of Plouézoch. Analysis of the construction of the cairn and the form of its passage graves indicates that the monument was built in several phases. Although some initial radiocarbon dates among a long series, when recalibrated, suggested that the Barnenez tombs were built very early in the fifth millennium b.c., analyses of the forms of the tombs and the contexts of the charcoal samples used for dating now point toward a date of approximately 4300–4100 b.c.
The footprint of the Barnenez cairn takes the form of a trapezoid. The entire monument is 74 meters long on its east-west axis, 29 meters wide at the western end, and 17.5 meters wide at the eastern end. Its eleven passage graves (A, B, C, D, E, F, G, G', H, I, and J) lie roughly parallel to each other. The passages enter at the south and run north to the chambers. Some of the Barnenez passage graves are constructed using dry-stone walling (flat stones stacked up) and corbeled vaulting (in which each course of stones is shifted toward the center of the chamber until the roof is eventually closed in). Others have orthostats (large upright stones) roofed over with capstones (large boulders laid flat across the orthostats, fig. 2). In several instances, orthostats are combined with dry-stone construction.
The Barnenez site was discovered in the mid-1950s. A quarry had been established at the site, and a pit opened in the mass of stones revealed burial chambers A, B, C, and D. They were brought to the attention of archaeologist Pierre-Roland (P.-R.) Giot, who headed the Anthropology Laboratory of the National Center for Scientific Research at the University of Rennes. At that time France lacked the archaeological resources it has today, but Giot spearheaded efforts to carry out a rescue excavation. At his insistence, work in the quarry was stopped. Consequently, France applied a national rule that the accidental discoverer of an archaeological site would be responsible for its preservation. Giot began his research in 1955 and closed most parts of the monument to the public while conducting his studies.
Barnenez and the neighboring monument of Carn were the first European passage graves to be radiocarbon dated. The first reported dates—in the first half of the fifth millennium b.c.—surprised scientists, who had expected a late-fourth millennium b.c. date, based on typological classification of the architecture. The unexpectedly early dating made it possible to affirm the presence of a Breton identity on the French archaeological landscape, this at a time when the preservation of Neolithic monuments was gaining importance. Giot's research accelerated the rate of learning about megalithic architecture and its origins. Nonetheless, it was not until 1987, more than thirty years after the site's discovery, that Giot's scientific monograph on Barnenez and Carn was published, giving archaeologists the hard data and scientific analysis to assess his conclusions.
Eleven passage graves stretch through the body of the Barnenez cairn, all of which open to the south through a rectilinear facade. Rather than being the product of one or two construction stages, this massive monument was in reality constructed in several stages, offering successive states that were very different from the final appearance of the enormous stone mound as it appears in its restored form. The Barnenez construction phases have been the subject of debate among archaeologists, but a plausible sequence based on the form of the burial chambers is presented here.
The cairn is divided into two distinct parts that can be identified by the composition of their respective building materials, which are of distinct geological origin and have different colorations, at least on their outer surfaces. One part of the cairn contains five graves in a high topographical location; the other includes the six remaining chambers built on the slight downslope. The second group of graves seems to be the more recently constructed, but the design of the graves are similar from one part of the massive structure to the other. In fact, it is necessary to consider these two constructions in detail to realize that the sequencing is more complex than it appears and involves the chronology of individual graves.
To understand these differences fully, it is necessary to sidetrack to a classification principle of the chambered tombs of western France. The typologies of megalithic funerary architecture in Brittany are well established and have been steadily improved by a long line of researchers. Despite the limitations of classifying funerary architecture, a main goal of such classifications is to define the structure and organization of the internal space. Examples include passage graves with a well-differentiated single chamber, passage graves and chambers divided into compartments, and passage graves and chambers with widened openings.
This classification of the Breton chambered tombs is based on a spatial differentiation of the tomb interiors into two principal parts: a burial chamber and an access passage to the burial chamber. These parts are naturally linked, and their relationship changed over time. As the chambers developed and grew longer, the access passage and surrounding burial mound grew shorter. This typological sequence of megalithic burial places is not rigidly established but rather is driven by a dynamic evolution leading from the first passage graves (moving from the fifth to the fourth millennium b.c.) up to the gallery graves (end of the fourth millennium b.c.). In the earlier tombs, there is a strong differentiation between the chamber and the entrance passage, while in later tombs the differences in width and height between chamber and passage grow smaller and eventually disappear.
It is exactly this progressive loss of differentiation of the internal space of the graves that makes it possible to distinguish the various phases in the Barnenez cairn. Thus, in the eastern cairn, the central tomb (H) differs typologically from the adjacent tombs (G and G'; I and J). Until recently, the carvings and megalithic construction of tomb H led to its interpretation as a sort of temple or monument of prestige, while the neighboring tombs that used only dry stone were interpreted as ritual spaces that were in simultaneous service with tomb H.
Such simultaneous use is thrown into doubt, however, upon examining the tomb interiors. The extreme differentiation between chamber and passage in tombs G, G', I, and J, not only discernible in plan but also in elevation (with vault heights reaching five meters), contrasts with the absence of such features in tomb H. Analysis of the variation in chamber and passage shape now allows new speculations on the layout and construction sequence of the original monument: Two small adjacent cairns initially coexisted, each containing two first-generation passage graves, G and G', I and J. Subsequently, tomb H was built between these two earlier cairns, according to a distinct plan and with distinct materials. The whole tomb complex was covered by a more enveloping cairn, making it necessary to lengthen the passageways of the older monuments.
The construction sequence of the second part of the massive cairn can also be reexamined according to this model. Application of the classification principle again differentiates tombs A and B, placed at the western extremity, from the other four adjacent chambers to the east. The lack of internal differentiation is seen in the volumes of the chambers of tombs A and B, where the ceiling heights are barely higher than the passage heights. They are indeed constructed differently than the neighboring tombs, using massive capstones rather than corbeled vaults. This method is the result of a choice to reduce the chamber volumes, and it is identical to the construction of the Table des Marchands, another famous monument of Brittany that cannot date further back than 3800 b.c. Tombs C and D exhibit a little more differentiation between passage and chamber than A and B, and the next ones, E and F, even more so. It is possible to imagine an initial small cairn containing these older passage graves as suggested by similar narrow sections in their passageways.
During the final process of covering over the graves with a pile of stones, it was necessary to lengthen the pre-existing passageways to adapt to the elongated trapezoidal plan of the final monument. It can be clearly seen that the orientation of the passageways in the two parts of the Barnenez cairn differ by several degrees. It was necessary to extend the passageways so that their opening could be reestablished on a relatively straight, rather than concave, facade.
QUESTIONS ABOUT RADIOCARBON DATING
Radiocarbon dating carried out on charcoal samples from Barnenez initially identified the monument as the oldest stone architecture in western Europe. The dating was seen as a successful application of the radiocarbon technique and was used to support arguments for a "long" chronology of Breton megalithic monuments beginning close to 5000 b.c. But a careful reinterpretation of the samples that were originally analyzed prior to the early 1990s has questioned these findings.
The oldest Barnenez radiocarbon date (between 5010 and 4400 b.c.) comes from the excavation conducted in chamber G in 1968. The charcoal samples were collected from the clay soil of the chamber, and this soil, as Giot wrote in Barnenez, Carn, Guennoc, was apparently intentionally brought in to level out the floor of the chamber. In tomb F, the charcoal samples came from a forty-centimeter-thick layer of sterile clay topped by the layer of gravel that contained the archaeological material (between 4705 and 3955 b.c.). In chamber A (between 4550 and 3895 b.c.), the charcoal samples were taken from a supply of broken stones deposited there to level out the natural slope of the terrain. As can be seen in all the cases, the materials from which the charcoal samples were collected—the sterile clay layer and soils brought from outside—do not in any way date the construction of the tombs. Instead, it is probable that the charcoal resulted from fires that occurred long before the monument was constructed.
When viewing Barnenez within the overall regional typological sequence of mortuary monuments, it appears that a more realistic date for the construction of its earliest passage graves would lie in the last centuries of the fifth millennium b.c. It was perhaps not until several centuries later that the monument reached its final form. Although a revision in dating of several centuries closer to the present may seem relatively insubstantial on the scale of the millennia of later prehistory, it is important to provide an accurate chronological position for the type of mortuary architecture seen at Barnenez. At the same time, it is important to keep in mind that this architecture was the product of a long period of development of monumental mortuary construction in the west of France. In this regard, the carved upright stones, or orthostats, found in several of the Barnenez tombs assume new significance.
MEGALITHIC SYMBOLISM AND STELAE AT BARNENEZ
Several orthostats from the chambers and passageways have carvings made by pecking on the rough surfaces of the granite. Motifs include axe blades, bows, horned signs, and goddesses, but the images are open to a variety of interpretations (in one recent view, the horned signs are judged to be birds and the goddesses to be phalluses). An important observation is that the stones on which they appear seem first to have been used elsewhere as upright standing stones or stelae and then were subsequently incorporated into the tomb architecture at Barnenez.
It is now known that passage graves appeared in Brittany only after the development of two phenomena of prime importance that took place between 4700 and 4300 b.c.: the use of upright stones as burial markers and public stelae and the creation of burial mounds. The marking of human burials by devices on the surface is one of the developments that indicates the transition from the Mesolithic to the Neolithic period. At first these markings were unobtrusive, characterized by deposits of earth over the individual grave pit. Later these mounds, or barrows, grew increasingly more ostentatious, in some cases extending more than one hundred meters in length and rising to more than ten meters in height. The concept of the stone stela quickly came to accompany these round and long barrows. In addition to the funerary stelae associated with the stone cist graves, gigantic public stelae were set up in lines, of which the most spectacular culmination is seen at the colossal site of the Erdeven-Carnac-La Trinité complex. There, thousands of upright stones were erected over a distance of several kilometers.
All the stelae at Barnenez, decorated or not, visible or hidden, give evidence of only one chronological stage before 4300 b.c. They can be viewed as proof of a formative period of monumentalism that preceded the construction of the first passage graves. It took place after Neolithic populations from the Parisian basin had settled on the fertile loess lands of Armorica (the ancient name of Brittany) around 4900 b.c. In the coastal areas they encountered the settlements of hunter-fisher-gatherer societies that already knew of the Neolithic presence far to the east. Given these earlier developments, the passage graves at Barnenez can be seen as a central point in the tradition of Neolithic mortuary monumentalism. The passage graves were preceded by long or short or round barrows and stelae and were followed by the construction of gallery graves. This sequence began early in the fifth millennium b.c. and concluded about 3000 b.c.
See alsoBoyne Valley Passage Graves (vol. 1, part 4).
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(Translated by Jeanne S. Zang)