La carte et le territoire : la dalle gravée du Bronze ancien de Saint-Bélec, Leuhan, Finistère

https://hal.archives-ouvertes.fr/hal-03507764

The intricately carved Saint-Bélec slab found in the Leuhan parish, Finistère was found within an early Bronze Age barrow in 1900 (fig. 1 and 2). Chatellier (1901a) mentioned that some scholars see it as a shapeless human representation, others as a beast, while Briard et al. (1994, 60) stated that it could be a map representing field systems, and made connection with Alpine rock art. A recent re-examination of the Saint-Bélec slab by the authors suggests that its sculptured surface and scattered motifs represent the surrounding landscape and a series of contemporary structures now known from archaeological evidence.

When discovered, the slab formed the western side of one of the largest stone-cists in the region. It was orientated east-west and measured 3.86 m long, 2.1 m wide, and 1.86 m high (fig. 3). However, at the time of its excavation, the slab was partly broken, presumably in antiquity, with the upper part missing. It was surmounted by several layers of rubble stone (fig. 3, no. 6). Within the grave, probably crushed during the decay of the timbers, was a broken ceramic vessel, now lost but characteristic of early Bronze Age pottery.

The study of the slab was conducted using whole slab observations, general and detailed photographs with oblique lighting (Cassen and Robin, 2010), and several 3D survey methods (photogrammetry, general and high definition 3D-scanning) to record the surface topography of the slab at different scales and to analyse the morphology, technology, and chronology of the engravings (tabl. 1, fig. 5 and 6). The generation of a 3D-Digital Elevation Map from high definition 3D-scanning and various visualisation techniques was the basis for subsequent interpretation and analysis (Cassen et al., 2014; fig. 7 and 8).

The slab is a grey-blue coloured schist, c. 2.2 m long, 1.53 m wide and 0.16 m thick. Under polarized light, the groundmass appears to be typical of the Douarnenez Phyllade series that form locally the bedrock in the Saint-Bélec area (fig. 4). All the engravings are relatively fresh and show no trace of weathering (fig. 8, no. 1 and 2). This suggests that the carved slab was not exposed in the open air for long. The motifs cut into the surface are relatively uniform and show simple geometric shapes: i.e. round and oval cup-marks; straight or curved lines; and squares, circles, ovals or curved shapes (fig. 10). Some associations between motifs appear to form recurrent patterns, for example one or more cup-marks included in a closed shape, and cup-marks at line ends or intersections.

One of the peculiarities of the Saint-Bélec slab is its sculptured surface. A triangular hollow has been carved out from the centre to the left-hand end. Its upper and lower edges have been shaped by two deep-pecked bas-reliefs (B1, B2/B3), the lower one having been split and cemented together in recent times (fig. 11). In between, the surface was variously weathered or freshly flaked by pecking related to superimposed motifs, suggesting that the triangular hollow probably took advantage of a pre-existing depression in the surface of the slab (fig. 8, no. 1). At the left-hand end of the triangular hollow, there is a square-shaped bas-relief (B4/L15).

While there are relatively few blank areas on the decorated surface, there is very little overlap of the motifs, except at their ends. Therefore, it appears that the successive phases in creating the panel did not significantly change the overall composition, but were rather added in a planned way (tabl. 2 and fig. 11). Taking into account morphological, technological, and chronological observations suggests a sequence in six main phases (fig. 12).

The main issue about the dating of the Saint-Bélec slab is its probable re-use. Stylistically, the motifs are quite different from those found in the regional Neolithic traditions of ‘megalithic’ art (Pailler and Nicolas, 2016). This is supported by the freshness of the engravings which implies a relatively short time-span between their creation and the subsequent burial of the slab.

The most spectacular characteristic of the Saint-Bélec slab is its map-like pattern that consists of a homogeneous composition of repeated motifs joined by a series of lines (Delano Smith, 1987). Comparisons with other similar representations from prehistoric times in Europe and elsewhere in the world show that they are commonly regarded as plan topographical maps (fig. 13 and 14); a hypothesis which is further supported as well by ethnographic data (fig. 15).

A key point is that the engravers seem to have modified the original surface relief of the slab to create the desired 3D-form that compares to the topography of the surrounding landscape. The Saint-Bélec barrow overlooks the valley of the Odet River, which shape nearly fits with the carved triangular hollow (B1–B3), the square bas-relief (B4/L15), and the horizontal central line (L17) that seemingly represents the course of the river (fig. 16, no. 1 and 2). Such correlations give the opportunity to get an idea of the possible scale of the space represented on the Saint-Bélec slab: an area c. 45 km long and 33 km wide (fig. 16, no. 3). Furthermore, the carved motifs might have depicted early Bronze Age settlements, barrows, field systems, and tracks (fig. 16, no. 3, and 16).

The early Bronze Age in Brittany is well known for its princely burials (fig. 18 which are regularly distributed in western Brittany and are assumed to reflect the centres of established territories that can be modelled using Thiessen Polygons (Brun, 1998; Nicolas, 2016).  Although no such burial is known in the area, the central motif (L49) on the Saint-Bélec slab could be interpreted as a central place of an early Bronze Age territory of c.1290±10 km² (fig. 16, no. 4). One outstanding question about the Saint-Bélec slab is why it was made? One possibility is that such a territorial depiction was a material and symbolic act enforcing. Set alongside the contemporary development of field systems in Brittany making the slab perhaps suggests the appearance of a new form of land tenure (Brun and Marcigny, 2012), while the distribution of elite graves is closely linked to soil fertility (Nicolas, 2016). Against this background, we can hypothesize that the Saint-Bélec slab was used as a cadastral plan for managing the territory and controlling land.