Navigation – Plan du site

AccueilNuméros58The engraved monoliths in the Man...

The engraved monoliths in the Mané er Groez Neolithic passage tomb in Kercado (Carnac, Morbihan)

Serge Cassen, Valentin Grimaud et Hervé Paitier
Traduction de Louise Byrne
p. 87-89
Cet article est une traduction de :
Les monolithes gravés dans la tombe à couloir néolithique du Mané er Groez à Kercado (Carnac, Morbihan) [fr]

Résumés

Dominant la vallée de Kerloquet et la ria colmatée débouchant à 2 km de là sur la plage de Kerdual, le site de Kercado à Carnac rassemble un probable tertre bas, le cairn du Mané er Groez contenant une tombe à couloir, et une enceinte curviligne d’une trentaine de pierres dressées qui borde l’ensemble plus au sud. Trois dalles de paroi dans le couloir, trois autres dans la chambre ainsi que la pierre de couverture conservent des signes gravés inventoriés pour l’essentiel entre 1866 et 1927. À la « hache-charrue » bien connue au plafond de la chambre vient désormais s’ajouter un registre inédit comprenant des couples de lames polies, un anneau, des arcs, des embarcations avec équipage et des variations sur le signe quadrangulaire.
L’objectif de cet article est de rendre compte d’un corpus de gravures, replacées dans la morphologie des supports qui aide à leur compréhension, tout en étant confrontées aux désordres qui en brouillent la perception.

Haut de page

Notes de la rédaction

This article is not quite a traduction but rather is a long summary of the french article « Les monolithes gravés dans la tombe à couloir néolithique du Mané er Groez à Kercado (Carnac, Morbihan) ».

Texte intégral

1The study of the Mané er Groez passage grave, close to the manor of Kercado in Carnac, recently received support from several research projects and enhanced our knowledge of this site, which had not been explored for several decades. The objects in rare rocks captured the attention of specialists involved in the JADE (Pétrequin et al. 2012) and CALLAÏS programs (Querré et al. 2014), and the engravings were systematically recorded as part of a collective research program focusing on the recording and analysis of Neolithic rock art in Brittany (Cassen et al. 2016). The preliminary results of this recent investigation of the site of Kercado are presented in this article.

2In order to draw up the most comprehensive catalogue possible, our inventory attempts to record and represent the engravings in their context; in relation to the stones with which they are closely associated, from a physical and symbolic perspective. The 3D contextualization of the decorated stones, in their topographic (the site) and architectural setting (the tomb, the stelae), is also essential for the interpretation of historical and functional associations. During the recording of these stone surfaces, in addition to the layout, we also observed various anomalies resulting from biological factors, as well as chromatic and mineral deterioration.

3The imposing cairn of Mané er Groez (40 m diameter and 3.5 m high; from the top in 1863, it was possible to see Gavrinis, which is 13.2 km away as the crow flies) is one of the rare passage tombs in the area with monoliths covered by a stony mound during the Neolithic (fig. 1). The first excavators reached the chamber on one side of the large cover stone (north-eastern angle), between two orthostats. Surprisingly, they did not discover any of the engravings on the walls of the passage or the quadrangular chamber (Lefèbvre and Galles 1863). The filling contained calcined human bones, which were only preserved in these acidic soils due to their charred state. The radius, fibula, skull elements and phalanges belong to at least two adults and a child (Closmadeuc 1863). L. Davy de Cussé presented the engravings of the monument in the second volume of the Recueil des signes sculptés, published in 1866. G. de Closmadeuc classified the engraving on the ceiling of the chamber in the axe-shaped (“asciforme”) family and considered it to resemble a hafted axe (Closmadeuc 1873). In 1924, during a restoration program, Z. Le Rouzic discovered an older buried level, on the same level as the entrance of the monument, trapped under the cairn (with at least one combustion structure under the pavement at the beginning of the passage; Le Rouzic 1927). The “axe-plough” engraved in the chamber was confirmed to be the emblematic instrument of the farming populations in Morbihan (Péquart et al. 1927). Subsequently, the drawings published by E. Shee Twohig were often reproduced by European archaeologists, in particular to describe this famous axe-plough (Shee Twohig 1981). Here, we propose a new interpretation of this sign, with a closed curve at the end of the motif, which is now interpreted as a cetacean, and more precisely as a sperm whale (Cassen and Vaquero Lastres 2000). However, very little data can be associated with the poorly understood layout of this engraving, in relation to the other engraved stones in the tomb (two orthostats in the chamber, three in the passage), as it is too damaged for visual recognition.

Fig. 1. Topography of the site of Kercado

Fig. 1. Topography of the site of Kercado

Position of the main structures

Surveys and CAD S. Cassen and V. Grimaud

4The study of engravings in Brittany is based on procedures of acquisition and representation that have developed gradually since 1998, following the integration of 3D models of the stones from the monument of Mané Kerioned in Carnac in 2003 (Cassen and Merheb 2004). The three-dimensional model of the objects results from a three-stage technical process: first of all, the lasergrammetric and/or photogrammetric terrestrial acquisition of the architecture (sub millimetric density) and accesses (centimetric density), then data processing (reconstruction and consolidation of the grids), and finally the plan and elevations, and the characterization of the structures (Grimaud 2015, Lescop et al. 2013). For the 2D model of the engraved signs, the method consists in compiling photographs taken with oblique lighting, in situ, with a single station (Boujot et al. 2000, Cassen and Vaquero Lastres 2003). The engraving is drawn with a graphic tablet. For the photography, only the strongly contrasting surfaces are considered and only the over-exposed part of the surface of the stone is placed on the side of the lighting (Cassen et al. 2014). This junction line is drawn in vector mode, and the interior of the engraved part is marked to avoid confusion (Cassen and Robin 2010). The experiment can be constantly checked, repeated, and corrected by another operator. This reproducibility and traceability of the experiment are a decisive advantage compared to former methods involving direct tracing or copies. The identification of the anteriority of the engravings and the removal of matter are an important step in the identification of the signs. Lastly, the photorealist map describing the colours provides information based on the DStretch plug-in of the ImageJ software. The decorrelation of images brings to light nuances in the RVB colour space and other information that is imperceptible with the naked eye, such as unobtrusive layouts or anomalies (Cassen et al. 2014).

5On the R3 orthostat, a bow is engraved on the right edge, with no connecting arrow (fig. 7). The morphology of this bow is in keeping with other representations inventoried in Brittany (Mané Kerioned B, Runesto, Île Longue, Barnenez H) and elsewhere in Western Europe during the 5th millennium BC, such as the Anglo-Norman islands (Le Déhus), the Paris basin (Le Berceau), or even Portugal (Vale Maria do Meio). We classified the European series according to the number of associated arrows (0 to 2; Cassen et al. 2015a and b). In the centre of R3, two pairs of polished axe blades are laid out in reverse symmetry. The pair on the left presents cutting-edges facing upwards whereas the cutting-edges of those on the right side seem to lie on a slightly curved horizontal line. On the high part of the slab, four other polished blades were identified. On the lower part of the composition, a circular motif is recorded on the left of the bow, similar to a ring.

Fig. 7. Orthostat R3 (passage)

Fig. 7. Orthostat R3 (passage)

Survey overview (not rectified) with ICEO (photos DSC_0002 to DSC_0100), inventory of the contours and removal of matter, and identification of the main signs

CAD S. Cassen

6The R4 orthostat presents a composition in mirror symmetry in terms of the motifs but an asymmetrical arrangement in terms of the number of signs. Two “pairs” seem to go together: a quadrangular figure and a boat with crew on the left side and another boat and quadrangular figure on the right side (fig. 10). This depiction has also been recorded on several other monoliths in the region, such as the Mané Lud passage tomb in Locmariaquer, where we noted an association of “right-angled square signs” and “crescent” or “boat” shapes (Cassen et al. 2005b, Cassen 2007). The same association is also depicted on the huge Kermaillard stele in Sarzeau (Morbihan), but in this case, there is no crew in the boat. Further away, in the sector of the Essonne valley (south Paris), where characteristic “Carnacean” signs have just been inventoried (Vallée aux Noirs 6; Cassen et al. 2017a), another boat with no crew is associated with an engraved quadrangular shape inside the body of an anthropomorphic figure.

Fig. 10. Orthostat R4 (passage)

Fig. 10. Orthostat R4 (passage)

Mosaic orthophoto treated with image decorrelation (ImageJ/DStretch), microtopography and survey of the engravings rectified with the photogrammetric model

CAD S. Cassen; 3D model V. Grimaud

7Unfortunately, the L4 orthostat is hardly legible, in particular on the whole left sector, and it is thus impossible to describe the iconographic layout. On the right sector, it is nevertheless possible to recognize the two emblematic symbols of the Neolithic Morbihan world; the throwing stick (crosse) and the polished axe (fig. 15).

Fig. 15. Orthostat L4 (passage)

Fig. 15. Orthostat L4 (passage)

Mosaic orthophoto with location of the ICEO acquisition windows, microtopography and rectified survey of the engravings in the photogrammetric model

CAD S. Cassen; 3D model V. Grimaud

8The C1 orthostat is a good example of the technical procedure used during the Neolithic in Brittany (fig. 20). The impact marks are relatively well preserved on the granite surface and show that varying degrees of force were used to strike the rock. Negative flake scars varying in length from 3 to 5 mm mark out the line to be engraved, and some centimetric removals accentuate the hollow layout, most often by oblique percussion.

Fig. 20. Orthostat C1 (chamber)

Fig. 20. Orthostat C1 (chamber)

Impact marks in the granite and inventory of the main anomalies

Photographs and CAD S. Cassen; mosaic orthophoto V. Grimaud

9The C3 orthostat is much too deteriorated to interpret in the same way as the other tomb stones. The large regular quadrangular motif (a square) –which is a new sign in relation to previous inventories– is a well-known symbol in the Armorican corpus. Unfortunately, it is impossible to associate it with the neighbouring signs, which are mainly in the lower panel (fig. 27). The pseudo-paintings described by Abbot Breuil were not validated (Breuil and Boyle 1959); they correspond to modern occurrences (in particular the charcoal highlighting).

Fig. 27. Orthostat C3 (chamber)

Fig. 27. Orthostat C3 (chamber)

Mosaic orthophoto with location of the ICEO acquisition windows, microtopography, virtual lighting and survey of the engravings rectified with the photogrammetric model

CAD S. Cassen; 3D model V. Grimaud

10The C4 orthostat had never been interpreted before due to the absence of recognizable signs. However, it presents surprising thematic specialization. At least five bows are registered in a vertical position. Unlike the specimens in the regional monuments of Runesto, Île Longue and Gavrinis, no arrows seem to be associated with them (fig. 32). An additional bow without an arrow was however identified on orthostat 13 in the Mané Kerioned B passage grave in Carnac (Cassen et al. 2015b). On these weapons, the bow string is systematically directed towards the left; this is also the case for the other Morbihan specimens, except for Gavrinis L6. The large central bow (no 1) deserves special mention, as it presents dissymmetrical ends: a notch and “curved” string on the top; and rectilinear string attached beside the round notch, below. This dissymmetry does not exist on the functional instruments and is a singular feature of Gavrinis L6. This is the engraving of a symbolic object where the iconic representation is probably more important than the initial projectile function (Cassen et al. 2015b).

Fig. 32. Orthostat C4 (chamber)

Fig. 32. Orthostat C4 (chamber)

Inventory of the main motifs in the photogrammetric model (ambient occlusion) and comparison of the orientations of arcs 1-5, then 2-3-4

CAD S. Cassen; 3D model V. Grimaud

11Predictably, generally speaking, the interpretation of the rather well-preserved “axe-plough” on the P6 cover slab is confirmed. However, for us, the suggested cetacean (male sperm whale) interpretation still seems to be relevant. This engraving is very difficult to interpret due to its location on the ceiling. Its marked off-centre position on the stone surface suggests that this is an older stele re-used in the construction of the passage tomb. Compared to our former drawing carried out in the middle of the 1990s, the new element here is the end of the head, which is no longer a simple curve representing the bump or “melon” of the sperm whale (our first interpretation), but which becomes an autonomous sign, detached from this head. This new motif, with the shape of a portion of disc or “crescent”, is connected to the family of “boats”, in particular to crew when rectilinear segments are added. Similar engravings have been described in Mané Rutual (Locmariaquer) and Cruguellic (Ploemeur).

12It seems to us to be premature to suggest a narration based on all the signs in the tomb. The iconographic depictions on orthostats R3 and C3 cannot be reconstructed as they are unobtrusive or cannot be detected by the techniques suggested here. Occulted motifs, signs probably truncated during the Neolithic, and badly orientated orthostats in relation to their ornamentation, raise the issue of the re-use of several monoliths, but do not imply that the understanding of the symbolic system of engravings was lost by the builders of Mané er Groez. The aim of this article was to give an updated account of this corpus of engravings, and to take slab morphology context into consideration, as well as the alterations that can obscure our perception of them, in order to enhance our understanding of this passage tomb.

Haut de page

Table des illustrations

Titre Fig. 1. Topography of the site of Kercado
Légende Position of the main structures
Crédits Surveys and CAD S. Cassen and V. Grimaud
URL http://journals.openedition.org/galliap/docannexe/image/885/img-1.jpg
Fichier image/jpeg, 1,3M
Titre Fig. 7. Orthostat R3 (passage)
Légende Survey overview (not rectified) with ICEO (photos DSC_0002 to DSC_0100), inventory of the contours and removal of matter, and identification of the main signs
Crédits CAD S. Cassen
URL http://journals.openedition.org/galliap/docannexe/image/885/img-2.jpg
Fichier image/jpeg, 757k
Titre Fig. 10. Orthostat R4 (passage)
Légende Mosaic orthophoto treated with image decorrelation (ImageJ/DStretch), microtopography and survey of the engravings rectified with the photogrammetric model
Crédits CAD S. Cassen; 3D model V. Grimaud
URL http://journals.openedition.org/galliap/docannexe/image/885/img-3.jpg
Fichier image/jpeg, 783k
Titre Fig. 15. Orthostat L4 (passage)
Légende Mosaic orthophoto with location of the ICEO acquisition windows, microtopography and rectified survey of the engravings in the photogrammetric model
Crédits CAD S. Cassen; 3D model V. Grimaud
URL http://journals.openedition.org/galliap/docannexe/image/885/img-4.jpg
Fichier image/jpeg, 1,3M
Titre Fig. 20. Orthostat C1 (chamber)
Légende Impact marks in the granite and inventory of the main anomalies
Crédits Photographs and CAD S. Cassen; mosaic orthophoto V. Grimaud
URL http://journals.openedition.org/galliap/docannexe/image/885/img-5.jpg
Fichier image/jpeg, 1,5M
Titre Fig. 27. Orthostat C3 (chamber)
Légende Mosaic orthophoto with location of the ICEO acquisition windows, microtopography, virtual lighting and survey of the engravings rectified with the photogrammetric model
Crédits CAD S. Cassen; 3D model V. Grimaud
URL http://journals.openedition.org/galliap/docannexe/image/885/img-6.jpg
Fichier image/jpeg, 1,0M
Titre Fig. 32. Orthostat C4 (chamber)
Légende Inventory of the main motifs in the photogrammetric model (ambient occlusion) and comparison of the orientations of arcs 1-5, then 2-3-4
Crédits CAD S. Cassen; 3D model V. Grimaud
URL http://journals.openedition.org/galliap/docannexe/image/885/img-7.jpg
Fichier image/jpeg, 752k
Haut de page

Pour citer cet article

Référence papier

Serge Cassen, Valentin Grimaud et Hervé Paitier, « The engraved monoliths in the Mané er Groez Neolithic passage tomb in Kercado (Carnac, Morbihan) »Gallia Préhistoire, 58 | 2018, 87-89.

Référence électronique

Serge Cassen, Valentin Grimaud et Hervé Paitier, « The engraved monoliths in the Mané er Groez Neolithic passage tomb in Kercado (Carnac, Morbihan) »Gallia Préhistoire [En ligne], 58 | 2018, mis en ligne le 04 octobre 2018, consulté le 15 août 2022. URL : http://journals.openedition.org/galliap/885 ; DOI : https://doi.org/10.4000/galliap.885

Haut de page

Auteurs

Serge Cassen

LARA, UMR 6566 CReAAH, Université de Nantes, rue de la Censive du Tertre, BP 81227, 44312 Nantes — serge.cassen@univ-nantes.fr

Valentin Grimaud

LARA, UMR 6566 CReAAH, Université de Nantes, rue de la Censive du Tertre, BP 81227, 44312 Nantes — valentin.grimaud@univ-nantes.fr

Hervé Paitier

INRAP, 37 rue du Bignon, 35577 Cesson-Sévigné — herve-pierre.paitier@inrap.fr

Haut de page

Droits d’auteur

Tous droits réservés

Haut de page
  • Logo Maison des sciences de l'Homme Mondes
  • Revue soutenue par l’Institut des sciences humaines et sociales du CNRS
    CNRS - Institut national des sciences humaines et sociales
  • OpenEdition Journals
Rechercher dans OpenEdition Search

Vous allez être redirigé vers OpenEdition Search