Stratégies d’acquisition des matières colorantes dans l’Arc liguro-provençal au cours des VI^e et V^e millénaires cal. BCE

In the N.W.‑Mediterranean area, exchange networks and social relationships gain an increasing complexity in the course of the Neolithic : varied goods diffuse in considerable quantities and distances. In particular, obsidian, Bedoulian and Oligocene flints, jadeite and eclogite are known to have been exchanged over long distances as shown by research that began thirty years ago.

Surprisingly, the place of colouring materials (“ochre”, bauxite, cinnabar), naturally abundant in the Mediterranean Franco-Italian area, has received scant attention despite their technical and symbolic value; very few is thus known on the ways of their procurement and on their geographic and geological origin.

With this purpose, the study of colouring materials from both archaeological sites and putative sources was undertaken in the Liguro-Provençal arch. Geological surveys were carried out in order to establish a reference collection of colouring materials. Their geological nature has been determined by a combination of complementary imaging, elementary and structural techniques (petrography, SEM-EDS, X-ray diffraction).

By this way, a wide range of raw materials was determined: Permian sandstones, Middle Cretaceous bauxites, Toarcian or Hauterivian oolithic ironstone, Cretaceous oxidized marcasite and ferruginous rocks derived from weathered glauconitic limestones (in the same diagenesis conditions as Roussillon ochre).

In addition, two archaeological series, from Early and Middle Neolithic, were investigated by same methods: those of Pendimoun (Castellar, France), a rock-shelter site occupied by Impressa and Cardial groups (Early Neolithic : 5750-5200 cal. BCE) and those of the open-air site of Giribaldi (Nice, France) that belongs to Pre-Chassey and formative stages of Chassey culture (Middle Neolithic : 4700-4050 cal. BCE).

The results compared to the frame of reference highlight two contrasting economic systems: one based on the procurement of local resources (Pendimoun) and the second one that shows a more complex acquisition network (Giribaldi).

At Pendimoun which represents the colonization stages of the Early Neolithic, the colouring materials imported are varied and heterogeneous, but widespread in the rock-shelter itself or in the close environment (less than 5 km) : oxidized marcasites, oolithic ironstone, goethitic calcareous rocks derived from glauconite. The sources are thus local and these results have to be considered in the context of an occupation assigned to specific functions (agriculture, pottery, sheep pen), as previously shown by other data.

At Giribaldi, colouring materials assemblage consists of close geological materials (ferruginous rocks derived from glauconite) but also of two types of exogenous rocks : yellow Permian sandstones and orange kaolinitic bauxites, respectively 60-70 and 70-90 km away. This Middle Neolithic settlement is known to be well inserted in complex exchange networks including western Provence (Bedoulian and Oligocene flint), French and Italian Alps (quartz, jadeite, eclogite), Liguria (jadeite, eclogite) and Lipari island (obsidian). The presence of these three types of rocks all along the occupation shows the permanence of exploitation of these colouring materials, which gives evidence of procurement regularity, the stability of exchange networks and the durability of relationships and technical practices.