Experimental approach of mesolithic rock art in the sandstone boulders of Paris basin (France): analysis of the engraved material, engraving techniques and human implication in a ritual practice dating from the 8th millennium BCE Approche expérimentale de l’art rupestre mésolithique des chaos gréseux du Bassin parisien (France) : analyse du matériau gravé, techniques de gravure et engagement humain dans une pratique rituelle du VIIIe millénaire BCE En Fr

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Our research is developing an experimental and archaeometrical approach of Fontainebleau rock art. This phenomenon encompasses a territory of 1500 km² corresponding to Fontainebleau sandstone outcropping area. Among those, more than 2000 small cavities bear accumulative and rectilinear engravings often organized in grids. A recent review of the archaeological data indicates intense engraving activity during the 8th millennium BCE due to abundant finds in the engraved cavities of typical lithic tools with use-wear of sandstone grooving.Our aim was to evaluate human involvment into these rupestrian practices by examining two dimensions : 1) the first one is technical and concerns the scarcity of curved grooves : is that scarcity resulting from a cultural choice or a material constraint linked to the engraved sandstone or the lithic tools ? ; 2) the second one is temporal with the engraving durations of the main patterns (grooves and grids) which is an essential data needed to establish a palaeoethnographical understanding of this rupestrian phenomenon. Our experimental methodology aimed at being closest to prehistorical engraving conditions. We also developed a new method in order to quantify the hardness of sandstone using a sclerometer.The first part of the results describes the engraved material and its properties. It is in fact an outer friable cortex of the sandstone boulders, often below 1 cm of thickness, which rests on a hard non-engravable sandstone core. This friable and engravable layer is only preserved in sandstone shelters, away from weathering.The possibility to produce curved grooves has been proven by multiple tests: the abundant rectilinear grooves are therefore the result of a cultural choice.Lastly, investigation of the variables influencing the completion time of the engravings allowed us to propose duration models with equations to perform grooves and grids. In this way, the average completion time of the most frequent grids has been evaluated between 5 and 15 minutes. These results lead to the question of human involvement in Fontainebleau's rock art. Considering the large amount of intensively engraved cavities dispersed in a large territory, the simple techniques and tools required and the short time needed to complete a pattern, we suggest that this rupestrian phenomenon could reflect the cultural practices of many individuals in multiple places easily reachable.