Traceological analyses of tool marks on western Iberian stelae and their replications: Stones and steel at the end of the Bronze Age

For the study of carved rock art, particular tool materials can only be meaningfully hypothesized, identified, or excluded by combining traceological analyses with an accurate understanding of the physical-mechanical properties of the carved rock as well as knowledge of the available tool materials from an archaeological, material analytical, and experimental point of view. The aim of this study was to identify the tools that were used during the Final Bronze Age-Early Iron Age transition (c. 1200-550 BC) for the carving of western Iberian stelae by comparing the work traces on originals and replications with the same rock supports and the archaeologically identified tool-set. This was achieved by the traceological-technological study and categorisation of the carved lines and motifs, based on the profile sections of the engravings, on a sample of four western Iberian stelae made from granite-aplite, meta-arkoses, and silicate quartz-arenite. All components were replicated according to petrological and metallurgical analyses. This approach, which is based on 3D-scans in combination with GIS and a thorough evaluation of digital data, material analyses, and archaeological data, will be presented here for the first time. The application of GIS and DEM for the analysis of the profile sections of carved ornaments provided analytical and graphical results from 444 profiles, allowing the classification in six different profile typologies. The most striking result is that silicate quartz-arenites cannot be carved with bronze tools and that lithic tools only left superficial traces that are very different from the original stelae from this lithology. Therefore, this particular material, which represents over 20 % of all stelae, could only be carved with hardened steel chisels, while many granitoid and sedimentary rocks could also be carved with lithic tools. • Replica production, traceological analysis, and digital documentation are combined for a novel traceological approach towards rock art. • The most evidence-based work is enabled by using rock characteristics as one of the main criteria for the analysis, • The approach allows for the analyses of carvings without obvious traces from the working edge of the tool and provide information on tool handling. • The method of recording line profile sections generated from DEM's of surfaces can be applied to other fields of rock art studies. • The multi-methodological evidence supports the hypothesis that Iberian stelae from silicate quartz-arenite were carved with hardened steel tools.