An experimental approach for tracing olive processing residues in the archaeobotanical record, with preliminary examples from Tell Tweini, Syria

To help the interpretation of possible olive processing residues at archaeological sites, this study examines the changes which occur in pre- and post-charring breakage surfaces of olive stones at tissue level. Fresh olives were experimentally broken before and after charring and heated to different temperatures (230, 330, 430°C) in oxidising and non-oxidising conditions. The structures obtained by the experiment were studied with scanning electron microscopy (SEM) and the characteristics for the different temperatures, oxidation regimes and pre- or post-charring fractures were recorded. Furthermore, the experimental specimens were compared with recent and possibly old fractures of several archaeological olive stones from Tell Tweini, Syria. Criteria to infer their formation are discussed. These criteria could be developed further through more experimental replication and additional charring variables, and verified extensively on archaeobotanical assemblages in future studies. The described structures and alterations in the olive stones can be observed using reflected light microscopy, which would allow the proposed approach to be rather easy to apply in practice.