Analysis of adhering organic residues of two “coupes-à-socles” from the Neolithic funerary site “La Hougue Bie” in Jersey: evidences of birch bark tar utilisation

The “coupes-à-socle” (footed cups) are ceramics which can be found in domestic Neolithic contexts in Brittany (Castellic, Auzay-Sandun), but more generally in non-domestic areas. Their ceremonial function has often been evoked, in particular as a perfume burner. The analysis by GC and GC/MS of two samples from the “Hougue Bie” (Jersey) passage graves showed the presence of vegetable fatty acids, degraded n-alkanes and terpenoïds, biomarkers of birch bark tar. The presence of such substances could be explained either by the use of the “coupes-à-socle” for burning birch bark tar as an odoriferous product or their use as an everyday vessel for heating and increasing tar plasticity. However, the limited occurrence of this type of ceramic in habitat sites supports the former utilisation. This first report of the presence of birch bark tar in “coupes-à-socle” thus suggests use of this tar as an odoriferous product, in addition to its numerous, previously recognised, more technical uses.