The necessity of sample quality assessment in 14C AMS dating: The case of Cova des Pas (Menorca – Spain)

The Cova des Pas cave is a karstic cave in the cliffs of the Barranc (canyon) de Trebalúger. It is a small cave only 6.5 m deep, 4.5 m wide and 1.7 m high. Yet more than 70 burials, in foetal position, from the Early Iron Age were found in this small cave. The conservation of the archaeological remains was very unusual. Not only wood, ropes and other plant material was found, but also remains of body tissue, hair and leather. In spite of the remarkable preservation of the bodies and artefacts, the state of conservation of the bone material was very bad. The bones contained little and heavily deteriorated collagen and the organic plant material was very fragile. The special environmental conditions of the cave are the cause of these unusual preservation conditions. Although the cave is situated in a limestone cliff, the soil of the cave is very acid. Unexpectedly bad sample quality seemed to be the major drawback for AMS radiocarbon dating on hair, wood, ropes and bone collagen, as well as on bio-apatite.