Research press release


Scientific Reports

Archaeology: Olive branch may not settle argument of Santorini eruption date



今回、Elizabetta Boarettoたちの研究グループは、オリーブの木の枝の最も外側の年輪が形成されるのは木が死滅する直前なのかどうか、そして、この年輪を信頼性の高い年代測定に利用できるかどうかを評価するため、オリーブの現生種の木の幹から採取した試料20点と、2013年に伐採された枝から採取した試料11点について、放射性炭素濃度分析を行った。その結果、いずれの試料群においても、樹皮に最も近い層から採取された試料の年代測定結果に最大40~50年の幅があることが判明した。この研究知見から、オリーブの木において、目視で確認できる年輪が系統的に形成されないこと、そして、同じ木の中で死滅時よりもかなり前に成長が停止してしまう部分があるという現象が一般的であることが示唆される。


An olive branch that has been used to date the Santorini volcanic eruption could predate the event by 40 to 50 years, according to a study in Scientific Reports.

The Santorini eruption provides a fixed point for aligning the chronology of the Bronze Age in the Mediterranean, yet its exact date has been difficult to determine. Recently, an olive branch found buried under rock fragments at Santorini was used to date the erruption to between 1627 and 1600 BCE, more than a century earlier than the 1500 BCE date suggested by archaeologists. The dating was based on the assumption that the outermost ring of wood was formed just before the branch was buried alive by the eruption.

To assess whether an olive tree’s outermost ring is produced just prior to the tree’s death and can thus be used for reliable dating, Elizabetta Boaretto and colleagues analyzed the radiocarbon concentrations in 20 samples taken from a modern olive tree trunk and 11 samples taken from a living branch cut in 2013. They found that in both cases individual samples, all of which were taken from the layer of wood nearest the bark, could vary in date by as much as 40 to 50 years. The findings suggest that olive trees do not systematically produce visible growth rings and that growth cessation of individual sections of the same tree well before its death is a common phenomenon.

The findings challenge the interpretation of the results obtained from dating the olive branch found at Santorini, which may be significant not only for the archaeological history of the Aegean, Egypt and the Levant but also for any future studies based on archaeologically preserved olive wood.

doi: 10.1038/s41598-018-29392-9 | 英語の原文

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