Olive branch may not settle argument of Santorini eruption date

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.

Santorini Landsat photo [Credit: NASA]

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.

Transverse section of one of the olive tree trunks, cut down in 2013 in Zippori, northern Israel, with sampling points
 for radiocarbon marked on cross section with small white dots (to scale of the 2.8 mm samples). The researchers
 found that the growth pattern of the olive tree was unusual and therefore may mean the original estimation
of the Santorini eruption was incorrect [Credit: Ehrlich et al. Scientific Reports, 2018]

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.

Source: Natureasia.com [August 10, 2018]