Posted on Aug 9, 2018
So violent was the eruption, some have speculated, that it ended the once-prosperous Minoan civilization, instigated a volcanic winter as far away as China, and inspired the 12 plagues of Exodus as well as the myth of Atlantis—claims that are to varying degrees controversial. But nothing is as controversial, it turns out, as the debate over when the Santorini volcano actually erupted.
The latest controversy in a bitter archaeological dispute involves a literal olive branch, continues Sarah Zhang in The Atlantic. The olive branch comes from the Greek island of Santorini, where a volcano erupted over three millennia ago, spewing gas, ash, pumice, and boulders into the sky. Once depleted, the volcano collapsed in on itself.
The olive branch was supposed to help resolve this. In the 2000s, the geoscientist Walter Friedrich and his graduate student Tom Pfeiffer at the University of Aarhaus found the branch in Santorini under several feet of pumice from that ancient eruption. It looked as if it had been buried alive. They got excited. Because trees grow a new ring every year, the variation in carbon-14 from year to year can be “wiggle-matched” to historical levels of carbon-14 in the atmosphere. Using this method, Friedrich arrived at an eruption date of 1627 to 1600 BC—a full century earlier than what archaeologists had previously decided based on pottery found near Santorini and elsewhere. The archeologists were not pleased.
It does not help that olive wood is notoriously hard to date. Olive wood doesn’t have clearly delineated rings. Its branches don’t grow in perfect concentric circles. Instead, a new paper in Scientific Reports finds, parts of a branch can stop growing for years and even decades before a tree dies. The olive branch in Santorini, depending on what part of it is sampled, may not give an accurate date for the volcano’s eruption. “It’s a beautiful tree full of significance for us,” Elisabetta Boaretto, a radiocarbon-dating researcher at the Weizmann Institute of Science who led the study, says of the olive tree. “But it’s a difficult tree. It likes to keep its secrets.”
Sturt Manning, an archaeologist and tree-ring researcher at Cornell—who, for the record, also believes the radiocarbon dating suggests an eruption date of around 1600 BC—points out that accounting for this problem would only move the date a few decades. That still doesn’t get to 1500 BC, the date many old-school archaeologists continue to defend. But he predicts the uncertainty raised in this paper will have consequences. “[Critics] will cite this paper for the next 50 years as one of the reasons to always be a bit worried about what scientists say,” says Manning.
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