When was Thera (Atlantis) destroyed?

New analyses that use tree rings could settle the long-standing debate about when the volcano Thera on Santorini erupted by resolving still existing discrepancies between archaeological and radiocarbon methods of dating the eruption[1].

[Santorini's craters]

Thera’s explosive eruption on Santorini more than 3,400 years ago buried the Minoan settlement on the island in a layer of ash and pumice more than 40 meters deep. The effects of the eruption were felt as far away as Egypt and it heralded the end of the Minoan civilisation. It is now understood that the explosive eruption of Thera was the basis of the story of Atlantis.

Archaeologists have estimated the eruption as occurring sometime between 1570 and 1500 BC by using human artifacts such as written records and pottery. Other researchers estimate the date of the eruption to about 1600 BC using carbon-14 measurements from organic material found just below the layer of volcanic ash.

“The volcanic eruption represents one short moment in time,” Charlotte Pearson, an assistant professor of dendrochronology said. “If you can date precisely when that moment is, then whenever you find evidence of that moment at any archaeological site, you suddenly have a very precise marker point in time.”

[Santorini]

By counting annual rings of trees that lived at the time of the eruption, the team dates the eruption to someplace between 1600 and 1525 BC, a time period which overlaps with the 1570-1500 date range from the archaeological evidence. In 2020, new evidence was presented that could support an eruption date around 1560 BC[2].

Pearson and her colleagues used two different tree-ring chronologies from long-lived trees that were alive at the time of the Thera eruption. Salzer’s extensive work on long-lived bristlecone pines living in California and Nevada provided the 200 tree-ring samples representing each year from 1700 to 1500 BC. Brown provided 85 Irish oak annual tree-ring samples that spanned the same years.

Because Irish oaks and bristlecone pines add a growth ring every year, the rings laid down year-by-year represent an environmental history going back thousands of years in time.

A massive volcano such as Thera ejects so much material into the atmosphere that it cools the earth. For cold-climate trees such as Irish oaks and bristlecones, that exceptionally cold year shows up as a much narrower tree ring. Salzer’s work reveals at least four different years within the new radiocarbon age range for Thera where the bristlecone pines had exceptionally narrow rings that might indicate a huge volcanic eruption.

But, curiously, there also exists historical evidence about the date of the catastrophic eruption of Santorini. The Athenean statesman Solon (Σόλων) lived from ca. 630 until ca. 560 BC. Solon went on a 'fact-finding mission' to Egypt. The Egyptian priests told Solon that a great seafaring nation perished 9,000 years before Solon. Solon told the story to Critias the elder (ca 600 BC), who recounted the story to his grandson Critias the younger (460 BC to 403 BC)[3]. Plato later wrote that 'Critias when he told this tale of the olden time, was ninety years old, I being not more than ten'[4]. Obviously, the repeated recounting of the story added an extra zero to the original number of years. There was no civilisation to speak of 9,000 years before Solon. Somehow, 900 years became 9,000 years.

Solon visited Egypt around 600 BC. When you add the 900 years, you arrive at 1,500 BC, which is rather close to the dates from both the archaeological and dendrochonolical research.

[1] Pearson et al: Annual radiocarbon record indicates 16th century BCE date for the Thera eruption in ScienceAdvances - 2018
[2] Pearson et al: Securing timelines in the ancient Mediterranean using multiproxy annual tree-ring data in Proceedings of the National Academy of Sciences - 2020
[3] Welliver: Character, Plot and Thoughts in Plato's Timaeus-Critias 1977. Appendix
[4] Plato: Timaeus. See here.