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Dating Thera Eruption

18 August 2018

At https://popular-archaeology.com/article/dating-the-ancient-minoan-erupti… … courtesy of the University of Arizona (dendrochronology unit). An attempt has been made to resolve discrepancies between archaeological and radiocarbon methods of dating the eruption of the Thera volcano by tying up in knots the timeline of ancient Egypt, Crete, Greece, Turkey and the Levant. 'What we can now say is that the radiocarbon evidence is compatible with the archaeological evidence of an eruption in the 16th century BC …' according to dendrochronologist Charlotte Pearson. Archaeologists have estimated the eruption as having taken place between 1570 and 1500BC by using Egyptian inscriptions and texts and by pottery styles across the eastern Mediterranean basin. Other researchers, using radiocarbon, came up with a date around 1600BC she said, using C14 methodology. Tree rings suggest an eruption at some point between 1600 and 1525BC, a date which overlaps with the archaeological data (1570-1500BC).

The current radiocarbon calibration curve extends some 14,000 years into the past. The article is a mine of information on how dendrochronology has been developed over the years – and its close affinity with radiocarbon levels in the atmosphere. This is the really intriguing link. The two can be tied together so perfectly. It makes you wonder why IntCal2013 went to the trouble of adding more dubious dating methodologies to the calibration curve – such as speleotherms.

Researchers from Queens University in Belfast's dendrochronology department also took part in the research – and Sheffield University. Irish oaks formed part of the research – and American bristlecone pines. Big volcanoes eject lots of ash and gases into the atmosphere which causes an opaque sky – limiting the intensity of sunshine reaching the surface of the Earth. Subsequently, they produce narrow growth in tree rings (especially if the summers were cool). It seems there are at least four narrow growth episodes in the century, 1500-1600. This means there is no need to focus on the narrow growth tree ring event at 1628-5BC (or any earlier low growth event). This is a promising result as we might just place the Hyksos invasion of Egypt on the back of the 1628-5 event and the Hyksos expulsion (with Thera) around a hundred years later. However, there are some caveats worth noting. The researchers concentrated on just two centuries (and mostly on one century) which means that a later date has been excluded as a possibility. Another point of doubt may arise on the extent of the low growth events fingered between 1600 and 1525BC – in other words were they one year low growth events rather than something more substantial. Lastly, no mention is made of the radiocarbon anomaly at Nineveh (in around 610BC). I have heard it is up to 180 years out of sync with mainstream dating – but more reasonably around 150 years. If this is applied across the board (and nobody so far has suggested doing this apart from Nick Thom who admits that he is not a scientist on the subject) this would bring down Thera to about 1450 to 1400BC. Is that at all viable. We don't know as the dendrochronology of the century 1400 – 1500 is not included in the study. Bear in mind that the first Greenland ice core had a spike at 1390BC (which as far as I know has never been replicated).

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