Tree rings could pin down Thera volcano eruption date

phys.org ^ | 03/30/2020 | University of Arizona

[BenLurkin]

"The longest chronology in the world stretches back 12,000 years. But in the Mediterranean, the problem is that we don't have a full, continuous record going back to the time of Thera," Pearson said. "We have recorded the last 2,000 years very well, but then there's a gap. We have tree rings from earlier periods, but we don't know exactly which dates the rings correspond to. This is what's called a 'floating chronology.'"

Filling this gap could help pin down the Thera eruption date and paint a climatic backdrop for the various civilizations that rose and fell during the Bronze and Iron ages, which together spanned between 5,000 and 2,500 years ago.

When cosmic rays from space enter the Earth's atmosphere, neutrons collide with nitrogen atoms to create a radioactive version of carbon, called carbon-14, which spreads around the planet. All other life on Earth, including tree rings, pick up the carbon-14, and because tree-rings lock away a measurement of carbon-14 for each year that they grow, they hold patterns showing how it changed over time.

Pearson and her team used the patterns of carbon-14 captured in the Gordion tree rings to anchor the floating chronology to similar patterns from other calendar dated tree ring sequences.

The team then thought to use a new piece of technology in the lab called the X-ray fluorescence machine to scan the wood for chemical changes.

While it's a slight fluctuation, it is significant and only occurs at one point in the years around 1560 B.C.

[SunkenCiv]

Yup. And the pumice serving tray (pumice floats, makes a nice doodad for the pharaoh) excavated in Egypt was long touted as having been from the supposed Theran eruption. When it was finally examined, it turned out to have come from the Kos volcano, which last erupted about 200K ago. :^)

[gleeaikin]

Thanks for the links.

[Red Badger]

I vaguely remember reading years ago some article that said Tree Rings weren’t all that accurate, maybe +/- 50 years or so, IIRC..................

[SteveH]

Greek volcano mystery: Archaeologist narrows on date of Thera eruption
Date:
September 21, 2022
Source:
Cornell University

science daily

https://www.sciencedaily.com/releases/2022/09/220921113133.htm