[sour-taste]

> The team deciphered this record using a new ultra–high-resolution method, in which a laser carves 120-micron slivers of ice, representing just a few days or weeks of snowfall, along the length of the core. Each of the samples—some 50,000 from each meter of the core—is analyzed for about a dozen elements. The approach enabled the team to pinpoint storms, volcanic eruptions, and lead pollution down to the month or even less, going back 2000 years, says UM volcanologist Andrei Kurbatov.

How do they know for sure that the ice samples are chronological? What happens if in a given year the top layer of ice melts away?

[navane]

They match the ice samples up with tree rings. There exists tree ring data of 7k+ years, the ice contains more info, but the tree rings allow for absolute pinpointing on a year. They match them on common info.

I am reading "tree story" by valerie trout.

[physicles]

My understanding was that dendrochronology records go back about 12k years. Is there anything about that in the book you’re reading?

[navane]

I had forgotten the exact number, i knew it was at least 7k. I didnt want to lie in my comment, but im almost sure you are right.

Im at work right now so cant look it up.