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"We took some chronological samples in the summer and we received the results which showed that wood is oak from Sweden, and it was cut in the winter between 16

"We took some chronological samples in the summer and we received the results which showed that wood is oak from Sweden, and it was cut in the winter between 1612 and 1613, which is a really good, precise measure." I'm really curious about the analysis process involved here. Is C-14 dating that precise? How do they know it was oak from Sweden?

maxerickson 9y ago
Just as likely they analyzed the width of the growth rings. Trees in a given area will have similar high growth and low growth years. And then there are big events where growth will correspond across wider regions.
- johansch 9y ago
  So you mean for a plank of wood, you would do some statistical analysis based on the series of the widths of the growth things and then match them with other recorded widths/deltas to try to find a match? (Yeah, it seems plausible that it would work.)
  - deleted 9y ago
    [deleted]
  - robin_reala 9y ago
    Yep. The field is called dendrochronology: https://en.wikipedia.org/wiki/Dendrochronology https://en.wikipedia.org/wiki/Dendrochronology
willvarfar 9y ago
We can rule out carbon dating because oak grows for hundreds approaching thousands of years and so the carbon dates wouldn't narrow things down. When archeologists send things to be carbon dated they try to find very short-lived woods or seeds. The way you can date oak so precisely is by the comparative widths of the tree-rings. This is called dendrochronology https://en.wikipedia.org/wiki/Dendrochronology https://en.wikipedia.org/wiki/Dendrochronology
- dithering 9y ago
  Carbon dating measures the ratio of C14 to C12. This ratio doesn't start to change until they die, and are no longer renewing their carbon from the environment. Radiocarbon dating does provide an accurate date (although less accurate than dendro) for wooden items, and works with a wider range of samples.
  - marcosdumay 9y ago
    That's for short lived organisms. Trees do not renew most of their carbon during their lifetime, cellular walls are created and very rarely destroyed.
progre 9y ago
https://en.m.wikipedia.org/wiki/Dendrochronology https://en.m.wikipedia.org/wiki/Dendrochronology Apperently there are enough core sample data to determine when a tree was cut down anytime the last few thousand years!
- johansch 9y ago
  (Thanks to everyone who pointed this out.) Wow. This is fascinating stuff. (I didn't think this field could be so interesting.)
cr1895 9y ago
>How do they know it was oak from Sweden? Maybe it has something to do with good records-keeping back then- these ship-worthy oak trees were treasured and protected: "Oaks and cultural history Over the centuries, the oak has been a significant tree in Swedish life and in many ways Johan’s book is also a cultural history of the tree. Oaks were central, for example, to the shipbuilding industry during the reign of King Gustav Vasa. A large ship required approximately 2,000 oaks so laws were introduced to protect them; anyone caught cutting down or damaging oaks or seedlings found themselves subject to severe penalties." http://www.su.se/english/about/news-and-events/a-pictorial-account-of-swedish-oaks-and-wildlife-1.5505 http://www.su.se/english/about/news-and-events/a-pictorial-a...
- jonrei 9y ago
  Funny anecdote time! The oaks mentioned in the article, on Visingsö, were planted in the early 19th century for future war ships. In 1975 the chief of the forest service called the chief of navy telling him the oaks were ready for harvest. For some reason he declined the offer, but thought it would be nice if the forest could be preserved, which it were.
  - toyg 9y ago
    A clear case of premature optimization.
  - B1FF_PSUVM 9y ago
    So, sometimes, in a century or two we figure out we were worrying about (and investing on) the wrong thing. Well, there's always the recreational value of worrying.
dzdt 9y ago
There are measured ring-width chronologies from all over Europe. Years which are hot and dry give small amounts of tree growth; wetter years give more growth. The sequence of thick and thin rings correlates across large regions, allowing the dating of oak wood with a sufficient number of rings -- about 100 for good certainty. In many cases it is possible to identify a much finer location where trees were grown. While there is some correlation between (say) weather in Sweden and Germany, the correlation is much higher in nearby locations. It is often possible to locate wood to a specific forest just based on the ring widths.

maxerickson 9y ago

Just as likely they analyzed the width of the growth rings. Trees in a given area will have similar high growth and low growth years. And then there are big events where growth will correspond across wider regions.

johansch 9y ago
So you mean for a plank of wood, you would do some statistical analysis based on the series of the widths of the growth things and then match them with other recorded widths/deltas to try to find a match? (Yeah, it seems plausible that it would work.)
- deleted 9y ago
  [deleted]
- robin_reala 9y ago
  Yep. The field is called dendrochronology: https://en.wikipedia.org/wiki/Dendrochronology https://en.wikipedia.org/wiki/Dendrochronology

willvarfar 9y ago

We can rule out carbon dating because oak grows for hundreds approaching thousands of years and so the carbon dates wouldn't narrow things down. When archeologists send things to be carbon dated they try to find very short-lived woods or seeds. The way you can date oak so precisely is by the comparative widths of the tree-rings. This is called dendrochronology https://en.wikipedia.org/wiki/Dendrochronology https://en.wikipedia.org/wiki/Dendrochronology

dithering 9y ago
Carbon dating measures the ratio of C14 to C12. This ratio doesn't start to change until they die, and are no longer renewing their carbon from the environment. Radiocarbon dating does provide an accurate date (although less accurate than dendro) for wooden items, and works with a wider range of samples.
- marcosdumay 9y ago
  That's for short lived organisms. Trees do not renew most of their carbon during their lifetime, cellular walls are created and very rarely destroyed.

progre 9y ago

https://en.m.wikipedia.org/wiki/Dendrochronology https://en.m.wikipedia.org/wiki/Dendrochronology Apperently there are enough core sample data to determine when a tree was cut down anytime the last few thousand years!

johansch 9y ago
(Thanks to everyone who pointed this out.) Wow. This is fascinating stuff. (I didn't think this field could be so interesting.)

cr1895 9y ago

>How do they know it was oak from Sweden? Maybe it has something to do with good records-keeping back then- these ship-worthy oak trees were treasured and protected: "Oaks and cultural history Over the centuries, the oak has been a significant tree in Swedish life and in many ways Johan’s book is also a cultural history of the tree. Oaks were central, for example, to the shipbuilding industry during the reign of King Gustav Vasa. A large ship required approximately 2,000 oaks so laws were introduced to protect them; anyone caught cutting down or damaging oaks or seedlings found themselves subject to severe penalties." http://www.su.se/english/about/news-and-events/a-pictorial-account-of-swedish-oaks-and-wildlife-1.5505 http://www.su.se/english/about/news-and-events/a-pictorial-a...

jonrei 9y ago
Funny anecdote time! The oaks mentioned in the article, on Visingsö, were planted in the early 19th century for future war ships. In 1975 the chief of the forest service called the chief of navy telling him the oaks were ready for harvest. For some reason he declined the offer, but thought it would be nice if the forest could be preserved, which it were.
- toyg 9y ago
  A clear case of premature optimization.
- B1FF_PSUVM 9y ago
  So, sometimes, in a century or two we figure out we were worrying about (and investing on) the wrong thing. Well, there's always the recreational value of worrying.

dzdt 9y ago

There are measured ring-width chronologies from all over Europe. Years which are hot and dry give small amounts of tree growth; wetter years give more growth. The sequence of thick and thin rings correlates across large regions, allowing the dating of oak wood with a sufficient number of rings -- about 100 for good certainty. In many cases it is possible to identify a much finer location where trees were grown. While there is some correlation between (say) weather in Sweden and Germany, the correlation is much higher in nearby locations. It is often possible to locate wood to a specific forest just based on the ring widths.