Originally posted by Essan
The oldest Bristlecones are 4,000 years old, and we have a continuous dendrochronological record from them going back 9,000 years.
Essan
et al.
When I mentioned that denrochronology extends almost as far back as C14 can go I meant it.
Examples people have given since my post stating this all involved
single plants that are very old.
The fact is, ancient
lumber has been matched with corresponding rings on trees or tree products (logs) that overlapped in age from tens of
thousands of years ago to the present day.
It's actually quite an accomplishment, and it hasn't been done worldwide or anything, but it has been done enough to investigate the accuracy of C14
and to aid in the calibration of ther dates give by that sort of analysis.
Rings in trees are laid down in precise patterns that are largely determined by the climate of that particular year. If a series of rings on the
outer part of a log can be matched to a series of rings on the inner part of a newer log, then you have two log's worth of records, not one.
Multiply this by thousands of overlapping time periods and you get the result we have arrived at today.
Like I said, since the ring pattern depends on climate, tree rings traced back over 20,000 years in Europe won't tell you much about tree rings you
find in ancient wood products from Bolivia.
But, you can bet that the atmospheric C14 creation rate 20,000 years ago was the same over Europe as it was over Bolivia. So if you can calibrate C14
using tree ring data in Europe, you've calibrated it for the entire world, no matter where the site is.
Harte
