[Tax-chick]

You're serious? Like a database of geology core samples? Pretty neat.

[devane617]

Several universities here in the U.S. keep detailed records for tree-ring dating. They can take a sample from a known time and compare it with the sample in question and tell within a few years when the tree grew.

I believe they have samples that date back a couple thousand years.

[CobaltBlue]

Better than geology, since each ring = one year, like clockwork. During the spring and summer, the tree grows a new ring, and during the winter, it's dormant and the ring stops growing. Next year, it happens again. Every year, over and over. In years of drought, the rings are thin, and in years with lots of rain, they are fat. So you can also tell what the climate was like.

[blam]

"You're serious? Like a database of geology core samples? Pretty neat."

Yes, it's a science named dendrochronology. The tree-ring chronology is now over 10,000 years long.