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Article: We found 22 white and well-formed calcite crystals brought to the site 105,000 years ago. We determined this using a method called "optically stimulate
by jph 6y ago
Article: We found 22 white and well-formed calcite crystals brought to the site 105,000 years ago. We determined this using a method called "optically stimulated luminescence", which dates sediments the crystals were excavated from. Our analysis indicates the crystals were not introduced into the deposits via natural processes, but rather represent a small cache of deliberately collected objects.
See https://en.wikipedia.org/wiki/Optically_stimulated_luminescence https://en.wikipedia.org/wiki/Optically_stimulated_luminesce...
- seneca 6y agoYes, I read the article. It specifically says the sediment was dated. I'm just curious how they're certain the placement of the crystals dates to the same time.
- AlotOfReading 6y agoThis dating method basically dates the last time the sediments were directly exposed to ionizing radiation (i.e. sunlight). The key here is that it sets a minimum age. Things can be older and have their "clocks reset", but the decay constant is fixed, so we can always determine the last time the object or sediment was exposed. There are a couple minor issues with it, but it's better (and sometimes cheaper!) than radioisotope dating. You can be pretty confident in OSL/TL dates more than a couple thousand years old.