What dating method do they use to determine the age of really old fossils?

Posted by admin | Earth Sciences & Geology | Wednesday 12 November 2008 1:44 am
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Yesterday there was news of a 3.3 million year old Australopithecus afarensis fossil from Ethiopia. I’m just curious as to how they ascertain the age. I know it’s not carbon-14 dating, that’s 2 orders of magnitude beyond its range. It’s been a while since I learned about this stuff, so thanks for refreshing my memory.