Earth Sciences & Geology « Blog Something

May 18, 2009

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

Filed under: Earth Sciences & Geology — Tags: Carbon Dating, Memory, Orders Of Magnitude — admin @ 2:30 pm

southeastside asked:

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.

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May 13, 2009

How does radiometric dating help scientists pinpoint the age of a fossil?

Filed under: Earth Sciences & Geology — Tags: Liquids, Scientists, Sediment — admin @ 3:45 am

twizz asked:

In radiometric dating, scientists use the rate of decay of radioactive materials in rocks to estimate the absolute age of a rock. That tells them the age of fossils found in that rock.

Radiometric dating allows scientists to find fossils in only the lowest and oldest layers of sediment.

In radiometric dating, scientists place samples of a fossil in certain liquids until the samples dissolve. The rate at which they dissolve indicates the age of the fossil.

In radiometric dating, scientists mix the carbon in a fossil with carbon from similar fossils whose age they know. By comparing, the carbon they can tell the exact age of the fossil.

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