Fossil dating method
Each isotope decays at a constant rate that is unique to that substance meaning that using the proportion of parent and daughter isotopes, you can calculate when the rock was formed.Radiocarbon dating measures isotopes in organic material using the decay of carbon-14 to nitrogen-14.Two methods are normally used relative dating and absolute dating. This method of dating uses rocks and other similar fossils in the area for working out a relative age, but this method doesn’t give an actual number.The law of superposition states that the older layers will be deeper into the earth meaning that scientists can determine roughly how old a fossil is depending on what layer of rock it was found in.So in order to date most older fossils, scientists look for layers of igneous rock or volcanic ash above and below the fossil.
For example, if you find a ammonite and it was found near a Triassic rock then you know that the ammonite is 200 million years old.
When people think of dating fossils they normally are most familiar with carbon dating but this isn’t normally used for fossils because the half life for carbon is too short to identify.
It is only possible to carbon date things that are younger than 75000 years old whereas potassium has a half life of 1.25 billion years so this is more common in rocks. Feel free to have your say in the comments below, leave a like if you enjoyed this article!
Some scientists prefer the terms chronometric or calendar dating, as use of the word "absolute" implies an unwarranted certainty of accuracy.
Absolute dating provides a numerical age or range in contrast with relative dating which places events in order without any measure of the age between events.
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Because carbon-14 decays fast the material can only be around 75,000 years old.