How to date a fossil using radiometric dating
In the case of radiocarbon dating, the half-life of carbon 14 is 5,730 years.
This half life is a relatively small number, which means that carbon 14 dating is not particularly helpful for very recent deaths and deaths more than 50,000 years ago.
It’s just that I kept adding and adding to make it all make more sense and before I knew it, I had 3000 words on dating fossils! So, last time, we discussed the basics of radiometric dating and ended with a quick and dirty example of how a parent:daughter isotope ratio can be used to find the age of a sample.
I skipped some details on purpose, but the foundational principles to these methods are really as easy as I explained.
So how come I started this whole thing by saying that it’s actually not possible to date fossils directly? Because although radiometric dating will almost always provide an answer, in most cases, unless you’re applying the methods to an igneous rock, it won’t answer the question you’re asking.
See, the clock for radioactive elements starts at crystallization.
Where t is the age of the fossil (or the date of death) and ln() is the natural logarithm function.
Instead, you’ll determine how long ago the rock formed—not very helpful. It might not seem like it, but that is a really short half-life, and Ealong.Archaeologists use the exponential, radioactive decay of carbon 14 to estimate the death dates of organic material.The stable form of carbon is carbon 12 and the radioactive isotope carbon 14 decays over time into nitrogen 14 and other particles.I asked in the caption to this figure, “How do you know C happened before D? If you’re familiar with the colors and patterns used in geologic diagrams like this, you probably know that D is an igneous intrusion and C is a layer of sedimentary rock.So we know that C came before D—but because D is igneous, we can put a date on it (now I have a Beyoncé song in my head, great…).
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After 5,730 years, the amount of carbon 14 left in the body is half of the original amount.