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Radiocarbon is produced in the upper atmosphere after Nitrogen-14 isotopes have been impacted by cosmic radiation.

Radiocarbon is then taken in by plants through photosynthesis, and these plants in turn are consumed by all the organisms on the planet.

Relative dating stems from the idea that something is younger or older relative to something else.

Half-lives vary according to the isotope, for example, Uranium-238 has a half-life of 4500 million years where as Nitrogen-17 has a half-life of 4.173 seconds!

Looking at the graph, 100% of radiocarbon in a sample will be reduced to 50% after 5730 years.

In 11,460 years, half of the 50% will remain, or 25%, and so on.

Limitations and calibration: When Libby was first determining radiocarbon dates, he found that before 1000 BC his dates were earlier than calendar dates.

Although relative dating can work well in certain areas, several problems arise.

Rodents, for example, can create havoc in a site by moving items from one context to another.Natural disasters like floods can sweep away top layers of sites to other locations.Absolute dating represents the absolute age of the sample before the present.Plants are not the only organism that can process Carbon-14 from the air.Plankton absorbs, Carbon-14 from the ocean much like terrestrial plants absorb Carbon-14 from the air.One good example would be the elevated levels of Carbon-14 in our atmosphere since WWII as a result of atomic bombs testing.

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