Carbon 14 radiometric dating is used for
Relative dating is used to determine a fossils approximate age by comparing it to similar rocks and fossils of known ages.
Absolute dating is used to determine a precise age of a fossil by using radiometric dating to measure the decay of isotopes, either within the fossil or more often the rocks associated with it.
By measuring the ratio of the amount of the original (parent) isotope to the amount of the (daughter) isotopes that it breaks down into an age can be determined.
We define the rate of this radioactive decay in half-lives.
After 5,730 years, the amount of carbon 14 left in the body is half of the original amount.
If the amount of carbon 14 is halved every 5,730 years, it will not take very long to reach an amount that is too small to analyze.
But, how can we determine how old a rock formation is, if it hasn’t previously been dated?
Experts can compare the ratio of carbon 12 to carbon 14 in dead material to the ratio when the organism was alive to estimate the date of its death.Since the rock formation contains both types of fossils the ago of the rock formation must be in the overlapping date range of 415 to 420 million years.