Rubidium 87 radioactive dating
In radiometric dating, the decaying matter is called the parent isotope and the stable outcome of the decay is called the daughter product.
Since the half-life of carbon-14 is 5730 years, scientists can measure the age of a sample by determining how many times its original carbon-14 amount has been cut in half since the death of the organism.
This is in part because uranium and lead are not retained in rocks as easily as some others, and in part because the parent isotopes and daughter products are not even directly related.
"The rate of diffusion will vary, based on the sample – what type of rock it is, the number of cracks and amount of surface area, and so on." The process as it's currently applied, Hayes says, is likely to overestimate the age of samples, and considering scientists have been using it for decades, our understanding of Earth's ancient timeline could be worryingly inaccurate.
The isotope potassium-40 (k-40) decays into a fixed ratio of calcium and argon (88.8 percent calcium, 11.2 percent argon).
Since argon is a noble gas, it would have escaped the rock-formation process, and therefore any argon in a rock sample should have been formed as a result of k-40 decay.
By calculating the ratios of rubidium-87 to strontium-86, and strontium-86 to strontium-87, a graph called an isochron is created, which scientists can then use to determine the age of a sample.
The process works best on igneous rocks, and has been used to study Earthly and lunar formations for decades.