For example, how do we know that the Iceman, whose frozen body was chipped out of glacial ice in 1991, is 5,300 years old?Well, we know this because samples of his bones and hair and even his grass boots and leather belongings were subjected to radiocarbon dating.
Uranium is not the only isotope that can be used to date rocks; we do see additional methods of radiometric dating based on the decay of different isotopes.
For example, with potassium-argon dating, we can tell the age of materials that contain potassium because we know that potassium-40 decays into argon-40 with a half-life of 1.3 billion years.
Because plants use carbon dioxide for photosynthesis, this isotope ends up inside the plant, and because animals eat plants, they get some as well.
When a plant or an animal dies, it stops taking in carbon-14.
In fact, this form of dating has been used to date the age of rocks brought back to Earth from the moon.
So, we see there are a number of different methods for dating rocks and other non-living things, but what if our sample is organic in nature?These differing rates of decay help make uranium-lead dating one of the most reliable methods of radiometric dating because they provide two different decay clocks.This provides a built-in cross-check to more accurately determine the age of the sample.The existing carbon-14 within the organism starts to decay back into nitrogen, and this starts our clock for radiocarbon dating.A scientist can take a sample of an organic material when it is discovered and evaluate the proportion of carbon-14 left in the relic to determine its age. Radiometric dating is a method used to date rocks and other objects based on the known decay rate of radioactive isotopes.So, if you know the radioactive isotope found in a substance and the isotope's half-life, you can calculate the age of the substance. Well, a simple explanation is that it is the time required for a quantity to fall to half of its starting value.