The abundances of parent and daughter isotopes in a sample can be measured and used to determine their age. This method is known as radiometric dating. The amount of time that it takes for half of the parent isotope to decay into daughter isotopes is called the half-life of an isotope (Figure 5b).

What is the age of something compared to something else?

ES Ch 13 VocabABThe age of something compared with other thingsRelative ageGap in the rock layer that is due to erosion or periods without any depositionUnconformityPrinciple stating that Earth processes occurring today are similar to those that occurred in the pastUniformitarianism11 more rows

What is the importance of determining the age of rocks?

Gaining estimates of ages of rocks is crucial for establishing not only the history of geological events but also for determining the rates of geological processes. It is possible to establish the relative order of events in some rocks.