ELI5: Explain Like I'm 5

Geochronology

Geochronology is the study of how old things are. It helps us figure out when different events like the formation of mountains or how old fossils are. Geochronologists look at rocks and other things to determine how old they are by measuring how much certain chemicals or elements have changed over time. Scientists measure things like the amount of certain chemicals or the breakdown of certain elements to figure out how old something is.