Geologic dating definition
Here is an easy-to understand analogy for your students: relative age dating is like saying that your grandfather is older than you.
Yet, you’ve heard the news: Earth is 4.6 billion years old. That corn cob found in an ancient Native American fire pit is 1,000 years old. Geologic age dating—assigning an age to materials—is an entire discipline of its own.
In a way this field, called geochronology, is some of the purest detective work earth scientists do.
There are two basic approaches: relative age dating, and absolute age dating.
The atoms of some chemical elements have different forms, called isotopes.
These break down over time in a process scientists call radioactive decay.