In archaeological terminology, there are two categories of dating methods: absolute and relative.

Absolute dating utilizes one or more of a variety of chronometric techniques to produce a computed numerical age, typically with a standard error.

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.

If a geologist claims to be 45 years old, that is an absolute age.

Superposition: The most basic concept used in relative dating is the law of superposition.

Geologists generally know the age of a rock by determining the age of the group of rocks, or formation, that it is found in.

The age of formations is marked on a geologic calendar known as the geologic time scale.

Geologists draw on it and other basic principles ( to determine the relative ages of rocks or features such as faults.

Development of the geologic time scale and dating of formations and rocks relies upon two fundamentally different ways of telling time: relative and absolute.

Relative dating places events or rocks in their chronologic sequence or order of occurrence.

Here is an easy-to understand analogy for your students: relative age dating is like saying that your grandfather is older than you.

Absolute age dating is like saying you are 15 years old and your grandfather is 77 years old.