Listen to part of a lecture in a geology class.

Ok,let's get started.

Great.

Today I want to talk about a way in which we are able to determine how old a piece of land,or some other geologic feature is - dating techniques.

I'm going to talk about a particular dating technique.

Why?

Good dating is a key to good analysis.

In other words,if you want to know how a land formation was formed,the first thing you probably want to know is how old it is.

It's fundamental.

Um'Take the Grand Canyon for instance.