Describe how the principle of superposition was used in determining the relative ages of the cross-sections?

Answer 1

What on earth are you talking about?

Answer 2

EARTH SCIENCE ; NOBODY WANT TO HELP ME -.-

Answer 3

We'd be glad to help you if we knew what you're asking.

Maybe this site has your answer.

http://en.wikipedia.org/wiki/Law_of_superposition