Is the youngest part of a rock from the bottom up or from the top to the bottom?

How do scientists tell how old a rock is other than that?

The youngest part of a rock is always on the top as the oldest is on the bottom.

Scientists look at the color and the form of rocks to also determine how old a rock is

Studying rocks are boring so I don't really find them interesting

Rocks are looked at by the shape to see how old they are And the youngest rock is at the top where it forms