Summary #4 (Geological Time)

If you look closely at a rock wall you may see that there are huge deposits of rock sediment built up one layer on top of the another. A mighty force of erusion dug throw the area and left behind what we can see. In this exposed wall we can see a geologic column.

When people dig through rock layers they found fossils. They help us to see what animals live in the past and how were their surroundings.Fossils can provide clues to rock's relative age. For example if they are index fossils they can help us to know why they became extinct. Fossils have became very useful in scientific studies.