Earth’s Story

How is the Earth shaped?

Uniformitarianism – the belief that Earth has changed gradually and continuously over time.

“the present is the key to the past”

Catastrophism – All geologic changes occur suddenly.

Which one is true?

Modern geologists believe Earth is shaped by both! Gradual processes such as

erosion and weathering Sudden changes like a meteor

impact or a volcanic eruption

Relative Dating??

Relative dating – is time in relationship to something else

Which came first??

It is like saying I am older than you but you do not know by how much!

Relative Dating Activity

I stood in the checkout line.

I selected two apples.

I walked home from the store.

I gave the cashier the money.

I went to the store.

The cashier gave me my change.

I was hungry.

Hopefully….. I was hungry.

I went to the store.

I selected two apples.

I stood in the checkout line.

I gave the cashier money.

The cashier gave me my change.

I walked home from the store.

Law of SuperpositionThe law states that the younger/newer rocks are on top of or above older rocks.

Everyday ExamplesPile of laundry.

Bricks used to build a house.

Your school folder.

Stack of magazines.

Disturbing Forces!Rock layers can be disturbed by forces from within the Earth.

rocks can intrude

rocks can tilt

rocks can fold

faults form

Because of these disturbances the sequence of the layers may be changed.

List in order from youngest to oldest.

Did you get the correct answer??

Youngest

E

D

A

B

C

Oldest

Geologic column A sequences of rock layers that contain all the known fossils and rock formations on Earth arranged from oldest to youngest.