Geologic Time 1

What is the longest unit of time?

• Eon

• Era

• Period

• Epoch

Each era is divided into

• Periods

• Eons

• Epochs

• eras

Each period is divided into

• an epoch

• an eon

• a period

• an era

A record of the geologic events and life forms in Earth's history.

• index fossil
• half-life
• radioactive dating
• geologic time scale

Change over time for organisms.

• geologic time scale
• evolution
• era
• period