1. Earth’s History How the earth works. How the earth has changed over time. Earth timeline activity. California geology.

2. Earth Structure

3. How the Earth Works: Plate Tectonics

4. The Earth’s Plates

5. Themes for Today The earth is very old. The earth is always changing.

6. Ages to Note 14 billion years - age of universe 4.5 billion years - age of earth 3.5 billion years - oldest know life on earth 544 million years - explosion of life 65 million years - dinosaur extinction 1.5 million years - first homo sapiens

7. Geologic Time Scale

8. Cambrian 540 Ma

9. Permian 270 Ma

10. Cretaceous 60 Ma

11. Present

12. North America: Plate Tectonics at Work

13. Timeline Activity Divide into groups of 2. Collect 4.5m of adding tape. Using the worksheet provided, measure out each time. Note that each time is the time from the present, not the previous time. Have fun!!