Across
- 3. high, uplifted are with steep slopes
- 4. the word after " pre" in Precambrian
- 5. last name of best science teacher
- 8. the second era
- 9. a low area between hills and mountains, often where a river flows
- 10. formed 200,000 years ago
Down
- 1. appeared 4 billion years ago
- 2. earliest life
- 3. the third era
- 6. became extinct 66 million years ago
- 7. the most current era
- 8. first and longest era