Across
- 2. 1st eon of earth, Earth looked "hellish" at this time.
- 5. longest time frame totaling half a billion years or more.
- 6. period where plants dominated the Earth to the point that there wasn't enough Carbon Dioxide to keep the plants alive.
- 9. is a method used to determine the age of rocks and fossils by comparing them to other materials in their vicinity.
- 10. Each totaling millions of years, 99 defined.
Down
- 1. Gaps in the geologic record due to erosion. They represent missing time in the rock layers.
- 3. Totaling tens to one hundred million years (Jurassic)
- 4. is a method used to determine the exact age of a rock or fossil in years.
- 5. Each totaling tens of millions of years, 34 epochs.
- 7. Each totaling several hundred million years (Cenozoic)
- 8. the youngest rocks are at the top, and the oldest rocks are at the bottom.