Across
- 3. the numeric age of a layer of rocks or fossils
- 5. means middle life and this is the time of the dinosaurs.
- 7. within a sequence of layers of. sedimentary rock, the oldest layer is at the bottom and. each layer above gets progressively.
- 8. formed from pre-existing rocks or pieces of once-living organisms.
- 9. means recent life.
Down
- 1. The age of a rock layer
- 2. divides up the history of the earth based on life-forms that existed during specific times since the creation of the planet.
- 4. period of time extending from about 4.6 billion years ago
- 6. a period of time in history or a person's life, typically one marked by notable