Across
- 5. a rock or fault is younger than any rock or fault through which it cuts.
- 6. fossils associated with specific time span
- 8. Divided into periods
- 10. layers of sediments are generally deposited in a horizontal position
- 12. Concepts that have shaped the earth
- 13. subdivision of a period
- 15. the procedure of calculating the absolute ages of rocks and minerals that contain radioactive isotopes.
- 16. the spontaneous decay of certain unstable atomic nuclei.
Down
- 1. each bed is older than the layers above and younger than the layers below.
- 2. establishing the equivalent of rocks of similar age in different areas.
- 3. divided into epochs
- 4. Remains or traces of an organism
- 7. largest unit on geologic timescale
- 9. process by which rocks are placed in their proper sequence or order
- 11. surface that represents a break in the rock record, caused by erosion or lack of deposition.
- 14. the time required for one half of the atoms of a radioactive substance to decay.