Across
- 4. What kind of relationships states that an intrusion or a fault is younger than the rock it cuts across.
- 10. A record of Earth's history from its origin 4.6 billions years ago to the present; A summary of major events in Earth's history that are preserved in the rock record. (two words)
- 12. the change in populations as a result of environmental change
- 13. fossils indirect evidence of plant and animal life (footprints, worm holes, etc.)
- 15. beds distinctive sediment layers, things like volcanic ash, sediments after asteroid impacts and lava flows are all markers that geologist use to separate time
- 17. preservation The soft and hard parts of plant and animal remains that have not undergone any kind of change since the organisms' deaths.
- 18. formed when the original shell parts of an organism within a sedimentary rock are weathered or eroded
- 21. is a gap in a rock record caused by erosion and weathering
- 22. horizontality States that sedimentary rocks are deposited in horizontal or nearly horizontal layers
- 23. the evidence or remains of once-living plants or animals
Down
- 1. what principle states that overlying rock layers can contain loose materials from the rocks below them
- 2. dating process used to determine the absolute age of a rock or fossil by determining the ratio of parent nuclei to daughter nuclei within a given sample
- 3. decay the emission of radioactive particles at a constant rate from a radioactive substance and its resulting change into other elements over time
- 5. is the matching of outcrops of one geologic region to another
- 6. period of time it takes for a radioactive isotope, such as carbon-14, to decay to one-half of its original amount
- 7. formed when the cavity inside of the original shell is filled with minerals or sediments that harden
- 8. hard parts form when all the organic material has been removed and the hard parts of a plant or animal have been changed by mineral replacement or recrystallization
- 9. the process by which pore spaces are filled in with mineral substances
- 11. the third longest unit of geologic time, measured in millions of years
- 12. the second longest unit of geologic time, measured in hundreds of millions and billions of years
- 14. the longest unit of geologic time, measured in billions of years
- 16. smallest units of geologic time, measured in millions and hundreds of thousands of years
- 19. what law says that the rocks on the bottom of a rock record are the oldest (law of _________)
- 20. fossils the remains of plants and animals that can be used for geologists to correlate rock layers over large geographic areas or to date a particular rock layer