Across
- 2. a principal that states that younger rocks lie above older rocks if the layers have not been disturbed.
- 5. decay the process in which a radioactive isotope tends to break down into a stable element or another element.
- 6. the time required for half of a sample of a radioactive isotope to break down by radioactive decay to form a daughter isotope.
- 8. the weather conditions in an area over a long period of time
- 9. Core a long cylinder of ice obtained from drilling through ice caps or ice sheets; used to study past climates
- 11. the scientific study of the origin, history, and structure of the earth and the processes that shape earth
- 13. dating any method of determining whether an event or object is older or younger than other events objects
- 14. the trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock
- 15. Fossil a fossilized structure, such as a footprint or a coprolite, that formed in sedimentary rock by an animal on or within soft sediment.
Down
- 1. a break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time.
- 3. a principal that geologic processes that occurred in the past can be explained by current geologic processes
- 4. Dating a method of determining the absolute age of an object by compare the relative percentages of a radioactive parent isotope and a stable daughter isotope.
- 7. Dating any method of measuring the age of an event or object in years.
- 10. column an ordered arrangement of rock layers that is based on the relative ages of the rocks and in which the oldest rocks are at the bottom
- 12. Time-Scale the standard method used to divide earth's long natural history into manageable parts