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