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