Across
- 2. The time required for half of a sample of a radioactive isotope to break down by radioactive decay to form a daughter isotope
- 5. A principle that states that younger rocks lie above older rocks if the layers have not been distributed.
- 7. The standard method used to divide earth's long natural history into manageable parts
- 9. 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. A principle that geologic processes that occurred in the past can be explained by current geologic processes
Down
- 1. The weather conditions in an area over a long period of time
- 3. Any method of measuring the age of an event or object in years
- 4. The trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock
- 6. A method of determining the absolute age of an object by comparing the percentages of a radioactive isotope to a stable isotope
- 8. A fossilized structure, such as a footprint or coprolite, that formed in sedimentary rock by animal activity on or within soft sediment.
- 10. Any method of determining whether an event or object is older or younger than other events or objects.
- 12. geologiccolum