Across
- 2. A trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock
- 3. A principle that states an younger rock is above an older rock if layers have not been distributed
- 6. The scientific study of the origin, history, and structure of earth and the processes that shape earth
- 8. The weather conditions in an area for a long period of time
- 10. A long cylinder of ice obtained by drilling through ice caps or ice sheets used to study past climate
- 12. Any method of determining an object older or younger than other events or objects
- 14. A method of determining the the absolute age of an object by comparing the relative percentages of a radioactive isotope and a stable isotope
- 15. A fossilized structure such as a footprint that formed in sedimentary rock
Down
- 1. The standard method used to divide earth’s long natural history into manageable parts
- 4. A principle that geologic processes that occurred in the past can be explained by current geologic processes
- 5. A break in geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time
- 7. The process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element
- 9. Any method of measuring the age of an event or object in year (260)
- 11. The time required for half of a sample of a radioactive isotope to break down by radioactive decay to form a daughter isotope
- 13. An ordered arrangement of of rock layers that is based on relative ages of the rocks and in which the oldest rocks are at the bottom