Across
- 2. core A long cylinder of ice obtained from drilling through ice caps used to study past climates
- 3. life The time required for half of a sample of a radioactive isotope to break down by radioactive decay to form a daughter isotope
- 6. dating A method of determining the absolute age of an object by comparing the relative percentages of a radioactive isotope and a stable isotope
- 7. A break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time
- 10. dating Any measuring the age of an event or object in years
- 12. The scientific study of the original history and structure of earth and the process that shape earth
- 13. time scale The standard method used to divide earth's long natural history into manageable part
- 14. dating Any method determining weather an event or object is older or younger that other events or objects
Down
- 1. A principle that geologic processes that occurred in the past can be explained by current geologic processes
- 4. A principle that states that younger rocks lie above older rocks if the players have not been distributed
- 5. The weather conditions in an area over a long period of time
- 8. The trace that remains of an organism that lived long ago
- 9. decay The process in which a radioactive iscope tends to break down into stable isotopes of the same element or another element
- 11. fossil A fossilized structure , such as a footprint or a copolite that formed in sedimentary rock by animal activity
- 12. 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