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