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