Science Vocab

4. A break in the geologic record created when rock layers are eroded or when sedimentary rock is not deposited for a long period of time.
5. time scale The standard method used to divide Earth’s long natural history into manageable parts.
7. Dating The method of determining the absolute age of an object by comparing the relative percentages of a radioactive isotope and a stable isotope.
8. A principle that geologic processes occurred in the past can be explained by current geologic processes.
11. The trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock.
12. The time required for half of a sample of a radioactive isotope to break down by radioactive decay to form a daughter isotope.
13. Fossil A fossilized structure, such as a footprint or coprolite, that formed in sedimentary rock by animal activity on or within soft sediment.
15. Dating Any method of determining whether an event or object is older or younger than other events or objects.

1. A principle that states younger rocks lie above older rocks if the layers have not been disturbed.
2. Column An order arrangement of rock layers that is based on the relative ages of rocks in which the older rocks are at the bottom.
3. Core A long cylinder of ice obtained from drilling through ice
6. The weather conditions in an area over a long period of time.
9. Decay The process in which a radioactive icotope tends to break down into a stable isotope of the same element or another element.
10. Dating Any method of measuring the age of an event or object in years.
14. scientific study of the origin. History, and structure of Earth and the process that shape earth.