Geologic time scale vocab

1. states that a layer of rock is younger than any layer it cuts through.
3. divides earths history into time intervals defined by major events or changes on earth.
4. igneous rock layer formed when magma hardens beneath earths surface
6. a principle that states that younger rocks lie above older rocks if the layers have not been disturbed
8. igneous rock layers formed when lava flows onto earths surface and hardens.
9. determining the actual age of an object or event in years
13. geological process that happen in the past can be explained by current geologic processes
15. determining whether an object or event is older or younger than the other objects or events
16. the weather conditions in the area over a long period of time
17. the trace or remains of an organism that lived long ago
18. a crack/break in the earth crust.

2. the breakdown of a radioactive isotope into a stable isotope of the same element or of another element
5. finding the absolute age of a sample by determining the relative percentages of a radioactive parent Isotope and a stable daughter isotope.
7. a break in the geologic record that is made when rock layers are eroded or when sediment is not deposited for a long period of time
10. ordered arrangement of rock layers that is based on the relative ages of the rocks and which the oldest rocks are at the bottom
11. fossilized structure that formed in a sedimentary rock by animal activity on or in soft sediment
12. the time needed for half of the sample of a radioactive substance to undergo radioactive decay to form daughter Isotopes.
14. a drill of ice that can help tell the climates of the past