Earth History

2. An _______ is the fossil of an organism that lived during a short, well defined interval of time.
5. Geologists believe that a global climate change caused the ______ of the dinosaurs.
7. During ________, unstable isotopes break down into stable isotopes.
9. _________ is the study of past life.
11. _______ is a process in which minerals fill in the pore spaces of an organism’s tissues.
14. Scientists use _______ to determine whether objects are older or younger than other objects.
15. A _____ is a cavity in the ground where an organism was buried.
16. _________ states that older rocks lie below younger rocks in undisturbed sequences.
18. _______ can be used to determine the age of an object by determining the number of years it has existed.
19. The ________ is an ideal rock-layer sequence, arranged from oldest to youngest, that contains all known fossil and rock formations on Earth.

1. According to ________, all geologic changes occur as rare, sudden disasters.
3. _______ states that geologic processes do not change over time.
4. Gaps in rock-layer sequences are called _________.
6. Atoms that have the same number of protons but a different number of neutrons are called
8. If this cavity (from the one before) is filled in with sediment, it can form a _____.
10. The time it takes for the amount of a radioactive parent material to decrease by one-half is called the _______.
12. _________ uses the ratio of parent to daughter material found in a sample to find the sample’s age.
13. A type of _______ called a coprolite is preserved animal dung.
17. The remains or physical evidence of an organism preserved by the geological process is called a _______.