1. Here is vocabulary to help you understand the terms to allow you to understand how scientists determine the age of Earth layers and things found in the Earth.

2. stratigraphy

3. the study of rock layers: 1 of 3 major laws is the law of original horizontality-states that when sediments are deposited, they settle in flat, horizontal layers. .

4. Absolute Dating/Age

5. is the process of determining an age on a specified time scale in archaeology and geology

7. Relative Dating/Age

8. is the science of determining the relative order of past events (i. e
 is the science of determining the relative order of past events (i.e., the age of an object in comparison to another)

10. uniformitarianism

11.  is the assumption that says that the same natural processes that operate in the universe now, have always done so, and at the same rates.

13. unconformities

14. (gaps) observed in geological strata formed by folding, uplift, and erosion etc.

16. Radioactive Decay

17.  is the process by which a nucleus of an unstable atom breaks down and loses energy by emitting radiation.

19. petrified

20. to convert into stone 

22. Sequence

23. the following of one thing after another

25. Diversity - state of being different (Variation: a different form of something) Vast –  very great size, amounts, or proportions extinct – has ended or died out vary - to cause to be different from something else