Vocab crossword

5. a fossil that is useful for dating
8. a nonliving condition or thing
10. shows rock formations of a region
11. prehistoric organism formed into a rock
17. a fossil of a footprint, trail, burrow,
19. a sequence of layers of sedimentary rock
20. the age of a rock layer
21. the process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide

1. when species vanish much faster
2. An igneous rock, fault, or other geologic feature
3. the numeric age of a layer of rocks or fossils
4. the idea that Earth has always changed in uniform ways
6. Developemnt of living oragnisms
7. a method of dating geological or archeological specimens
9. a large natural lake
12. the action of flowing in or out
13. a surface of contact between two groups of unconformable strata.
14. living organism that shapes its environment.
15. the time taken for the radioactivity of a specified isotope to fall to half its original value.
16. using energy derived from reactions involving inorganic chemicals
18. the study of the history of life on Earth as based on fossils.