Across
- 2. A class of organisms that have the same characteristics
- 4. A period of time which started in 409 and ended in 353
- 5. When a species suddenly dies off
- 6. A period of time which started in 251 and ended in 205
- 8. Flow of electric charge through a gas, liquid or solid
- 15. Something that holds up the human body
- 16. Lava and gas are discharged
- 18. Organic matter exposed to minerals over a long period
- 20. Reduction and weakening of something
Down
- 1. Any alteration in the structure or function of an organism
- 2. A type of rock made up of dirty and different rocks
- 3. Studies forms of life existing in prehistoric
- 7. It shines bright
- 9. Period of time
- 10. Layers made up of sedimentary rock
- 11. A period of time which started in 510 and ended in 434
- 12. A period of time which started in 298 and ended in 251
- 13. A substance that occurs naturally in rocks and in the ground
- 14. A period of time which started in 141 and ended in 65
- 17. A force applied in a perpendicular fashion to a surface
- 19. Remains or trace of a preserved organism