Earth & Space

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