Earth and Space Crossword

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Across
  1. 2. a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding
  2. 5. is a branch of geology which studies rock layers
  3. 7. the star around which the earth orbits
  4. 9. of, relating to, or denoting the last period of the Paleozoic era, between the Carboniferous and Triassic periods.
  5. 11. discharge a discharge of electricity
  6. 12. the remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock.
  7. 14. any of the pieces of hard, whitish tissue making up the skeleton in humans and other vertebrates.
  8. 16. the process of eroding or being eroded by wind, water, or other natural agents.
  9. 17. a specialist in paleontology
  10. 19. of, relating to, or denoting the earliest period of the Mesozoic era, between the Permian and Jurassic periods.
  11. 20. of, relating to, or denoting the fourth period of the Paleozoic era, between the Silurian and Carboniferous periods.
Down
  1. 1. the continuous physical force exerted on or against an object by something in contact with it.
  2. 3. the sudden occurrence of a violent discharge of steam and volcanic material
  3. 4. An extinction event is a widespread and rapid decrease in the amount of life on earth.
  4. 5. rock formed from consolidated clay sediments
  5. 6. the action or process of adapting or being adapted.
  6. 8. of, relating to, or denoting the last period of the Mesozoic era, between the Jurassic and Tertiary periods.
  7. 10. a solid inorganic substance of natural occurrence.
  8. 13. the process by which organic matter exposed to minerals over a long period is turned into a stony substance.
  9. 15. a long and distinct period of history with a particular feature or characteristic.
  10. 18. of relating to, or denoting the second period of the Paleozoic era, between the Cambrian and Silurian periods.