Atmosphere and the Earth

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Across
  1. 2. the gas that we breathe out
  2. 4. the useful gas in the atmosphere
  3. 6. the outer layer of the earth
  4. 8. the gas layer around the Earth
  5. 9. rock that is made when magma cools
  6. 11. the process by which rocks can change from one to another
  7. 12. the rock that fossils are found in
Down
  1. 1. the most abundant gas in the atmosphere
  2. 3. rock that is made under heat and pressure
  3. 5. the process where plants make their own food and give out oxygen
  4. 7. the process by which carbon is recycled
  5. 10. the remains of animals or plants that lived millions of years ago