Solve the crossword "NATURAL WORLD"

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Across
  1. 3. Very beautiful or pleasant
  2. 6. Plants in general
  3. 12. A line of mountains connected
  4. 13. Something very valuable
  5. 14. A large mass of ice, formed by snow on mountains
  6. 15. An area of low land between hills or mountains
  7. 17. A forest with tall trees with long, thin leaves shaped like needles
  8. 18. Short trees
Down
  1. 1. Rock or earth from which metal can be obtained
  2. 2. To separate two different regions
  3. 4. Important or noticeable
  4. 5. Grassland
  5. 7. About, almost
  6. 8. Different from one another
  7. 9. To keep something as it is, especially in order to prevent it from decaying or being damaged or destroyed
  8. 10. Features belonging to the culture of a particular society, such as traditions, languages, or buildings, that were created in the past and still have historical importance
  9. 11. A carving or drawing on rock, especially one made by prehistoric people
  10. 16. A hard black mineral that is found below the ground and burnt to produce heat