Nature

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Across
  1. 3. the time in the morning when the sun appears
  2. 6. a natural chamber
  3. 7. a disturbance or variation
  4. 10. to go on vacation
  5. 12. the main woody stem of a tree
  6. 13. to move and break up earth
  7. 14. to shelter or screen
  8. 15. the time when the upper limb of the sun disappears
  9. 16. the act of choosing or selecting
Down
  1. 1. a division or subdivision of the stem
  2. 2. to harden into ice
  3. 4. the first appearance of light in the morning
  4. 5. make for
  5. 7. the hard fibrous material
  6. 8. the highest level
  7. 9. to move about without a fixed course
  8. 11. very long-period waves
  9. 15. loose surface material