Nature

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Across
  1. 4. the surface of the earth
  2. 5. use waste or chemicals to make rivers and seas dirty
  3. 6. the power from sources such as the sun, water, wind and coal
Down
  1. 1. an area to grow crops
  2. 2. a very high area of land with steep sides
  3. 3. the parts of a tree with leaves, flowers, or fruit on them
  4. 7. something like air, not liquid or solid