Puzzle 28 — Planet Surface

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Across
  1. 2. A steep rock wall.
  2. 4. A bowl-shaped hole in the ground.
  3. 6. A small raised pile of earth.
  4. 7. Ground that goes up or down.
  5. 9. Tiny grains found on some ground.
  6. 10. A hill made of sand.
Down
  1. 1. Low land between hills or mountains.
  2. 3. A small piece of rock.
  3. 5. A long narrow raised part of land.
  4. 8. A wide flat area of land.