Across
- 6. - Massive ice formation moving slowly downhill.
- 7. - Dense, tropical forest.
- 9. - Violently rotating column of air.
- 11. - Logic-based number puzzle.
- 13. - Strategic board game with pieces like rooks and knights.
- 14. - Monumental structure with a square base and triangular sides.
- 15. - Sound accompanying a lightning strike.
- 19. - Colorful arc in the sky caused by light refraction.
- 20. - Succulent plant typically found in arid regions.
Down
- 1. - Enigmatic game or problem.
- 2. - Flightless bird native to Antarctica.
- 3. - Mountain that erupts molten rock.
- 4. - Celestial object with a tail, composed of ice and dust.
- 5. - Deep gorge typically carved by a river.
- 8. - Landmass surrounded by water.
- 10. - Fertile area in a desert with water and vegetation.
- 12. - Boundary where the earth meets the sky.
- 16. - Sheltered area for docking boats.
- 17. - Arid land with little or no vegetation.
- 18. - Landform rising prominently above its surroundings.