As the global temperature began to drop, animals migrated to other continents or became extinct. Ice A typical large Antarctic iceberg may weigh 400 million tons and rise 10 stories above the surface of the water. A berg of this size contains enough freshwater to supply a city of three million people for a year. Surprisingly, Ann and Liv will not be skiing across a flat, white terrain. Ann and Liv must be very careful where they ski and watch for snow bridges.
Snow bridges are areas of snow forming the roofs of crevasses.
Caused by drifting snow, they hide the dangers of a crevasse.