New Zealand is currently home to more than 3,000 glaciers. Glaciers are basically huge masses of compacted ice and snow. As gravity pulls the enormously heavy sheets of glacial ice downhill towards the sea, pieces of rock are picked up and frozen into the ice. As the ice slides downhill, the rocks trapped in the glacier work like sandpaper to grind down mountains into dramatic vertical u-shaped canyons. This entire process can take millions of years. Read more in our post, Fox Glacier Heli Hike.