Why does a glacier move

Friction is also involved in the movement of glaciers: Glaciers are large ice masses that were created when snow was transformed into ice during the last ice age. The formation of a glacier is quite simple. Snow turns into granular ice, the so-called firn, under a constant cycle of thawing and freezing. Large amounts of firn create such a high pressure that the firn solidifies into ice. This is how most of the glaciers were formed during the last ice age, which ended around 10,000 years ago.

Impressive glacier landscape © dpa

Glaciers are in constant motion, creating valleys and other mountain structures. A typical glacier in the Alps, for example, moves downhill about 50 meters per year under the influence of gravity. This usually happens because the entire glacier slides down on the bedrock. The friction is not enough to keep gravity balanced. The reason is often pressure melting. The high pressure at the bottom of the glacier turns the ice into water, so that the glacier glides on a thin film of meltwater.

It can be dangerous if the glacier movement suddenly increases significantly. Thawing or excessive pressure can cause large amounts of meltwater to accumulate at the bottom of the glacier. This will reduce the friction with the ground and the glacier will begin to hurtle down the mountain.