Glaciers built up in mountain hollows and enlarge them to form a with three steep sides and an opening to the front. The glaciers then move down through river valleys, widening, straightening and deepening them to form valleys. The point where smaller valleys, called valleys join the main valley is often marked by a waterfall.

Glaciers transport their load of loose rock by . The most common moraine is the moraine, found at the sides of a glacier. When two of these join up, they form a moraine.