A glacial valley is a U-shaped valley formed by the erosion of a glacier as it moves through a landscape. The immense weight and slow movement of the ice carve out the valley's shape, creating steep sides and a flat bottom. These valleys are often found in mountainous regions where glaciers have existed in the past. Glacial valleys can be filled with water, forming lakes, or may contain rivers that flow through them. They are important geological features that provide insight into past climate conditions and the movement of glaciers, such as those found in the Alps or Rocky Mountains.