Here's why:
* Glacial Erosion: Glaciers are massive sheets of ice that move slowly over the land. As they move, they carve out the landscape through two primary processes:
* Plucking: As the glacier moves, it freezes to bedrock and pulls away pieces of rock.
* Abrasion: The embedded rocks and sediment within the glacier scrape and grind against the bedrock, further eroding the valley.
* V-shaped to U-shaped: River valleys are typically V-shaped, formed by the downward cutting action of the river. When a glacier flows through a V-shaped valley, it widens and deepens it, creating a characteristic U-shape with steep, almost vertical sides.
Other agents of erosion, like wind and water, can also contribute to shaping valleys, but glaciers are the primary force behind the formation of U-shaped valleys.
