Here's why:
* Glaciers: Glaciers are large masses of ice that move slowly over land.
* Erosion: As they move, glaciers carve out the landscape through a process called erosion. They pick up rocks and sediment, which scrape and grind against the bedrock.
* U-shaped Valleys: The characteristic U-shape of these valleys is due to the way glaciers erode the landscape. They erode more deeply in the center of the valley, where the ice is thickest, and less so along the sides, creating a steep, U-shaped profile.
Let me know if you have any more questions about glaciers or landforms!