What is the name of the U-shaped valley formed by glacial erosion?

The U-shaped valley formed by glacial erosion is called a glacial trough, also known as a trough valley. It typically has steep sides and a broad, relatively flat floor, unlike the V-shaped profile commonly carved by rivers.

As a glacier moves downhill, embedded rocks scrape and pluck material from the valley walls and floor. The moving ice widens and deepens an older river valley over thousands of years. When the glacier retreats or melts, its characteristic U-shaped cross-section remains visible.

A cirque is a bowl-shaped hollow where a glacier begins, while a hanging valley is a smaller tributary valley left high above the main trough. A fjord is a glacial trough that has been flooded by the sea; therefore, every fjord began as a glacially carved valley, but not every glacial trough is a fjord.

Classic examples occur in the Alps, Himalaya, Rocky Mountains, Scandinavian Mountains and New Zealand. Some glacial troughs contain ribbon lakes, moraines and unusually small streams called misfit streams.