U-shaped valley
Also called: Glacial trough · Topic: Landforms and their Evolution: Rivers, Groundwater, Glaciers, Waves and Wind · NCERT: Class 9, Ch 2 "Shaping of the Earth's Surface"; Class 11, Ch 6 "Landforms and their Evolution"; Class 11, Ch 5 "Topographical Maps"
Meaning
A U-shaped valley, or glacial trough, is a valley carved by a glacier. It has a broad, flat floor and steep, smooth sides. A glacier often moves into an old river valley. As it moves, it widens and deepens the valley on all sides and changes its V-shape into a U-shape. The floor may hold moraines (ridges of glacial debris) and lakes scooped out by the ice. Side valleys may be left as hanging valleys high on its walls.
Example
The upper Bhagirathi valley near Gaumukh in Uttarakhand has a broad, trough-like shape carved by the Gangotri glacier.
Don't confuse with
- V-shaped valley: cut by a river cutting down fast, with a narrow floor. A U-shaped valley is cut by ice and has a broad floor.
- Fjord: a U-shaped trough in high latitudes that has been drowned by the sea, as in Norway.
Related concepts
- Glacier
- Valley glacier
- Continental glacier
- Plucking
- Cirque
- Tarn
- Horn
- Arete
- Hanging valley
- Truncated spur