How do valleys form in mountains?
Show answer & explanation
Answer: Glaciers and rivers carve rock
Glaciers and rivers carve rock ✓ — Correct! Valleys form through erosion over millions of years. Rivers cut V-shaped valleys by wearing away rock and carrying sediment downstream. Glaciers carve U-shaped valleys—their immense weight and movement grind rock like sandpaper. Freeze-thaw cycles fracture rock, accelerating the process. Gravity pulls loosened material downhill, deepening valleys!
Wind erodes softer areas — Wrong. Wind can erode, especially in dry climates, but water and ice are far more powerful at carving mountain valleys.
Underground caves collapse — Wrong. While cave collapses create sinkholes, mountain valleys are primarily carved by surface erosion from glaciers and rivers.
More Earth Science questions
- In folded Appalachians, why can one rock layer become a ridge while its neighbor becomes a valley?
- Loose material moves downhill from a fresh fault scarp, rounding it. What sets the smoothing speed?
- Why can a long active fault affect more river basins than a short one?
- Why does erosion happen faster near active faults than in areas with heavy rain?
- Why can quartz sand with beryllium-10 reveal how fast a whole river basin erodes?
- Earthquake shaking lasts seconds. How can it leave rock easier for later rivers to erode?