Why are valleys V-shaped or U-shaped?
Show answer & explanation
Answer: River vs glacier erosion
River vs glacier erosion ✓ — Correct! V-shaped valleys form from river erosion. Water cuts downward, with gravity pulling debris down steep sides—creating a V. U-shaped valleys form from glacial erosion. Massive glaciers scour wide paths, plucking rock from sides and base, creating broad U-profiles. Yosemite Valley is a classic glacial U!
Rainfall amount varies — Wrong. Rainfall doesn't determine shape. The erosion mechanism does—rivers create V-shapes, glaciers create U-shapes.
Age of valley determines shape — Wrong. Older valleys may be deeper, but shape is determined by erosion type—water creates V, ice creates U—not age.