Hanging Valley

A hanging valley is a tributary valley whose floor sits noticeably higher than the floor of the main valley it joins. It typically forms where a smaller tributary glacier meets a larger trunk glacier: the larger glacier, carrying far more ice, cuts a deeper U shaped valley than the smaller tributary glacier can cut alongside it, even though both once had ice surfaces at the same elevation. When the ice melts away, the shallower tributary valley is left standing above the floor of the main valley, and a waterfall often forms where its stream drops into the valley below. A similar hanging effect can also result from a tributary valley being cut into more resistant rock that erodes more slowly than the main valley floor.