Wind gaps exist where the topography funnels airﬂow through a notch in a ridge. The persistent winds further incise such traces. Many wind gaps began as water gaps that were later left high and dry. This can happen through stream piracy, where the river that cut the gap is later captured by another river more vigorously extending its channel upstream through headward erosion. Wind gaps do not always indicate former stream courses, however, and often lie at a higher level than neighboring water gaps. Cols, passes, and saddles are all forms of wind gaps, as is the cleft formed when back-to-back cirques meet and their arête fails. The Keyhole on Longs Peak in Rocky Mountain National Park, Colorado, forms a memorable wind gap, especially for climbers passing through it in a gale.