Headcutting is a form of bed degradation. It differs from general bed degradation in that it involves bed lowering by upstream progression of vertical discontinuities (steps, drops, or waterfalls) rather than more or less uniform lowering along a reach. These vertical discontinuities are referred to as headcuts or knickpoints. Headcuts do not form in sand, gravel or cobble beds, but general bed degradation will occur. Headcutting may occur in several waves, one after the other. Symptoms of headcutting include the vertical steps or drops in the bed profile mentioned previously and massive bank failure downstream of the main headcut with fairly stable conditions upstream. It is important to note that bank stabilization is generally ineffective if bed degradation is ongoing.