A mechanism by which an increase in the mass of ice at a particular point in a glacier is transmitted down the glacier. If ice accumulates, the glacier will be thicker at that point and the locally increased mass will slide 2–5 times faster than the ice on its downslope side. The resulting compression will raise a bulge on the downslope side, which will press against the ice on its downslope side. Thus the local increase in mass will be transmitted down the glacier as a wave.