<Dd> n (\ displaystyle n \,) = a constant between 2--4 (typically 3 for most glaciers) that increases with lower temperature </Dd> <Dd> k (\ displaystyle k \,) = a temperature - dependent constant </Dd> <P> The lowest velocities are near the base of the glacier and along valley sides where friction acts against flow, causing the most deformation . Velocity increases inward toward the center line and upward, as the amount of deformation decreases . The highest flow velocities are found at the surface, representing the sum of the velocities of all the layers below . </P> <P> Glaciers may also move by basal sliding, where the base of the glacier is lubricated by meltwater, allowing the glacier to slide over the terrain on which it sits . Meltwater may be produced by pressure - induced melting, friction or geothermal heat . The more variable the amount of melting at surface of the glacier, the faster the ice will flow . </P>

In a cross-section of a glacier the greatest flow velocities (speeds) occur