The highest zone of the Inland Ice is dry, and snow accumulates without any melting. At a lower level there is a zone with some melting and percolation of melt water. In the next zone, the snow can become waterlogged in the course of the summer, but the percolating water re-freezes in the deeper-lying snow layers. Closer to the ice margin the refrozen snow creates a new zone at the snow line, which in the Ilulissat area is 1300 metres above sea level; here, the refrozen melt water is added to the glacier ice. This zone ends 1200 metres above sea level at the equilibrium line, where the addition of snow and frozen melt water equals the net loss through melting. The lowest level, extending out to the boundary with the land, is the ablation zone, where melting exceeds the net gain.
At the summit of the Inland Ice the movement of the ice is slow and is mainly downwards. The degree of sideways movement increases the further one moves towards the ice margin. Outside the limits of the ice streams, the average horizontal flow of the ice reaches velocities of 50-200 metres per year near the equilibrium line, after which the movement falls to near zero at the ice margin.