During glaciation large amounts of ice put tremendous pressure on to the land below it. Not only did this erode the land underneath the ice it also weighed down the land, squashing it further below sea level. When the ice started to melt the pressure was released and the land started to bounce back-the land lifted again. This is isostatic uplift.
Eustatic Change The slow rise of the land after an Ice Age (isostatic uplift) created changes levels. This change is called eustatic change.