This process of Frost action happens in regions where the temperature drops below the freezing point of water. The water that is accumulated between the cracks gets frozen. Frozen water expands, and exerts pressure on the walls of the rock, thus breaking down the rock. Freeze-thaw weathering is a process of erosion that happens in cold areas where ice forms. A crack in a rock can fill with water which then freezes as the temperature drops. As the ice expands, it pushes the crack apart, making it larger.