Freeze thaw weathering occurs when water seeps into cracks in rocks or the pores between soil particles and freezes. The expansion of the water creates high pressures, which can widen the cracks or force apart the soil particles. Frost wedging is the process by which water seeps into cracks in a rock, expands on freezing, and thus enlarges the cracks. The effectiveness of frost wedging is related to the frequency of freezing and thawing. Frost wedging is most effective in a climate. A glacier is a huge mass of ice that moves slowly over land.