Final answer:
Freeze thaw erosion is the process where water that seeps into rock cracks freezes and expands, causing the rock to break apart. This is a type of physical weathering common in climates with fluctuating temperatures around the freezing point.
Step-by-step explanation:
What occurs when water seeps into cracks in rocks, freezes, and expands is known as freeze thaw erosion. This process is a form of physical weathering that takes place when water infiltrates cracks and joints in rock. When temperatures drop, the water freezes and expands, which exerts pressure on the rock, causing it to crack and break apart over time.
This weathering process is particularly common in areas with a climate that allows for repeated cycles of freezing and thawing. It's also a significant contributing factor in shaping landscapes in temperate and polar regions. As water expands by around 9% when it freezes, it can exert considerable force, which is strong enough to fracture and disintegrate rock.