Final answer:
Frost wedging is best described as mechanical weathering due to the freezing and thawing of water within rock cracks, leading to the rock breaking apart. It's particularly effective in climates with regular temperature swings around the freezing point and contributes significantly to shaping landscapes.
Step-by-step explanation:
The phrase that best describes frost wedging is a. Mechanical weathering due to freezing and thawing. This process involves water seeping into cracks in rocks, freezing when temperatures drop, and then expanding. This expansion exerts significant force on the surrounding rock, eventually causing it to break apart. This is a form of mechanical weathering, as it does not involve any chemical changes to the rock material itself. Frost wedging is a particularly common and effective form of weathering in environments where the temperature fluctuates above and below the freezing point regularly, contributing to the breaking down of rocks into smaller particles which can be transported by erosion.
Frost wedging is largely responsible for shaping landscapes in colder climates, and one example of this is Bryce Canyon in Utah. Here, the freeze-thaw cycle occurs for about 200 days a year, with water expanding by 9% when it turns to ice, causing immense pressure that eventually shatters and pries the rock apart.