Frost wedging is a physical weathering process that occurs in environments where temperatures fluctuate around freezing. The mechanism involves several steps that lead to the widening of cracks in rocks:
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Water Infiltration: Water can seep into existing cracks and crevices in rocks during periods of warmer temperatures.
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Freezing: When temperatures drop and the water within these cracks freezes, it expands. Water expands by about 9% as it transitions from liquid to solid state.
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Pressure Increase: This expansion exerts significant pressure on the walls of the crack. The pressure can reach up to 2000 pounds per square inch or even more, depending on the conditions.
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Crack Widening: As the ice pushes against the rock, it forces the crack to widen. Over successive cycles of freezing and thawing (when the ice melts and the water can again infiltrate the cracks), the continuous expansion and contraction cause the cracks to become larger over time.
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Repetition of Cycle: Each cycle of freezing and thawing can further exploit the weaknesses in the rock, leading to a cumulative effect where the cracks become progressively larger with repeated frost wedging.
This repeated process can eventually lead to the fragmentation of the rock, breaking it into smaller pieces. Frost wedging is particularly effective in environments that experience frequent freeze-thaw cycles, which enhances the overall weathering of rocks in those areas.
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