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Freeze-thaw
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Freeze-thaw

Blockfield resulting from freeze-thaw activity Blockfield resulting from freeze-thaw activityZoomFreeze-thaw weathering generally occurs within mountainous regions when rainwater collects in small cracks within rocks. As the temperature drops at night the water freezes and expands, pushing the cracks a little wider. During the day the ice melts, but more water can collect within the now expanded cracks. At night the water freezes again and this cycle repeats itself until eventually the rock splits apart completely.

Freeze-thaw action also sorts out the stones in the soil.  Water in the soil freezes and pushes the stones and smaller grains upwards.  When it thaws the smaller grains drop underneath the stones, preventing them from falling back. Over time the stones are pushed to the surface and sorted into rows of different sizes.