Ice wedging is when ice causes rocks to crack by expanding in openings, and ice wedging is the most important form of mechanical weathering. Given these facts, what is a form of mechanical weathering among the following options:
- microbes breaking down rock
 - By coral exoskeletons
 - wind and erosion
 - oxygen breaking down rock
 - ice expanding in rock openings
 - removal of rock by acid rain
 - remains of prehistoric life
 - fissures of hot, acidic water


 

     ice expanding in rock openings    