Ice thaws and water flows away. Then more water can seep in and freeze, forming bigger cracks. Eventually, angular fragments break off from the rock. Brittle rocks crack. Igneous rock slabs break loose to form layers in a process called sheeting .
Rocks expand when heated and contract when cooled.
Repeated cycle stresses rock and causes fracturing. Not a major mechanism. Experimental evidence suggests that this mechanism works in concert with other weathering activities. Burrowing animals mix up rock material, further exposing it to weathering. Climatic Factors Warm temperatures and abundant moisture optimize the rate of weathering.