Freeze thaw weathering is when water comes in a hole. Then freezes overnight and slowly will break up. This most common in places like mountains where the day the snow melts and then overnight the water expands by 10 percent. Overtime this will break up the rock. Mechanical weathering, also called physical weathering, causes rocks to crumble. Water seeps into cracks and crevices in rock. If the temperature drops low enough, the water will freeze. When water freezes, it expands. The ice then works as a wedge. It slowly widens the cracks and splits the rock. When ice melts, the water carry the tiny rocks away and the process is repeated.