Water expands when it freezes. In winter, water gets into minute cracks in the rocks and then as it freezes it expands and makes the cracks bigger. So more water gets in then freezes so the cracks...
Water can chemically weather rocks by dissolving minerals, water can also physically weather rocks by fracturing them by hydraulic pressure or frost wedging.
Plant root growth penetrates small cracks and crevices in rock and spreads them further apart with hydraulic action. Root growth can also lift rock, causing fracture to occur. Other plants can attack...