There are two types of weathering, FREEZE THAW and ONION SKIN.
FREEZE THAW: When a rock has a crack in it water gets in the crack.The water freezes when it is cold the water expands and contracts, eventually the crack gets bigger and lets more water in after that water freezes, expands and contracts it will break the piece of rock off.
ONION SKIN: Onion skin weathering happens in hot places like the deserts. In the day when it is hot the outer layer particles of the rocks expand in the heat. In the night it gets freezeing cold and now the outer layers of the rock contract. Every day this happens and over millions of years the outer layer particles get so weak they just crack off.
