* Physical weathering: This breaks down rocks into smaller pieces without changing their chemical composition. Examples include:
* Frost wedging: Water seeps into cracks in rocks, freezes, expands, and wedges the rock apart.
* Thermal expansion and contraction: Rocks expand when heated and contract when cooled. This repeated expansion and contraction can cause cracks to form and widen.
* Abrasion: Rocks are worn down by friction, like when they are carried by wind, water, or ice.
* Chemical weathering: This breaks down rocks by changing their chemical composition. Examples include:
* Oxidation: Iron in rocks reacts with oxygen, forming rust and weakening the rock.
* Carbonation: Carbon dioxide in the air dissolves in rainwater, making it slightly acidic. This acid can dissolve some types of rocks, like limestone.
* Hydrolysis: Water reacts with minerals in rocks, breaking them down.
Both physical and chemical weathering can work together to change the size and shape of rocks over time.
