1. Water: Rain, rivers, and oceans are powerful forces that can wear away rock and soil. This is called hydraulic action, and it's the main way canyons are formed. Water can also carry sediment, which acts like sandpaper, wearing down surfaces. This is called abrasion.

2. Wind: Wind can pick up and carry sand and dust, which can then erode rock and soil. This is especially common in deserts and coastal areas. This is called wind erosion, and it's how sand dunes are formed.