The five agents of erosion are wind, water, ice, waves and gravity. Erosion is the process in which particles of the earth are moved by naturally occurring external forces.
As the wind picks up particles, they brush across rocks or compacted earth, causing more particles to break away. Water erosion takes place when the water in a stream carries pieces of the shore with the current. When an ice glacier moves down its bed, bit of the earth become embedded in it and are carried along. Waves crashing along the shore pound and grind rock and dirt into tiny particles that are moved as the waves recede. Gravity pulls any loose bits down the side of a hill or mountain.