Wind, water, ice and waves carry off soil particles and cause soil erosion. Although this is a natural process, human activities that disturb the surface of the earth increase the rate of soil erosion. Activities such as mining, construction, deforestation and intensive agriculture leave the topsoil exposed and vulnerable to the agents of erosion.
When wind, water, ice and waves encounter bare topsoil, soil erosion occurs. Rainfall and rainfall runoff cause splash, sheet, rill and gully erosion. Streams and rivers cause valley or stream erosion and bank erosion. The action of waves and currents causes shoreline erosion along sheltered and exposed coasts.
Glaciers freeze to their beds and move frozen sediment with them as they surge forward in a process called ice thrusting. When water freezes in rock cracks in cold weather, the cracks freeze and expand, shattering the rock. On steep slopes, this leads to gravity erosion.
When wind collects soil particles and carries them away, one of three types of deflation occurs. Surface creep refers to large particles rolling along the surface, saltation refers to particles lifting into the air, and bouncing and suspension refer to the wind lifting small particles into the air and transporting them over long distances.