Landscapes are not permanent. Erosion is the removal and transport of rock and soil by natural agents—water, wind, ice, and gravity. It lowers elevated areas and supplies the sediment that builds new landforms elsewhere.

Running water is the most effective erosional agent on most of Earth’s surface, cutting valleys and carrying material to the sea. Glaciers scour bedrock and transport huge loads of debris. Wind abrades and deflates in arid regions. Mass wasting moves material downslope under gravity.

Human activities such as deforestation and intensive agriculture often accelerate erosion far beyond natural rates, degrading soils and clogging waterways with sediment. Geologists study erosional landforms to reconstruct past climates and tectonic uplift. The balance between erosion and uplift determines how long mountain ranges persist.

• Removal and transport of surface material
• Driven by water, wind, ice, and gravity
• Shapes valleys, coasts, and deserts
• Can be greatly increased by human land use