Weathering and erosion

In short: Weathering breaks down and decomposes rock where it lies, while erosion removes the loosened material and carries it away. Together, over long periods, they shape valleys, coasts and mountains.

In more detail: The main drivers are water, ice, wind, changes in temperature and living things. The removed material is deposited again elsewhere, for example as sand, gravel or mud.

In detail

• Physical weathering: Freezing water expands in cracks and splits rock apart, and strong temperature changes and salt crystals loosen it further.
• Chemical weathering: Water and the substances dissolved in it dissolve or alter minerals, for instance when limestone dissolves or iron-bearing rocks rust.
• Biological weathering: Plant roots push into cracks, and lichens and microorganisms attack the rock surface.
• Erosion by water: Rivers cut down into the ground; a famous example is the Grand Canyon, shaped by the Colorado River over a very long time.
• Erosion by ice: Glaciers grind valleys into broad U-shaped valleys and push debris together into moraines.
• Erosion by wind: In dry areas wind blows fine material away and abrades rocks; elsewhere it piles up dunes.
• Coastal erosion: Waves and storm surges wear away at cliffs and can cause them to collapse.
• Soil erosion: Where plant cover is missing, rain and wind wash or blow fertile soil away; hedges, terraces and vegetation protect against this.
• Deposition: The transported material builds new landscapes elsewhere, for example river deltas, beaches or floodplains (gletscher-und-eiszeiten, flussdeltas-und-ihre-entstehung, wuesten-und-wuestenbildung).