Key learning points

1. Weathering is the slow breakdown of rocks on Earth's surface. It happens while the rocks are ‘in place’.
2. Erosion is the process that removes material from where bedrock has been broken down or weathered.
3. Rock can be weathered biologically, chemically or physically.
4. Rock can be eroded by the wind, rain, or by flowing streams and rivers, oceans, ice flows or gravity.
5. Small changes caused by weathering and erosion can have large impacts over time.

Keywords

• Weathering - The wearing down or breaking of rocks while they are in place. Weathering can be biological, chemical or physical.

• Expansion - An increase in volume which happens when most solids get hotter, but also when water freezes to form ice.

• Freeze-thaw - A physical weathering process whereby water seeps into cracks, freezes and expands. This gradually wedges open cracks until the rock breaks.

• Erosion - The breakdown and removal of rock material by flowing water, wind, or moving ice.

Common misconception