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River processes
weathering and mass movement terms
| Term | Definition |
|---|---|
| Weathering | the decomposition of the Earth's rocks, soils and minerals through direct contact with the planet's atmosphere or plants and animals. |
| Chemical weathering | rainwater contains weak acids that can react with certain rock types. the carbonates in limestone are dissolved by these acids and this causes the rock to break up or disintegrate. |
| Biological weathering | seeds get dropped in cracks by animals e.g. rabbits. The seeds grow and the crack expands. The animals may then dig or burrow in the hole. |
| Physical weathering | Rainwater freezes in the cracks and the ice expands. The expansion causes bits of rock to break off. |
| Soil creep | The slow downhill movement of soil. Water is pulled by gravity, and takes the soil with it. It is not possible to see this happening. Heavy rainfall quickens this process. The slope left may appear rippled. |
| Slumping | Common on river banks, like clay banks. It is where a large area of land moves down a slope, and it leaves behind a curved surface. During dry weather, the clay contracts and cracks. When it rains, the water runs into the crack and is absorbed. |
| Mass movement | The downward slope movement of earth caused by gravity. |
| lag time | The time between rain falling and reaching the river. |
| Thalweg | The fastest velocity in a meander. |
Created by:
Maddie16
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