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WEATHERING, MASS MOVEMENT AND EROSION

WEATHERING, MASS MOVEMENT AND EROSION. There are 3 main types of weathering:. Physical Chemical Biological. Physical (Freeze-Thaw) Weathering. Water runs into a crack in the rock. The water freezes and expands causing cracks in the rocks.

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WEATHERING, MASS MOVEMENT AND EROSION

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  1. WEATHERING,MASS MOVEMENT AND EROSION

  2. There are 3 main types of weathering: • Physical • Chemical • Biological

  3. Physical (Freeze-Thaw) Weathering Water runs into a crack in the rock. The water freezes and expands causing cracks in the rocks. Over time, the rocks expand further and break up.

  4. BiologicalWeathering • Seeds that fall into cracks in rock start to grow when moisture is present. • The roots of the young plants force the cracks to become wider. • Over time the rock breaks up into small pieces. • Burrowing animals, such as rabbits, can also be responsible for the further break-up of rocks.

  5. Chemical Weathering • Rainwater contains small amounts of weak acid. • The acid can react with certain rock types e.g. limestone. • Over time the rock is dissolved by the acid. This causes the rock to break up or disintegrate.

  6. Mass Movement Mass movement is when material moves down a slope due to the pull of gravity. SLUMPING SOIL CREEP

  7. Soil Creep This is the slow downhill movement of soil. Gravity pulls the water that is contained in the soil down the slope. The soil moves downhill with the water. The slope may appear rippled. These ripples are known as terracettes.

  8. Slumping (or rotational slipping) Slumping is very common on clay river banks. During dry weather the clay contracts and cracks. When it rains the water runs into the cracks and is absorbed until the rock becomes saturated. This weakens the rock and, due to the pull of gravity, it slips down the slope on its slip plane. Slip Plane

  9. Processes Operating on Valley Sides

  10. WEATHERING & MASS MOVEMENT Burrowing animals and plant roots can be responsible for the break up of rocks. The weak acids in rainwater react with certain rock types, such as limestone. Gravity pulls down water that is contained within the soil down a slope. When water enters cracks in a rock it freezes and expands when temperatures fall below freezing causing the rock to weaken. Large areas of land move down a slope leaving behind a curved surface. SOIL CREEP CHEMICAL WEATHERING SLUMPING PHYSICAL WEATHERING BIOLOGICAL WEATHERING

  11. Erosion • Erosion is the wearing away of the land. • There are four main processes by which a river can cause erosion: attrition, corrasion, corrosion and hydraulic action. • Rivers may erode horizontally (sideways) and vertically (downwards).

  12. The processes of river erosion... Hydraulic action - The force of the water hits the riverbed and banks wearing them away. Corrasion-The river picks up material and rubs it against the riverbed and banks of the channel during flow. Corrosion- The dissolving of rocks and minerals by the slightly acidic river water. Attrition- Any material carried in the river will become rounder and smaller over time as they collide with other particles.

  13. Which show weathering, which show erosion? 1 5 2 3 4

  14. Which show weathering, which show erosion? 1 Erosion 5 Erosion 2 Biological weathering 3 Chemical weathering 4 Erosion

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