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MASS MOVEMENT

MASS MOVEMENT. LET’S LOOK AT PAGE 32 OF NEW GEO . Mass movement. Mass movement is the movement of any loose weathered material down a slope under the influence of gravity. WHAT CAUSES MASS MOVEMENT. HUMAN TRIGGERS OVER GRAZING CATTLE DEFORESTATION ROAD BUILDING QUARRYING.

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MASS MOVEMENT

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  1. MASS MOVEMENT LET’S LOOK AT PAGE 32 OF NEW GEO 

  2. Mass movement • Mass movement is the movement of any loose weathered material down a slope under the influence of gravity

  3. WHAT CAUSES MASS MOVEMENT • HUMAN TRIGGERS • OVER GRAZING CATTLE • DEFORESTATION • ROAD BUILDING • QUARRYING • NATURAL TRIGGERS • HEAVY RAINFALL • SNOW • EARTHQUAKE OR VOLCANOES

  4. Factors affecting mass movement • How steep the slope is- • The amount of water present- • The presence of vegetation- roots of trees and plants bind the soil together and prevent movement • Human activity-

  5. MASS MOVEMENT CAN BE 1. FAST = LANDSLIDE/BOGBURST/MUDFLOW • OR • SLOW = SOIL CREEP

  6. SOIL CREEP Slow movement

  7. Soil creep • Soil creep is the downward movement of soil because of gravity • Soil creep is the slowest type of mass movement (1cm per year) • It may only be noticed when posts, fences or trees are tilted downhill

  8. Soil creep

  9. Regolith • Regolithis weathered rock material • It includes soil and scree

  10. LANDSLIDES FAST MOVEMENT

  11. Landslides • A landslide is a very rapid movement of earth and rock down a steep slope. • Landslides happen when the slope becomes unstable • Landslides are very fast

  12. Landslides occur because of • Deforestation- cutting down of trees on a steep slope • Road building • A sudden shocktothe ground – due to an earthquake or a volcanic eruption • Erosion • Diggers cutting under a steep bank or slope

  13. landslide

  14. MUDFLOWS Fast movement

  15. MUDFLOWS • Mudflows are an example of very rapid mass movement • They occur on both gentle and steep slopes • They occur after heavy rainfall, when the soil is saturated and turns into a river of mud • They can occur after a volcanic eruption

  16. mudflow

  17. BOGBURST Fast movement

  18. BOGBURSTS • Bog bursts are common in upland areas that have a thick covering of peat • Upland areas have large amounts of rainfall and the peat may become saturated with water • When this happens the peat moves down the slope very quickly

  19. bog burst

  20. HOMEWORK

  21. THANK YOU! and well done first years on reaching the end of first term in St Tiernan’s

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