Exogenic Processes Mass Wasting Powerpoint.pptx

Mass wasting, or mass movement, is the downslope movement of rock, soil, and debris under the sole force of gravity, without the aid of a moving medium like water or wind. Common types of mass wasting include rock falls, slides, flows (like earthflows and mudflows), and creeps.

1. Mass Wasting Presented by Ms.Mariann Joy S. Tanilon

2. M ass W asting The collective term for gravitational or downslope movements of weathered rock debris is known as m ass wasting . The downslope material transfers through the direct action of gravity, component of erosion and transport of sediment follows weathering which weakens and breaks the rock.

3. M ass W asting Gravity is the main force behind mass wasting, but water often plays a role in several ways. Water is involved in many weathering processes that break and weaken rocks, making them more vulnerable to mass movement. Unconsolidated soil and regolith have pore spaces between particles that can fill with water from storms, wet seasons, or human activities.

4. Material and Motion Physical geographers classify mass wasting events based on the type of Earth materials involved and how they move . Almost any surface material on an unstable or potentially unstable slope is susceptible to mass wasting. Common materials include rock, snow, ice, soil, earth, debris, and mud.

5. Material S oil is a thin, fine-grained, unconsolidated surface layer. Earth refers to a thicker unit of fine-grained, unconsolidated material, often tens of meters thick. Debris is a mix of sediment with a wide range of grain sizes, with at least 20% being gravel-sized. Mud is saturated sediment made mostly of clay and silt.

6. Movement Slow Mass Movement Fast Mass Movement

7. Slow Movement Creep is a slow, downward mass movement of soil or rock on a slope, driven by gravity and often facilitated by freeze-thaw cycles, wetting and drying, or other factors

8. Slow Movement Solifluction , which means "soil flow," is the slow downslope movement of water-saturated soil or regolith. Occurs mostly in cold areas.

9. Fast Mass Movement There are three main types of fast mass wasting that occur quickly enough—from seconds to days—to be observed directly.

10. Types of Fast M ass W asting 1 . Falls a. Rocks Fall b. Rock Avalanche 2. Slides a. Rock Slides b. Slump 3. Flow a. Debris Flow b. Earthflow

11. A. Rock Fall : A rock fall consists of one or maybe a few rocks that detach from the high part of a steep slope, dropping and perhaps bouncing a few times as they move very rapidly down slope. Rock falls are very dangerous because they can occur without warning, and because the rocks are traveling at high velocity.You can usually tell where rock falls are common by identifying talus at the base of steep slopes.     1. Falls

12. B . Rock Avalanche : This type of fall usually forms when a massive rock fall explodes apart on contact with a slope.   As this occurs, thousands of rocks continue their flying trajectories down slope, colliding with each other and the slope itself, overwhelming anything in their paths.   A rock avalanche is a transitional sort of mass wasting event, changing from a pure rock fall to something more like a rapid flow of material as the material moves further from the base of a slope.

13. 2. S lides A. Rock Slides : It can be defined as a descending rock mass remaining more or less solid and moving along a definite surface. This type of slide occurs where there is a tilted,  pre-existing  plane of weakness within a slope which serves as a slide surface for overlying sediment/rock to move downward.

14. B. Slump : Slump is defined as the sliding of rock fragments ,rock fragments, rock blocks or soils downslope along a curved plane caused by rotational movement .

15. A. Debris Flow : These are defined as mass wasting events in which turbulence occurs throughout the mass. Mainly small to large rock fragments but also trees, animal carcasses, cars and buildings. Debris flows usually contain a high-water content which enables them to travel at fairly high velocity for some distance from where they originated . 3. F lows

16. B. Earthflow :   Earth flows typically develop at the low end of a large slump, where the slump block breaks apart and material continues moving down slope. This down-slope movement can be rapid and short-lived, as a debris flow.

17. CAUSES OF MASS WASTING 1.Volcano Eruptions : Its causes huge mudflows.its invloves of gaes , vapour,carbon dioxide,sulphur dioxide.

18. 2.Earthquakes Shocks : It results in portions of mountain and hills to break loose and slide wards.

19. 3.Landslides : When masses of rocks, earth or debris move down a slope there is landslide

20. 4.Mudslide : Also known as debris flows, mudslides especially after torrential rain or cloud burst are moving body of rock earth and other debris saturated with water causing mass movement.

21. 5.Weathering and Erosion : It helps in loosening large chunks of earth and start them sliding downhill.

22. 6.Ice Wedging : It causes mass movement. during an earthquake. An  ice wedge  is a crack in the ground formed by a narrow or thin piece of  ice  that measures up to 3–4 meters in length at ground level and extends downwards into the ground up to several meters. During the winter months, the water in the ground freezes and expands.

23. C onclusion Different types of mass wasting creates distinctive morphological features on hillslope and river valleys sides and coastal lands. Mass wasting is the movement of earth material under the influence of gravity and water. It is responsible for shaping the earth and forming different landforms. It causes destruction to human beings, if it occurs in living areas.

24. reference Geomorphology by Dr.Savindra Singh (Chapter 14, Page No.257) https://www.slideshare.net/masswasting . https://www.eartheclipse/geology/masswasting . https://www.google.com/masswasting . https://www.britanica.com/masswasting

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