MASS WASTING

PHYSICAL GEOLOGY

1. Seminar presentation

2. Mass Wasting Presented by Kaijirsong Rongpi B.Sc 1 st Semester Roll No. 377 Department – Geology Arya V idyapeeth College Guwahati

3. Contents INTRODUCTION CONCEPT OF MASS WASTING CLASSIFICATION OF MASS WASTING CAUSES OF MASS WASTING TYPES OF MASS WASTING CONLCUSION REFERENCE

4. INTRODUCTION The study of Mass Movement of rock wastes involves the analysis of meaning and concept, classification, causes, and geomorphic process of mass movement and lastly, its types.

5. Concept of mass wasting The collective term for gravitational or downslope movements of weathered rock debris is known as Mass 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.

6. Classification of Mass Movement(WASTING) 1. Very rapid movement ( No water required ) i . Landslides – ( a) Slump (b) Debris slides (c) Debris fall (d) Rock Fall ( e) Rock Slides

7. 2. Slow Movement ( Flowage or slide) – Little water is required ( i ) Rock Creep (ii) Soil Creep (iii) Solifluction

8. 3. Rapid Movement ( Flowage or Slide) - Enough Water is required ( i ) Earthflow ( ii) Mudflow ( iii) Sheet wash

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

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

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

12. 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.

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

14. 6.Ice Wedging : It causes mass movement. during a 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.

15. Types of mass wasting 1. Falls a. Rocks Fall b. Rock Avalanche 2. Slides a. Rock Slides b. Slump 3. Flow a. Debris Flow b. Earthflow c. Slump

16. 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

17. 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 .

18. 2. slides 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.

19. 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 .

20. 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.flows

21. 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.

22. C . Creep : It is a slow downslope movement of particles that occur on every slope cover with loose weathered ,material. This is the slowest type of mass wasting, requiring years of gradual movement to have a pronounced effect on a slope.Slopes creep due to the expansion and contraction of surface sediment, and the pull of gravity.   

23. conclusion 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. 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, P age No.257) https://www.slideshare.net/masswasting . https://www.eartheclipse/geology/masswasting . https://www.google.com/masswasting . https://www.britanica.com/masswasting

25. THANK YOU