Unit - 3

1. Unit - 3 Chapter – 8 Mass Movements, Wind and Glaciers

2. 8 Mass Movements, Wind, and Glaciers Section 8.1: Mass Movements Section 8.2: Wind Section 8.3: Glaciers

3. Section 8.1 Objectives Mass Movements Analyze the relationship between gravity and mass movements. Identifyfactors that affect mass movements. Distinguish between types of mass movements. Relate how mass movements affect people.

4. Section 8.1 Mass movements alter Earth’s surface over time due to gravity moving sediments and rocks downslope. Review Vocabulary gravity: the force every object exerts on every other object due to their masses

5. New Vocabulary Mass movement Creep Mudflow Landslide Slump Avalanche

6. Section 8.1 Mass Movements The downslope movement of soil and weathered rock resulting from the force of gravity is called mass movement. Climate has a major effect on the weathering activities that occur in a particular area, climatic conditions determine the extent of mass movement.

7. Section 8.1 Factors that Influence Mass Movements Several factors influence the mass movements of Earth’s material: • Material weight • Resistance to sliding or flowing • Triggers that shake material loose • Water

8. Section 8.1 Types of Mass Movements Mass Movements Creep The slow, steady, downhill flow of loose, weathered Earth materials, especially soils, is called creep. The effects of creep are usually noticeable only over long periods of time.

9. Section 8.1 Types of Mass Movements Mass Movements Creep One way to way to findwhether creep has occurred is to observe the positions of structures and objects.

11. Section 8.1 Types of Mass Movements Flows Earth flows are moderately slow movements of soils, whereas mudflows are swiftly moving mixtures of mud and water.

12. Section 8.1 Types of Mass Movements Flows Mudflows can be triggered by earthquakes or similar vibrations and are common in volcanic regions where the heat from a volcano melts snow on nearby slopes that have fine sediment and little vegetation. Mudflows are also common in sloped, semi-arid regions that experience intense, short-lived rainstorms.

13. Section 8.1 Types of Mass Movements Mass Movements Slides A rapid, downslope movement of Earth materials that occurs when a relatively thin block of soil, rock, and debris separates from the underlying bedrock is called a landslide.

14. Section 8.1 Types of Mass Movements Mass Movements Slides When the mass of material in a landslide moves along a curved surface, a slump results. Material at the top of the slump moves downhill, and slightly inward, while the material at the bottom of the slump moves outward.

15. Section 8.1 Types of Mass Movements Mass Movements Rockfalls On high cliffs, rocks that are loosened by physical weathering processes or by plant growth can break up and fall directly downward. Rockfalls commonly occur at high elevations, in steep road cuts, and on rocky shorelines.

16. Section 8.1 Mass Movements Affect People Mass Movements Human activities such as construction of buildings, roads, and other structures can make slopes unstable, contributing to the factors that cause mass movements.

17. Section 8.1 Mass Movements Affect People Mass Movements Reducing the risks The best way to reduce the number of disasters related to mass movements is to educate people about the problems of building on steep slopes.

18. SUMMARY Mass movements are classified in part by how rapidly they occur. Factors involve in the mass movement of the Earth materials include the material’s weight, its resistance to sliding, the trigger, and the presence of water. Mass movements are natural process that can affect human life and activities. Human activities can increase the potential for the occurrence of mass movements.