1. Mass Movement UNIT 5 STANDARDS: STATE OBJECTIVES: NCES 2.1.1, 2.1.3, 2.1.4 LESSON 4

2. Lesson Objectives  In this lesson, you will learn about:  What is mass movement  The factors that affect mass movement  How mass movement affects people  The relationship between gravity and mass movement

3. What is Mass Movement  Definition  Video (4:44 min) Video  The down slope movement of loose sediments & weathered rock as a result of gravity.  As weathering breaks down the rocks into smaller pieces, gravity will cause the broken pieces to move down hill.  All mass movements occur on a slope.

4. Variables to Mass Movement  Material’s Weight  Resistance to Sliding  Trigger  Mass of the material and the force pulling on it by gravity  The surface texture is responsible for resistance to sliding  What triggers the initial movement of the material

5. Let’s not forget Water  Effects of water on mass movement  Video (2:28 min) Video  Too little water prevents sediment holding together  Too much causes particles to slip  Saturation is too much water  Acts as a lubricant  Can also cause streams or flows of water thus moving the material

6. Types of Mass Movement  Mass movements are classified as:  Creeps  Flows  Slides, Slumps, Avalanches  Falls

7. Creep  Definition  The steady downhill flow of loose materials  Flow is a few centimeters per year (inch/yr)  Only noticeable over years  Can cause tilting of utility poles, fences, damage to walls

8. Solifluction  Definition  The slow downhill movement of loose water- logged materials that occurs in regions of permafrost.  The material is mudlike  Melted iced on top cannot drain because of the frozen permafrost below

9. Flows  Definition  Video 1 Video 1  Video 2 Video 2  When earth materials flow as if they are a liquid  Mudflows are swift moving mixtures of mud and water Mudflows  Mudflows common in volcanic regions  Mudflows may result in times of severe rain and flooding

10. Slides: Get out of the Way  Landslide Landslide  Slump Slump  Avalanche Avalanche  When a section of earth breaks free of the bedrock and moves rapidly downhill  When sections of the soil become supersaturated and flows down behind the advancing flow of material  Generally in mountainous regions. When ice forms over snow and then breaks free causing a downhill movement of snow and ice

11. Falls…Help I’ve fallen and…  What classifies as a fall  Rock falls commonly occur in high elevations  Rocks are loosened by weathering, freezing, and thawing, as well as plant growth  The rock breaks off and falls…down

12. Human Impact of Mass Movement  People living in areas of potential landslides or avalanches are at the greatest risk  Precautions can be taken using early warning systems  People should be aware of their surroundings and the amount of rainfall in these areas  People living in the valleys or downhill of these areas are the the greatest risk

13. Lesson Review  Identify and describe one type of rapid mass movement and one type of slow mass movement  Describe the underlying force behind all mass movements  How does water affect the process of mass movement  Explain how one type of human activity can increase the risk of mass movement  Suggest a solution to the problem you just explained.