Mass Movement UNIT 5 STANDARDS: STATE OBJECTIVES: NCES 2.1.1, 2.1.3, 2.1.4 LESSON 4
Jan 04, 2016
Mass Movement
UNIT 5
STANDARDS:
STATE OBJECTIVES: NCES 2.1.1, 2.1.3, 2.1.4
LESSON 4
Lesson Objectives
In this lesson, you will learn about:What is mass movementThe factors that affect mass movementHow mass movement affects peopleThe relationship between gravity and mass movement
What is Mass Movement Definition
Video (4:44 min)
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.
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
Let’s not forget Water Effects of water on mass
movement
Video (2:28 min)
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
Types of Mass Movement
Mass movements are classified as:
CreepsFlowsSlides, Slumps, AvalanchesFalls
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
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
Flows Definition
Video 1 Video 2
When earth materials flow as if they are a liquid
Mudflows are swift moving mixtures of mud and water
Mudflows common in volcanic regions
Mudflows may result in times of severe rain and flooding
Slides: Get out of the Way Landslide
Slump
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
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
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
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.