Download Mass Movement lesson 4

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 movement
 The factors that affect mass movement
 How mass movement affects people
 The 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

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Material’s Weight

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
Resistance to Sliding
Trigger
Let’s not forget Water

Effects of water on mass
movement

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
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:
 Creeps
 Flows
 Slides,
 Falls
Slumps, Avalanches
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 waterlogged 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
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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.
