Transcript Rapid Mass Movement

10.4
Erosion and Deposition by
Mass Movement
Describe places where the warning sign
“Watch for falling rocks!”
would be necessary or useful.
Rapid Mass Movement

Landslide – the sudden
rapid movement of a large
amount of material
downslope.
 Slump
 Most common
landslide
 Occur when a block
of material moves
downslope over a
curved surface.
Mass Movement

The movement of any
material, such as rock,
soil, or snow,
downslope.
Angle of Repose

The steepest angle,
or slope, at which
loose material no
longer moves
downslope.
Rapid Mass Movement

Rock fall – loose
rocks fall down a
steep slope.
Landslides
..\..\video clips\10.4 mass
movement\Landslides__Products_of_Opposing_Forces__Heat_vs__Gravity.asf
How can a landslide affect wildlife habitats?
A landslide can change a human or wildlife
habitat by carrying away plants and animals
or by burying a habitat.
Rapid Mass Movement

Mudflow –
 mass movement of
a large mass of
mud.
 Happens when a
large amount of
water mixes with
soil and rock.
Rapid Mass Movement


Creep –
Extremely slow
movement of material
downslope.

Water loosens soil, plant
roots act as wedges that
force rocks and soil
apart, burrowing animals
loosen rock and soil
particles.
Why must city planners determine the risk of
mass movement when deciding how to use
land?
It is not advisable to build near a known hazard.
The frequency and severity of mass movement
would need to be considered when making this
decision.
Review Questions
1.
What is mass movement?
Mass movement is the movement of any material
downslope.
2. How do mass movements affect humans?
Mass movements affect humans by affecting the
habitats in which humans live. Mass movements
can destroy houses and roads.
3. Which types of mass movement are most dangerous to
humans?
Rapid mass movements, such as rock falls, landslides,
and mudflows are the most dangerous types of mass
movements for humans because large amounts of
material move rapidly downslope without warning.
4. Creep is a type of mass movement that occurs slowly.
Describe the kinds of effects that you think creep has on
trees, buildings, and roads.
Creep slowly changes trees, buildings, and roads. The
trunks of trees may appear ot bend as they grow.
Buildings may become unstable or their foundations
may crack. Roads may crack as a result of creep.