Transcript Mass Movements, Wind, and Glaciers

Mass Movements,
Wind, and Glaciers
Chapter 8
Mass Movements,
Wind, and Glaciers
• Section 8.1: Mass Movements
• Section 8.2: Wind
• Section 8.3: Glaciers
Section 8.1:Mass Movements
•
Objectives
1) Analyze the relationship between gravity
and mass movements.
2) Identify factors that affect mass movements.
3) Distinguish between types of mass
movements
4) Relate how mass movements affect people.
Over Riding Concept
• Mass movements
alter Earth’s surface
over time due to
gravity moving
sediment and rock
down slope.
Mass Movements
• The down slope
movement of soil and
weathered rock resulting
from the force of gravity
is called mass
movement.
• Because climate has a
major effect on the
weathering activities that
occur in a particular area,
climatic conditions
determine the extent of
mass movement.
Factors that Influence Mass
Movements
•
Several factors influence the mass
movements of Earth’s Materials:
1.
2.
3.
4.
Material Weight
Resistance to sliding or flowing
Triggers that shake material lose
Water
Types of 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.
Types of Mass Movements
Creep
One way to tell
whether creep has
occurred is to
observe the
positions of
structures and
objects.
Types of Mass Movements
Flows
Earth flows are
moderately slow
movements of soils,
whereas mudflows
are swiftly moving
mixtures of mud and
water.
Types of Mass Movements
• 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, semiarid regions that
experience intense,
short-lived rainstorms.
Types of Mass Movements
Slides
A rapid, down slope
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.
Types of Mass Movements
Slides
Landslides are common
on steep slopes,
especially when soils
and weathered bedrock
are fully saturated by
water.
A rock slide is a type of
landslide that occurs
when a sheet of rock
moves downhill on a
sliding surface.
Rockslides are often
triggered by
earthquakes.
Types of Mass Movements
When the mass of material in a landslide moves
along a curved surface, a slump results.
The material at the top moves slightly inward,
while the material at the bottom moves outward.
Types of Mass Movements
Rock falls
On high cliffs, rocks that
are loosened by physical
weathering processes or
by plant growth can break
up and fall directly
downward.
Rock falls commonly
occur at high elevations,
in steep road cuts, and on
rocky shorelines.
Mass Movements Affect People
• Human activities such
as construction of
buildings, roads, and
other structures can
make slopes
unstable, contributing
to the factors that
cause mass
movements.
Mass Movements Affect People
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 or near steep slopes.