Transcript What effect do destructive waves have on the coastline?

What effect do destructive
waves have on the coastline?
Friday, 17 July 2015
Homework: due next lesson.
Using examples explain how waves can
shape the coastline (4)
Gigantic visual
Last lesson we studied the different types of
waves that land on our coast.
This lesson we will examine how the
destructive waves can shape our coastline.
You will continue to prepare for the
Swanage field visit.
By the end of the lesson:
• All pupils can explain what erosion is and
the four types of erosion
• All pupils understand how geology effects
the rate of erosion
• All pupils will work in groups and produce
a presentation
• All pupils will be able to explain how
destructive waves erode cliffs
Thinking back.
What is a destructive wave?
When are destructive waves most likely to
occur?
Which picture is the destructive wave? Why?
What impact have destructive
waves had on these two
landscapes?
Both are being shaped by erosion.
Erosion. What do you want to
know?
• What is erosion?
• How does erosion happen?
• Why do different rocks erode at different
rates?
Task
•In groups of 3 to 4 you are going to perform
a 2-3 minute presentation on the 4 main
types of erosion.
•Your audience is going to be year 9 pupils
who are considering doing geography next
year.
•You will be marked on group work,
creativity (the use of resources and ideas)
and vocabulary.
What is erosion?
Use the animation to help you identify the
following:
• The different kinds or erosion
• How each type of erosion works.
Processes of erosion
Processes of erosion
Attrition
Materials carried by the waves bump into each other and so are
smoothed and broken down into smaller particles.
Hydraulic action
This process involves the force of water against the coast. The waves
enter cracks (faults) in the coastline and compress the air within the
crack. When the wave retreats, the air in the crack expands quickly,
causing a minor explosion. This process is repeated continuously.
Corrosion
This is the chemical action of sea water. The acids in the salt water
slowly dissolve rocks on the coast. Limestone and chalk are particularly
prone to this process.
Abrasion/Corrasion
This is the process by which the coast is worn down by material carried
by the waves. Waves throw these particles against the rock, sometimes
at high velocity.
Task
•In groups of 3 to 4 you are going to perform
a 2-3 minute presentation on one of the
four main types of erosion.
•Your target audience are year 8 pupils who
are considering doing geography next year.
•You will be marked on group work,
creativity (the use of resources and ideas)
and vocabulary.
Task
In your exercise book describe and explain
how each type of erosion occurs.
A good description will be sequenced.
Why do different rocks erode at
different speeds?
It’s all to do with the geology of the area.
What is the difference between chalk and
clay?
Why do different rocks erode at
different speeds?
Rocks such as chalk and limestone are
stronger, more resistant materials which
will erode at a …………., whereas material
like sand and clay ……………………….
Task
Draw a series of diagrams to show how
cliff erode.
How do these types of erosion attack cliffs?
How are cliffs and wave-cut platforms formed?
Before you watch the animation can you predict what will happen?
Wave-cut platform
The waves attack the base of the cliff through the processes of
abrasion, corrosion, hydraulic action and attrition.
Over time the cliff will be undercut and a wave-cut notch is
formed.
Eventually the cliff becomes unstable and collapses. Further
cliff retreat will form a wave-cut platform.
Task
Draw a series of annotated diagrams to show how cliff erosion
happens.
You should include the following words in your annotations:
•
•
•
•
•
•
•
•
•
•
Abrasion
Attrition
Solution
Hydraulic action
Collapse
Shatters
Overhang
Collapse
Platform
Notch
Task
Draw a series of diagrams to show cliff foot erosion.
Use the statements to help you label the diagrams
cliff collapses
hydraulic action
wave retreats
air is trapped inside
cracks
cliff is undercut
rocks thrown with
waves against base
of cliff
rock shatters
wave reaches base of
cliff
explosion of air
an overhang
develops
wave advances
Corrasion (also
known as abrasion)
Homework: due next lesson.
Using examples explain how waves can
shape the coastline (4)
Before you leave
Which type of erosion does each image represent?