Download Geography Revision - Geography at InterHigh

Geography Revision
Do we
have
to?
1
The things to do
Three topics only
Changing Earth ( Earthquakes + oceans)
Working world (economic activity +
tourism)
Fragile environments (Climate change,
acid rain, energy sources, rubbish)
PLUS
Map question
Keyword section
2
Any question I ask will
have the answers in the
‘notes’ section under the
slide if you open to see
Changing earth
The structure of the earth and
earthquakes
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A thin crust - 10100km thick and
not very dense
The Structure of
the Earth
A mantle – extends
almost halfway to the
centre, hot and dense
A core – made of molten
nickel and iron. Outer
part is liquid and inner
part is solid. Gets hot
due to radioactive decay.
The crust is made up of pieces – what are they called?
4
The convection currents in the
mantle force the plates to move
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Now this is a strange looking map
What is happening and what is the name
of the theory?
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Plate Margins
For each one, explain
what is happening, and
why it has its name.
The 4 examples we
talked about were the
Mid-Atlantic ridge, the
Himalayas, the San
Andreas Fault and the
Andes.
Which of these places
go with each types of
plate margins?
What can happen along any of these faults? (not pleasant!)
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So what happens when there is an
earthquake?
Most earthquakes happen near the boundaries
of tectonic plates, both where the plates
spread apart and where they crunch or grind
together
But large temblors also strike from time to
time in the normally stable interior of
continents.
Movement of body waves away
from the focus of the
earthquake. The epicentre is
the location on the surface
directly above the earthquake's
focus.
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How big it is, can be measured …
.. using a seismograph.
The amount it shakes is
measured on the
Richter scale
1 – 3.5: you would no be able
to feel, even it was quite
close by – but it would show
up on a seismograph
3.6 – 6: you would feel it,
but it is unlikely to do much
damage
6.0 – 6.9: can be fairly
destructive up to 100km
7 -7.9: Major earthquake can be very damaging – e.g.
Haiti and New Zealand
8 +:Great earthquake.
Causes serious damage of
100s of km. Japan 8.9
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There are 2 types of waves in an
earthquake
Body waves and surface waves.
Body waves travel outward in all directions, including
downward, from the quake's focus -- that is, the
particular spot where the fault first began to
rupture.
Surface waves, by contrast, are confined to the
upper few hundred miles of the
crust.
They travel parallel to the
surface, like ripples on the
surface of a pond. They are also
slower than body waves.
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This what it would be like …
..the body waves (P-wave) strike first and are the
fastest kind. People often report a sound like a train
just before they feel a quake, which is the P-wave
moving as an acoustic wave in the air.
Then the secondary, or S-waves, arrive. A person in a
building perceives the arrival of S-waves as a sudden
powerful jolt, as if a giant has pounded his fist down
on the roof.
Finally, the surface waves strike. In very strong
earthquakes, the up-and-down and back-and-forth
motions caused by surface waves can make the ground
appear to roll like the surface of the ocean, and can
literally topple buildings over.
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What kind of damage can be done?
Look what the surface waves and body waves did!
The whole earth moved 5
metres in 1906 in San
Francisco
Mudslides
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What is this a picture of from
Japan this year?
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So you are in an earthquake zone –
and you do not want to move away,
so what can you do to stay safe?
1. Make sure the building you are in are
well built, to withstand earthquakes as
well as possible
2. Have a personal plan
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Movement is earthquakes
is of 2 types, up-anddown and side-to-side.
Most reasonable strong
building can cope with
the first. It is the 2nd
that brings challenges!
The Buildings
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On a personal level
Don’t leave bookcase just standing against the wall –
screw them into it.
Make sure cupboards have safety catches on them –
even a small earthquake can make a big mess (or even a
dangerous one, in the case of bleach or weed killer) if
the bottles tumble out onto the floor and smash.
Identify safe places indoors and out – places where
glass will not fall on top of you for example – in
doorways, under heavy tables etc
Practice what do.
Have an emergency contact plan.
Have emergency supplies in a secure – if possible metal
– container – e.g passports, birth certificates, money,
batteries, torch etc
Do check out
http://www.fema.gov/plan/prevent/earthquake/prepar
edness_home.shtm#1
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What am I talking about?
Body waves
Collision plate
Conservative plate
Constructive plate
Continental drift
Convection current
Core
Crust
Destructive plate
Epicentre
Focus
Mantle
Plates
Richter scale
Seismograph
Surface waves
Tsunami
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The coast
The processes that change the
environment and what is
happening to the coasts
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There are 3 processes at work
I am using my
hammer to
wear away this
rock
Erosion
I am carrying
away the pieces
Transportation
I cannot carry them
any further so I
drop them
Deposition
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Erosion is carried out in a number of ways
Can you work out
what each word
means?
Attrition? Solution?
Hydraulic action?
Abrasion?
ACTION
CORROSION
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I know this is river transportation
– but the seas are the same
Here are the 4 ways in which the load – the
material the waves are moving from one place
to another – is transported.
Learn these words and meanings
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Deposition
A waves drop their load when the speed or volume of
the waves decrease.
The load, which it carries, is deposited.
The heavier material is deposited first and the finer
material carried further.
Deposition is likely to occur when:
– waves enter an area of shallow water
– waves enter a sheltered area
– there is little wind
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What features can erosion make?
How easily a coast is eroded depends on how hard the
rock is
Headlands and Bay!
All the varieties of erosion figure here.
Anyone want to have a go at explaining how one does it?
Notice the darker patch in the bay in the last picture –
what could that be?
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How cliffs are eroded
The tougher rocks of the
headlands are gradually
eroded away by all the
methods of erosion and
gradually a small ‘Wave-cut
notch’ is made by the waves
at high tide
As it gets bigger, the
overhanging rock will
eventually tumble into the
sea.
Over time the cliff retreats
leaving a wave-cut platform
just below the surface, that
shows only when the tide is
out
This is in Dorset near
Purbeck at Kimmeridge Bay.
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This is an arch in limestone – which was the main
way in which it was eroded?
1. A large
crack opened
up
3. The cave
gets bigger
2. The crack
grows into a cave
5. The arch is
eroded and
collapses
4. The cave breaks
through the head land
to make an arch
3. This is
eroded to
form a
stump
3. This leaves
a tall stack
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What happens next?
Once the rock has been eroded away from the cliff by
abrasion and corrosion and hydraulic action
The pieces will be further broken down by attrition,
becoming smoother and smaller over time
Some of it will be transported away and deposited
somewhere else
Broken rock ends up on beaches as sand or shingle
(round pebbles)
But beaches do not stay the same
Most of the waves break on the beaches at an angle.
Some of the waves are constructive, which means they
bring material from another place and leave it.
These waves are swash waves – quiet little waves that
drop anything they are carrying as they break
These make beaches bigger.
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Some of the waves are destructive,
which means that they break on the
beach and as the water runs back, it
drags part of the beach away with it.
These waves are backwash waves – big
waves that make more noise as they
retreat, taking the sand and shingle with
them.
These make beaches smaller.
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Some waves are a bit of both.
This is called longshore drift
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This can lead to the formation of
a spit
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What with rising sea levels (climate
change) and coastal erosion, some coasts
are disappearing fast.
So we have to have ways of trying control at
least some of our coastlines if whole towns are
not to disappear under the waves!
There 2 groups of methods – hard engineering
-These solutions generally involve concrete,
metal, stone and other hard wearing materials
that are intended to stop erosion and take
little account of the environment.
Soft Engineering
These methods try not to disrupt the
environment and tend to be used where the
environment is more important than say a town
or road.
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Are these hard or soft? Do you
know what they are called?
What these
for?
What do you
think they
have done
here? Why?
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Are these hard or soft? Do you
know what they are called?
What is
happening
here?
What is this
for?
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There are others ..
Revetments,
Gabions
Riprap
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What am I talking about
Erosion
Transportation
Deposition
Attrition
Corrosion
Hydraulic action
Abrasion
Suspension
Solution
Traction
Saltation
Load
Headlands
Wave cut notch
Wave cut
platform
Arch
Stack
Stump
constructive
waves
Swash wave
destructive wave
Backwash wave
Longshore drift
Spit
Hard engineering
Soft engineering
Replenishment
Revetments
Gabions
Riprap
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