Download Drawing things together - Ysgol Rhyngrwyd

Drawing things
together
About how the scenery is
changed
1
So far …
We looked at
They different types of rock and how they
are formed
Then there was that small diversion by
way of plate tectonics and volcanoes
So we are now going back to scenery but
from a different angle
2
Do you remember what
were the 2 types of
processes that create
sediment?
3
Looking at weathering briefly first
Weathering is the break down of the
rocks by various processes. There are 3
broad types of weathering
P..
B..
C..
Can you remember how each works?
4
What does erosion mean?
Do you remember what we said was also
part of erosion- what tended to happen
afterwards?
So we have 2 other processes following it
Transportation
Deposition
There are various ways that rock can be
worn away – depends a bit what was is
doing it (these are called agents of
erosion)
What are the agents of erosion – the things
that wear the rock away? (3 all together)
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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
Transport
I cannot
carry them
any further
so I drop
them
Deposition
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Wind Erosion
Typical sharp-edged wind
erosion Grand Canyon
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Water Erosion
(Near the source of a river)
.
Notice the 'V'
profile, absence
of vegetation and
steep slopes
How a waterfall
and gorge are
formed
8
Water Erosion
(Nearer the mouth of a river)
.
See how the edge of this river
has been eroded to form a
river cliff
9
Water Erosion - Coast
.
10
There is also ice
erosion
That is what glaciers domaybe another time?
11
Transportation
Is the movement of eroded material by
water, wind or ice.
And is a bit difficult to see!
But here is a lot
of sediment
And
That is a tree
trunk floating
down the River
Wye last October
12
Transportation
And here we have the wind doing some
transporting
This one was
taken in Iraq.
The soldier who
took the picture
said they have at
least one of
these a week
13
Deposition is a bit easier!
Is what happens when the wind or the
water or ice runs out of energy and drops
whatever it is carrying
Kiama Downs Beach,
just north of Sydney
Where is that?
See those rocks in
the foreground?
They are being
eroded away and will
end up on the beach.
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Deposition is a bit easier!
Is what happens when the wind or the
water or ice runs out of energy and drops
whatever it is carrying
Sand dunes
Location:
Sabria, Tunisia
15
Deposition is a bit easier!
Is what happens when the wind or the
water or ice runs out of energy and drops
whatever it is carrying
Mississippi Delta
16
Review
1. What ere the 4 processes involved in
changing the scenery? And what do each
do?
2. What are the 3 agents of erosion?
3. We saw various pictures – these
examples of which processes?
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How do these
processes work?
As applied to coasts, but
they work river rivers too
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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
Transport
I cannot
carry them
any further
so I drop
them
Deposition
Remember when we talked about rocks?
Which rocks were made by wearing away,
carrying the bits and then dropping them?
19
Erosion 1
Attrition is the collision of rock fragments in the
water against one another.
The waves carrying rocks that knock against each
other and pieces get broken off, making them
smoother and rounder
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Erosion 2
Abrasion occurs when rocks and stones carried by the
waves wear away the base of the cliffs
21
Erosion 3
Hydraulic action.
When waves fall against the cliffs, air is forced into
the cracks and is squashed.
As the wave withdraws, the air expands causing little
explosions and so the cracks become enlarged
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Erosion 4
Corrosion is the process by which water reacts
chemically with soluble minerals in the rocks and
dissolves them.
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If you would like to watch
the animation from which
the diagrams for erosion,
look here! (I borrowed it
from the BBC!)
http://ysgolrhyngrwyd.wikispaces.com/Uni
t+4+Changing+Earth
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Transportation 1
A waves carry or transport eroded materials
such as mud, sand, boulders and dissolved
materials. Sometimes this is towards the land
or sometimes is it away from the land but often
it is along the coast to somewhere else
These materials are known as its load.
The load is carried along by four processes.
traction
saltation
suspension
solution
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Transportation 2
Traction is where boulders or stones are rolled
along the ocean-bed by the force of the water
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Transportation 3
Saltation is when small pebbles bounce
along and leapfrog over each other.
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Transportation 4
Suspension very fine particles such as
clay, silt and fine sand are carried along
in the river.
They are held up by the water as they
float because they are very, very small!
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Transportation 5
Transportation in solution is when
dissolved materials resulting from
corrosion (when the eroded material is
dissolved out of the rocks) and are
invisible to the naked eye.
You cannot see
anything
because they are
too small!
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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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Can you sort the
words we have
learnt into erosion
and deposition?
Try here!!
http://classtools.net/my/dust
bin35961TESTER.htm
31
Match the word to the definition
Attrition
Abrasion
Hydraulic
action
Corrosion
Traction
Saltation
Suspension
Solution
The water dissolving away the cliffs
The force of the water wearing
away the cliffs
Tiny particles of clay or sand being
carried away by floating in the
waves
Rocks hitting each other, breaking
pieces off, making them smaller and
smoother
Rocks wearing away the coast line
Larger boulders being dragged along
the floor of the ocean
Dissolved chemical being taken away
by the wave
Smaller pebbles leapfrogging over
each other as they move
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