WEATHERING AND EROSION
SECTION ONE
Information Book
(a)
Introduction
A landscape is the shape of the land surface. For example, in a coastal
landscape you may see cliffs and beaches. Landscapes are formed and
changed by processes such as weathering, erosion, transport and
deposition.
• Weathering is the process by which rocks are broken up in the place
where they are sitting.
• Erosion is the process by which the land is worn away by moving
wind, water and ice.
• Transport is the process by which eroded material is moved across
the landscape by water, wind and ice.
• Deposition is the process by which materials such as pebbles, sand
and mud are laid down by wind, water and ice.
Weathering takes place in two main ways:
2.
In physical weathering the rock is broken without being
chemically changed.
In chemical weathering the rock is changed into new chemicals.
(b)
Freeze-thaw action – an example of physical weathering
1.
Rocks often have cracks or joints in them. In wet weather water seeps
into these cracks. If it freezes, the water turns to ice and expands. This
widens the crack – just like the way water pipes burst in the winter.
Fig 1.1
Crack fills
with water
rock
Ice takes up
more room
than water
Crack widened
by pushing
forces
GEOGR APHY: LANDSCAPES
17
WEATHERING AND EROSION
Later the ice melts. (This is when water leaks out of your burst pipes.)
Then the crack fills with water again, the water freezes and the crack is
made even wider. Eventually the rock is broken up into sharp-edged
(angular) fragments.
Blocks of rock, broken off by this freeze-thaw process, fall off a cliff and
pile up at the bottom to form a slope of scree (Fig 1.2). Hillwalkers find
scree very difficult to climb because it constantly slips downhill.
Fig 1.2
Scree slope
(c)
The effect of rainwater on limestone – an example of chemical
weathering
The structure of limestone rock is a series of layers (beds) laid one on
top of the other. Within each bed there are vertical cracks called joints
(Fig 1.3).
Fig 1.3
joint
beds of
limestone
bedding plane
18
GEOGR APHY: LANDSCAPES
WEATHERING AND EROSION
Limestone is composed of the mineral calcium carbonate, which reacts
with and is dissolved by acid. Rainwater is a weak acid because it
dissolves carbon dioxide from the air. Therefore, over a long period of
time, limestone is dissolved by rain. This action occurs mostly along the
joints and bedding planes (Fig 1.4), because rainwater is channelled into
these. Slowly the joints become widened. It is these widened joints
that people wriggle down and along when they are taking part in the
sport of potholing.
Fig 1.4
River on surface
Joint
Stage 1
Bedding plane
Beds of
limestone
Pothole
Stage 2
Cave
Joints
widened
Underground stream
As well as potholes chemical weathering produces a variety of other
landscape features which are unique to limestone areas. These are
studied in Section Four.
(d)
Erosion, Transport and Deposition
Rivers, the sea, wind and ice all erode the landscape. These are the
agents of erosion. However, the material that is worn away does not
disappear. It is carried (transported) by the agent of erosion and
dropped (deposited) somewhere else.
In fact, human activities can have similar effects, for example, if stone is
quarried and moved to build a harbour (Fig 1.5).
Fig 1.5
Quarry
Bla
Erosion
stin
g
Transport
Deposition
GEOGR APHY: LANDSCAPES
19
WEATHERING AND EROSION
Thus, if erosion occurs in one place, deposition must occur somewhere
else. Both these processes – erosion and deposition – are responsible
for features of our landscape.
(e)
The Work of Rivers
(i)
A river has energy as it flows to the sea. This enables the river
to transport material.
Fig 1.6
Some material (e.g. salt) is dissolved in the water
Some material (e.g. fine
mud) is suspended in
the water
Some material is bounced
along the bed
Bed
Some material rolls or slides along the bed
If the river is flowing down a steep slope or is ‘in spate’
(flowing very fast during very wet weather), it can carry a lot
of material. Think how muddy your local river or stream
becomes in wet weather. The material carried by a river is
called alluvium.
(ii)
The boulders and pebbles that are rolled along the bed wear
away the rock below. If they settle in a hollow they are
swirled around by the current. Potholes are formed in the
bed of the river and so the river cuts down into the land to
form a valley (Fig 1.7).
Fig 1.7
→
20
→
→
Pebbles swirled by current
Potholes form
Potholes join together
Stage 1
Stage 2
Stage 3
GEOGR APHY: LANDSCAPES
WEATHERING AND EROSION
The valley may be narrow and steep-sided – a gorge, or if the
sides have been weathered and eroded the valley will have a
V-shape (Fig 1.8).
Fig 1.8
River
Gorge
River
V-shaped valley
(iii) When the slope of the river bed becomes gentle, the river
loses the energy to transport its load and deposits alluvium.
The course of the river becomes less straight and may form
big loops, called meanders.
As the river flows round the meander the main current
swings to the outside, so that the bank and bed are eroded.
However, on the inside the current is much slower, so
alluvium is deposited (Fig 1.9).
Fig 1.9: Meander
erosion
direction of
current
deposition
top view of
meanders
(iv) A river deposits most alluvium when it completely loses its
energy. This happens when it meets a lake or the sea – at the
mouth of the river. If currents in the sea do not carry the
alluvium away it piles up at the mouth of the river.
Eventually new land is formed – called a river delta (Fig
1.10).
GEOGR APHY: LANDSCAPES
21
WEATHERING AND EROSION
Fig 1.10: Formation of a delta
Layers of alluvium
deposited by the river
Alluvium appears as mud and
sand banks at low tide
New land
Main channel of river splits up
(f)
More alluvium being deposited
The Work of the Sea
Waves break constantly against the coastline. In stormy weather they
have enormous power. Sea cliffs are eroded in two main ways (Fig
1.11):
1.
As a wave breaks air is compressed into cracks in the rock. The
rock is loosened so that fragments are washed off.
2.
Pebbles are repeatedly picked up from the sea bed and hurled
against the cliff, wearing it away.
22
GEOGR APHY: LANDSCAPES
WEATHERING AND EROSION
Fig 1.11
The fragments broken from the cliffs are constantly rolled back and forth
and become broken down into smaller and smaller rounded fragments,
eventually becoming sand. This is washed away by waves and currents to
be deposited as a beach farther along the coast.
Sand on beaches may also form from broken shells (for example, the
white sand beaches of the Outer Hebrides) or from material washed into
the sea by rivers.
The processes of erosion and deposition produce stunning coastal
landscapes with a variety of features. These are examined in Section
Five.
(g)
The Work of Ice
In Scotland the winter snow melts in the summer. Only in some shady
corners high on Ben Nevis and in the Cairngorm Mountains does snow
lie all year. However, in colder climates like Greenland, the Norwegian
mountains and the Alps a lot of the winter snowfall survives the summer.
Therefore, year after year snow builds up and is compacted into ice.
This ice moves slowly downhill as a glacier. A large mass of ice covering
a vast area is known as an ice sheet. Where the moving ice is
channelled into a valley a valley glacier forms (Fig 1.12).
GEOGR APHY: LANDSCAPES
23
WEATHERING AND EROSION
Fig 1.12
In the Ice Age, which lasted from 2.5 million years ago until 10,000 years
ago, Britain’s climate was much colder. At one time ice covered the
land as far south as the River Thames (Fig 1.13), so that much of
Britain’s landscape has been shaped by glacial erosion and deposition.
Fig 1.13
Britain during the Ice Age
Ice sheet
Ice erodes the landscape in two ways.
1.
Plucking
Loose rocks on the valley floor become frozen into the glacier and
are ‘plucked’ away as the glacier moves on.
2.
Abrasion
The plucked rocks frozen into the bottom of the glacier act like the
teeth of a file and scratch and scrape the rocks that the ice moves
over.
24
GEOGR APHY: LANDSCAPES
WEATHERING AND EROSION
These two processes are responsible for the largest and most spectacular
landscape features in the British Isles and these will be studied in
Section Three.
The material transported by the glacier is called moraine. This is
deposited where the ice melts. Thus the glacier acts like a slow-moving
conveyor belt, depositing a steady supply of rocks in a pile at the end of
the glacier (Fig 1.14).
Fig 1.14
This pile of rocks is called the terminal (end) moraine. If the glacier
melts at one particular spot for a long time, the terminal moraine can
become quite large.
The meltwater from the end of the glacier washes away a lot of moraine
and spreads it out over the valley floor as an outwash plain (Fig 1.14).
These deposits look very different from the moraine (Fig 1.15).
Fig 1.15
The rocks in the moraine are different shapes and sizes and often have
sharp edges. On the other hand the outwash has been deposited by
rivers of meltwater flowing from the ice. The running water rolls the
rock fragments so that they become rounded. During warm weather the
ice melts rapidly so that torrents of water flow from the ice. These can
carry large fragments. However, in cold weather only a trickle of water
may flow. This can only carry small fragments like sand. In this way the
running water sorts the deposit into layers of sand and gravel.
GEOGR APHY: LANDSCAPES
25
WEATHERING AND EROSION
When the climate warmed up and the ice retreated, the moraine frozen
into the bottom of the ice was left as a soil called boulder clay.
(h)
The Work of the Wind
The wind erodes the landscape in two ways.
1.
It picks up material and blows it away.
2.
Sand which is being carried by the wind may be blown against
rocks. It ‘sandblasts’ the rocks. This method is used to clean the
surface of a dirty building. A jet of air and sand is directed at the
stonework.
Wind erosion is most powerful in situations where there is neither
moisture nor plant roots to hold soil or sand particles together – as is
the case in hot deserts. However, in the mild, damp climate of the
British Isles wind action is limited to:
(i) bare gravel patches in high mountains;
(ii) ploughed fields in a dry Spring; and
(iii) along coastlines where there are extensive sandy beaches.
In the last case onshore winds may blow sand up the beach. This may
become lodged around obstructions such as the strand line of dried
seaweed and driftwood (Fig 1.16).
Fig 1.16
wind
0.5m
sea
strand line
sand
lodging
behind
strand line
material
This can build up into a sand dune as more sand accumulates (Fig 1.17).
>
Fig 1.17
10m
>
26
GEOGR APHY: LANDSCAPES
WEATHERING AND EROSION
Because the wind constantly blows sand up the gentle side and down
the steep side, the dune can advance inland (Fig 1.18).
Fig 1.18
This can lead to good farmland being buried by sand (for example, at
Culbin, near Elgin). To prevent this sand dunes can be fixed by planting
fast-growing marram grass and coniferous trees. The Culbin dunes are
now Culbin Forest.
However, dunes are eventually colonised naturally by plants. On dune
coasts in the British Isles there are series of dunes lying parallel to the
coast, with those farthest inland being oldest and covered by the biggest
variety of plants (Fig 1.19).
Fig 1.19
old dunes covered by a
range of different
plants
new dunes becoming covered
by a few plants
wind
sea
These dry, salty areas have little agricultural value other than for
forestry. But, they have considerable value for wildlife and recreation.
Consequently, many are conserved as Nature Reserves or are converted
into golf courses, such as at St Andrews in Fife, Troon in Ayrshire and
Royal Birkdale in Lancashire.
GEOGR APHY: LANDSCAPES
27
WEATHERING AND EROSION
Activity Sheets
Outcomes
Intermediate 1 and Intermediate 2
Knowledge and Understanding
Example of physical weathering process – freeze-thaw action.
Example of chemical weathering process – solution of limestone.
Processes of erosion, transport and deposition by:
•
•
•
•
work
work
work
work
of
of
of
of
rivers,
the sea,
ice,
the wind.
GMTs
Draw annotated sketches.
Do experiments.
Draw cross-section.
28
GEOGR APHY: LANDSCAPES
WEATHERING AND EROSION
Information Book Section 1(a): Introduction
1.
What is the difference between weathering and erosion?
2.
Which one of the following is an example of weathering?
(a)
(b)
(c)
3.
Waves meet the coast at an angle and carry sand along the
beach.
Some minerals in a rock react with rainwater and the rock
crumbles.
A glacier moves slowly down a valley and makes it deeper and
wider.
Your teacher may show you a piece of sandstone and a piece of
shale. These have been soaked in water for a few hours and then
frozen or VIDEO .
Describe what happens to these rocks as they thaw out.
Information Book Section 1(b): Freeze-thaw action
Physical Weathering
4.
What happens to the volume of water when it freezes?
5.
What happens to cracks in rocks when water in them freezes?
6.
If freeze-thaw action continues for a long time, what will eventually
happen to the rock?
7.
What is scree?
8.
Look at Fig Q8.
Draw a sketch and annotate it to show
(i)
(ii)
where freeze-thaw action is occurring,
scree.
GEOGR APHY: LANDSCAPES
29
WEATHERING AND EROSION
Fig Q8: Dow Crag, Lake District
Information Book Section 1(c): The effect of rainwater on
limestone
Chemical Weathering
Using small pieces of limestone or chalk set up two test tubes or VIDEO .
Test Tube 1: limestone + water
Test Tube 2: limestone + dilute acid
9.
(a)
(b)
What happens to the limestone in water?
What happens to the limestone in acid?
10.
Why is rainwater acidic?
11.
What happens to cracks (joints) in limestone when rainwater
drains along them?
Checkpoint 1
STUDENT
CHECK
30
Answers
1–7, 9–11
GEOGR APHY: LANDSCAPES
TEACHER
CHECK
Answer
8
WEATHERING AND EROSION
Extension exercises
Use the resources provided by your teacher to help you do the
following exercises. Write notes and draw diagrams.
E1
Find out how exfoliation occurs.
E2
Find out how plant roots cause weathering.
E3
Find out how salt weathering occurs.
TEACHER
CHECK
Answers
E1, E2, E3
Information Book Section 1(d): Erosion, Transport and
Deposition
12.
Give two examples of human activities which resemble the effects
of erosion.
13.
Indicate whether the statements below refer to erosion, transport
or deposition.
(a)
In the desert the wind blasts the rocks with sand to eat away
the rocks in its path.
(b)
When the ice sheet melted, material called boulder clay was
left behind.
(c)
An esker is a long ridge of sand and pebbles which was once
the bed of a river within a glacier. It was dumped when the
glacier melted.
(d)
Vast areas of Canada have been carved by ice sheets. Many
hollows in the landscape, often filled by lakes, were scraped
out of the surface rock by the ice.
(e)
The sand storm in the desert was violent. The wind had
picked up the sand and was moving it through the air with
terrific force.
GEOGR APHY: LANDSCAPES
31
WEATHERING AND EROSION
The Work of Rivers
Workcard 1
Copy the table below.
Do the experiment and record the results in the table or VIDEO .
Angle of Slope
(degrees)
14.
Distance
(in cm)
Time
(in seconds)
Speed = Distance
(in cm per sec) Time
When is the current faster – with the gentle or the steep slope?
Workcard 2
Copy the table below.
Do the experiment and record the results in the table or VIDEO .
Slope
Material
Time
Sand
Gentle
(5°-10°)
Gravel
Sand
Steep
(20°-30°)
Gravel
15.
Which is moved more easily – sand or gravel?
16.
Why do you think this is the case?
17.
What effect does steepening the slope have on the speed at which
sand and gravel are moved?
32
GEOGR APHY: LANDSCAPES
WEATHERING AND EROSION
Workcard 3
Do the experiment or VIDEO .
18.
What happens to the speed of the current when the discharge is
bigger?
19.
What happens to the sand and gravel when the discharge is bigger?
Information Book Section 1(e)(i)
20.
Describe four ways in which a river transports material.
21.
In which of these ways are large pebbles and boulders moved?
22.
In which of these ways are the fine mud particles moved?
23.
Under what two conditions is a river able to move large pebbles or
boulders?
A
B
C
D
24.
when
when
when
when
the
the
the
the
river flows down a steep slope.
river flows down a shallow slope.
discharge is high (the river is in spate or flood).
discharge is low (the river is not in spate).
What is alluvium?
Workcard 4
Do the experiment or VIDEO .
25.
Where does the stream cut down most quickly?
26.
Do the rapids stay in the same place or move upstream or move
downstream?
27.
What kind of valley is made as the stream erodes at the rapids? (Is
it wide or narrow? Are the side slopes steep or gentle?)
28.
What happens at the end (the mouth) of the stream?
29.
Why do you think the pebbles on a river bed are rounded?
GEOGR APHY: LANDSCAPES
33
WEATHERING AND EROSION
Information Book Section 1(e)(ii)
30.
Describe how a pothole is formed in a river bed. Use diagrams to
help you explain the process.
31.
What is a narrow steep-sided valley called?
32.
What shape does a river valley have if the slopes have been
weathered and eroded?
33.
Why is alluvium deposited at the mouth of a river?
34.
What is a meander?
35.
Draw a diagram to show where erosion and deposition occur on a
meander.
36.
Where is the current fastest around a meander – on the outside or
the inside of the bend?
37.
Look at Fig Q37 below, showing a meander. Draw a simple sketch
and label it to show:
where erosion is occurring;
where deposition is occurring;
where the main current is flowing.
Fig Q37: River meander, Chirnside, Scottish Borders
Photo: British Geological Survey, © NERC. All rights reserved.
34
GEOGR APHY: LANDSCAPES
WEATHERING AND EROSION
38.
(a)
Copy framework Fig Q38B. Use the depth data in Fig Q38C
to draw a cross-section of the river bed.
Fig Q38A: A meander on the River Devon
current direction
20m
N
X
1
2
3
river
Y
line of section with numbered
sample points
Fig Q38B
0
X
1
2
3
Y
0.5
Depth
of
water
(m)
1.0
1.5
2.0
2.5
3.0
Fig Q38C: Statistical data at sample points
Sample point
1
2
3
Speed (cm/sec)
25
61
88
Depth (m)
0.4
1.5
2.2
GEOGR APHY: LANDSCAPES
35
WEATHERING AND EROSION
(b)
Look at Figs Q38A, Q38C and your cross-section. Explain the
relationships between river speed, river depth, erosion and
deposition.
39.
Describe how a delta is formed. Use diagrams.
40.
Why do deltas not form at the mouth of every river?
Extension exercises
Use the resources provided by your teacher to answer the
following. Wherever possible, draw diagrams to illustrate your
answers.
E1
What are interlocking spurs?
E2
How is a waterfall formed?
E3
Explain why river valleys in dry areas are often gorges,
whereas river valleys in wet areas are usually V-shaped.
E4
What is a braided river channel?
E5
How is an ox-bow lake formed?
E6
Name three rivers which have deltas.
Checkpoint 2
STUDENT
CHECK
Answers
12–29, 31–34
36, 40
TEACHER
CHECK
Answers
30, 35, 37–39
E1–E6
Information Book Section 1(f): The Work of the Sea
41.
In what sort of weather is wave action most powerful?
42.
Describe two ways in which waves erode cliffs.
43.
Why are the pebbles on a beach rounded?
36
GEOGR APHY: LANDSCAPES
WEATHERING AND EROSION
44.
Explain how sand is formed by wave action.
45.
Describe two other ways in which sand is formed.
46.
Copy Fig Q46 below and label it to show where erosion and
deposition are occurring.
Fig Q46
Checkpoint 3
STUDENT
CHECK
Answers
41–46
The Work of Ice
Information Book Section 1(g)
47.
In what sort of climate do glaciers occur?
48.
Name at least three countries in which glaciers are found. You
may need to look at an atlas.
49.
How is snow changed into ice?
50.
What is the difference between an ice sheet and a valley glacier?
51.
When did the Ice Age end in Britain?
52.
How far south did ice cover Britain during the Ice Age?
A piece of hardboard painted with emulsion paint and an ice
cube with sand grains frozen into one side or VIDEO .
GEOGR APHY: LANDSCAPES
37
WEATHERING AND EROSION
53.
(a)
Rub the painted board with the smooth side of the cube.
What happens?
(b)
Rub the painted board with the rough side of the ice cube.
What happens?
54.
Describe the two ways in which ice erodes the landscape.
55.
What is moraine?
56.
Describe how a terminal moraine is formed. Draw diagrams.
57.
How do extra-large terminal moraines form?
58.
What shape are the fragments in moraine?
59.
What shape are the fragments in meltwater deposits?
60.
Explain the difference between moraine and meltwater deposits.
61.
Why are the meltwater deposits formed in layers of sand and
gravel?
Checkpoint 4
STUDENT
CHECK
Answers
47–55
57–61
TEACHER
CHECK
Answer
56
Extension exercises
E1
38
Copy the cross-section below and annotate it to show
terminal moraine, boulder clay and outwash plain. Also,
draw in the position of the glacier during the Ice Age.
GEOGR APHY: LANDSCAPES
WEATHERING AND EROSION
E2
Explain the formation and distribution of the surface deposits
in Zones 2, 3 and 4 in Denmark.
sand dunes
movement
of ice from
upland
Scandinavia
Y
maximum
extent
of ice
N
boulder
clay
X
100km
sand and
gravel
zone 1
zone 2
terminal moraine
zone 3
zone 4
X
surface
deposit
E3
Y
sand
dunes
sand and
gravel
(rounded
and sorted)
terminal
moraine
boulder clay
(angular and unsorted)
Use resources provided by your teacher to help you answer
these questions.
(a)
What are glacial striations and how are they formed?
(b)
What is a fluvio-glacial deposit?
TEACHER
CHECK
Answers
E1–E3
GEOGR APHY: LANDSCAPES
39
WEATHERING AND EROSION
The Work of the Wind
Workcard 5
62.
Which pile of sand is more easily blown?
63.
Which particles, large or small, are more easily blown?
64.
Which process, erosion or deposition, occurs where the wind is
strongest?
65.
Which process occurs where the wind slows down?
66.
(a)
In which of the following places would wind erosion be most
likely?
Sahara Desert
(b)
Central Scotland
Amazon Rain Forest
Explain your answer.
67.
Where is wind action effective in the British Isles?
68.
With the help of a diagram describe how a sand dune can develop
on a coast.
69.
Explain how a sand dune can advance inland. Draw a diagram.
70.
What problem can this cause?
71.
Describe the measures that can be taken to fix sand dunes.
72.
Look at Fig Q72.
Fig Q72: Cross-section of a dune coast
C
B
A
east
west
40
GEOGR APHY: LANDSCAPES
WEATHERING AND EROSION
(a)
In which direction is the prevailing wind blowing?
(b)
Which of the dunes, A, B or C is the youngest?
(c)
Which of the dunes A, B or C will have the widest variety of
plants growing on it?
73.
Give two uses to which dune coasts can be put.
74.
Look at Fig Q74.
Draw a sketch and label it to show sand and trees.
Draw an arrow on the sketch to show direction of wind.
Fig Q74: Advancing sand dune
Photo: British Geological Survey, © NERC. All rights reserved.
Checkpoint 5
STUDENT
CHECK
Answers
62–67
70–73
TEACHER
CHECK
Answers
68, 69
74
GEOGR APHY: LANDSCAPES
41
WEATHERING AND EROSION
Extension exercises
Use resources provided by your teacher to describe and explain
the formation of the features below. Write notes and draw
diagrams.
E1
E2
E3
E4
E5
Barchan
Loess
Rock pedestal or ‘mushroom’ rock
Ventifact
Yardang
Checkpoint
TEACHER
CHECK
42
Answers
E1–E5
GEOGR APHY: LANDSCAPES
WEATHERING AND EROSION
Workcard 1
1.
Take a piece of plastic guttering (ideally more than 150cm long)
and set it up as shown with one end supported by a thin wooden
block. This should give the guttering a gentle slope of less than 5°.
Measure the slope with a protractor or angle meter.
Pour water very slowly into the upper end of the gutter.
Drop a spot of red dye into the stream.
Use a stopwatch to time how long it takes to reach the end of the
gutter.
Enter the result in the table.
2.
Replace the thin block with a thicker one so that the slope is
steeper (at least 15°).
Repeat the experiment and record the result in your table.
GEOGR APHY: LANDSCAPES
43
WEATHERING AND EROSION
Workcard 2
1.
Set up the guttering as in Workcard 1, making the slope very
gentle (5°–10°).
Spread a little sand along the bottom of the guttering.
Pour water steadily from a sprinkler on to the top end of the
guttering.
Time how long it takes to wash all the sand into the bucket.
Record result in your table.
2.
Repeat the experiment with gravel (ideally large, flat pieces) in the
guttering.
3.
Repeat the experiment with a steep slope (20°–30°) using sand.
4.
Repeat the experiment with a steep slope (20°–30°) using gravel.
Remember to record the results in your table.
44
GEOGR APHY: LANDSCAPES
WEATHERING AND EROSION
Workcard 3
The amount of water which flows is called the discharge.
This experiment examines what happens when the discharge is
increased in a river channel.
1.
Set up the guttering at an angle of 5°–10°.
Put a mixture of gravel and sand into the guttering.
Pour half a litre of water slowly (taking at least 10 seconds) on to
the top of the guttering. This is a small discharge.
2.
Repeat the experiment, but increase the discharge by pouring a
litre of water in 5 seconds.
GEOGR APHY: LANDSCAPES
45
WEATHERING AND EROSION
Workcard 4
You will need:
sand tray – 20cm x 30cm and 7cm deep approximately (an A4 size
cardboard box lined with polythene will do)
fine sand
water bottle with pourer
foil top from a milk bottle
plastic carton and a bucket for bailing out water
polythene
1.
Make a landscape like that shown above, as follows. Make the
shape with damp sand, cover it with polythene, place more sand
on the polythene, and make a straight channel with your finger.
2.
Pour water gently on to the milk top.
Bail out water from the bottom if you need to.
Watch carefully as the stream makes a valley.
46
GEOGR APHY: LANDSCAPES
WEATHERING AND EROSION
Workcard 5
You will need:
hairdryer
sand and fine gravel
water and a sheet of paper or tray 50cm long.
1.
Mix up some sand and fine gravel.
2.
Take half the mixture and mix in some water.
3.
Place a pile of dry sand/gravel and a pile of damp sand/gravel side
by side at the end of the tray or paper.
4.
Turn on the hairdryer and direct the ‘wind’ along the surface.
5.
Watch carefully what happens.
GEOGR APHY: LANDSCAPES
47
ROCKS
SECTION TWO
Information Book
(a)
Introduction
Landscape is significantly affected by the characteristics of the rocks
below the Earth’s surface. For example, harder rocks are generally more
resistant to weathering and erosion than softer rocks.
There are three main types of rocks – igneous, sedimentary and
metamorphic – distinguished by their different properties and different
methods of formation.
(b)
Igneous rocks
(i)
The experiment in Activity 1 will have demonstrated that
igneous rocks are made of crystals and are hard.
They are formed when molten magma cools down and
becomes solid. As it cools, crystals form and lock together
like pieces of a jig-saw. This strong interlocking structure
makes igneous rocks difficult to break (Fig 2.1).
(ii)
The longer the magma takes to cool the larger the crystals are
able to grow (Fig 2.1).
Fig 2.1: Views of magnified igneous rocks
48
GEOGR APHY: LANDSCAPES
ROCKS
It is much warmer deep within the crust than it is at the Earth’s surface,
so rocks like granite and gabbro, which cool slowly at great depth, have
large crystals. These can be quite sharp and rock climbers soon get raw,
tender fingertips on the gabbro of Skye! Basalt, on the other hand,
forms when lava cools quickly as it flows over the Earth’s surface.
The colour of the rock depends on its composition. Granite is much
lighter in colour than basalt and gabbro, because it contains 30% quartz
– a white or colourless mineral. Basalt and gabbro have no quartz, but
have more dark minerals than granite.
(c)
Sedimentary rocks
Section One showed that rocks at the Earth’s surface are broken down
by a process called weathering. Some weathering processes break rocks
into smaller fragments. The land is also worn away or eroded by rivers,
the sea, wind and ice. The materials picked up are then carried or
transported to be deposited as sediment in another place.
Sedimentary rocks are formed in three ways.
1.
Fragments of other rocks (pebbles, sand or mud) become buried
by layers of other sediment, squashed by their weight and
cemented together by minerals (Fig 2.2).
Fig 2.2: Formation of fragmental sedimentary rock
new sediment
weight of overlying
beds compacts
loose sediment
into solid rock
old sediment
A sedimentary rock made of pebble-sized fragments is called
conglomerate.
Sandstone is made of sand-sized particles.
Mudstone and clay are made of fine particles.
GEOGR APHY: LANDSCAPES
49
ROCKS
2.
Some minerals are transported in solution. These, like calcite
(lime), are deposited if the water evaporates.
A rock made of the mineral calcite is called limestone.
3.
Some sedimentary rocks are made from the remains of living
things.
Coal is formed from the remains of land plants.
Chalk is made from the skeletons of tiny sea plants.
Limestone can be made from coral or shell fragments (Fig 2.3).
Fig 2.3: Limestone with fossils
Calcite
Fossil
The preserved remains of traces of plants and animals are called
fossils. They can include leaves, shells, worm-burrows or dinosaur
footprints (Fig 2.4).
50
GEOGR APHY: LANDSCAPES
ROCKS
Fig 2.4: Trace fossils
Sedimentary rocks are usually laid down in layers or beds.
Sediments deposited in water often lie in distinct layers. The
layers are called beds and the layering is called bedding.
Generally, sedimentary rocks are soft and easily eroded, because
they do not have an interlocking crystal structure (Fig 2.5).
Fig 2.5: Sandstone
Individual sand grains can be easily broken off, especially if the
cement is weak.
Sand grain
Cement
However, the hardness of sedimentary rocks varies. For example,
chalk and limestone resist erosion better than mudstone and clay.
GEOGR APHY: LANDSCAPES
51
ROCKS
(d)
Metamorphic rocks
(i)
These rocks have been changed by heat or by heat and
pressure.
When other rocks are heated, or heated and squeezed, they
remain solid but they recrystallise to form metamorphic rocks
(Fig 2.6).
Fig 2.6: Showing how the minerals in a rock recrystallise
during metamorphism.
Rock before
metamorphism
Minerals recrystallising
while remaining solid
Metamorphic rock
There are two main ways in which metamorphic rocks are
formed:
1.
Thermal Metamorphism
The rocks are heated by an igneous intrusion. In this
case, the rocks are not squeezed so the minerals in the
metamorphic rock are not lined up and flattened.
2.
Regional Metamorphism
When mountains are pushed up a great deal of heat and
pressure is generated. Deep within the mountain range
huge volumes of rock recrystallise. The high pressure
causes the mineral grains to line up to produce a
layering called foliation (Fig 2.7).
52
GEOGR APHY: LANDSCAPES
ROCKS
Fig 2.7: Formation of foliation
Original rock layers heated
and squeezed
·
Original layering starts to
disappear as new
minerals crystallise
·
New layering (foliation)
develops oldlayering
disappears
The three main foliated rocks are slate, schist and gneiss. Slate is
very fine-grained. It splits easily into thin sheets. Schist is mediumgrained and it usually has flakes of mica lying in the foliation
making it glitter (Fig 2.8).
Fig 2.8: Views of magnified metamorphic rocks
Gneiss is a coarse-grained rock where the foliation usually takes
the form of obvious banding. The differences among slate, schist
and gneiss represent differences in the strength of metamorphism.
If a mudstone is weakly metamorphosed a slate is produced. As
the strength of metamorphism increases, schist then gneiss result:
no metamorphism → weak metamorphism → strong metamorphism
mudstone
→
slate
→ schist
→ gneiss
GEOGR APHY: LANDSCAPES
53
ROCKS
Like igneous rocks, metamorphic rocks are usually hard, because
they consist of interlocking crystals.
(e)
Rocks and Relief
Relief describes height differences in an area. Since igneous and
metamorphic rocks are generally more resistant to weathering and
erosion than sedimentary rocks, they tend to form higher ground.
54
GEOGR APHY: LANDSCAPES
ROCKS
Activity Sheets
Outcomes
Intermediate 2
Knowledge and Understanding
Characteristics, formation and examples of the three main rock types:
• igneous rocks
• sedimentary rocks
• metamorphic rocks.
The differing hardness of these rock types and their effect on landscape
in the British Isles.
GMTs
Conduct experiments.
Draw annotated sketches from photographs.
Identify rock types from magnified views of rocks (Extension only).
GEOGR APHY: LANDSCAPES
55
ROCKS
Two rock samples (one sedimentary and the other igneous),
magnifying glass, cloth, penknife, hammer, safety goggles.
Carry out the following tests on both rocks or VIDEO .
1.
2.
Look at the rocks through a magnifying glass.
(a)
Do the particles look like sharp-edged crystals or rounded
grains?
(b)
Can you see tiny surfaces glinting in the light?
(i)
Rub the rock between your fingers. If it doesn’t crumble,
(ii)
scrape the rock firmly with a penknife. If it doesn’t crumble,
(iii) wrap it with a cloth and hit it with a hammer.
(iv) Look at the broken bits with a magnifying glass. Is the rock
made from separate grains or crystals?
(a)
Which rock is harder?
(b)
Does the harder rock consist of grains or crystals?
(c)
Does the softer rock consist of grains or crystals?
Section 2 (a): Introduction
3.
Why do different rocks have different effects on the shape of the
landscape?
4.
Name the three different types of rocks.
Section 2 (b) (i): Igneous Rocks
5.
How are igneous rocks formed?
6.
Why are igneous rocks difficult to break?
56
GEOGR APHY: LANDSCAPES
ROCKS
Workcard 1 and a microscope.
Do the experiment or VIDEO .
7.
(a)
Make drawings of the crystals which have been produced by
rapid and by slow cooling.
(b)
Use these words to complete the sentences:
slowly; quickly, long; grow; small; large
. Its crystals are
A rapidly cooled liquid freezes
because they have not had time to
to large sizes. A slowly cooled liquid freezes
. Its crystals are
because they
time to grow.
have had a
8.
Some igneous rocks are made up of large crystals. They are
described as coarse-grained. Rocks made up of small crystals are
fine-grained.
(i)
At what rate will coarse-grained igneous rocks have cooled?
(ii)
At what rate will fine-grained igneous rocks have cooled?
(iii) At what rate will medium-grained igneous rocks have cooled?
9.
Intrusive igneous rocks form from magma which solidified before
it reached the Earth’s surface. Extrusive igneous rocks form from
magma which has run as lava onto the Earth’s surface.
(i)
Use these words to complete the sentence:
fine-; medium-; coarse-; insulated; extrusive; quickly.
by the rocks
Instrusive igneous rocks are
around them. This allows them to cool fairly slowly so they
or
grained.
are usually
igneous rocks are not insulated by other rocks.
so they are usually
They cool
grained.
GEOGR APHY: LANDSCAPES
57
ROCKS
10.
Copy Fig Q10 and place the following in the correct places:
intrusive; extrusive; fine-; medium-; coarse-; magma; quickly;
slowly; density.
Fig Q10
cooled
rock is
igneous rock
. The
grained.
Intrusive igneous rock
cooled fairly slowly. The
grained.
rock is
igneous rock
at
cooled
depth. The rock is
grained.
The liquid rock rises because
it has a relatively low
.
Deep within the Earth, rocks
partly melt to form liquid
.
Section 2 (b) (ii)
11.
Why does gabbro have bigger crystals than basalt?
12.
Why do rock climbers in Skye get sore fingertips?
13.
Why is granite paler in colour than gabbro?
58
GEOGR APHY: LANDSCAPES
ROCKS
14.
Look at Fig Q14
Draw a sketch and annotate it to show the paler Red Cuillins and
the darker Black Cuillins. Also indicate the two rock types.
Fig Q14: Cuillin Hills, Skye
Checkpoint 1
STUDENT
CHECK
Answers
1–13
TEACHER
CHECK
Answer
14
Section 2 (c): Sedimentary Rocks
15.
Name three sedimentary rocks formed from fragments.
16.
Explain how these rocks are changed from loose sediment into
solid rock.
17.
Name a rock made from the remains of land plants.
18.
Name a rock made from fossil shells.
19.
In what type of climate will calcite be deposited from sea water to
form limestone?
GEOGR APHY: LANDSCAPES
59
ROCKS
20.
What are fossils?
21.
Give two examples of trace fossils.
22.
Why are sedimentary rocks such as sandstone softer than igneous
rocks?
Screwtop jar, soil, salt
Add soil to a screwtop jar until it is about one third full. Add a
little salt then pour in water until the jar is nearly full. Put the lid
on tightly. Shake the jar very hard for about a minute then lay it
on the bench. When the soil has settled draw what you see.
23.
What happens to the sizes of the particles from the bottom towards
the top?
24.
Can you see some evidence of layers in the settled soil?
25.
What name is given to layering in sedimentary rocks?
Checkpoint 2
STUDENT
CHECK
60
Answers
15–25
GEOGR APHY: LANDSCAPES
ROCKS
Pieces of damp, dried and fired clay.
26.
(a)
Draw a table with three columns, headed ‘damp clay’, ‘dried
clay’, ‘fired clay’.
Use these words and phrases to complete the table. You may
use any description more than once.
hard; brittle; flexible; soft; inflexible; tough; strong; weak;
plastic; becomes plastic when water added; non-plastic;
remains non-plastic when water added
(b)
Which type of clay resembles sediment?
(c)
Which type of clay resembles sedimentary rock?
Workcard 2
Do the experiments or VIDEO .
27.
For Experiment 1 draw the layers and veins before and after
squeezing.
28.
For Experiment 2 draw the positions of the rice grains before and
after squeezing.
Section 2 (d): Metamorphic rocks
29.
Refer back to 26. Which type of clay resembles a metamorphic rock?
30.
During metamorphism, what happens to the minerals in a rock?
31.
What changes rocks during thermal metamorphism?
32.
Describe what happens during regional metamorphism.
33.
In which type of metamorphism do rocks become foliated?
34.
Why is gneiss coarser-grained than schist and slate?
35.
Why are fossils only found very rarely in igneous and metamorphic
rocks?
36.
Are metamorphic rocks harder or softer than sedimentary rocks?
Give a reason for your answer.
GEOGR APHY: LANDSCAPES
61
ROCKS
37.
Draw a table with three columns headed ‘igneous rocks’,
‘sedimentary rocks’, ‘metamorphic rocks’. Write the names of
these rocks in the correct columns:
sandstone; gabbro; slate; gneiss; chalk; basalt; granite; coal;
mudstone; schist; conglomerate; limestone.
Section 2 (e): Rocks and Relief
38.
Study Fig Q38 which shows the general distribution of the three
main rock types in Britain, and an atlas map showing relief. Which
rock type is associated with:
(a)
(b)
(c)
(d)
(e)
(f)
(g)
the main mass of the Scottish Highlands?
the lowlands of Eastern England?
the highest ground in Southern England (Dartmoor)?
the English Lake District?
Snowdonia in North Wales?
the lowlands in the centre of Ireland?
the Wicklow Mountains south of Dublin?
Fig Q38
Checkpoint 3
STUDENT
CHECK
62
Answers
26, 29–38
GEOGR APHY: LANDSCAPES
TEACHER
CHECK
Answers
27, 28
ROCKS
Extension exercises
E1.
Look at Fig QE1
Match the rocks below to the correct numbers
slate; sandstone; mudstone; schist; conglomerate; limestone;
basalt; gabbro.
Fig QE1
Description of rock
1.
Contains many shell fragments
2.
Made up of boulders and pebbles
3.
Made up of small crystals not
lined up
4.
Fine-grained crystalline rock
which splits easily
5.
Made up of large crystals not
lined up
6.
Made up mostly of mica. The
mica flakes are lined up in the
same direction
7.
Made up of medium sized,
rounded grains
8.
Made up of small particles
deposited in quiet water
Drawing of magnified rock
GEOGR APHY: LANDSCAPES
63
ROCKS
E2.
Find an atlas containing a more detailed Geology map of the
UK than Fig Q38. Compare it to a Relief map. Which rock
types are associated with:
The Cotswold Hills?
The Yorkshire Wolds?
The Lowlands of East Anglia?
The Peak District, east of Manchester?
Your answer should confirm that there is great variation in
the resistance of sedimentary rocks.
Checkpoint 4
STUDENT
CHECK
64
Answers
E1, E2
GEOGR APHY: LANDSCAPES
ROCKS
Workcard 1
The effect of cooling rate on crystal size
WEAR YOUR SAFETY GOGGLES
1.
Melt some urea on two glass slides.
2.
Lay one slide on a cold surface and place a cold slide on top of the
liquid drop.
3.
Place a hot slide on top of the other slide. Lay these slides on a
cloth to allow them to cool slowly.
4.
When the crystals have formed, examine them under a microscope.
GEOGR APHY: LANDSCAPES
65
ROCKS
Workcard 2
Effects of squeezing
Experiment 1
1.
Strongly squeeze some layers and veins of Plasticine.
WEAR YOUR SAFETY GOGGLES FOR ALL EXPERIMENTS
2.
Watch what happens to the layers and veins.
Experiment 2
1.
Embed some rice grains in a random pattern in one face of a block
of Plasticine.
2.
Strongly squeeze the Plasticine.
3.
Watch what happens to the arrangements of the grains.
66
GEOGR APHY: LANDSCAPES
GLACIATED UPLANDS
SECTION THREE
Information Book
(a)
Introduction
Section One demonstrated how moving ice is able to erode the land by
plucking and abrasion and that, in upland areas, glaciation has formed
large-scale landscape features.
All the upland areas north of the River Thames have features of glacial
erosion, but the finest examples and most spectacular scenery are found
in the highest mountain areas, such as those in the Scottish Highlands,
North Wales and the Lake District.
In England and Wales, these dramatic landscapes are prized so highly
that a number of them are National Parks.
Fig 3.1: Effect of glaciation on mountain landscape
before glaciation
during glaciation
after glaciation
Fig 3.1 shows the enormous impact that glaciation has on the landscape
and the variety of erosion features that are created. The nature and
formation of these and the contour patterns that they produce on OS
maps will now be examined.
(b)
Corrie and Tarn
A corrie is a large ‘armchair-shaped’ hollow high on a mountainside.
The back and side walls are high (often at least 150m above the floor of
the corrie) and steep – often with cliffs which provide good sport for
rock climbers. The shelter of a corrie is ideal for skiing (for example
Coire Cas, Cairngorm). The floor of the corrie is often scooped out so
that it contains a small lake or tarn.
GEOGR APHY: LANDSCAPES
67
GLACIATED UPLANDS
Fig 3.2: Contour pattern of corrie
cliffs often present
steep sides
tarn
800
700
gentle slope in
floor of corrie
NB
• ‘horse-shoe’ shape of contours
• tarn not always present
If the corrie is named on an OS map it will be coire (in Scotland), cwm
(in Wales) and combe or cove (in the Lake District).
The following sequence of diagrams (Fig. 3.3) shows the stages in the
formation of a corrie.
Stage 1
snow and ice
Snow gathers in a hollow on
the hillside and becomes
compacted into ice.
Stage 2
ice
plucking
abrasion
Ice moves downhill. At the
back of the hollow plucking
and freeze-thaw action
steepen and wear back the
slope. Abrasion deepens the
hollow.
Stage 3
tarn
68
GEOGR APHY: LANDSCAPES
After the ice melts the corrie
remains and water gathers in
the bottom forming a tarn.
GLACIATED UPLANDS
(c)
Arête
This is a narrow knife-edged ridge. It can provide exhilarating hill
walking or rock scrambling, for example Striding Edge in the Lake
District, and Forcan Ridge in the Scottish Highlands.
Fig 3.4: Contour pattern of an arête
cliffs may be present
steep
An arête can be difficult to
identify on the OS map. Hint
– find places where two
corries are back to back. If
the ridge between is narrow
it is an arête.
820
72
0
corrie
corrie
arête
Originally the ridge would have been broad and rounded, but if it is
flanked by two corries then eventually it will become narrow and knifeedged as Fig 3.5 shows.
Fig 3.5: Formation of an arête
rounded ridge
Before
corrie
ice
side view
plucking and freeze-thaw action causes back
walls of the corries to retreat – headward erosion
After
arête
back walls of corries have been eroded back so far
that only a narrow ridge separates them
GEOGR APHY: LANDSCAPES
69
GLACIATED UPLANDS
(d)
Pyramidal Peak
This is a well defined peak shaped like a pyramid, usually at least 800m
high. It has a small summit and steep slopes on at least three sides.
Good examples are Snowdon in North Wales and Ben Lui in Scotland.
Fig 3.6: Contour pattern of pyramidal peak
arête
corrie
corrie
720
•932
To identify on an OS map
look for a spot height or
triangulation station with at
least three corries
surrounding it.
740
740
820
820
corrie
A pyramidal peak may form at the junction of three or more corries, as
shown in Fig 3.7. Headward erosion by plucking and freeze-thaw action
causes the back walls of the corries to retreat towards each other,
producing arêtes and a pyramidal peak in between.
Fig 3.7: Formation of a pyramidal peak
Stage 1
rounded summit
corrie
corrie
corrie
corrie
corrie
side view
Stage 2
aerial view
horn
arête
arête
corrie
horn
corrie
70
GEOGR APHY: LANDSCAPES
corrie
arête
GLACIATED UPLANDS
(e)
U-shaped Valley
The bigger valleys in glaciated uplands are straight and steep-sided with
wide, fairly flat floors, for example Borrowdale in the Lake District.
Fig 3.8: Contour pattern of U-shaped valley
U-shaped valleys are easy to find on an OS map if you already know the
area is glaciated upland. Look for the main rivers – their valleys will
probably have a U-shape.
280
steep
160
flat floor
misfit
stream
160
280
Fig 3.9: Cross-sections showing stages in the formation of a U-shaped
valley.
Stage 1
Before glaciation –
V-shaped river valley
Stage 2
During Ice Age – glacier
moves down valley
rocks frozen
into ice
Stage 3
Stage 4
Glacier deepens, straightens
and widens the valley by
plucking and abrasion – the
ground moraine acts like the
teeth of a file.
After ice melts – U-shaped
valley remains.
GEOGR APHY: LANDSCAPES
71
GLACIATED UPLANDS
(f)
Truncated Spur
This is a shoulder of high land which slopes gently near the top, but is
very steep at the bottom – often with cliffs which can be a playground
for rock climbers, for example the Three Sisters in Glencoe.
Fig 3.10: Contour pattern of truncated spur
steep slope
which may have
cliffs
gentle
slope
On OS maps contours have a
horseshoe shape, but do not
confuse this with a corrie –
check which way the land is
sloping. Hint – look at
stream directions.
500
30
0
200
400
Before glaciation a V-shaped river valley in an upland area would have
had gently sloping interlocking spurs on either side. However, the
movement of a glacier down the valley chops off or truncates the
spurs(Fig 3.11).
Fig 3.11
interlocking spurs
before glaciation
(g)
truncated spurs
after glaciation
Hanging Valley
This is a side (tributary) valley of a larger U-shaped valley. It is smaller
than the main valley and its floor is at a higher level than the main valley
floor. The stream flowing from a hanging valley often cascades over
waterfalls into the main valley. A good example is the Lost Valley in
Glencoe.
72
GEOGR APHY: LANDSCAPES
GLACIATED UPLANDS
Fig 3.12: Contour pattern of a hanging valley
gentle slope
260
400
main valley floor
misfit stream
waterfall
hanging valley
During glaciation the small side valley contains less ice than the main
valley. Therefore it is not as deeply eroded as the main valley (Fig 3.13).
Fig 3.13: Formation of a hanging valley
small side glacier does
not erode as deeply as
main glacier
when ice melts side valley
is left 'hanging' above the
main valley
main glacier
after glaciation
during glaciation
waterfall
(h)
Ribbon Lake
This is a long narrow lake occupying a U-shaped valley. It can provide
opportunities for sailing and other water sports, for example Lake
Windermere in the Lake District, Loch Earn in the Scottish Highlands.
GEOGR APHY: LANDSCAPES
73
GLACIATED UPLANDS
When the glacier eroded the U-shaped valley, some parts of the valley
floor, where the rock was less resistant, were more deeply eroded.
When the ice melted, water gathered in the overdeepened hollow to
form the lake.
Fig 3.14: Ribbon lake
200
100
ribbon lake
100
200
74
GEOGR APHY: LANDSCAPES
GLACIATED UPLANDS
Activity Sheets
Outcomes
Intermediate 1 and Intermediate 2
Knowledge and Understanding
Distribution of glaciated uplands in the British Isles.
Identification of main scenic areas of glaciated uplands in the British
Isles.
Characteristics, formation and named examples of the following
landscape features:
corrie, tarn, pyramidal peak, arête, U-shaped valley.
GMTs
Identify examples of the above features from photographs, sketches,
diagrams and OS maps.
Draw annotated sketches from photographs.
Draw cross-sections.
Orientate OS maps to identify named places in landscape views.
Intermediate 2
As above plus landscape features:
truncated spur, hanging valley, ribbon lake.
GEOGR APHY: LANDSCAPES
75
GLACIATED UPLANDS
Section 3 (a): Introduction
1.
Look at Fig Q1, showing the glaciated uplands of the British Isles.
With the help of an atlas match the numbers on the map to the
following scenic areas:
Torridon
Cairngorms
Macgillacuddy’s Reeks
Cuillin Hills
Arran
Ben Nevis/Glencoe
Loch Lomond
Snowdonia National Park
Lake District National Park
Fig Q1: Glaciated uplands in the British Isles
3
1
4
2
8
5
6
9
7
Section 3 (b): Corrie and Tarn
2.
Describe the appearance of a corrie.
3.
What words on a map would identify a corrie in
(a)
(b)
(c)
76
Scotland?
the Lake District?
North Wales?
GEOGR APHY: LANDSCAPES
GLACIATED UPLANDS
4.
Name two outdoor sporting activities that can take place in corries.
5.
Draw a series of annotated diagrams to explain how a corrie is
formed.
6.
Explain how a tarn is formed.
Section 3 (c): Arête
7.
Describe the appearance of an arête.
8.
Name an example of an arête in the British Isles.
9.
Use annotated diagrams to explain how an arête is formed.
Checkpoint 1
STUDENT
CHECK
Answers
1–4, 7, 8
TEACHER
CHECK
Answers
5, 6, 9
Section 3 (d): Pyramidal Peak
10.
Describe the appearance of a pyramidal peak.
11.
Name an example of a pyramidal peak in the British Isles.
12.
With the help of annotated diagrams explain how a pyramidal peak
is formed.
Section 3 (e): U-shaped Valley
13.
Describe the appearance of a U-shaped valley.
14.
Name an example of a U-shaped valley in the British Isles.
15.
Draw a series of annotated diagrams to explain how a U-shaped
valley is formed.
GEOGR APHY: LANDSCAPES
77
GLACIATED UPLANDS
Section 3 (f): Truncated Spur
16.
Describe the appearance of a truncated spur.
17.
Name examples of truncated spurs in Scotland.
18.
Explain how a truncated spur is formed.
Section 3 (g): Hanging Valley
19.
Describe the characteristics of a hanging valley.
20.
Name an example of a hanging valley in Scotland.
21.
With the aid of diagrams explain how a hanging valley is formed.
Section 3 (h): Ribbon Lake
22.
What is a ribbon lake?
23.
Name two examples of ribbon lakes in the British Isles.
24.
Explain how a ribbon lake is formed.
Checkpoint 2
STUDENT
CHECK
25.
Answers
10, 11, 13, 14
16, 17, 19, 20
22, 23
TEACHER
CHECK
Answers
12, 15, 18
21, 24
Look at Fig Q25.
Match the numbers to the correct landscape features choosing
from:
corrie; tarn; arête; pyramidal peak; U-shaped valley; truncated
spur; hanging valley; ribbon lake.
78
GEOGR APHY: LANDSCAPES
GLACIATED UPLANDS
Fig Q25: Glaciated mountain landscape
6
6
7
7
8
8
8
26.
(a)
Look at Fig Q26 on the next page.
(i)
Copy the framework below and draw a cross-section from X-Y.
(NB: the contour interval on the map is 25m).
m
m
700
700
600
600
500
500
400
400
300
300
200
200
100
100
X
(ii)
Y
What shape is the valley?
GEOGR APHY: LANDSCAPES
79
GLACIATED UPLANDS
26.
(b)
Look at the contour map (Fig Q26) and Figs 3.2, 3.4, 3.6, 3.8,
3.10, 3.12 and 3.14 in the Information Book. Match the
numbers to the correct landscape features, choosing from:
corrie; tarn; pyramidal peak; arête; hanging valley; ribbon
lake; truncated spur; U-shaped valley; waterfall.
Fig Q26
725
825
1
90
0
3
2
4
5
750
X
6
650
500
400
7
300
8
Key
cliffs
contour line
300
lake
400
500
river
Y
Scale 1: 25 000
80
GEOGR APHY: LANDSCAPES
9
GLACIATED UPLANDS
27.
Look at Fig Q27.
Draw a simple sketch and label it to show the following features:
arête; pyramidal peak; corrie; tarn; truncated spur.
Fig Q27: An Teallach, NW Highlands of Scotland
Photo: British Geological Survey, © NERC. All rights reserved.
OS map 1:50,000 Aviemore
28.
Look at the map and Fig Q28.
(a)
Match numbers 1 to 6 to the place names below. (Hint – first
orientate the map so that you are looking in the same
direction as the view.)
Braeriach
Ben Macdui
Pools of Dee
Lurcher’s Crag
Coire an Lochain
Devil’s Point
GEOGR APHY: LANDSCAPES
81
GLACIATED UPLANDS
(b)
Match the letters A to D to the landscape features below:
U-shaped valley; truncated spur; tarn; corrie.
Fig Q28: View from aeroplane, looking south from above
Castle Hill (958058)
Lairig Ghru
Carn-a'Mhaim
A
Corrour Bothy
Cairn Toul
D
3
4
1
B
5
C
6
2
Checkpoint 3
STUDENT
CHECK
82
Answers
25, 26(b),
28
GEOGR APHY: LANDSCAPES
TEACHER
CHECK
Answers
26(a), 27
GLACIATED UPLANDS
29.
Look at the Aviemore map and Fig Q29
(a)
Match numbers 1 to 5 to the place names below:
Ben Macdui
Loch Etchachan
Loch Avon
(b)
Beinn Mheadhoin
Cairn Gorm
Match letters A and B and numbers 3 and 4 to the landscape
features below:
truncated spur; tarn; ribbon lake; hanging valley.
Fig Q29: View from aeroplane, looking south west from above
A’Choinneach (032048)
1
3
2
5
A
B
4
Checkpoint 4
STUDENT
CHECK
Answer
29
GEOGR APHY: LANDSCAPES
83
GLACIATED UPLANDS
OS Project Map 1:50,000 Fort William
30.
Match the landscape features on the left to the correct grid
references on the right.
Pyramidal peak
Corrie
Truncated spur
U-shaped valley
Arête
Hanging valley
Tarn
1871
1272
178717
148654
180687
150745 to 165725
198739
Checkpoint 5
STUDENT
CHECK
Answer
30
OS Project Map 1:50,000 Torridon
31.
Match the landscape features on the left to the correct grid
references on the right.
Truncated spur
Arête
Ribbon lake
Pyramidal peak
U-shaped valley
Corrie
Tarn
Hanging valley
8552
866613
794426
803470
887528 to 899512
817447
7448
7943
Checkpoint 6
STUDENT
CHECK
84
Answer 31
GEOGR APHY: LANDSCAPES
GLACIATED UPLANDS
Extension exercises
OS Project Map 1:50,000 Fort William
E1
In the framework below draw a cross-section from 140760 to
170720
metres
metres
800
800
700
700
600
600
500
500
400
400
300
300
200
200
100
100
E2
Why does the slope steepen at 147753?
E3
What type of valley has the section been drawn along?
E4
Use resources provided by your teacher to help you describe
and explain the formation of the following features of
glaciation:
roche moutonnée; esker; drumlin.
TEACHER
CHECK
Answers
E1–E4
GEOGR APHY: LANDSCAPES
85
UPLAND LIMESTONE LANDSCAPES
SECTION FOUR
Information Book
(a)
Introduction
Limestone is a grey sedimentary rock which was laid down in layers
(beds) on ancient sea floors. It usually contains fossils like coral and
shell fragments. Earth movements have lifted these rocks high above sea
level in parts of the British Isles. Since it is harder than most
sedimentary rocks, these areas have remained as uplands, usually over
300m high.
Section One explained the way in which limestone is chemically
weathered. The rock reacts with and is dissolved by rainwater. This
unique property of limestone creates a very distinctive landscape, often
referred to as karst after an area of Yugoslavia where this type of
landscape is well developed.
The main upland limestone areas of the British Isles were deposited
during the Carboniferous period between 345 and 310 million years ago.
Three very significant areas are the Yorkshire Dales, the Peak District
and the Mendip Hills.
(b)
Limestone Pavement, Clints and Grikes
Limestone is composed of separate beds. The top surface of each bed is
called a bedding plane. Within each bed there are vertical cracks called
joints.
During the Ice Age these upland areas were scraped over by moving ice.
This removed the soil over large areas and exposed the top bedding
plane of the limestone. This exposed surface is known as a limestone
pavement (Fig 4.1). A well known example is at Malham in North
Yorkshire.
86
GEOGR APHY: LANDSCAPES
UPLAND LIMESTONE LANDSCAPES
Fig 4.1: Limestone pavement
pavement
soil
bedding
plane
joint
beds of
limestone
On 1:25,000 OS maps pavements can be identified by rock outcrop
symbols on high, flat or gently sloping land.
Rainwater will tend to soak into the vertical joints on the pavement and
dissolve the limestone. Consequently the joints become widened into
grooves called grikes (Fig 4.2). The small blocks of limestone left
standing between the grikes are called clints (Fig 4.2).
Fig 4.2: Formation of clints and grikes
clint
after
before
gryke
well-jointed
limestone
joints attacked by
solution
(c)
joint
Swallow Holes and Intermittent Drainage
Where the joints have been considerably enlarged by solution, water can
seep downwards. A rock such as limestone which allows water to pass
through it is said to be permeable. A rock which does not let water
through is impermeable.
GEOGR APHY: LANDSCAPES
87
UPLAND LIMESTONE LANDSCAPES
When a stream flows onto limestone it enlarges the joints over which it
flows. Eventually, when a joint has been enlarged sufficiently the stream
will disappear underground and flow down potholes and along
underground channels, which have been formed by water dissolving the
limestone along joints and bedding planes (Fig 4.3). The stream also
erodes the channels by the usual process of river erosion (see Section
One). A popular sport in limestone country is potholing where people
climb down and explore these underground passages.
Fig 4.3: Formation of a swallow hole
River on surface
Joint
Stage 1
Bedding plane
Beds of
limestone
Swallow hole
Stage 2
Cave
Joints
widened
Underground stream
The point at which a stream disappears underground is called a swallow
hole, for example Gaping Ghyll on Ingleborough in the Pennines.
The underground stream will work its way down through the limestone
until it reaches an impermeable rock, over which it flows until it reemerges at the surface (Fig 4.4).
Fig 4.4: Cross-section showing the course of Fell Beck on the south-east
slopes of Ingleborough
Fell Beck Gaping Ghyll
Ingleborough
stream re-emerges
limestone
impermeable rock
88
GEOGR APHY: LANDSCAPES
Fell Beck flows
underground
UPLAND LIMESTONE LANDSCAPES
Thus, on an OS map there will be very few streams marked on parts of
the map where the rock is limestone. Where there is a mixture of
limestone and impermeable rocks, streams will disappear and then reappear – intermittent drainage.
(d)
Caverns
Where underground rivers are particularly effective in weathering and
eroding the limestone, caves will form. These can be enlarged into large
caverns if the roof of the cave collapses (Fig 4.5).
swallow hole
Fig 4.5
cavern
cave
(e)
collapsed blocks on
cavern floor
Gorges
A gorge is a deep, steep-sided narrow valley. One theory for the
formation of gorges in limestone areas is that the rocks above a series of
caves and caverns have collapsed to produce a gorge (Fig 4.6). Cheddar
Gorge in the Mendip Hills is a well known example. Because limestone
is permeable there is not much freeze-thaw action on the sides of the
gorge, so they remain steep.
Fig 4.6: Formation of a gorge
Stage 1
surface
impermeable rock
cave
Stage 2
gorge
roof collapsed
GEOGR APHY: LANDSCAPES
89
UPLAND LIMESTONE LANDSCAPES
(f)
Stalactites and Stalagmites
A stalactite is an icicle-shaped piece of limestone hanging from the
ceiling of a cave.
A stalagmite is a stumpy column of limestone sticking up from the floor
of a cave.
The water that seeps down through the limestone is heavily loaded with
dissolved lime. Where the water drips from a cave roof a small amount
of water will evaporate and leave a tiny deposit of lime. This is repeated
every time water drips from the roof, so that in time the lime deposits
grow down to form a stalactite (Fig 4.7).
In a similar way lime is deposited on the floor of the cave where the
drips land and these deposits build up to form a stalagmite. The splash
spreads the lime so that stalagmites are thicker than stalactites (Fig 4.7).
Fig 4.7: Formation of stalactites and stalagmites
ceiling of cave
floor of cave
stalactite – growing
down as lime is
deposited
stalagmite –
growing up as
lime is deposited
Eventually the stalactite and the stalagmite may meet to form a solid
pillar (Fig 4.8):
pillar
stalactite and
stalagmite join
at this point
90
GEOGR APHY: LANDSCAPES
UPLAND LIMESTONE LANDSCAPES
Activity Sheets
Outcomes
Intermediate 1 and Intermediate 2
Knowledge and Understanding
Distribution of Upland Limestone areas in the British Isles.
Characteristics, formation and named examples of the following
landscapes features:
pavements; swallow holes; caverns; stalactites; stalagmites; gorges.
GMTs
Identify examples of the above features from photographs, sketches,
diagrams and OS maps.
Draw annotated sketches from slides or photographs.
Intermediate 2
As above plus landscape features:
clint, gryke, intermittent drainage.
GEOGR APHY: LANDSCAPES
91
UPLAND LIMESTONE LANDSCAPES
Information Book Section 4 (a): Introduction
1.
Describe the appearance of limestone.
2.
Name two fossils often found in limestone.
3.
Limestone was originally deposited on the sea bed. Why does it
now form hilly areas in parts of the British Isles?
4.
What property of limestone gives it such distinctive landscape
features?
5.
What name is often given to limestone landscapes?
6.
How old are the limestone rocks which make up the upland
limestone areas of the British Isles?
7.
The map (Fig Q7) shows the outcrop of Carboniferous limestone
in the British Isles. The numbered areas show scenically important
uplands. With the help of an atlas match the numbers to the
following areas:
the Burren in Western Ireland
Mendip Hills
Pennines
North Wales
Brecon
Yorkshire Dales
Peak District
Checkpoint 1
STUDENT
CHECK
92
Answers
1–7
GEOGR APHY: LANDSCAPES
UPLAND LIMESTONE LANDSCAPES
Fig Q7: Carboniferous limestone areas in the British Isles
areas of carboniferous
limestone
4
5
6
1
7
2
3
Section 4 (b): Limestone Pavement, Clints and Grikes
8.
What is a limestone pavement?
9.
Why is there no soil on the pavement?
10.
What are clints?
11.
What are grikes?
12.
Using an annotated diagram explain how clints and grikes are
formed.
GEOGR APHY: LANDSCAPES
93
UPLAND LIMESTONE LANDSCAPES
13.
Look at Fig Q13 (or a slide). Draw a sketch and label it to show:
limestone pavement; clint; grike.
Fig Q13: Malham, Yorkshire Dales
Photo: British Geological Survey, © NERC. All rights reserved.
Checkpoint 2
STUDENT
CHECK
Answers
8–11
TEACHER
CHECK
Answers
12, 13
Section 4 (c): Swallow Holes and Intermittent Drainage
14.
What word is used to describe a rock which allows water to pass
through it?
15.
What word describes a rock which does not allow water to pass
through it?
16.
Which of these two words applies to limestone?
17.
Describe the process by which underground channels and potholes are formed in limestone.
94
GEOGR APHY: LANDSCAPES
UPLAND LIMESTONE LANDSCAPES
18.
What is a swallow hole?
19.
Name an example of a swallow hole in the British Isles.
20.
What term is used to describe a drainage pattern where streams
disappear at the surface and then re-appear farther downstream?
21.
Fig 4.4. shows the course of the stream Fell Beck.
(a)
(b)
Why does it disappear?
Why does it re-emerge at the surface?
Section 4 (d): Caverns
22.
Explain how a cavern is formed.
Section 4 (e): Gorges
23.
What is a gorge?
24.
Describe how a gorge may be formed in limestone areas?
25.
Name an example of a gorge in a limestone area.
Checkpoint 3
STUDENT
CHECK
Answers
14–21,
23, 25
TEACHER
CHECK
Answers
22, 24
Section 4 (f): Stalactites and Stalagmites
26.
Describe the appearance of a stalactite.
27.
Describe the appearance of a stalagmite.
28.
With the aid of an annotated diagram describe how stalactites and
stalagmites are formed.
GEOGR APHY: LANDSCAPES
95
UPLAND LIMESTONE LANDSCAPES
29.
30.
Look at Fig Q29.
(a)
Draw a sketch and
label it to show a
stalactite and a
stalagmite.
(b)
In what sporting
activity is the man in
the picture engaged?
Look at the block diagram (Fig Q30). Match the numbers to the
following features:
cavern
swallow hole
beds of limestone
limestone pavement
re-emerging stream
gorge
impermeable rock
Fig Q30
3
1
5
³
³
³
³
2
96
GEOGR APHY: LANDSCAPES
4
7
6
UPLAND LIMESTONE LANDSCAPES
31.
Look at Fig Q31 on the next page.
Match the numbers 1 to 5 to the following landscape features:
re-emerging stream; swallow hole; limestone beds; pavement;
gorge.
GEOGR APHY: LANDSCAPES
97
Fig Q31: Malham area, Yorkshire Dales viewed from the south.
UPLAND LIMESTONE LANDSCAPES
98
GEOGR APHY: LANDSCAPES
UPLAND LIMESTONE LANDSCAPES
Checkpoint 4
STUDENT
CHECK
Answers
26, 27
30, 31
TEACHER
CHECK
Answers
28, 29
OS Map Extract 1:25,000 Malham
32.
Match the grid references on the right to the correct landscape
features on the left.
swallow hole
limestone pavement
re-emerging stream
gorge
915643
903646
894657
897642
OS Map Extract No 1056/OLM2 1:25,000 Ingleton
33.
Look at grid square 6977.
What evidence is there that this area is limestone?
34.
Look at grid square 7176.
The NW half of this square contains symbols for rock outcrop. What
feature is this? (Hint – look at contours to establish steepness of
slope.)
Checkpoint 5
STUDENT
CHECK
Answers
32–34
GEOGR APHY: LANDSCAPES
99
UPLAND LIMESTONE LANDSCAPES
Extension exercises
OS Project Map 1:50,000 Wensleydale
E1.
Look at grid square 9891.
Give two pieces of evidence that the underlying rock is
limestone.
E2.
Look at the grid squares below
9993
9095
9494
8683
Which two squares contain limestone? Explain your answer.
E3.
At which of the grid references below is there a swallow hole?
878826
E4.
958858
009958
986817
Using resources provided by your teacher find out how the
following features are formed:
scars; dry valleys; shake holes.
Checkpoint 6
STUDENT
CHECK
100
Answers
E1–E3
GEOGR APHY: LANDSCAPES
TEACHER
CHECK
Answer
E4
COASTAL LANDSCAPES
SECTION FIVE
Information Book
(a)
Introduction
The coastline of the British Isles provides spectacular and varied
scenery, ranging from long, sandy beaches to rugged, windswept cliffs.
For many years beaches have attracted tourists in large numbers for
swimming and sunbathing and have provided the sites for major seaside
resorts such as Blackpool, Brighton and Margate. The wilder, craggier
coasts also attract visitors for their natural beauty, wildlife, walking and
climbing. The Pembroke coast in SW Wales is a National Park.
Section One(f) showed that our coastline is shaped by the action of
waves. The landscape features created by wave action are now
examined.
(b)
Headlands and Bays
The hardness of rocks varies, so that certain rocks are more easily
eroded than others. Thus, a soft rock like mudstone will be quickly
eroded to form a bay, whereas a hard rock like granite will be eroded
much more slowly and be left protruding into the sea as a headland.
The sand and pebbles eroded from the headlands are washed by the
waves into bays and are deposited as beaches (Fig 5.1).
Fig 5.1
headland
hard rock
waves
beach
waves
soft rock
hard rock
GEOGR APHY: LANDSCAPES
101
COASTAL LANDSCAPES
(c)
Cliffs
These form where the land slopes towards the sea (Fig 5.2).
Fig 5.2
waves erode the land between
high tide and low tide levels
Stage 1
level of high tide
level of low tide
Stage 2
overhang
high tide
low tide
a notch is
created
Stage 3
overhang collapses
high tide
low tide
Stage 4
further action produces
another notch
high tide
low tide
102
GEOGR APHY: LANDSCAPES
COASTAL LANDSCAPES
Stage 5
cliff moves back
wave-cut platform
high tide
low tide
cliff continues to collapse and move back as waves erode its base
If the rocks are hard or sloping inwards the cliff will tend to be steep
(Fig 5.3). However, if they are soft or outward sloping, the cliff will be
less steep (Fig 5.4).
Fig 5.3
Fig 5.4
GEOGR APHY: LANDSCAPES
103
COASTAL LANDSCAPES
(d)
Caves, Arches and Stacks
The weakest part of a sea cliff will be eroded most deeply. Therefore, at
these weak points caves will form (for example, Fingal’s Cave, Island of
Staffa). If the weakness runs right through a headland then caves will
form on opposite sides. Eventually, as the back of each cave continues
to be eroded, the waves will break right through the headland to form
an arch (for example, Durdle Door, Dorset). In time the roof of the
arch will collapse to leave an upstanding block of rock called a stack (for
example, the Old Man of Hoy, Orkney).
Fig 5.5: Stages in the formation of cave, arch and stack
cave
Stage 1
weakness
waves erode weak rock in headland to form a cave
arch
Stage 2
cave is eroded so deeply that it meets another cave, forming arch
stack
Stage 3
roof of arch collapses
104
GEOGR APHY: LANDSCAPES
COASTAL LANDSCAPES
(e)
Spit, Bar and Tombolo
A spit is a strip of sand or shingle sticking out from the shore.
A bar is a ridge of sand, mud or shingle separating the sea from a lagoon.
A tombolo is a narrow ridge of sand or shingle linking two islands or an
island to the mainland.
All three of these features result from the following process (Fig 5.6).
Fig 5.6 shows what happens when waves break at an angle to the coast.
Fig 5.6
Every time a wave breaks it washes sand up the beach at an angle. (Fig
5.6 shows the movement of one sand grain.) However, the water
washes straight back down the slope of the beach taking sand with it.
Therefore, as the diagram shows, sand is moved along the beach. This
process is called longshore drift.
If sand is drifted in this way across a bay, a spit of sand is formed. If a
spit forms across a river mouth then the position of the mouth is forced
to change.
GEOGR APHY: LANDSCAPES
105
COASTAL LANDSCAPES
Fig 5.7: Spit
A good example is Spurn Head at the mouth of the River Humber.
If the sand drifts right across a bay it forms a bar with a lagoon behind
(Fig 5.8), for example Slapton Sands, Devon.
Fig 5.8: Bar and lagoon
bar
lagoon
waves
106
GEOGR APHY: LANDSCAPES
COASTAL LANDSCAPES
If the drifted sand connects an island to the mainland, this is called a
tombolo (fig. 5.9), for example Chesil Beach which connects the Island
of Portland to the Dorset Coast.
Fig 5.9: Tombolo
tombolo
island
waves
To prevent longshore drift, barriers called groynes are built at right
angles to the coast. On an OS map it may be possible to work out the
direction of longshore drift by looking at the shapes the sand makes
between the groynes (Fig 5.10).
Fig 5.10
coast
groyne
waves
GEOGR APHY: LANDSCAPES
107
COASTAL LANDSCAPES
Activity Sheets
Outcomes
Intermediate 1 and Intermediate 2
Knowledge and Understanding
Identification of main scenic areas associated with coastal landscapes.
Characteristics, formation and named examples of landscape features:
cliffs; caves; stacks; headlands; bays.
GMTs
Identify examples of the above features on photographs, sketches and
OS maps.
Draw annotated sketches from photographs.
Intermediate 2
As above plus landscapes features:
arches; spits; bars; tombolos.
108
GEOGR APHY: LANDSCAPES
COASTAL LANDSCAPES
Information Book Section 5 (a): Introduction
1.
Describe the attraction of coastlines for holiday-makers.
2.
Look at Fig Q2 showing popular beach resorts in the British Isles.
With the help of an atlas match the numbers to the resorts listed
below:
Brighton
Blackpool
Largs
Colwyn Bay
Clacton
Bognor Regis
Newquay
Aberystwyth
Skegness
Weston-super-Mare
Margate
Torquay
Great Yarmouth
Southport
Scarborough
Bournemouth
Morecambe
Eastbourne
Southend
Fig Q2: Popular beach holiday resorts in the British Isles
19
9
10
11
12
20
1
17
2
8
15
13
3
16
4
7
6
5
18
14
GEOGR APHY: LANDSCAPES
109
COASTAL LANDSCAPES
3.
Explain why most large seaside resorts are in the south of the
British Isles.
Checkpoint 1
STUDENT
CHECK
Answers
1-3
Workcard
Do the experiment or VIDEO .
4.
Do the waves erode both kinds of ‘rock’ at the same speed?
5.
Where exactly on the cliff do the waves cut into the rock?
6.
Which kind of ‘rock’ forms a headland? Explain your answer.
Section 5 (b): Headlands and Bays
7.
Name a type of rock which would be likely to form a headland.
8.
Copy Fig Q8 and, in the correct places, add the labels below:
bay; beach; headland.
Write the letter E where erosion is taking place and D where
deposition is occurring.
Fig Q8
110
GEOGR APHY: LANDSCAPES
COASTAL LANDSCAPES
9.
Study Fig Q9A and Fig Q9B and answer the questions.
Fig Q9A: Rock types around Swanage
Fig Q9B: Sketch of Ballard Down looking west
(a)
(b)
(c)
(d)
(e)
(f)
Which rock forms the highest ground in the sketch?
Which rock forms the low ground to the left?
Which rocks form the low ground on the far right?
Explain the variations in height that you have observed.
Which two rocks form headlands? Explain your answer.
Which rocks are eroded to form bays? Explain your answer.
Checkpoint 2
STUDENT
CHECK
Answers
4–9
GEOGR APHY: LANDSCAPES
111
COASTAL LANDSCAPES
Section 5 (c): Cliffs
10.
Draw labelled diagrams to explain the formation of a sea cliff.
11.
Look at Fig Q11.
Draw a simple sketch and label it to show:
cliff; wave-cut platform; high tide level; low tide level and where
wave erosion is occurring.
Fig Q11: Cuckmere Haven, Sussex
Photo: British Geological Survey, © NERC. All rights reserved.
12.
What two factors could explain why a cliff is particularly steep?
13.
What happens to the position of a cliff as it continues to be eroded
by waves?
14.
Look at Fig Q14.
Why should the diver have known that the water would be shallow?
112
GEOGR APHY: LANDSCAPES
COASTAL LANDSCAPES
Fig Q14
If he'd studied Geography he would
have known that water was shallow
O.S. Map Extract No 830/0148-9 1:25,000 Banff/MacDuff
15.
Match the landscape descriptions on the left to the correct grid
references on the right and for each state whether erosion or
deposition is occurring.
Sandy beach in a bay
Headland and wave-cut platform
Shingle beach
658659
665649
695642
OS Map Extract No 645/66 1:50,000 Haddington
16.
Match the landscape descriptions on the left to the correct grid
reference on the right and for each state whether erosion or
deposition is occurring.
Headland
Bay with sandy beach
Bay with shingle beach
Wave-cut platform
447785
438775
461830
475833
Checkpoint 3
STUDENT
CHECK
Answers
12–16
TEACHER
CHECK
Answers
10, 11
GEOGR APHY: LANDSCAPES
113
COASTAL LANDSCAPES
Section 5 (d): Caves, Arches and Stacks
17.
Using annotated diagrams explain how each of these features is
formed:
cave; arch; stack.
18.
Name a British example of
(a)
(b)
(c)
19.
cave
arch
stack.
Look at Fig Q19.
Match the numbers 1 to 8 to the following features:
beach
headland
cave
stack
arch
cliff
wave-cut platform
bay
Fig Q19
7
6
4
1
5
2
3
Section 5(e): Spit, Bar and Tombolo
20.
What is a spit?
21.
Name an example of a spit in the British Isles.
22.
What is a bar?
114
GEOGR APHY: LANDSCAPES
8
COASTAL LANDSCAPES
23.
Name an example of a bar in the British Isles.
24.
What is a tombolo?
25.
Name an example of a tombolo in the British Isles.
26.
With the aid of a diagram explain the process of longshore drift.
27.
Draw labelled diagrams to show how longshore drift can create:
(a)
(b)
(c)
28.
a spit
a bar
a tombolo
How can longshore drift be prevented?
OS Map Extract No 866/134 1:50,000 Great Yarmouth
29.
Look at the course of the River Bure.
(a)
What happens to the direction of the river’s course as it nears
its mouth?
(b)
Longshore drift has caused the mouth to move. In which
direction are waves moving sand along the coast?
30.
On what landscape feature has the north-east half of Great
Yarmouth been built?
31.
At Gorleston Cliffs (5302), what has been built to prevent
longshore drift removing sand from the beach?
32.
At 529114, what has been built to protect the coast from erosion?
Checkpoint 4
STUDENT
CHECK
Answers
18–25
28–32
TEACHER
CHECK
Answers
17, 26
27
GEOGR APHY: LANDSCAPES
115
COASTAL LANDSCAPES
OS Map Extract No 972/195 1:50,000 Bournemouth
33.
Match the landscape features on the left to the correct grid
references on the right.
Tombolo
Bar
Lagoon
Spit
Mud beach
Headland with cliffs
182912
178904
045876
046889
032881
029880
34.
In which two ways is the coast being protected in grid square 1590?
35.
In which direction is longshore drift occurring at
(a)
(b)
048880
185915?
Give reasons for your answers.
Checkpoint 5
STUDENT
CHECK
116
Answers
33–35
GEOGR APHY: LANDSCAPES
COASTAL LANDSCAPES
36.
Look at Fig Q36.
With the help of an atlas match the numbers on the map to the
scenic coastal features listed below:
Great Ormes Head
Durdle Door (near Swanage) – arch
White Cliffs of Dover
Land’s End – headland
Old Man of Hoy – stack
Fingal’s Cave (Staffa)
Chesil Beach – tombolo
Spurn Head – spit
Giant’s Causeway – wave-cut platform
Pembrokeshire National Park – caves, arches, stacks
Seven Sisters (East Sussex) – chalk cliffs
Bow Fiddle (near Buckie) – arch
Old Man of Stoer (near Lochinver) – stack
Flamborough Head
Slapton Sands (near Dartmouth) – bar
Sands of Forvie (near Ellon) – dunes
The Needles (Isle of Wight) – stacks
GEOGR APHY: LANDSCAPES
117
COASTAL LANDSCAPES
Fig Q36: Scenic coastal features of the British Isles
17
1
West coasts of Ireland
and Scotland have
numerous spectacular
features
2
3
16
15
4
14
5
13
6
12
10
7
11
9
Checkpoint 6
STUDENT
CHECK
118
Answer
36
GEOGR APHY: LANDSCAPES
8
COASTAL LANDSCAPES
Extension exercises
OS Map Extract No 645/66 1:50,000 Haddington
E1.
Describe the coastline between Ferny Ness (440776) and
Black Rocks (483846). Mention beach deposits, wave cut
platforms, headlands, bays, river mouth, etc. Quote
appropriate grid references.
E2.
Using resources supplied by your teacher, explain how the
following features are formed:
blow-hole
off-shore bar
ria
fiord
raised beach.
TEACHER
CHECK
Answers
E1, E2
GEOGR APHY: LANDSCAPES
119
COASTAL LANDSCAPES
Workcard
You will need:
Sand tray
Sand
Clay and a wavemaker (made of strong cardboard or hardboard 16cm x
8cm)
1.
Set up the sand tray with a damp sand cliff and a band of clay.
Carefully pour water into the bottom to represent the sea. Make
sure the ‘coast’ is straight.
2.
Use the wavemaker to gently make waves. Watch carefully what
happens at the coastline.
120
GEOGR APHY: LANDSCAPES
VOLCANIC LANDSCAPES
SECTION SIX
Information Book
(a)
Formation of Volcanoes
When you shake a lemonade bottle and unscrew the cap the lemonade
froths out of the bottle. This happens because unscrewing the cap
releases pressure and allows the gas bubbles to rise, carrying the
lemonade with them.
This explains how hot, gassy molten rock, called magma, can rise to the
surface from deep in the Earth. Where the Earth’s crust is weak and
breaks (faults) occur in the rock, pressure is released and magma can
rise up the break to the surface, where it flows out as lava.
As the lava cools crystals form and it solidifies into an igneous rock, such
as basalt (Fig 6.1).
Fig 6.1: Enlarged view of basalt
Note the interlocking
crystal structure
Because the crystals lock together the rock is hard. Ash may also be
blown out of the volcano, so that layers of ash and lava may build up on
top of each other to depths of many hundreds of metres.
GEOGR APHY: LANDSCAPES
121
VOLCANIC LANDSCAPES
(b)
Types of Volcano
(i)
Central Type
Magma rises up a round pipe and escapes to the surface
through an opening called a vent (Fig 6.2 and Fig 6.3).
·
Fig 6.2: Central type volcano
MAGMA RISES UP PIPE
Fig 6.3: Cross-section of central type volcano
122
GEOGR APHY: LANDSCAPES
VOLCANIC LANDSCAPES
(ii)
Fissure Type
Very runny magma rises up long cracks in the Earth’s crust.
Small cones may form along the crack (Fig 6.4).
Fig 6.4: Fissure eruption
(c)
Volcanic Activity in the British Isles
There are no active volcanoes in Britain today, but in the distant past
there have been (Fig 6.5).
Volcanic rocks were formed in the British Isles at the following times:
500 million years ago in Snowdonia, the Lake District and Southern
Ireland.
350-400 million years ago in Central Scotland, Ben Nevis, Glencoe and
the Cheviot Hills.
60 million years ago in Western Scotland and Northern Ireland.
GEOGR APHY: LANDSCAPES
123
VOLCANIC LANDSCAPES
Fig 6.5: Volcanic rocks in the British Isles
350-400 million
years old
60 million
years old
500
million
years old
During the many millions of years since the volcanoes erupted they have
been deeply eroded. Consequently, in the British Isles we do not see
the features of an active volcanic landscape such as cones and craters.
Instead we see the eroded remnants of volcanic landscapes.
(d)
Lava Plateau
(i)
124
Very runny lava, such as that which forms basalt, can flow over
very long distances before solidifying. Often these lavas come
from fissure eruptions. Huge eruptions of this type occurred
in Central Scotland 400 million years ago and in Northern
Ireland and the North-West Highlands of Scotland 60 million
years ago. Great thicknesses of basalt were left, for example
in the Antrim Plateau in Ireland and the Kilpatrick, Ochil,
Campsie, Sidlaw and Pentland Hills in Scotland. In some
places the successive lava flows give the landscape a ‘stepped’
appearance (Fig 6.6). Since the lavas are roughly horizontal,
the surface left after erosion is a relatively flat upland – a
plateau.
GEOGR APHY: LANDSCAPES
VOLCANIC LANDSCAPES
Fig 6.6: Lava flows, Antrim, Northern Ireland
In Glencoe, Ben Nevis, the Lake District and Snowdonia the
vertical faces of the lava flows provide steep crags for rock
climbing.
(ii)
Sometimes, as the lava cooled and contracted, cracks
occurred in such a way that hexagonal columns were formed
(Fig 6.7).
Fig 6.7: Columnar jointing in basalt
The most notable examples of these are at Fingal’s Cave,
Staffa and at the Giant’s Causeway, Antrim (Fig 6.8).
GEOGR APHY: LANDSCAPES
125
VOLCANIC LANDSCAPES
Fig 6.8: Giant’s Causeway, Antrim
(e)
Dykes and Sills
Magma can be injected as sheets into the overlying rock. The magma
can cool and solidify before it reaches the surface. A dyke (shaped like a
wall) is a roughly vertical sheet intrusion which cuts across other rocks.
A sill is a sheet intruded between the beds of other rocks (Fig 6.9).
Fig 6.9: Intrusion of dyke and sill into sedimentary rocks
beds of sedimentary rock
surface
sill
dyke
magma chamber
126
GEOGR APHY: LANDSCAPES
VOLCANIC LANDSCAPES
As time goes by the overlying rocks are eroded, exposing dykes and sills.
Since they consist of igneous rocks, they are hard and less easily worn
away than the surrounding sedimentary rocks, and they stand out from
the landscape (Fig 6.10).
Fig 6.10: Dyke and sill exposed by erosion
Fig 6.11 below shows a dyke protruding from the shore in Arran.
Dykes are particularly common in the West of Scotland (Fig 6.12) and in
some cases they stretch into Northern England.
GEOGR APHY: LANDSCAPES
127
VOLCANIC LANDSCAPES
Fig 6.12: Dykes in Scotland
Igneous intrusions
Dykes
As a result of their angle of intrusion sills are often eroded to give a
steep slope on one side and a gentle slope on the other (Fig 6.13).
Fig 6.13: Contour pattern of a sill
gentle slope
40
50
40
30
steep slope
30
Like lava flows, when sills cool they can crack into hexagonal columns
(Fig 6.14).
128
GEOGR APHY: LANDSCAPES
VOLCANIC LANDSCAPES
Fig 6.14: Sill at Drumadoon Point, Arran
sill with
columnar
jointing
sandstones
scree
Some well known sills in Scotland are those on which Stirling Castle and
Wallace’s Monument are sited, and Salisbury Crags in Edinburgh. Sills
are also associated with rocky outcrops on the northern approaches to
the Forth Bridge, at Kirk o’ Shotts on the M8 and at White Craigs
overlooking Loch Leven.
The Great Whin Sill extends for 130 kilometres across Northern
England, at an average thickness of 30 metres. Hadrian’s Wall, which
was built to defend the Romans in England from attacks from Scotland,
lies partly along its crest.
(f)
Volcanic Plug
Once a volcano becomes extinct the forces of weathering and erosion
start to reduce its size. Eventually all the volcanic rocks may get worn
away except for the hard igneous rock in the vent. This forms an
isolated steep hill, a volcanic plug (Fig 6.15).
Fig. 6.15: Formation of volcanic plug
volcanic
plug
original position of volcano –
now eroded (e.g., Arthur's
Seat, Edinburgh)
sedimentary
rocks
GEOGR APHY: LANDSCAPES
129
VOLCANIC LANDSCAPES
When erosion continues into the softer sedimentary rocks below, the
much harder igneous rock will form a particularly steep-sided plug (Fig
6.16).
Fig 6.16
steep-sided plug
(e.g., Dumbarton
Rock)
sedimentary rocks
igneous rock
There are a number of plugs in Central Scotland, sometimes topped by
castles, since, being steep on all sides, they form good defensive
positions. Among the best known are Arthur’s Seat and Castle Rock in
Edinburgh, Dumbarton Rock, North Berwick Law and the nearby Bass
Rock, Ailsa Craig, and Loudoun Hill near Darvel.
(g)
Crag and Tail
Some plugs are not steep on all sides but form a crag and tail – this is a
steep crag rising to a high point from where a gently sloping ridge (the
‘tail’) descends.
These features are found particularly in the East of Central Scotland.
North Berwick Law is an example and Edinburgh contains several,
including Castle Rock and Calton Hill.
They formed during the last Ice Age when an ice sheet moved eastwards
down the Forth Valley. Where the ice confronted a volcanic plug, the
hard igneous rock was not so easily eroded as the surrounding soft
sedimentary rocks. However, to the east of the plug the sedimentary
rocks were not eroded, because they were protected by the ‘shield’ of
the hard volcanic plug. Thus, the plug forms the ‘crag’ and the
protected soft sedimentary rocks, the ‘tail’ (Fig 6.17).
130
GEOGR APHY: LANDSCAPES
VOLCANIC LANDSCAPES
Fig. 6.17: Formation of crag and tail
movement of
ice
tail
crag
volcanic plug –
hard igneous rock
soft sedimentary
rocks
The most famous example is Castle Rock in Edinburgh, with the castle
being built on the crag and the Royal Mile running down the crest of the
tail (Fig 6.18).
Fig. 6.18: Edinburgh Castle and the Royal Mile – a crag and tail
Royal Mile
Princes Street
sheltered tail
formed by softer
sedimentary
rocks
crag formed by
old volcanic
plug of hard
igneous rock
direction of ice movement
GEOGR APHY: LANDSCAPES
131
VOLCANIC LANDSCAPES
Activity Sheets
Outcomes
Intermediate 2
Knowledge and Understanding
Identify main scenic areas associated with volcanic landscapes.
Characteristics, formation and named examples of the following
landscape features:
lava plateaus, dykes, sills, volcanic plugs, crag and tail.
GMTs
Identify above features on photographs, sketches and diagrams.
Draw annotated sketches from photographs.
Correlate contour map with geology map, using overlay.
Orientate OS map to identify named places in landscape views.
Conduct experiments.
132
GEOGR APHY: LANDSCAPES
VOLCANIC LANDSCAPES
TEACHER
DEMONSTRATION
1.
Your teacher will show you an experiment using
soda water or lemonade or VIDEO .
What happens when the bottle is shaken and the cap is suddenly
released?
Section 6(a): Formation of Volcanoes
2.
What is magma?
3.
What is lava?
4.
Explain how magma is able to rise from deep in the crust to the
Earth’s surface.
5.
What type of rock is formed when magma cools?
6.
Name an example of this type of rock.
7.
Explain why these rocks are hard.
8.
What other material is blown out of a volcano?
Section 6 (b): Types of Volcano
9.
Draw a diagram of a central type volcano and label its features.
10.
In what type of eruption does lava emerge from a long crack in the
Earth’s surface?
Section 6 (c): Volcanic Activity in the British Isles
11.
When were volcanoes last active in the British Isles?
12.
When were there active volcanoes in central Scotland?
13.
In which of the following parts of the British Isles were volcanoes
most recently active:
Lake District: Snowdonia: Northern Ireland: Central Scotland?
GEOGR APHY: LANDSCAPES
133
VOLCANIC LANDSCAPES
14.
Why are there no volcanic craters visible in the British Isles?
Checkpoint 1
STUDENT
CHECK
Answers
1–8
10–14
TEACHER
CHECK
Answer
9
Section 6 (d)(i): Lava Plateau
15.
Name a rock formed from very runny lava.
16.
What type of eruption often produces runny lava?
17.
What is a plateau?
18.
Name three places in the British Isles where lava plateaux are
located.
19.
Look at Fig Q19. Draw a sketch to show the main features of the
landscape. Label it to show lava flows, stepped hillside, plateau
surface.
Fig Q19: Campsie Fells
134
GEOGR APHY: LANDSCAPES
VOLCANIC LANDSCAPES
20.
Why does the hillside have a stepped appearance?
21.
What outdoor sport attracts people to the lavas of Glencoe?
Your teacher will show you what happens when
hot glass is suddenly cooled, or VIDEO .
TEACHER
DEMONSTRATION
Note: for this demonstration everyone should wear safety goggles.
22.
What happens when the glass is cooled?
Section 6 (d)(ii)
23.
When lava cools, what shapes are created as it cracks?
24.
Name two places in the British Isles where there are good
examples of this structure.
25.
Look at Fig Q25.
With the help of an atlas match the numbers to the lava plateaus
and hills below:
Cheviot Hills
Ochil Hills
Mull
Morvern
Antrim Plateau
Sidlaw Hills
Pentland Hills
Campsie Fells
Skye
Renfrew Heights
GEOGR APHY: LANDSCAPES
135
VOLCANIC LANDSCAPES
Fig Q25: Lava plateaux/hills in the British Isles
10
9
8
1
7
2
3
4
6
5
Checkpoint 2
STUDENT
CHECK
Answers
15–18
20–25
Answer
19
TEACHER
CHECK
Section 6 (e): Dykes and Sills
26.
Look at Fig Q26.
V
Fig Q26: Block diagram
V
1
1 km
136
2
GEOGR APHY: LANDSCAPES
Igneous rocks
VOLCANIC LANDSCAPES
(a)
(b)
(c)
Match numbers 1 and 2 to dyke and sill.
Which intrusion lies between the layers of other rocks?
Which intrusion cuts vertically across other rocks?
27.
Why do the dyke and sill in Fig Q26 appear at the surface?
28.
Why do they form the highest ground in Fig Q26?
29.
Look at Fig Q29. Why was the Great Whin Sill a good choice of site
for Hadrian’s Wall?
Fig Q29: Great Whin Sill
30.
Where in the British Isles are dykes most common?
31.
Why does the outcrop of a sill often have one steep and one gentle
slope?
32.
Why are sills often associated with waterfalls, for example High
Force on the River Tees?
33.
Name an island in the West of Scotland where you find dykes.
34.
Name an example of a sill in Scotland.
Checkpoint 3
STUDENT
CHECK
Answers
26–34
GEOGR APHY: LANDSCAPES
137
VOLCANIC LANDSCAPES
Section 6 (f): Volcanic Plug
35.
With the aid of a diagram explain how a volcanic plug is formed.
36.
Why do volcanic plugs have steep sides?
37.
Name three examples of volcanic plugs in Central Scotland.
38.
Why are castles often built on plugs?
39.
Look at Fig Q39.
(a)
With the help of an atlas match the numbers 1 to 3 to the
names of the sills below:
Stirling Sill, Great Whin Sill, Lomond Hill.
(b)
Match the numbers 4 to 10 to the volcanic plugs below:
Arthur’s Seat (Edinburgh)
Castle Rock (Edinburgh)
Loudoun Hill (near Darvel)
Ailsa Craig
Dumbarton Rock
North Berwick Law
Bass Rock
Fig Q39: Selected volcanic plugs and sills
1
2
10
5
Glasgow
7
9
8
6
4
Carlisle
138
GEOGR APHY: LANDSCAPES
3
VOLCANIC LANDSCAPES
Section 6 (g): Crag and Tail
40.
Describe the appearance of a crag and tail.
41.
What type of rock forms the ‘crag’?
42.
What type of rock forms the ‘tail’?
43.
Name two Scottish examples of a crag and tail.
44.
With the aid of a diagram explain the formation of a crag and tail.
45.
Look at Fig Q45A and Fig Q45B.
(a)
Name the two highest features shown on the contour map.
(b)
(i)
(ii)
(iii)
(iv)
(c)
Look carefully at the contour patterns in Fig Q45A.
Trace Fig Q45B.
Lay tracing over contour map.
Which rock type forms the highest ground?
Explain your answer to (iii)
(i) On top of what landscape feature is the castle situated?
(ii) On what feature is the Royal Mile situated?
(iii) What type of structure is Salisbury Crags?
Fig Q45A: Contour map, Edinburgh
GEOGR APHY: LANDSCAPES
139
VOLCANIC LANDSCAPES
Fig Q45B: Geology map, Edinburgh
igneous rock
igneous rock
½ mile
0
0
500m
sedimentary rock
OS Project Map 1:50,000 Edinburgh
46.
Look at Fig 46: aerial view of Edinburgh
(a)
Match the numbers 1 to 8 to the following places:
Castle
Old Town
Salisbury Crags
(b)
Waverley Station
Portobello
What numbers apply to the landscape features below
(some numbers apply to more than one feature)?
sill, plug, crag, tail.
140
Calton Hill
New Town
Arthur’s Seat
GEOGR APHY: LANDSCAPES
VOLCANIC LANDSCAPES
Fig Q46: Edinburgh – view towards east from above 247736
3
6
8
7
5
4
2
1
Photo: Aerographica/Patricia & Angus Macdonald/P & A Macdonald
Checkpoint 4
STUDENT
CHECK
Answers
36–43
45, 46
TEACHER
CHECK
Answers
35, 44
GEOGR APHY: LANDSCAPES
141
VOLCANIC LANDSCAPES
Extension exercises
Use resources provided by your teacher to help you do the
following.
E1.
Why are some lavas sticky (viscous) while others are runny?
E2.
Draw a sketch of a volcano which erupts sticky lava.
E3.
Draw a sketch of a volcano which erupts runny lava.
A blank map of the world.
E4.
Shade in the active volcanic zones of the world.
E5.
Calculate the shortest distance from Scotland to an active
volcano.
E6.
How are volcanoes of use to people?
TEACHER
CHECK
142
Answers
E1–E6
GEOGR APHY: LANDSCAPES