Download landforms?

WHAT ARE
LANDFORMS?
Think about the shape of the land where you live. Is it flat or rolling? Are
there valleys or mountains? Often, we overlook the landforms that are
around us. Landforms are the natural features that make up Earth’s surface.
Even if we don’t notice them, they are important. They affect us whether we
know it or not.
Sometimes disasters in the news remind us of how landforms affect
people. Earthquakes are deadly events that are linked to landforms. An
earthquake is the shaking of Earth’s surface due to changes taking place
beneath it. Earthquakes can trigger landslides, like the one shown in
Figure 1.1, mudslides, and tsunamis.
FIGURE 1.1 A landslide caused by an earthquake
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landforms the natural
features that make up
Earth’s surface
earthquake release of
energy through Earth’s crust
due to changes taking place
beneath it
I wonder if landslides happen in some places more than others?
UNIT 1: Physical Patterns in a Changing World
NEL
LANDFORMS AND DAILY LIFE
shield the base rock of an
ancient mountain region that
has been worn away, leaving
a flat, rocky landform region
plateau a high, flat region
that has been lifted up by
movement of Earth’s surface
plain a large, flat to gently
rolling region
In the past, especially, the landforms in a region affected people’s way of
life. They influenced the kind of food that was available and how people
obtained it. Landforms affected how people travelled and the kinds of
structures they built for shelter.
Today, landforms continue to affect the size and layout of our buildings
and communities. The forces that created shields and mountains also
helped to create the deposits of minerals that we now depend on, for
example, gold, nickel, and iron ore. Figure 1.2 shows the major landforms
around the world. A shield is the flat, rocky base created when an ancient
mountain region has been worn away. Mountains are areas of land that rise
high above the surrounding land. Movements under Earth’s surface create
high, flat plateaus.
Plains are generally flat to gently rolling stretches of land. Valleys are
depressions in the land created by running water, moving ice, or the
movement of land. We use these fertile regions to grow food. We enjoy using
the features of different landforms for recreational activities, such as skiing
and camping.
The land supports us and provides the resources that we need. But the
land is always changing. Most of the changes are taking place over millions
of years and are too slow for people to notice in one lifetime. But sometimes
the changes are sudden and severe. They may cause great damage or even
loss of life.
Major Landform Regions around the World
150˚ W 120˚ W 90˚ W 60˚ W 30˚ W
150˚EW60˚
120˚
90˚
60˚
30˚
0˚ 30˚
E W90˚
E W
120˚
E W150˚
E W 0˚ 30˚ E 60˚ E
ARCTIC OCEAN
ARCTIC OCEAN
Arctic Circle
Arctic Circle
60˚N
60˚N
60˚N
EUROPE
EUROPE
NORTH
AMERICA
NORTH
AMERICA
30˚ N
30˚ N
Tropic of Cancer
ASIA
ASIA
ATLANTIC
ATLANTIC
Tropic of Cancer
PACIFIC
OCEAN
OCEAN
PACIFIC
Equator
0˚
OCEAN
OCEAN
PACIFIC
Equator
OCEAN
SOUTH
AMERICA
0˚
INDIAN
SOUTH INDIAN
AMERICA OCEAN
OCEAN
Tropic of Capricorn
Tropic of Capricorn
AUSTRALIA
30˚ S
30˚ S
Antarctic Circle
60˚ S
60˚S
ANTARCTICA
ANTARCTICA
FIGURE 1.2 This map shows the major landform
regions
in the
Landform
Regions
world. Because valleys occur in all the other mountains
types of landforms,
plains
they are not shown separately on this map.
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0˚
0
2000 km
Antarctic Circle
150˚ W 120˚ W 90˚ W 60˚ W 30˚ W
30˚ S
N
N
0
60˚ S
30˚N
AFRICA
AFRICA
0˚
90˚ E 120˚ E 150˚ E
150˚EW60˚
120˚
90˚
60˚
30˚
30˚
E W90˚
E W
120˚
E W150˚
EW
0˚
30˚ E 60˚ E
90˚ E 120˚ E 150˚ E
Landform Regions
plateaus mountains
shields
plains
plateaus
shields
CHAPTER 1: Landform Patterns
19
2000
A
LANDFORM TYPES
The large landforms that make up most of Earth’s surface
are mountains (including fold and volcanic), plateaus,
plains, shields, and valleys. Locate each of these examples
of a landform region (Figure 1.3) on the map on page 19
(Figure 1.2). What patterns can you see? These patterns can
give us clues about how landforms were created, how they
are changing, and how they might affect humans.
What connection can I find between different landform
types and their locations on Earth?
FIGURE 1.3 (A) plain, Australia; (B) volcanic mountain, Japan, Asia;
(C) valley, Italy, Europe; (D) fold mountain, Nepal, Asia; (E) shield,
Canada, North America; (F) plateau, United States, North America
C
D
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UNIT 1: Physical Patterns in a Changing World
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B
E
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F
CHAPTER 1: Landform Patterns
21
READING
ELEVATION ON MAPS
Maps have only two dimensions: length and width. Map-makers use colours
and contour lines to show the height of landforms. Contour lines are lines
on a map used to join places of equal height above sea level, the average
level of the ocean’s surface. They show the difference between the highest
and lowest areas.
30 0 m
30 00
0m
2800m
2800m
Contour Lines
100
2 20
2 200
m
0m
0m
80
0m
20
28
26 0
26 00
0 mm
m
m
00
206 0
26
0m
0m
2040
24
20
200
00m
0m
50
m
150
26 0 0 m
26 0 0 m
22
202
00m
0
Pinnacle
Pinnacle
Mountain
Mountain
FIGURE 1.4 Contour map of a hill
0m
30
00
30
280
2 80
0m
0m
2 0
24 4
m
0 00
m
3
m
28 0 0
28 0 0 m
m
26 0 0
26 0 0 m
0m
24040 0 m
2
Elevation is the height of a location or object above sea level. Topographic
maps use contour lines to show elevation (Figure 1.4 and Figure 1.5). They
show the surface features of an area in great detail. For example, these
maps can show waterways, populated areas, and place names. Topographic
maps use symbols and colours to represent characteristics of the area,
such as roads and forests.
Any place along a contour line is at the elevation represented by that
line. Any place not on the line is either higher or lower than that elevation.
Index contour lines are contour lines with numbers that indicate the height
above sea level. You can use them to figure out the elevation of the other
contour lines.
Map-makers decide on a contour interval for their maps and then draw
FIGURE 1.5 Topographic map
lines at these intervals. A contour interval is the difference in elevation
representing an area near
between two consecutive lines. For example, if the contour interval is 5 m,
Lake Louise, Alberta
they draw a contour line at 5 m above sea level and at
each increase or decrease of 5 m. On a contour map,
Lake Louise, Alberta
lines close together show a steep slope while lines far
0m
00m
204
apart indicate a gentle slope.
MountTemple
Temple 2302000mm 0m
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Mount
200
200
0m
0m
USING CONTOUR LINES TO SHOW ELEVATION
0
23 60 m
23 60 m
index contour line
Moraine
Moraine
Lake
Lake
contour line
00
150
2
220 0m 0200
220 0m
00m
0m
24 0
2400
m
0m
NN
2240m
2240m
500mm
500
10 0
50
0
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UNIT 1: Physical Patterns in a Changing World
glacier
glacier
forest
forest
road
road
trail
trail
picnicarea
area
picnic
stream
stream
icecap
cap
ice
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N
C
Some maps use colour to show elevation (Figure 1.6). Different colours
show different categories of height, such as 0 to 100 m, 100 to 200 m,
and so on. Often, dark green shows the lowest land elevations, and light
green or brown shows the higher elevations.
Colours on maps mean different things depending on the kind of map. For
example, look at Figure 3.23 in Chapter 3. It is a map that shows the change
in the size of a forest over time. The forests are shown in two different
colours of green. However, the green colour on an elevation map only shows
a level of elevation. It does
Elevation Map of Thailand
not describe the type of
vegetation. For example,
on some elevation maps
BURMA
LAOS
much of the Sahara Desert
(MYANMAR)
is shown in green. This is
because the land is at low
elevations, not because the
area is fertile.
HI
NA
USING COLOURS TO SHOW ELEVATION
South
China Sea
THAILAND
INDIAN OCEAN
Bangkok
CAMBODIA
Elevation
3000 m
VIETNAM
1500
600
Gulf of
Thailand
300
150
FIGURE 1.6 This map of Thailand
uses colour to show elevation.
0
0
150 km
HOW TO READ
ELEVATION ON A MAP
Look at the topographic map in Figure 1.5. What
is the contour interval for this map? Why are some
contour lines on the map thicker than others?
STEP 1
STEP 2
Geography 7 SB
What other symbols can you see on the map?
0-17-659048-X
What are some
human activities in this area?
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FN
CO
C01-F02-G07SB
Crowle Art Group
Pass
Approved
Not Approved
4th pass
Are the slopes of the land steep or gentle? Do they
change? How can you tell? Describe the shape.
STEP 3
STEP 4
Suppose you were standing on the shore of
Moraine Lake talking to a friend on your cellphone.
Describe the scenery all around you to your friend.
CHAPTER 1: Landform Patterns
23
MOUNTAINS
volcano an opening in Earth’s
crust from which molten rock
or magma escapes to reach
the surface
magma extremely hot fluid
or semi-fluid material under
Earth’s crust
lava molten rock flowing
from a volcano
FIGURE 1.7 A fold mountain
I wonder why these mountains
look the way they do?
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There are mountains on every continent on Earth. There are several types
of mountains, (you can see examples of volcanic and fold mountains in
Figure 1.3B and Figure 1.3D) but they are all formed by huge movements in
Earth’s crust. The crust is the top layer of rock on the surface of Earth. Fold
mountains are the most common type of mountain (Figure 1.7). They are
created by powerful forces folding and buckling the rock layers of Earth’s
surface.
Volcanic mountains are created by volcanic eruptions. A volcano is a
mountainous landform through which fluid and semi-fluid material from
far beneath Earth’s surface escapes. This material is called magma. When
it reaches Earth’s surface, it is called lava. Sometimes it piles up in layers.
When it cools, it becomes a mountain. Sometimes, a mixture of rock and
ash spews from the mouth of a volcano. If it builds up and hardens in the
shape of a cone around the volcano’s mouth, it creates a mountain.
UNIT 1: Physical Patterns in a Changing World
NEL
SHIELDS
Shields are areas of very old rock that make up the continents. They were
formed from ancient mountain regions that have been worn down over
millions of years. Shields exist on every continent in the world.
The Canadian Shield (Figure 1.3E) is the largest landform in Canada.
Sometimes the rock of shields is exposed. Sometimes it is covered by
vegetation.
VALLEYS
A valley is an area of low land between areas of higher land. Valleys often
have a river or stream flowing through them in the direction of the slope.
They are created in several ways.
A V-shaped valley is created when rivers and streams run over the surface
of the land and carry away materials. A U-shaped valley is created when
ice moves over the rock or land and carries away materials. Sometimes
forces within Earth move layers of rock, forming cracks. The land that falls
between the cracks can become a rift valley.
PLAINS
There are plains on every continent. Plains are usually at low elevations.
Some were formed at the bottom of what were once seas. As you can see
by looking at Figure 1.3A, they are generally quite flat. However, plains can
also have areas of gently rolling hills. Plains are well suited to agriculture and
farming, such as the Interior Plains of Canada.
PLATEAUS
Plateaus are large areas of mainly flat land found at high elevations
(Figure 1.3F). While both plains and plateaus are quite flat, plateaus occur
at higher elevations than plains. Plateaus are found in mountainous regions,
sometimes between two mountains. Plateaus are created by movements
under Earth’s surface that lift the land. Another name for plateaus
is tablelands.
CHECK-IN
1. SPATIAL SIGNIFICANCE Sketch each of the five major
landform types. Add labels to identify what you
consider to be the characteristics of each landform
type. Be prepared to defend your choices.
2. PATTERNS AND TRENDS Work with a partner. Review
Figure 1.2 on page 19. Discuss the patterns in the
locations of each landform type. Also identify
the reasons why it might be useful to know the
patterns of landforms in the world.
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3. INTERRELATIONSHIPS Think of the ways that the
landforms near your home affect you and your
activities in the community. Explain your ideas
in a labelled diagram, a paragraph, podcast, or
a photo essay.
CHAPTER 1: Landform Patterns
25