Chapter 1 - Jenkins Independent Schools

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1 Views of Earth
V
iewing Earth from satellites,
often called remote sensing,
is a powerful way to learn
about Earth’s landforms, weather,
and vegetation. This colorful image
shows the metropolitan area of New
York City and surrounding regions.
Vegetation shows up as green, uncovered land is red, water is blue, and
human-made structures appear gray.
In this chapter, you will learn about
studying Earth from space. You’ll
learn about Earth’s major landforms,
and you’ll learn how to locate places
on Earth’s surface.
What do you think?
Science Journal Look at the picture
below with a classmate. Discuss what
you think this might be. Here’s a hint:
It can keep you from getting lost on
land or at sea. Write your answer or
best guess in your Science Journal.
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EXPLORE P
ACTIVITY
ictures of Earth from space are acquired by
instruments attached to satellites. Scientists
use these images to make maps because they show
features of Earth’s surface, such as mountains and
rivers. In the activity below, use a map or a globe to
explore Earth’s surface.
Describe landforms
Using a globe, atlas, or a world map,
locate the following features and describe
their positions on Earth relative to other
major features. Provide any other details
that would help someone else find them.
1. Andes mountains
2. Amazon, Ganges, and Mississippi
Rivers
3. Indian Ocean, the Sea of Japan, and
the Baltic Sea
4. Australia, South America, and North America
Observe
Choose one country on the globe or map and describe its major physical
features in your Science Journal.
FOLDABLES
Reading &Study
& Study
Skills
Making a Main Ideas Study Fold Make the following Foldable
to help you identify the major topics about landforms.
1. Stack two sheets of paper in front of you so the short side
Mountains
Plateaus
of both sheets is at the top.
Plains
2. Slide the top sheet up so about 4 cm of the bottom
sheet show.
Main Landform Types
3. Fold both sheets top to bottom to form four tabs and
staple along the fold. Turn the Foldable so the staples are at
the bottom. Cut mountain shapes on the top tab.
4. Label the tabs Main Landform Types, Plains, Plateaus, and Mountains.
Before you read the chapter, write what you know about each landform
under the tabs.
5. As you read the chapter, add to and correct what you have written.
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7
SECTION
Landforms
Plains
Discuss differences between plains
and plateaus.
■ Describe folded, upwarped, faultblock, and volcanic mountains.
■
Vocabulary
plain
plateau
folded mountain
upwarped mountain
fault-block mountain
volcanic mountain
Landforms influence how people can
use land.
Figure 1
Three basic types of landforms are
plains, plateaus, and mountains.
Earth offers abundant variety—from tropics to tundras,
deserts to rain forests, and freshwater mountain streams to saltwater tidal marshes. Some of Earth’s most stunning features are
its landforms, which can provide beautiful vistas, such as vast, flat,
fertile plains; deep gorges that cut through steep walls of rock;
and towering, snowcapped peaks. Figure 1 shows the three basic
types of landforms—plains, plateaus, and mountains.
Even if you haven’t ever visited mountains, you might have
seen hundreds of pictures of them in your lifetime. Plains are
more common than mountains, but they are more difficult to
visualize. Plains are large, flat areas, often found in the interior
regions of continents. The flat land of plains is ideal for agriculture. Plains often have thick, fertile soils and abundant, grassy
meadows suitable for grazing animals. Plains also are home to a
variety of wildlife, including foxes, ground squirrels, and snakes.
When plains are found near the ocean, they’re called coastal
plains. Together, interior plains and coastal plains make up half
of all the land in the United States.
Mountains
Plateau
Plain
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CHAPTER 1 Views of Earth
Ap
ian
Pl a
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AC
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NM
an
OU
tic
N
Coa
stal
Plain
Ozark
Plateau
pa
AL
ch
DA
Colorado
Plateau
Central
Lowlands
PP
Great
Plains
S
IN
A
T
la
CAS
CAD
ER
AN
GE
NEVA
S
TAIN
OUN
YM
CK
RO
SIE R R A
Great
Basin
Superior
Uplands
A
Major U.S. Landforms
Pacific Mountain and Valley System
Rocky Mountains
Superior Uplands
Appalachian Highlands
Coastal Plains
Interior Highlands
Interior Plains
Intermontane Plateaus and Basin
Gu
lf
At
l
ain
tal Pl
s
a
Co
Coastal Plains A coastal plain often is called a lowland
Figure 2
because it is lower in elevation, or distance above sea level, than
the land around it. You can think of the coastal plains as being the
exposed portion of a continental shelf. The continental shelf is the
part of a continent that extends into the ocean. The Atlantic
Coastal Plain is a good example of this type of landform. It
stretches along the east coast of the United States from New Jersey
to Florida. This area has low rolling hills, swamps, and marshes.
A marsh is a grassy wetland that usually is flooded with water.
The Atlantic Coastal Plain, shown in Figure 2, began forming about 70 million years ago as sediment began accumulating
on the ocean floor. Sea level eventually dropped, and the
seafloor was exposed. As a result, the coastal plain was born. The
size of the coastal plain varies over time. That’s because sea level
rises and falls. During the last ice age, the coastal plain was
larger than it is now because so much of Earth’s water was contained in glaciers.
The Gulf Coastal Plain includes the lowlands in the southern
United States that surround the Gulf of Mexico. Much of this
plain was formed from sediment deposited in deltas by the
many rivers that enter the Gulf of Mexico.
The United States has eight
major landform regions, which
include plains, mountains, and
plateaus. After looking at this
map, describe the region that
you live in.
How are coastal plains formed?
SECTION 1 Landforms
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Interior Plains The central portion of the United States is
Profiling the
United States
Procedure
1. Place the bottom edge of a
piece of paper across the
middle of Figure 2, extending from the west coast to
the east coast.
2. Mark where different landforms are located along
this edge.
3. Use a map of the United
States and the descriptions of the landforms in
Section 1 to help you draw
a profile, or side view, of
the United States. Use
steep, jagged lines to represent mountains. Low, flat
lines can represent plains.
Analysis
1. Describe how your profile
changed shape as you
moved from west to east.
2. Describe how the shape of
your profile would be different if you oriented your
paper north to south.
Figure 3
Plains and plateaus are
fairly flat, but plateaus have
higher elevation.
This
short-grass prairie in Kansas
is part of an interior plain.
The Colorado River has
carved the Grand Canyon
into the Colorado Plateau.
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CHAPTER 1 Views of Earth
comprised largely of interior plains. Shown in Figure 3, you’ll
find them between the Rocky Mountains, the Appalachian
Mountains, and the Gulf Coastal Plain. They include the Central
Lowlands around the Missouri and Mississippi Rivers and the
rolling hills of the Great Lakes area.
A large part of the interior plains is known as the Great
Plains. This area lies between the Mississippi River and the
Rocky Mountains. It is a flat, grassy, dry area with few trees. The
Great Plains also are referred to as the high plains because of
their elevation, which ranges from 350 m above sea level at the
eastern border to 1,500 m in the west. The Great Plains consist
of nearly horizontal layers of sedimentary rocks.
Plateaus
At somewhat higher elevations, you will find plateaus
(pla TOHZ). Plateaus are flat, raised areas of land made up of
nearly horizontal rocks that have been uplifted by forces within
Earth. They are different from plains in that their edges rise
steeply from the land around them. Because of this uplifting, it
is common for plateaus, such as the Colorado Plateau, to be cut
through by deep river valleys and canyons. The Colorado River,
as shown in Figure 3, has cut deeply into the rock layers of the
plateau, forming the Grand Canyon. Because the Colorado
Plateau is located mostly in what is now a dry region, only a few
rivers have developed on its surface. If you hiked around on this
plateau, you would encounter a high, rugged environment.
Mountains
Mountains with snowcapped peaks often are shrouded in
clouds and tower high above the surrounding land. If you climb
them, the views are spectacular. The world’s highest mountain
peak is Mount Everest in the Himalaya—more than 8,800 m
above sea level. By contrast, the highest mountain peaks in the
United States reach just over 6,000 m. Mountains also vary in
how they are formed. The four main types of mountains are
folded, upwarped, fault-block, and volcanic.
Research Visit the
Glencoe Science Web site at
science.glencoe.com
to learn how landforms can
affect economic development.
What is the highest mountain peak on Earth?
Folded Mountains The Appalachian Mountains and the
Rocky Mountains in Canada, shown in Figure 4, are comprised
of folded rock layers. In folded mountains, the rock layers are
folded like a rug that has been pushed up against a wall.
To form folded mountains, tremendous forces inside Earth squeeze horizontal rock layers, causing them to
fold. The Appalachian Mountains formed between 480 million
and 250 million years ago and are among the oldest and longest
mountain ranges in North America. The Appalachians once were
higher than the Rocky Mountains, but weathering and erosion
have worn them down. They now are less than 2,000 m above
sea level. The Ouachita (WAH shuh tah) Mountains of Arkansas
are extensions of the same mountain range.
Figure 4
Folded mountains form when
rock layers are squeezed from
opposite sides. These mountains
in Banff National Park, Canada,
consist of folded rock layers.
SECTION 1 Landforms
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Figure 5
The southern Rocky
Mountains are
upwarped mountains that formed
when crust was
pushed up by forces
inside Earth.
Upwarped Mountains The Adirondack Mountains in New
York, the southern Rocky Mountains in Colorado and New
Mexico, and the Black Hills in South Dakota are upwarped
mountains. Figure 5 shows a mountain range in Colorado.
Notice the high peaks and sharp ridges that are common to this
type of mountain. Upwarped mountains form when blocks of
Earth’s crust are pushed up by forces inside Earth. Over time,
the soil and sedimentary rocks at the top of Earth’s crust erode,
exposing the hard, crystalline rock underneath. As these rocks
erode, they form the peaks and ridges.
Fault-Block Mountains Fault-block mountains are made
of huge, tilted blocks of rock that are separated from surrounding
rock by faults. These faults are large fractures in rock along which
mostly vertical movement has occurred. The Grand Tetons of
Wyoming, shown in Figure 6, and the Sierra Nevada in California, are examples of fault-block mountains. As Figure 6 shows,
when these mountains formed, one
block was pushed up, while the adjacent block dropped down. This
mountain-building process produces
majestic peaks and steep slopes.
Figure 6
Fault-block mountains such as the Grand
Tetons are formed when faults occur.
Some rock blocks move up, and others
move down. How are fault-block mountains
different from upwarped mountains?
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CHAPTER 1 Views of Earth
Figure 7
Mount Shasta is a
volcanic mountain
made up of layers of
lava flows and ash.
Volcanic Mountains Volcanic mountains, like the one
shown in Figure 7, begin to form when molten material reaches
the surface through a weak area of the crust. The deposited
materials pile up, layer upon layer, until a cone-shaped structure
forms. Two volcanic mountains in the United States are Mount
St. Helens in Washington and Mount Shasta in California. The
Hawaiian Islands are the peaks of huge volcanoes that sit on the
ocean floor. Measured from the base, Mauna Loa in Hawaii
would be higher than Mount Everest.
Plains, plateaus, and mountains offer different kinds of landforms to explore. They range from low, coastal plains and high,
desert plateaus to mountain ranges thousands of meters high.
Section
Assessment
1. Describe the eight major landform regions
in the United States that are mentioned in
this chapter.
2. How do plains and plateaus differ?
3. Why are some mountains folded and
others upwarped?
4. How are volcanic mountains different from
other mountains?
5. Think Critically If you wanted to know
whether a particular mountain was formed
by movement along a fault, what would
you look for?
6. Concept Mapping Make an events-chain concept map to explain how upwarped mountains
form. For more help, refer to the Science Skill
Handbook.
7. Using an Electronic Spreadsheet Design a
spreadsheet that compares the origin and
features of the following: folded, upwarped,
fault-block, and volcanic mountains. Then,
explain an advantage of using a spreadsheet to
compare different types of mountains. For more
help, refer to the Technology Skill Handbook.
SECTION 1 Landforms
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13
SECTION
Viewpoints
Latitude and Longitude
During hurricane season, meteorologists track storms as
they form in the Atlantic Ocean. To identify the exact location of
a storm, latitude and longitude lines are used. These lines form
an imaginary grid system that allows people to locate any place
on Earth accurately.
Define latitude and longitude.
Explain how latitude and longitude are used to identify locations
on Earth.
■ Determine the time and date in
different time zones.
■
■
Latitude Look at Figure 8. The equator is an imaginary line
Vocabulary
equator
latitude
around Earth exactly halfway between the north and south
poles. It separates Earth into two equal halves called the northern hemisphere and the southern hemisphere. Lines running
parallel to the equator are called lines of latitude, or parallels.
Latitude is the distance, measured in degrees, either north or
south of the equator. Because they are parallel, lines of latitude
do not intersect, or cross, one another.
The equator is at 0° latitude, and the poles are each at
90° latitude. Locations north and south of the equator are
referred to by degrees north latitude and degrees south latitude,
respectively. Each degree is further divided into segments called
minutes and seconds. There are 60 minutes in one degree and
60 seconds in one minute.
prime meridian
longitude
Latitude and longitude allow you to
locate places on Earth.
Figure 8
Latitude and longitude are measurements that are used to indicate locations on Earth’s surface.
North Pole (90º North Latitude)
80ºN
60ºN
40ºN
Prime Meridian
20ºN
60º
0º Equator
20ºS
90ºE
30ºW
0º
60º
60ºE
40ºS
60ºS
80ºS
South Pole (90º South Latitude)
Latitude is the measurement of the imaginary angle created by the equator, the center of
Earth, and a location on Earth.
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CHAPTER 1 Views of Earth
Longitude is the measurement of the angle
along the equator, between the prime meridian,
the center of Earth, and a meridian on Earth.
Milwaukee,
Wisconsin
180°
Figure 9
The city of Milwaukee, Wisconsin is
located at about 43°N, 88°W. How
is latitude different from longitude?
O°
60°
165°
15°
150°
30°
45°
135°
45°
120°
105° 90°
30°
75°
60°
15°
0°
Longitude The vertical lines, seen in Figure 8B, have two
names—meridians and lines of longitude. Longitude lines are
different from latitude lines in many important ways. Just as the
equator is used as a reference point for lines of latitude, there’s a
reference point for lines of longitude—the prime meridian.
This imaginary line represents 0° longitude. In 1884, astronomers decided the prime meridian should go through the Greenwich (GREN ihtch) Observatory near London, England. The
prime meridian had to be agreed upon, because no natural
point of reference exists.
Longitude refers to distances in degrees east or west of the
prime meridian. Points west of the prime meridian have west
longitude measured from 0° to 180°, and points east of the prime
meridian have east longitude, measured similarly.
Prime Meridian The prime meridian does not circle Earth as
the equator does. Rather, it runs from the north pole through
Greenwich, England, to the south pole. The line of longitude on the
opposite side of Earth from the prime meridian is the 180° meridian. East lines of longitude meet west lines of longitude at the 180°
meridian. You can locate places accurately using latitude and longitude as shown in Figure 9. Note that latitude position always
comes first when a location is given.
What line of longitude is found opposite the
prime meridian?
Interpreting Latitude
and Longitude
Procedure
1. Find the equator and prime
meridian on a world map.
2. Move your finger to latitudes north of the equator,
then south of the equator.
Move your finger to longitudes west of the prime
meridian, then east of the
prime meridian.
Analysis
1. Identify the cities that have
the following coordinates:
a. 56°N, 38°E
b. 34°S, 18°E
c. 23°N, 82°W
2. Determine the latitude and
longitude of the following
cities:
a. London, England
b. Melbourne, Australia
c. Buenos Aires, Argentina
SECTION 2 Viewpoints
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Figure 10
The United States has six time
zones.
But students in Seattle,
Washington, which lies in the
Pacific time zone, are eating
dinner. What time would it be
in Seattle when the students in
Washington, D.C., are sleeping
at 9:00 P.M.?
Washington, D.C., lies in the
eastern time zone. Students
there would be going to sleep
at 9:00 P.M.
Seattle, WA
Pacific
Standard
Time
Alaska
Standard Time
Mountain
Standard
Time
Washington, D.C.
Eastern
Central
Standard
Standard
Time
Time
Hawaii
Standard Time
Time Zones
If you travel east or west
across three or more time
zones, you could suffer
from jet lag. Jet lag occurs
when your internal time
clock does not match the
new time zone. Jet lag can
disrupt the daily rhythms
of sleeping and eating.
Have you or any of your
classmates ever suffered
from jet lag?
What time it is depends on where you are on Earth. Time is
measured by tracking Earth’s movement in relation to the Sun.
Each day has 24 h, so Earth is divided into 24 time zones. Each
time zone is about 15° of longitude wide and is 1 h different
from the zones on each side of it. The United States has six different time zones. As you can see in Figure 10, people in different parts of the country don’t experience dusk simultaneously.
Because Earth rotates, the eastern states end a day while the
western states are still in sunlight.
What is the basis for dividing Earth into
24 time zones?
Time zones do not follow lines of longitude strictly. Time
zone boundaries are adjusted in local areas. For example, if a
city were split by a time zone boundary, the results would be
confusing. In such a situation, the time zone boundary is moved
outside of the city.
Calendar Dates
In each time zone, one day ends and the next day begins at
midnight. If it is 11:59 P.M. Tuesday, then 2 min later it will be
12:01 A.M. Wednesday in that particular time zone.
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CHAPTER 1 Views of Earth
75°
60°
45°
30°
15°
0°
15°
30°
45°
60°
75°
Prime Meridian
90° 105° 120° 135° 150° 165° 180° 165° 150° 135° 120° 105° 90°
ASIA
International Date Line
NORTH
AMERICA
90°
ASIA
EUROPE
AFRICA
SOUTH
AMERICA
AUSTRALIA
Areas where standard time differs by half an
hour or where a zone system is not followed
International Date Line You gain or lose time when you
Figure 11
enter a new time zone. If you travel far enough, you can gain or
lose a whole day. The International Date Line, shown on Figure 11,
is the transition line for calendar days. If you were traveling west
across the International Date Line, located near the 180° meridian, you would move your calendar forward one day. If you were
traveling east when you crossed it, you would move your calendar back one day.
Lines of longitude roughly determine the locations of time zone
boundaries. These boundaries
are adjusted locally to avoid splitting cities and other political subdivisions, such as counties, into
different time zones.
Section
Assessment
1. What are latitude and longitude?
2. How do lines of latitude and longitude help
6. Interpreting Scientific Illustrations Use a
people find locations on Earth?
3. What are the latitude and longitude of
New Orleans, Louisiana?
4. If it were 7:00 P.M. in New York City, what
time would it be in Los Angeles?
5. Think Critically How could you leave
home on Monday to go sailing on the
ocean, sail for 1 h on Sunday, and return
home on Monday?
world map to find the latitude and longitude of
the following locations: Sri Lanka; Tokyo, Japan;
and the Falkland Islands. For more help, refer
to the Science Skill Handbook.
7. Using Fractions If you started at the prime
meridian and traveled east one fourth of the
way around Earth, what line of longitude would
you reach? For more help, refer to the Math
Skill Handbook.
SECTION 2 Viewpoints
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SECTION
Maps
Map Projections
Explain the differences among
Mercator, Robinson, and conic
projections.
■ Describe features of topographic
maps, geologic maps, and satellite
maps.
■
Vocabulary
conic projection
topographic map
contour line
map scale
map legend
Maps help people navigate and
understand Earth.
Figure 12
Lines of longitude are drawn parallel to one another in Mercator
projections. What happens near
the poles in Mercator projections?
Maps—road maps, world maps, maps that show physical
features such as mountains and valleys, and even treasure
maps—help you determine where you are and where you are
going. They are models of Earth’s surface. Scientists use maps to
locate various places and to show the distribution of various features or types of material. For example, an Earth scientist might
use a map to plot the distribution of a certain type of rock or
soil. Other scientists could draw ocean currents on a map.
What are possible uses a scientist would have
for maps?
Many maps are made as projections. A map projection is
made when points and lines on a globe’s surface are transferred
onto paper, as shown in Figure 12. Map projections can be made
in several different ways, but all types of projections distort the
shapes of landmasses or their areas. Antarctica, for instance,
might look smaller or larger than it is as a result of the projection
that is used for a particular map.
Greenland
South
America
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CHAPTER 1 Views of Earth
Figure 13
Robinson projections show little
distortion in continent shapes and sizes.
Mercator Projection Mercator (mer KAY ter) projections
Figure 14
are used mainly on ships. They project correct shapes of continents, but the areas are distorted. Lines of longitude are projected onto the map parallel to each other. As you learned
earlier, only latitude lines are parallel. Longitude lines meet at
the poles. When longitude lines are projected as parallel, areas
near the poles appear bigger than they are. Greenland, in the
Mercator projection in Figure 12, appears to be larger than
South America, but Greenland is actually smaller.
Small areas are mapped accurately using conic projections.
Robinson Projection A Robinson projection shows accurate continent shapes and more accurate land areas. As shown in
Figure 13, lines of latitude remain parallel, and lines of longitude are curved as they are on a globe. This results in less distortion near the poles.
Conic Projection When you look at a road map or a
weather map, you are using a conic (KAH nihk) projection.
Conic projections, like the one shown in Figure 14, often are
used to produce maps of small areas. These maps are well suited
for middle latitude regions but are not as useful for mapping
polar or equatorial regions. Conic projections are made by projecting points and lines from a globe onto a cone.
How are conic projections made?
SECTION 3 Maps
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Topographic Maps
For nature hiking, a conic map projection can be helpful by
directing you to the location where you will start your hike. On
your hike, however, you would need a detailed map identifying
the hills and valleys of that specific area. A topographic map,
shown in Figure 15, models the changes in elevation of Earth’s
surface. With such a map, you can determine your location relative to identifiable natural features. Topographic maps also indicate cultural features such as roads, cities, dams, and other
structures built by people.
Contour Lines Before your hike, you study the contour lines
Topographic maps of
Venus and Mars have
been made by space
probes. The probes send
a radar beam or laser
pulses to the surface and
measure how long it takes
for the beam or pulses to
return to the probe.
on your topographic map to see the trail’s changes in elevation.
A contour line is a line on a map that connects points of equal
elevation. The difference in elevation between two side-by-side
contour lines is called the contour interval, which remains constant for each map. For example, if the contour interval on a
map is 10 m and you walk between two lines anywhere on that
map, you will have walked up or down 10 m.
In mountainous areas, the contour lines are close together.
This situation models a steep slope. However, if the change in
elevation is slight, the contour lines will be far apart. Often large
contour intervals are used for mountainous terrain, and small
contour intervals are used for fairly flat areas. Why? Table 1 gives
additional tips for examining contour lines.
Index Contours Some contour lines, called index contours,
are marked with their elevation. If the contour interval is 5 m,
you can determine the elevation of other lines around the index
contour by adding or subtracting 5 m from the elevation shown
on the index contour.
Table 1 Contour Rules
1. Contour lines close around hills and basins. To decide whether you’re
looking at a hill or basin, you can read the elevation numbers or look for
hachures (ha SHOORZ). These are short lines drawn at right angles to the
contour line. They show depressions by pointing toward lower elevations.
2. Contour lines never cross. If they did, it would mean that the spot where
they cross would have two different elevations.
3. Contour lines form Vs that point upstream when they cross streams.
This is because streams flow in depressions that are beneath the elevation of
the surrounding land surface. When the contour lines cross the depression,
they appear as Vs pointing upstream on the map.
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CHAPTER 1 Views of Earth
VISUALIZING TOPOGRAPHIC MAPS
Figure 15
P
lanning a hike? A topographic map will
show you changes in elevation.With such a
map, you can see at a glance how steep a
mountain trail is, as well as its location relative to
rivers, lakes, roads, and cities nearby. The steps
in creating a topographic map are shown here.
A To create a topographic map
of Old Rag Mountain in Shenandoah
National Park, Virginia, mapmakers
first measure the elevation of the
mountain at various points.
B These points are then projected
onto paper. Points at the same elevation
are connected, forming contour lines that
encircle the mountain.
C Where contour lines
on a topographic map are
close together, elevation
is changing rapidly—and
the trail is very steep!
SECTION 3 Maps
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Map Scale When planning your hike, you’ll want to deterData Update Visit the
Glencoe Science Web site at
science.glencoe.com for
recent news or magazine articles about map technology.
mine the distance to your destination before you leave. Because
maps are small models of Earth’s surface, distances and sizes of
things shown on a map are proportional to the real thing on
Earth. Therefore, real distances can be found by using a scale.
The map scale is the relationship between the distances on
the map and distances on Earth’s surface. Scale often is represented as a ratio. For example, a topographic map of the Grand
Canyon might have a scale that reads 1:80,000. This means that
one unit on the map represents 80,000 units on land. If the unit
you wanted to use was a centimeter, then 1 cm on the map
would equal 80,000 cm on land. The unit of distance could be
feet or millimeters or any other measure of distance. However,
the units of measure on each side of the ratio must always be the
same. A map scale also can be shown in the form of a small bar
that is divided into sections and scaled down to match real distances on Earth.
Map Legend Topographic maps and most other maps have a
legend. A map legend explains what the symbols used on the
map mean. Some frequently used symbols for topographic
maps are shown in the appendix at the back of the book.
Map Series Topographic maps are made to cover different
amounts of Earth’s surface. A map series includes maps that
have the same dimensions of latitude and longitude. For example, one map series includes maps that are 7.5 minutes of latitude by 7.5 minutes of longitude. Other map series include
maps covering larger areas of Earth’s surface.
Figure 16
Geologists use block diagrams
to understand Earth’s subsurface.
The different colors represent different rock layers.
Geologic Map
Cross Sections
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CHAPTER 1 Views of Earth
Geologic Maps
One of the more important tools to Earth scientists is the
geologic map. Geologic maps show the arrangement and types
of rocks at Earth’s surface. Using geologic maps
and data collected from rock exposures, a geologist can infer how rock layers might look below
Earth’s surface. The block diagram in Figure 16 is
a 3-D model that illustrates a solid section of
Earth. The top surface of the block is the geologic
map. Side views of the block are called cross sections, which are derived from the surface map.
Developing geologic maps and cross sections is
extremely important for the exploration and
extraction of natural resources. What can a scientist do to determine whether a cross section accurately represents the underground features?
Three-Dimensional Maps Topographic maps and geologic
maps are two-dimensional models that are used to study features of Earth’s surface. To visualize Earth three dimensionally,
scientists often rely on computers. Using computers, information is digitized to create a three-dimensional view of features
such as rock layers or river systems. Digitizing is a process by
which points are plotted on a coordinate grid.
Map Uses As you have learned, Earth can be viewed in many
different ways. Maps are chosen depending upon the situation.
If you wanted to determine New Zealand’s location relative to
Canada and you didn’t have a globe, you probably would examine a Mercator projection. In your search, you would use lines of
latitude and longitude, and a map scale. If you wanted to travel
across the country, you would rely on a road map, or conic projection. You also would use a map legend to help locate features
along the way. To climb the highest peak in your region, you
would take along a topographic map.
Problem-Solving Activity
How can you create a cross section from a geologic map?
E
arth scientists are interested in knowing
the types of rocks and their configurations
underground. To help them visualize this, they
use geologic maps. Geologic maps offer a twodimensional view of the three-dimensional situation found under Earth’s surface. You don’t
have to be a professional geologist to understand a geologic map. Use your ability to create
graphs to interpret this geologic map.
780
790
800
810
820
830
840
B
A
Coal
0.5 km
Identifying the Problem
Above is a simple geologic map showing where a coal seam is found on Earth’s surface.
Place a straight edge of paper along the line marked A–B and mark the points where it meets
a contour. Make a different color mark where it meets the exposure of coal. Make a graph on
which the various elevations (in meters) are marked on the y-axis. Lay your marked edge of
paper along the x-axis and transfer the points directly above onto the proper elevation line.
Now connect the dots to draw in the land’s surface and connect the marks you made for the
coal seam separately.
Solving the Problem
1. What type of topography does the map represent?
2. At what elevation is the coal seam?
3. Does this seam tilt, or is it horizontal? Explain how you know.
SECTION 3 Maps
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Remote Sensing
Scientists use remote-sensing techniques
to collect much of the data used for making
maps. Remote sensing is a way of collecting
information about Earth from a distance,
often using satellites.
Landsat One way that Earth’s surface has
Figure 17
Sensors on Landsat 7 detect light
reflected off landforms on Earth.
been studied is with data collected from
Landsat satellites, as shown in Figure 17.
These satellites take pictures of Earth’s surface
using different wavelengths of light. The images can be used to
make maps of snow cover over the United States or to evaluate
the impact of forest fires, such as those that occurred in the western United States during the summer of 2000. The newest Landsat satellite is Landsat 7, which was launched in April of 1999. It
can acquire the most detailed Landsat images yet.
Global Positioning System The Global Positioning System,
or GPS, is a satellite-based, radio-navigation system that allows
users to determine their exact position anywhere on Earth.
Twenty-four satellites orbit 20,200 km above the planet. Each
satellite sends a position signal and a time signal. The satellites are
arranged in their orbits so that signals from at least six can be
picked up at any given moment by someone using a GPS receiver.
By processing the signals, the receiver calculates the user’s exact
location. GPS technology is used to navigate, to create detailed
maps, and to track wildlife.
Section
Assessment
1. How do Mercator, Robinson, and conic projections differ?
2. Why does Greenland appear to be larger on
a Mercator projection than it does on a
Robinson projection?
3. Why can’t contour lines ever cross?
4. What is a geologic map?
5. Think Critically Would a map that covers
a large area have the same map scale as a
map that covers a small region? How
would the scales differ?
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CHAPTER 1 Views of Earth
6. Making Models Architects make detailed
maps called scale drawings to help them plan
their work. Make a scale drawing of your classroom. For more help, refer to the Science Skill
Handbook.
7. Communicating Draw a map in your Science
Journal that your friends could use to get from
school to your home. Include a map legend and
a map scale. For more help, refer to the Science Skill Handbook.
Making a Topographic Map
H
ave you ever wondered how topographic
maps are made? Today, radar and remotesensing devices aboard satellites collect data, and
computers and graphic systems make the maps.
In the past, surveyors and aerial photographers
collected data. Then, maps were hand drawn by
cartographers, or mapmakers. In this activity,
you can practice cartography.
Materials
plastic model of a landform
water tinted with food coloring
transparency
clear, plastic storage box with lid
beaker
metric ruler
tape
transparency marker
What You’ll Investigate
How is a topographic map made?
Goals
■ Draw a topographic map.
■ Compare and contrast contour intervals.
60
50
40
30
20
10
6. Using the scale 2 cm 10 m, mark the elevation on the line.
7. Remove the lid and add water until a depth of
4 cm is reached.
8. Map this level on the storage box lid and
record the elevation.
9. Repeat the process of adding 2 cm of water
and tracing until the landform is mapped.
10. Transfer the tracing of the landform onto a
sheet of white paper.
Conclude and Apply
Procedure
1. Using the ruler and the transparency marker,
make marks up the side of the storage box
that are 2 cm apart.
2. Secure the transparency to the outside of the
box lid with tape.
3. Place the plastic model in the box. The bottom of the box will be zero elevation.
4. Using the beaker, pour water into the box to a
height of 2 cm. Place the lid on the box.
5. Use the transparency marker to trace the top
of the water line on the transparency.
1. What is the contour interval of this topographic map?
2. How does the distance between contour lines
on the map show the steepness of the slope
on the landform model?
3. Determine the total elevation of the
landform you have selected.
4. How was elevation represented on your map?
5. How are elevations shown on topographic
maps?
6. Must all topographic maps have a contour
line that represents 0 m of elevation? Explain.
ACTIVITY
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Constructing Landforms
M
ost maps perform well in helping you get from place to place. A road map, for
example, will allow you to choose the shortest route from one place to another.
If you are hiking, though, distance might not be so important. You might want to
choose a route that avoids steep terrain. In this case you need a map that shows the
highs and lows of Earth’s surface, called relief. Topographic maps use contour lines to
show the landscape in three dimensions. Among their many uses, such maps allow
hikers to choose routes that maximize the scenery and minimize the physical exertion.
Recognize the Problem
What does a landscape depicted on a two-dimensional topographic map look like in
three dimensions?
Thinking Critically
How can you model a landscape?
Goals
■ Research how contour lines show
relief on a topographic map.
■ Determine what scale you can
best use to model a landscape of
your choice.
■ Working cooperatively with
your classmates, model a
landscape in three dimensions
from the information given on
a topographic map.
Possible Materials
U.S.Geological Survey 7.5 minute
quadrangle maps
sandbox sand
rolls of brown paper towels
spray bottle filled with water
ruler
Data Source
Go to the
Glencoe Science Web site at
science.glencoe.com
for more information about
topographic maps.
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CHAPTER 1 Views of Earth
Planning the Model
1. Choose a topographic map showing a landscape easily modeled
using sand. Check to see what contour interval is used on the map.
Use the index contours to find the
difference between the lowest and
the highest elevations shown on the
landscape. Check the distance scale
to determine how much area the
landscape covers.
2. Determine the scale you will use to
convert the elevations shown on
your map to heights on your model.
Make sure the scale is proportional
to the distances on your map.
3. Plan a model of the landscape in
sand by sketching the main features
and their scaled heights onto paper.
Note the degree of steepness found
on all sides of the features.
Check the Model Plans
1. Prepare a document that shows
the scale you plan to use for your
model and the calculations you
used to derive that scale. Remember to use the same scale for distance as you use for height. If your
landscape is fairly flat, you can
exaggerate the vertical scale by
a factor of two or three. Be sure
your paper is neat, is easy to follow, and includes all units. Present
the document to your teacher
for approval.
2. Research how the U.S. Geological
Survey creates topographic maps
and find out how it decides upon a
contour interval for each map. This
information can be obtained from
the Glencoe Science Web site.
Making the Model
1. Using the sand, spray bottle, and
ruler, create a scale model of your
landscape on the brown paper
towels.
2. Check your topographic map to be
sure your model includes the landscape features at their proper heights
and proper degrees of steepness.
Analyzing and Applying Results
1. Did your model accurately represent
3. Why did the mapmakers choose the
the landscape depicted on your topographic map? Discuss the strengths
and weaknesses of your model.
2. Why was it important to use the
same scale for height and distance?
If you exaggerated the height, why
was it important to indicate the
exaggeration on your model?
contour interval used on your topographic map?
4. Predict the contour intervals
mapmakers might choose for topographic maps of the world’s tallest
mountains—the Himalaya—and for
topographic maps of Kansas, which
is fairly flat.
ACTIVITY
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SCIENCE AND
HISTORY
SCIENCE
CAN CHANGE
THE COURSE
OF HISTORY!
LOCATION,
New York Harbor in 1849
Rich Midwest farmland
Georgia
peaches
W
hy is New York City at the mouth of
the Hudson River and not 300 km
inland? Why are there more farms
in Iowa than in Alaska? What’s the reason for
growing lots of peaches in Georgia but not
in California’s Death Valley? It’s all about
location. The landforms, climate, soil, and
resources in an area determine where cities
and farms grow and what people connected
with them do.
Landforms Are Key
When many American cities were
founded hundreds of years ago, waterways
were the best means of transportation. Old
cities such as New York City and Boston are
located on deep harbors where ships could
land with people and goods. Rivers also were
major highways centuries ago. They still are.
A city such as New Orleans, located at the
mouth of the Mississippi River, receives
goods from the entire river valley.
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It then ships the goods from its port to places
far away.
Topography and soil also play a role in
where activities such as farming take root. States
such as Iowa and Illinois have many farms
because they have lots of flat land and fertile
soil. Growing crops is more difficult in mountainous areas or where soil is stony and poor.
Climate and Soil
Climate limits the locations of cities and
farms, as well. The fertile soil and warm,
moist climate of Georgia make it a perfect
place to grow peaches. California’s Death
Valley can’t support such crops because it’s a
hot desert. Deserts are too dry to grow much
of anything without irrigation. Deserts also
don’t have large population centers unless
water is brought in from far away. Los
Angeles and Las Vegas are both desert cities
that are huge only because they pipe in water
from hundreds of miles away.
Resources Rule
The location of an important natural
resource can change the rules. A gold deposit
or an oil field can cause a town to grow in a
place where the topography, soil, and climate
are not favorable. For example, thousands of
people now live in parts of Alaska only
because of the great supply of oil there.
People settled in rugged areas of the Rocky
Mountains to mine gold and silver. Maine has
a harsh climate and poor soil. But people settled along its coast because they could catch
lobsters and fish in the nearby North Atlantic.
LOCATION
Alaska pipeline
The rules that govern where towns grow
and where people live are a bit different now
than they used to be. Often information, not
goods, moves from place to place on computers that can be anywhere. But as long as people farm, use minerals, and transport goods
from place to place, the natural environment
and natural resources will always help determine where people are and what they do.
Maine
fishing
and
lobster
industry
Cities,
farms, and
industries
grow in
logical places
CONNECTIONS Research Why was your community built where it
is? Research its history. What types of economic activity were important
when it was founded? Did topography, climate, or resources determine
its location? Are they important today? Report to the class.
For more information, visit
science.glencoe.com
Chapter
1
Study Guide
Section 1 Landforms
1. The three main types of landforms are
plains, plateaus, and mountains.
2. Plains are large, flat areas. Plateaus are relatively flat, raised areas of land made up of
nearly horizontal rocks that have been
uplifted. Mountains rise high above the surrounding land. Which type of landform is
shown in the photograph below?
4. Earth is divided
into 24 time
zones. Each
time zone
represents a
1-h difference.
The International Date Line
separates different calendar days. How many
time zones are in the United States?
Section 3 Maps
1. Mercator, Robinson, and conic projections
are made by transferring points and lines
on a globe’s surface onto paper.
Section 2 Viewpoints
1. Latitude and longitude form an imaginary
grid system that enables points on Earth to
be located exactly.
2. Latitude is the distance in degrees north or
south of the equator. Longitude is the distance in degrees east or west of the prime
meridian.
3. Reference lines have been established for
measuring latitude and longitude. Latitude
is measured from Earth’s equator, an imaginary line halfway between Earth’s poles.
Longitude is measured from the prime
meridian. The prime meridian runs from
pole to pole through Greenwich, England.
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CHAPTER STUDY GUIDE
2. Topographic
maps show the
elevation of
Earth’s surface.
Geologic maps
show the types
of rocks that
make up Earth’s
surface. What
type of map is
shown here?
3. Remote sensing is a way of collecting
information about Earth from a distance.
Satellites are important remote-sensing
devices.
FOLDABLES
After You Read
To help you review the
three main landform
types, use the Foldable
you made at the beginning of this chapter.
Reading &Study
& Study
Skills
Chapter
1
Study Guide
Complete the following concept map on landforms.
Landforms
can be
can be
Plains
Mountains
types
types
Interior
Folded
Vocabulary Words
a.
b.
c.
d.
e.
f.
g.
h.
can be
Fault-block
Using Vocabulary
conic projection
contour line
equator
fault-block mountain
folded mountain
latitude
longitude
map legend
i. map scale
j. plain
k. plateau
l. prime meridian
m. topographic map
n. upwarped
mountain
o. volcanic mountain
Study Tip
Make a plan! Before you start your homework,
write a checklist of what you need to do for each
subject. As you finish each item, check it off.
For each set of terms below, choose the one
term that does not belong and explain why it does
not belong.
1. upwarped mountain, equator, volcanic
mountain
2. plain, plateau, prime meridian
3. topographic map, contour line, volcanic
mountain
4. prime meridian, equator, folded
mountain
5. fault-block mountain, upwarped mountain,
plateau
6. prime meridian, map scale, contour line
CHAPTER STUDY GUIDE
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Chapter
1
Assessment
Choose the word or phrase that best answers
the question.
1. What makes up about 50 percent of all land
areas in the United States?
A) plateaus
C) mountains
B) plains
D) volcanoes
2. Where is the north pole located?
A) 0°N
C) 50°N
B) 180°N
D) 90°N
3. What kind of mountains are the Hawaiian
Islands?
A) fault-block
C) upwarped
B) volcanic
D) folded
4. What are lines that are parallel to the
equator called?
A) lines of latitude
C) lines of longitude
B) prime meridians D) contour lines
5. How many degrees apart are the 24
time zones?
A) 10
C) 15
B) 34
D) 25
6. Which type of map is most distorted at
the poles?
A) conic
C) Robinson
B) topographic
D) Mercator
7. Which type of map shows changes in elevation at Earth’s surface?
A) conic
C) Robinson
B) topographic
D) Mercator
8. What is measured with respect to
sea level?
A) contour interval C) conic projection
B) elevation
D) sonar
9. What kind of map shows rock types making
up Earth’s surface?
A) topographic
C) geologic
B) Robinson
D) Mercator
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CHAPTER ASSESSMENT
10. Which major U.S. landform includes the
Grand Canyon?
A) Great Plains
B) Colorado Plateau
C) Gulf Coastal Plain
D) Appalachian Mountains
11. How would a topographic map of the
Atlantic Coastal Plain differ from a topographic map of the Rocky Mountains?
12. If you left Korea early Wednesday morning
and flew to Hawaii, on what day of the week
would you arrive?
13. If you were flying directly south from the
north pole and reached 70° north latitude,
how many more degrees of latitude would
you pass over before reaching the south
pole?
14. Using the map below, arrange these cities in
order from the city with the earliest time to
the one with the latest time on a given day:
Anchorage, Alaska; San Francisco, California; Bangor, Maine; Denver, Colorado;
Houston, Texas.
Anchorage, Alaska
Bangor, ME
San Francisco, CA
Denver, CO
Houston, TX
15. How is a map with a scale of 1:50,000 different from a map with a scale of 1:24,000?
Chapter
1
Assessment
Test Practice
16. Comparing and Contrasting Compare and
contrast Mercator, Robinson, and conic
map projections.
17. Forming Hypotheses You are visiting a
mountain in the northwest part of the
United States. The mountain has steep sides
and is not part of a mountain range. A
crater can be seen at the top of the mountain. Hypothesize about what type of
mountain you are visiting.
Alicia was looking at a map of the
United States because her science teacher
suggested that she learn about the landform regions in the United States.
18. Concept Mapping Complete the following concept map about parts of a
topographic map.
Topographic Maps
include
Contour lines
Major U.S. Landforms
Intermontane
Plateaus and Basin
Coastal Plains
Interior Highlands
Interior Plains
Pacific Mountain
and Valley System
Rocky Mountains
Superior Uplands
Appalachian Highlands
Symbols
Study the diagram and answer the
following questions.
19. Poem Create a poem about the different
types of landforms. Include characteristics
of each landform in your poem. Display
your poem with those of your classmates.
20. Poster Create a poster showing how
satellites can be used for remote sensing.
TECHNOLOGY
Go to the Glencoe Science Web
site at science.glencoe.com or
use the Glencoe Science CD-ROM
for additional chapter assessment.
1. Which technological development
would have had the greatest impact on
the accuracy of Alicia’s map?
A) radio communications
B) measurement with lasers
C) computer-assisted design
D) satellite imaging
2. Which of the following landform
regions would contain high, rugged
mountains?
F) Coastal Plains
G) Interior Plains
H) Appalachian Highlands
J) Rocky Mountains
CHAPTER ASSESSMENT
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