~
After reading this chapter, review what you have written. Make any
changes that will improve your answers.
PHYSICAL GEOGRAPHY
There are many factors that make up the geography of an area. These include
climate, topography, resources, and water forms. Combined, these factors are
known as physical geography.
Landforms and Water Forms
As you learned earlier, every place has its topography or landforms. There are
four main kinds of landforms on Earth: mountains, hills, plateaus, and plains.
Most of the land surface of Earth is made up of one of these four landforms.
There is much more water than land on Earth. In fact, three-quarters of Earth is
made up of water. So, water is an important part of Earth's physical geography.
Earth has four oceans: the Pacific, the Atlantic, the Indian, and the Arctic. The parts
of the Indian, Pacific, and Atlantic oceans near Antarctica are sometimes called the
Antarctic Ocean. Earth also has several seas. Seas are large bodies of water almost
completely surrounded by land. The Mediterranean, the Caribbean, the Arabian
Seas, and the Sea of Japan are all major seas. There are many other seas, as well. In
addition, there are also many smaller bodies of water, including rivers and lakes.
Climate
As you also have learned, each area has its own climate-that is, the kind of
weather it has over a long period of time, year after year. Differences in climate
mean differences in temperature, rainfall, and length of the growing season. All
of these differences strongly influence the kinds of crops that are grown in an
area. Housing and clothing are also strongly influenced by climate.
Resources
Biological resources are also part of the physical geography of an area. Biological
resources are the plants and animals that an area can support. They can be found on
land and in water. Their life forms differ with the climate, type of soil, closeness to
water, and topography of a place. For example, polar bears are not found in a
tropical rain forest. Tropical plants are not found near the North Pole or in a desert.
Natural resources are another important part of the physical geography of an
area. The natural resources of a place are those things found in nature that people
can use. For example, uranium has been on Earth much longer than people have. It
became a resource only when people learned to use it. Natural resources are used
for making food, fuel, and raw materials for the production of finished goods.
Unit 4
67
'f
J,j
":lI~
/:1f;
) "\(Illi
.'.,
<I
uJ
""j
f-"·-
;~t
Water is a natural resource that most people take for granted. However, without
clean, drinkable water, people would not survive. So, water may be the most
important natural resource on Earth. A city of 1 million people could use as much as
50 million gallons of water a day. People also need water for growing crops. In areas
with little rainfall, people must irrigate, or transport water to the dry areas. Water
also gives people a means of travel and of carrying goods. It is an important source
of power. Power plants near rivers and waterfalls use water to turn machines or to
cool nuclear reactors that produce electricity. This process is called hydroelectricity.
The soil that covers Earth is a valuable natural resource. People need fertile
soil in order to grow crops. Throughout
the world, the layer of fertile soil is
usually only about 8 inches deep. This thin layer, called topsoil, is made up
mainly of minerals and living things. Topsoil contains plants and insects as well
as water, air, and minerals. The minerals are called nutrients. As long as the
nutrients remain in the soil, the land is useful for growing crops.
Forests are another valuable natural resource. They cover about one-fifth of
Earth's surface. Most of the large forests are found in areas in the northern climate
zones such as Canada, Alaska, Norway, Sweden, Finland, and Siberia. Other large
forests, called rain forests, are found in South America, central Africa, and Southeast
Asia. Forests provide a home for wildlife. Trees help keep the valuable soil on steep
hillsides from being washed away. People have found many other uses for trees.
Houses, fuel, paper, and turpentine are a few of the products from forests.
Minerals are not as important as soil, water, and vegetation in supporting life.
However, they are very important for modern living. Minerals are often used as
raw materials. They are used to make finished goods such as automobiles,
dishes, clothing, and computers. Some minerals, such as coal, oil, and natural
gas, are used for fuels. They give people heat, light, and power for their homes.
As you study geography, you will learn more about natural resources. Natural
resources differ from region to region throughout
the world. People make use of
natural resources in different ways. Unfortunately,
there is a limited supply of
many natural resources.
I
f
In the North Sea, there
are approximately 300 oil
production platforms like
the one shown here.
Many operate 24 hours a
day, 7 days a week,
bringing oil up from far
below the ocean floor.
Unit 4
PEOPLE AND PLACES
When people move into a place they tend to change it in order to meet their
needs. They use technology to change the environment. Sometimes, these changes
in the environment attract even more people to a place. These changes might
include building railroads, houses, roads, and schools. The rules that people
establish for a place, such as religious freedom, often attract more people. When a
large number of people begin to live in one area, a city grows there. During the
process of building cities, people make great changes in the environment.
Cities
Geographical location is an important factor in the growth of cities. Some early
settlements grew into large cities. Others did not. The location of a settlement
was often the main reason for its growth. The better the location, the more likely
it is that a city developed. The earliest cities in history were located in the river
valleys of Asia and Africa. In these fertile valleys, people were able to grow
crops, and the rivers provided a source of transportation. People in these early
cities were able to trade with neighboring settlements or even with people who
lived far away. Some early towns and cities also developed near crossroads at
which people met to trade goods and near good harbors.
Throughout history, settlements have grown where one kind of transportation
ended and another began. At these places, goods have to be unloaded and
loaded. People stop for a rest. They buy supplies to continue their journey. When
early railroad tracks were laid in the western United States, settlements grew
where the railroad line ended, Omaha, Nebraska, and Topeka, Kansas, are
examples of these railroad cities. Port cities also developed where rivers and
oceans met. The map on page 77 shows some railroad and port cities.
At New Orleans,
Louisiana, goods
were unloaded
from riverboats and
loaded onto
oceangoing ships.
76
Unit 4
(~
National Capital
•
City
" Railroad
~~River
Many of the world's largest cities started as ports, or places where
o
I
ships could dock. These ports were located on coastlines or on large
'0
rivers. As the amount of goods shipped by boat to and from these cities
grew, the cities also grew. By 1860,there were nine cities in the United
States with 100,000people. Six of these cities were seaports; the other three cities
were river ports. Large cities, such as Chicago and Cleveland, began on lakes. Many
New England and southern towns are located near water because early settlers
used waterfalls and swift-flowing streams as water power to run their mills. Locate
the seaport or river port cities on the map shown above.
,
500 mi
!
I
!
500 km
Other cities grew because of mining, or digging to uncover minerals. Cities
sometimes developed near mineral deposits because large numbers of miners
were needed to uncover the valuable mineral deposits from far under Earth.
Pittsburgh, Pennsylvania, and Birmingham, Alabama, are examples of cities that
are located near iron ore and coal deposits. Coal and iron ore are important
resources because they are used to make steel. The discovery of gold in 1849
turned San Francisco, California, into a city of 50,000 people from only a few
hundred in the early 1840s. Another factor in the growth of cities is a favorable
climate. Because of their warm climate, cities in Florida and California are among
the fastest growing in the United States.
Population Density
Maps can be used to show where people live. Maps that show the density, or
the number of people living in an area, are called population density maps. It is
Places thathavetew
people, such as AlasKa or northern Canada, are sald to nave
~:,p~~~~,
~~'STh~t\~~'fi~\~f.~\},
ci~\}s:'~~.~&.1S,CJ~~~,l.~\.~~~~~\.~~l.~tr_\~.
C!.\}((~ci
States, where many people live, are densely populated. Turn to page 79 to see an
<?Kamv!e 0/.7 popuiati'£lJ)
_
_
Liensi{v ~
JlldLJ.
I.
~
~;,~,_f{_
(7
~;,;-~
1Jt:"'''')'
;;;,"
!
.
.
I,','"
,f""':.,,"'"
,
..
,
",
,/
'~>""~'~,
fJt;. '
\
\
ATLANTIC
OCEAN
120W
100W
70'W
O'N\
-3
''''
National Capital
•
City
90W
Railroad
~~River
Many of the world's largest cities started as ports, or places where
o
I
ships could dock. These ports were located on coastlines or on large
o
rivers. As the amount of goods shipped by boat to and from these cities
grew, the cities also grew. By 1860, there were nine cities in the United
States with 100,000 people. Six of these cities were seaports; the other three cities
were river ports. Large cities, such as Chicago and Cleveland, began on lakes. Many
New England and southern towns are located near water because early settlers
used waterfalls and swift-flowing streams as water power to run their mills. Locate
the seaport or river port cities on the map shown above.
!
j
;g
e,..
Q.
i
co
I:
l
!B,
e~
~
t
i
Q
C
~
0
(J
0
~
c
0
:
r:
:;::>
B
:::I
1:1
W
I:
u
~
i
,u
500 mi
I
I
I
!
500 km
Other cities grew because of mining, or digging to uncover minerals. Cities
sometimes developed near mineral deposits because large numbers of miners
were needed to uncover the valuable mineral deposits from far under Earth.
Pittsburgh, Pennsylvania, and Birmingham, Alabama, are examples of cities that
are located near iron ore and coal deposits. Coal and iron ore are important
resources because they are used to make steel. The discovery of gold in 1849
turned San Francisco, California, into a city of 50,000 people from only a few
hundred in the early 1840s. Another factor in the growth of cities is a favorable
climate. Because of their warm climate, cities in Florida and California are among
the fastest growing in the United States.
~
W
C
~
os
If
~
•
f
0
0
Population Density
Maps can be used to show where people live, Maps that show the density, or
the number of people living in an area, are called population density maps. It is
easy to tell from one of these maps how many people live in a particular place.
Places that have few people, such as Alaska or northern Canada, are said to have
a sparse, or small, population density. Areas such as the northeastern United
States, where many people live, are densely populated. Turn to page 79 to see an
example of a population density map.
Unit 4
77