The Five Themes of Geography
A HUMAN PERSPECTIVE Between 1838 and 1842, Captain Charles Wilkes led an American expedition to the South Pacific and Antarctica. At one stop at a South Sea island, a friendly islander drew a map on the wooden deck planks of the ship. To Wilkes's amazement, the map accurately showed the location of the Tuamotu Archipelago—a chain of about 80 coral islands that stretches more than 1,000 miles across the South Pacific. The islander relied on personal experience sailing in the area and a mental map to accurately show the positions of the islands.
The Geographer's Perspective
Maps like the one that the islander drew are important tools in geography. The word geography comes from the Greek word geographia, which means “to describe the earth.” Geographers study the world in a different way than do other social scientists. Historians look at events over time. Geographers, on the other hand, view the world by looking at the use of space on the earth and the interactions that take place there. They look for patterns and connections between people and the land that they live on. Geography, then, is the study of the distribution and interaction of physical and human features on the earth.
METHODS OF GEOGRAPHY
Geographers use a variety of tools to study the use of space on earth. The most common one is a map. Maps are visual representations of a portion of the earth. Maps do not have to be written down to be useful. Since people began roaming the earth, they have created mental maps—maps that they carry in their minds. You use a mental map every day as you go to and from school.
The maps that you are probably most familiar with appear in printed form, such as in road atlases and books. In recent years, more maps have appeared in electronic media such as CD-ROMs and on the Internet. Geographers also use photographs to gain visual evidence about a place. They organize information into charts, graphs, or tables to learn about geographic patterns and to understand changes over time. They may also construct scale models to make study of the real world easier. Sometimes they use graphic models to illustrate an idea.
Other basic tools used by geographers are the five themes of geography, which also describe patterns and connections in the use of space. These themes organize information about geography into five distinct categories, shown at right. These themes are important to geographic study. They help the geographer to describe the use of space.
The geographic question “Where is it?” refers to location. Geographers describe location in two ways. Absolute location is the exact place on earth where a geographic feature, such as a city, is found. Relative location describes a place in comparison to other places around it.
To describe absolute location, geographers use a grid system of imaginary lines for precisely locating places on the earth's surface. Earth is divided into two equal halves. Each half of the globe is called a hemisphere. Because the earth is round, a hemisphere can be north and south, or east and west. The equator is the imaginary line that divides the north and south halves. The prime meridian is the imaginary line dividing the earth east and west. Sometimes this line is called the Greenwich meridian line because the line runs through Greenwich, England.
To locate places north or south, geographers use a set of imaginary lines that run parallel to the equator. These lines are called latitude lines. The equator is designated as the zero-degree line for latitude. Lines north of the equator are called north latitude lines, and lines south of the equator are called south latitude lines.
To complete the grid system, geographers use a set of imaginary lines that go around the earth over the poles. These lines, called longitude lines, mark positions in the east and west hemispheres. The prime meridian is the zero-degree line for longitude.
Each site on the earth can have only one absolute location. To find an absolute location using the grid system, you need to find the point where the latitude and longitude lines cross. For example, the absolute location of Melbourne, Australia, is 37° South latitude, 145° East longitude. To see how latitude and longitude lines cross and to learn more about absolute location.
Relative location describes how a place is related to its surrounding environment. For example, you may tell a person that the library is three blocks west of the park. This helps the person find the library—if he or she knows where the park is located. Using relative location may help you become familiar with the specific characteristics of a place. Learning that Cairo, Egypt, is located near the mouth of the Nile River in Africa, for example, tells you something about Cairo, the Nile River, and even Africa itself.
The question “What is it like?” refers to place. Place includes the physical features and cultural characteristics of a location. All locations on earth have physical features that set them apart, such as climate, landforms, and vegetation. Other features are the product of humans interacting with the environment, such as by building dams, highways, or houses. Still others are the result of humans interacting with animals or with each other. In the photograph above, you can see place features of Rio de Janeiro. Since a location's culture and its use of space may change over time, the description of a place may also change.
The question “How are places similar or different?” refers to region. A region is an area of the earth's surface with similar characteristics. Regions usually have more than one characteristic that unifies them. These may include physical, political, economic, or cultural characteristics. For example, the Sunbelt in the southern United States is a physical region. Geographers categorize regions in three ways: formal, functional, and perceptual regions.
A formal region is defined by a limited number of related characteristics. For example, the Sahel region of Africa is a desert area characterized by specific climate, vegetation, and land use patterns. In this textbook, the regions you'll explore generally are defined by continental area and by similar cultural styles. The following are considered formal regions:
- The United States and Canada
- Latin America
- Russia and the Republics
- Africa and Antarctica
- Southwest Asia
- South Asia
- East Asia
- Southeast Asia, Oceania
A functional region is organized around a set of interactions and connections between places. Usually a functional region is characterized by a hub, or central place, and links to that central place. For example, a city and its suburbs may form a functional region. Highways, commuter railroads, subways, and bus lines move people from the suburbs to the city for jobs and other activities. Because the city and its suburbs are connected by a great deal of movement back and forth, they form a functional region.
A perceptual region is a region in which people perceive, or see, the characteristics of the region in the same way. However, the set of characteristics may not be precisely the same for all people. For example, although many people are familiar with the region called the American Midwest, they sometimes differ on how that region is defined. Some people believe the Midwest begins in Ohio. Others believe the region begins in the middle of Illinois.
Theme: Human–Environment Interaction
The question “How do people relate to the physical world?” refers to the relationship between humans and their environment. People learn to use what the environment offers them and to change that environment to meet their needs. They also learn to live with aspects of the environment that they cannot control, such as climate.
People living in similar environments do not respond to them in the same way. For example, some people view a hot, sunny climate near a body of water as ideal for recreational activities. Others may see this as an opportunity for raising citrus, olives, or grapes. Human beings work to alter their environments to make them better places or to provide needed goods. People may drain swamps or dig irrigation ditches to grow crops in a particular environment. Sometimes the alterations create new problems, such as pollution. As you study geography, you will learn about many ways humans interact with their environment.
The question “How do people, goods, and ideas move from one location to another?” refers to movement. Geographers are interested in the ways people, goods, and ideas move from place to place. Think about the clothing you wear, the music you listen to, or the places you go for entertainment. All of these things involve movement from one place to another. Geographers analyze movement by looking at three types of distance: linear distance, time distance, and psychological distance.
LINEAR DISTANCE AND TIME DISTANCE
Linear distance simply means how far across the earth a person, an idea, or a product travels. Physical geography can affect linear distance by forcing a shift in a route to avoid impassable land or water.
Time distance is the amount of time it takes for a person, an idea, or a product to travel. Modern inventions have shortened time distances. For example, in the 1800s, pioneers traveled up to six months to reach California. Today you can get there by airplane from almost any U.S. location in under six hours. With the use of the Internet, ideas can travel around the world in seconds.
Psychological distance refers to the way people view distance. When you were younger, some locations seemed very far away. As you grew older, the distance to these locations probably seemed to shrink. Studies show that, as we become familiar with a place, we think it is closer than it actually is. Less familiar places seem to be further away. Psychological distance may influence decisions about many different human activities.
Across the world, people make important choices based on linear distance, time distance, and psychological distance. These choices make up patterns that geographers can study. In the next section, you'll read about the tools they use to study these patterns.