Mapping Our World

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BIG tIdea

Earth scientists use mapping technologies to investigate and describe the world.

2.1 Latitude and Longitude I^iiBRii Lines of latitude and longitude are used to locate places on Earth.

2.2 Types of Maps fT^fldia Maps are flat projections that come in many different forms.

2.3 Remote Sensing

H^Biaa New technologies have changed the appearance and use of maps.

GeoFacts

Maps predate written history. The earliest known map was created as a cave painting in ancient Turkey.

China spans five international time zones; however, the entire country operates on only one standard time.

Global Positioning System (GPS) satellites were originally designed for strategic defense and navigation purposes.

Cave Paintings Ancient Turkey

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Activities

Activities

LAUNCH L

Can you make an accurate map?

If you have ever been asked to give someone directions, you know that it is important to include as many details as possible so that the person asking for directions will not get lost. Perhaps you drew a detailed map of the destination in question.

Procedure

1. Read and complete the lab safety form.

2. With a classmate, choose a location in your school or schoolyard.

3. Use a sheet of graph paper and colored pencils to draw a map from your classroom to the location you chose. Include landmarks such as drinking fountains and restrooms.

4. Share your map with a classmate. Compare the landmarks you chose and the path each of you chose to get to your locations. If they were different, explain why.

5. Follow your map to the location you and your partner chose. Was your map correct? Were there details you left out that might have been helpful?

Analysis

1. Discuss with your classmate how you could improve your maps.

2. Examine What details could you add?

Types of Mapping Technologies

Make this Foldable to help organize information about the four major types of mapping technologies.

Types of Mapping Technologies

Make this Foldable to help organize information about the four major types of mapping technologies.

STEP 1 Find the middle of a horizontal sheet of paper and mark it. Fold the left and right sides of the paper to the middle and crease the folds.

STEP 2 Fold the piece of paper in half.

STEP 3 Open the last fold and cut along the fold lines to make four tabs.

STEP 4 Label the tabs Landsat, GPS/GIS, TOPEX/ Poseidon, and Sea Beam.

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Use this Foldable with Section 2.3.

As you read this section, summarize information about the mapping technologies.

Visit glencoe.com to ^ study entire chapters online;

► explore h Mqjj^ animations:

• Interactive Time Lines

• Interactive Figures

• Interactive Tables

^ access Web Links for more information, projects, and activities;

► review content with the Interactive Tutor and take Self-Check Quizzes.

Visit glencoe.com to ^ study entire chapters online;

► explore h Mqjj^ animations:

• Interactive Time Lines

• Interactive Figures

• Interactive Tables

^ access Web Links for more information, projects, and activities;

► review content with the Interactive Tutor and take Self-Check Quizzes.

Section 2.1

Objectives

I Describe the difference between latitude and longitude. I Explain why it is important to give a city's complete coordinates when describing its location. I Explain why there are different time zones from one geographic area to the next.

Review Vocabulary time zone: a geographic region within which the same standard time is used

New Vocabulary cartography equator latitude longitude prime meridian

International Date Line

Latitude and Longitude mMMNKLines of latitude and longitude are used to locate places on Earth.

Real-World Reading Link Imagine you were traveling from New York City, New York, to Los Angeles, California. How would you know where to go? Many people use maps to help them plan the quickest route.

Latitude

Maps are flat models of three-dimensional objects. For thousands of years people have used maps to define borders and to find places. The map at the beginning of this chapter was made in 1570. What do you notice about the size and shape of the continents? Today, more information is available to create more accurate maps. The science of mapmaking is called cartography.

Cartographers use an imaginary grid of parallel lines to locate exact points on Earth. In this grid, the equator horizontally circles Earth halfway between the north and south poles. The equator separates Earth into two equal halves called the northern hemisphere and the southern hemisphere.

Lines on a map running parallel to the equator are called lines of latitude. Latitude is the distance in degrees north or south of the equator as shown in Figure 2.1. The equator, which serves as the reference point for latitude, is numbered 0° latitude. The poles are each numbered 90° latitude. Latitude is thus measured from 0° at the equator to 90° at the poles.

Locations north of the equator are referred to by degrees north latitude (N). Locations south of the equator are referred to by degrees south latitude (S). For example, Syracuse, New York, is located at 43° N, and Christchurch, New Zealand, is located at 43° S.

Figure 2.1 Lines of latitude are parallel to the equator. The value in degrees of each line of latitude is determined by measuring the imaginary angle created between the equator, the center of Earth, and the line of latitude as seen in the globe on the right.

Figure 2.1 Lines of latitude are parallel to the equator. The value in degrees of each line of latitude is determined by measuring the imaginary angle created between the equator, the center of Earth, and the line of latitude as seen in the globe on the right.

Latitudes north of 0°

0° Latitude (equator)

Latitudes south of 0°

Latitudes north of 0°

0° Latitude (equator)

Latitudes south of 0°

Angle of latitude

Equator

Angle of latitude

Equator

Prime Meridian Degrees

Prime meridian 0°

Equator

Line of longitude

Prime meridian 0°

Equator

Line of longitude

Earth Prime Meridian

Prime meridian 0°

Equator

Figure 2.2 The reference line for longitude is the prime meridian. The degree value of each line of longitude is determined by measuring the imaginary angle created between the prime meridian, the center of Earth, and the line of longitude as seen on the globe on the right.

Prime meridian 0°

Equator

Figure 2.2 The reference line for longitude is the prime meridian. The degree value of each line of longitude is determined by measuring the imaginary angle created between the prime meridian, the center of Earth, and the line of longitude as seen on the globe on the right.

Degrees of latitude Each degree of latitude is equivalent to about 111 km on Earth's surface. How did cartographers determine this distance? Earth is a sphere and can be divided into 360°. The circumference of Earth is about 40,000 km. To find the distance of each degree of latitude, cartographers divided 40,000 km by 360°.

To locate positions on Earth more precisely, cartographers break down degrees of latitude into 60 smaller units, called minutes. The symbol for a minute is '. The actual distance on Earth's surface of each minute of latitude is 1.85 km, which is obtained by dividing 111 km by 60'.

A minute of latitude can be further divided into seconds, which are represented by the symbol ". Longitude is also divided into degrees, minutes, and seconds.

Longitude

To locate positions in east and west directions, cartographers use lines of longitude, also known as meridians. As shown in Figure 2.2, longitude is the distance in degrees east or west of the prime meridian, which is the reference point for longitude.

The prime meridian represents 0° longitude. In 1884, astronomers decided that the prime meridian should go through Greenwich, England, home of the Royal Naval Observatory. Points west of the prime meridian are numbered from 0° to 180° west longitude (W); points east of the prime meridian are numbered from 0° to 180° east longitude (E).

Semicircles Unlike lines of latitude, lines of longitude are not parallel. Instead, they are large semicircles that extend vertically from pole to pole. For instance, the prime meridian 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. There, east lines of longitude meet west lines of longitude. This meridian is also known as the International Date Line, and will be discussed later in this section.

Vocabulary

Science usage v. Common usage Minute

Science usage: a unit used to indicate a portion of a degree of latitude

Common usage: a unit of time comprised of 60 seconds

Degrees of longitude Degrees of latitude cover relatively consistent distances. The distances covered by degrees of longitude, however, vary with location. As shown in Figure 2.2, lines of longitude converge at the poles into a point. Thus, one degree of longitude varies from about 111 km at the equator to 0 km at the poles.

Using coordinates Both latitude and longitude are needed to locate positions on Earth precisely. For example, it is not sufficient to say that Charlotte, North Carolina, is located at 35°14' N because that measurement includes any place on Earth located along the 35°14' line of north latitude.

The same is true of the longitude of Charlotte; 80°50' W could be any point along that longitude from pole to pole. To locate Charlotte, use its complete coordinates—latitude and longitude—as shown in Figure 2.3.

Time zones Earth is divided into 24 time zones. Why 24? Earth takes about 24 hours to rotate once on its axis. Thus, there are 24 times zones, each representing a different hour. Because Earth is constantly spinning, time is always changing. Each time zone is 15° wide, corresponding roughly to lines of longitude. To avoid confusion, however, time zone boundaries have been adjusted in local areas so that cities and towns are not split into different time zones.

jijjjjj^jjjp Locate places on Earth

How can you locate specific places on Earth with latitude and longitude? Procedure

1. Read and complete the lab safety form.

2. Use a world map or globe to locate the prime meridian and the equator.

3. Take a few moments to become familiar with the grid system. Examine lines of latitude and longitude on the map or globe.

Analysis

1. Locate the following places:

• Mount St. Helens, Washington; Niagara Falls, New York; Mount Everest, Nepal; Great Barrier Reef, Australia

2. Locate t he following coordinates, and record the names of the places there:

• 0°03'S, 90°30'W; 27°07'S, 109°22'W; 41°10'N, 112°30'W; 35°02'N, 111°02'W; 3°04'S, 37°22'E

3. Analyze How might early cartographers have located cities, mountains, or rivers without latitude and longitude lines?

Glencoe Earth Science Latitude Longitude
Figure 2.3 The precise location of Charlotte is 35°14'N, 80°50'W. Note that latitude comes first in reference to the coordinates of a particular location.
Pangea Mercatore

Figure 2.4 In most cases, each time zone represents a different hour. However, there are some exceptions. Identify two areas where the time zone is not standard.

For convenience, however, time-zone boundaries have been adjusted in local areas. For example some cities have moved the time-zone boundary so that the entire city shares a time zone. As shown in Figure 2.4, there are six time zones in the United States.

International Date Line Each time you travel through a time zone, you gain or lose time until, at some point, you gain or lose an entire day. The International Date Line, which is 180° meridian, serves as the transition line for calendar days. If you were traveling west across the International Date Line, you would advance your calendar one day. If you were traveling east, you would move your calendar back one day.

Figure 2.4 In most cases, each time zone represents a different hour. However, there are some exceptions. Identify two areas where the time zone is not standard.

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Interactive Figure To see an animation of time zones, visit glencoe.com.

Section 2.1 Assessment

Section Summary

I Latitude lines run parallel to the equator.

I Longitude lines run east and west of the prime meridian.

I Both latitude and longitude lines are necessary to locate exact places on Earth.

I Earth is divided into 24 time zones, each 15° wide, that help regulate daylight hours across the world.

Understand Main Ideas

1. man4TTfla Explain why it is important to give both latitude and longitude when giving coordinates.

2. Describe how the distance of a degree of longitude varies from the equator to the poles.

3. Estimate the time difference between your home and places that are 60° east and west longitude of your home.

Think Critically

4. Evaluate I f you were flying directly south from the north pole and reached 70° N, how many degrees of latitude would be between you and the south pole?

Earth Science

5. Imagine what it would be like to fly from where you live to Paris, France. Describe what it would be like to adjust to the time difference.

Self-Check Quiz glencoe.com

Section 1 • Latitude and Longitude 33

Section 2.2

Objectives

I Compare and contrast different types of maps. I Explain why different maps are used for different purposes. I Calculate gradients on a topographic map.

Review Vocabulary parallel: extending in the same direction and never intersecting

New Vocabulary

Mercator projection conic projection gnomonic projection topographic map contour line contour interval geologic map map legend map scale

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Interactive Figure To see an animation of map projections, visit glencoe.com.

■ Figure 2.5 In a Mercator projection, points and lines on a globe are transferred onto cylinder-shaped paper. Mercator projections show true direction but distort areas near the poles.

Types of Maps

■ Figure 2.5 In a Mercator projection, points and lines on a globe are transferred onto cylinder-shaped paper. Mercator projections show true direction but distort areas near the poles.

Types Geology Careers

MANMaps are flat projections that come in many different forms.

Real-World Reading Link Just as a carpenter uses different tools for different jobs, such as a hammer to drive in a nail and wrench to tighten a bolt, a cartographer uses different maps for different purposes.

Projections

Because Earth is spherical, it is difficult to represent on a piece of paper. Thus, all flat maps distort to some degree either the shapes or the areas of landmasses. Cartographers use projections to make maps. A map projection is made by transferring points and lines on a globe's surface onto a sheet of paper.

Mercator projections A Mercator projection is a map that has parallel lines of latitude and longitude. Recall that lines of longitude meet at the poles. When lines of longitude are projected as being parallel on a map, landmasses near the poles are exaggerated. Thus, in a Mercator projection, the shapes of the landmasses are correct, but their areas are distorted.

As shown in Figure 2.5, Greenland appears much larger than Australia. In reality, Greenland is much smaller than Australia. Because Mercator projections show the correct shapes of landmasses and also clearly indicate direction in straight lines, they are used for the navigation of planes and ships.

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Conic projections A conic projection is made by projecting points and lines from a globe onto a cone, as shown in Figure 2.6. The cone touches the globe at a particular line of latitude. There is little distortion in the areas or shapes of landmasses that fall along this line of latitude. Distortion is evident, however, near the top and bottom of the projection. As shown in Figure 2.6, the landmass at the top of the map is distorted. Because conic projections have a high degree of accuracy for limited areas, they are excellent for mapping small areas. Hence, they are used to make road maps and weather maps.

Gnomonic projections A gnomonic (noh MAHN ihk) projection is made by projecting points and lines from a globe onto a piece of paper that touches the globe at a single point. At the single point where the map is projected, there is no distortion, but outside of this single point, great amounts of distortion are visible both in direction and landmass, as shown in Figure 2.7.

Because Earth is a sphere, it is difficult to plan long travel routes on a flat projection with great distortion, such as a conic projection. To plan such a trip, a gnomonic projection is most useful. Although the direction and landmasses on the projection are distorted, it is useful for navigation. A straight line on a gnomonic projection is the straightest route from one point to another when traveled on Earth.

Picture Gnomic Projection
Figure 2.6 In a conic projection, points and lines on a globe are projected onto cone-shaped paper. There is little distortion along the line of latitude touched by the paper.
North Pole Gnomonic Projection
Figure 2.7 In a gnomonic projection, points and lines from a globe are projected onto paper that touches the globe at a single point.

Pr°file view

500 m Sea level i

Figure 2.8 1o>ints o4 el3vation on Earth's surface are projected onto paper to make a topographic map.

Interpret How many meters high is the highest point on the map?

Topographic Maps

Detailed maps showing the hills and valleys of an area are called topographic maps. Topographic maps show changes in elevation of Earth's surface, as shown in Figure 2.8. They also show mountains, rivers, forests, and bridges, among other features. Topographic maps use lines, symbols, and colors to represent changes in elevation and features on Earth's surface.

Contour lines Elevation on a topographic map is represented by a contour line. Elevation refers to the distance of a location above or below sea level. A contour line connects points of equal elevation. Because contour lines connect points of equal elevation, they never cross. If they did, it would mean that the point where they crossed had two different elevations, which would be impossible.

Contour intervals As Figure 2.8 shows, topographic maps use contour lines to show changes in elevation. The difference in elevation between two side-by-side contour lines is called the contour interval. The contour interval is dependent on the terrain.

For mountains, the contour lines might be very close together, and the contour interval might be as great as 100 m. This would indicate that the land is steep because there is a large change in elevation between lines. You will learn more about topographic maps in the Mapping GeoLab at the end of this chapter.

Index contours To aid in the interpretation of topographic maps, some contour lines are marked by numbers representing their elevations. These contour lines are called index contours, and they are used hand-in-hand with contour intervals to help determine elevation.

If you look at a map with a contour interval of 5 m, you can determine the elevations represented by other lines around the index contour by adding or subtracting 5 m from the elevation indicated on the index contour. Learn more about contour maps and index contours in the Problem-Solving Lab on this page.

ffl Reading Check Analyze If you were looking at a topographic map with a contour interval of 50 m and the contour lines were far apart, would this indicate a rapid increase or slow increase in elevation?

Depression contour lines The elevations of some features such as volcanic craters and mines are lower than that of the surrounding landscape. Depression contour lines are used to represent such features.

On a map, depression contour lines look like regular contour lines, but have hachures, or short lines at right angles to the contour line, to indicate depressions. As shown in Figure 2.9, the hachures point toward lower elevations.

Depression Contour Lines

■ Figure 2.9 The depression contour lines shown here indicate that the center of the area has a lower elevation than the outer portion of the area. The short lines pointing inward are called hachures and indicate the direction of the elevation change.

■ Figure 2.9 The depression contour lines shown here indicate that the center of the area has a lower elevation than the outer portion of the area. The short lines pointing inward are called hachures and indicate the direction of the elevation change.

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Responses

  • laura
    Has very little distortion in the areas or shapes that fall along a certain line of latitude?
    8 years ago
  • Dora
    What is the exact place of these coordinates 27 07's, 109 22'w?
    8 years ago
  • Leah Weaver
    Why do cartographers break down degrees of longitude and latitude into minutes and seconds?
    8 years ago
  • mariam
    What does a depression contour look like?
    7 years ago
  • falco
    What do hachures on contour lines indicate?
    7 years ago
  • Eino
    What takes a globe map and tranfers it into a cone shaped paper?
    6 years ago
  • Anni
    Are contour lines to prevent global warming?
    3 years ago

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