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LAB MODULE 2: THE GEOGRAPHERS’ TOOLS

Note: Please refer to the GETTING STARTED lab module to learn tips on how to set up and maneuver through the Google Earth ( ) component of this lab.

KEY TERMS

The following is a list of important words and concepts used in this lab module:

Absolute location Geographic Information System (GIS)

Remote sensing

Aerial photographs Land Use/Land Cover Satellite images (Landsat)

Cartographer Larger scale map Scale Contours, contour lines Latitude Slope

Contour interval (CI) Longitude Small scale map

Coordinate systems Map scale (Scale) Spatial analysis

False color composite Map types Thematic maps

Geospatial technologies Relative location

LAB MODULE LEARNING OBJECTIVES

After successfully completing this lab module, you should be able to:

• Use latitude and longitude to find an absolute location • Explain the difference between large and small scale maps • Calculate map scale • Identify and describe the three types of maps • Interpret contour maps • Identify changes in land use and land cover using remotely sensed images

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INTRODUCTION

This lab module examines fundamental concepts and tools geographers use to study the Earth. Topics include latitude and longitude, absolute and relative location, geospatial technologies, map types and scale. While these topics may seem disparate, you will learn how they are inherently related.

The modules start with four opening topics, or vignettes, found in the accompanying Google Earth file. These vignettes introduce basic concepts related to geospatial tools and technologies. Some of the vignettes have animations, videos, or short articles that will provide another perspective or visual explanation for the topic at hand. After reading each vignette and associated links, answer the following questions. Please note that some components of this lab may take a while to download or open, especially if you have a slow internet connection.

Expand GEOGRAPHER’S TOOLS, and then expand the INTRODUCTION folder. Double click Topic 1: Tools for Geography.

Read Topic 1: Tools for Geography.

Question 1: According to the article, what are three geographic technologies geographers use to study the Earth?

A. GIS, GPS, and compasses B. GPS, remote sensing, and GIS C. GIS, AutoCAD, and remote sensing D. GPS, Glovis, and GIS

Read Topic 2: Maps.

Question 2: In what state was the first topographic map (relief map using contour lines) issued in the United States?

A. Delaware B. Louisiana C. Maryland D. Mississippi

Read Topic 3: Coordinate Systems and Location.

Question 3: What continent is found at grid cell 35N?

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A. The continent of Africa B. The continent of Australia C. The continent of Europe D. The continent of South America

Read Topic 4: Geospatial Technologies.

Question 4: Looking at the map layers on the vignette image, which layers would be most likely remotely sensed data?

A. States and cities B. Countries and Territories C. Background D. Radar and Satellite

Collapse and uncheck INTRODUCTION.

GLOBAL PERSPECTIVE

Latitude and Longitude form a grid on the Earth’s surface, enabling us to determine an absolute location for any given place or phenomenon.

Expand GLOBAL PERSPECTIVE.

Turn on the latitude and longitude grid by selecting View > Grid, or by using the keyboard shortcut CTRL + L ( + L on the Mac)

Lines of latitude, or parallels, divide the globe at the Equator, and run parallel in both the Northern and Southern Hemispheres (Figure 1). Locations in the Northern Hemisphere are denoted with an N (or a positive number), while locations in the Southern Hemisphere are denoted with an S (or a negative number). The parallel at the Equator is 0°N or 0°S, and increases to 90°N (or +90) at the North Pole, and 90°S (or -90) at the South Pole.

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Latitude (parallels)

Longitude (meridians)

Figure 1. Lines of latitude (parallels) and longitude (meridians) (Arbogast)

Double-click and select Prime Meridian.

Lines of longitude, or meridians, run from pole to pole. Along the Prime Meridian (which runs through Greenwich, UK), the Earth is divided into Eastern and Western Hemispheres. Locations in the Eastern Hemisphere are denoted with an E (or a positive number), while locations in the Western Hemisphere are denoted with a W (or a negative number). The Prime Meridian is 0°E or 0°W, and increases to toward 180°E (or +180) or 180°W (or -180).

Latitude and longitude are measured in degrees, minutes, and seconds. Similar to a clock, where one hour equals 60 minutes, and one minute equals 60 seconds, each degree of latitude or longitude can be divided into 60 minutes (60’) and each minute of latitude or longitude can be further subdivided into 60 seconds (60”). For example, the White House in Washington, DC is located at 38° 53’ 51” N, 77° 02’ 11” W. Latitude and longitude can also be measured in decimal degrees, or degrees and decimal minutes, by converting the minutes and/or seconds into decimal fractions. Cardinal directions (North, East, South and West) are replaced with positive or negative signs. Therefore, the absolute location of the White House in decimal degrees would be 38.8976, -77.0365.

Click Exit Street View in the top right corner of the Google Earth 3D viewer.

Change your units to degrees, minute and seconds. (Refer to the GETTING STARTED lab module for directions on how to change latitude and longitude units).

Double-click and select Location A.

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Question 5: What are the latitude and longitude coordinates for Location A?

A. 51N, 114E B. 114S, 51 E C. 51S, 114W D. 51N, 114W

Double-click and select Location B.

Question 6: What are the latitude and longitude coordinates for Location B?

A. 53N 6E B. 6N, 53E C. 53S, 6W D. 53N, 6W

Question 7: Which is closer – the distance between Location A and the Equator or the distance between Location B and the Equator?

A. Location A and the Equator B. Location B and the Equator C. Locations A and B are the same distance from the Equator D. Cannot discern from the information provided

Question 8: Which is closer – the distance between Location A and the Prime Meridian or the distance between Location B and the Prime Meridian?

A. Location A and the Prime Meridian B. Location B and the Prime Meridian C. Locations A and B are the same distance from the Prime Meridian D. Cannot discern from the information provided

Double-click and select Location C.

Question 9: What are the latitude and longitude coordinates for Location C?

A. 50N, 68S B. 50N, 68W C. 50S, 68E D. 50S, 68W

Question 10: Which is farther– the distance between Location B and the Equator or the distance between Location C and the Equator?

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A. Location B and the Equator B. Location C and the Equator C. Locations B and C are the same distance from the Equator D. Cannot discern from the information provided

Question 11: Which is farther – the distance between Location A and the Prime Meridian or the distance between Location C and the Prime Meridian?

A. Location A and the Prime Meridian B. Location C and the Prime Meridian C. Locations A and C are the same distance from the Prime Meridian D. Cannot discern from the information provided

Collapse and uncheck GLOBAL PERSPECTIVE.

Turn off the latitude/longitude grid (CTRL + L, or + L on the Mac).

MAP SCALES

Map scale (or scale) is the ratio of the distance between two features or absolute locations on the map and the distance between the same two features or absolute locations on the ground. Maps should provide a scale to the user; typically, map scales are shown in the bottom margin of the map.

Map scales are expressed in four ways: ratio, representative fraction, verbal scale (also called a lexical scale), and bar scale (also called a scale bar, graphic scale or graphical scale). An example of each of these map scales is illustrated below.

Scale Expression

Ratio 1:12,000

Representative Fraction (RF) 1/12,000

Verbal 1 inch equals 1,000 feet

Scale Bar

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Expand MAP SCALES and then double-click and select Boothbay Harbor (Note: The topographic map might take a few seconds to display). To close the citation, click the X in the top right corner of the window.

Question 12: How is the scale on this map expressed or presented (Hint: look toward the bottom of the map image)?

A. Scale bar and RF B. RF and Verbal C. Verbal and Ratio D. Scale Bar and Ratio

If you enlarge (zoom in) or reduce (zoom out) of the map, the scale of the image changes, but the scales found the map do not. It is important to note only a bar scale can be used to make distance calculations to a map that is enlarged or reduced because it is the only map scale that remains correct if the map size changes.

If a bar scale is not provided, it is important to know how to calculate distance. In Google Earth, the Ruler tool will help you calculate the approximate distance between two (or more) points.

To calculate scale, we will use the equation

S = 𝒅𝑫

where:

• S = scale

• d = distance between two features on the map

• D = distance between two feature on the ground

Whether using the metric system or the British/Imperial system, make sure that you know the conversions between the units.

Metric Units

1 m = 100 cm

1 km = 1000 m

1 km = 100,000 cm

British/Imperial Units 1 ft = 12 in

1 mile = 5,280 ft

1 mile = 63,360 in

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Now for an example that will use the scale equation (S = 𝒅𝑫

) and British/Imperial units.

Example 1: Two buildings are 8 inches apart on a map (d). The same buildings are 16,000 feet apart on the ground (D). Calculate the scale of the map.

To calculate the scale, first let’s make sure that are units are the same. Currently, the map units (d) are in inches and the ground units (D) are in feet. Therefore, we will convert feet to inches.

We know there are 12 inches in a foot, so we can multiply D by 12 to convert the distance on the ground from feet (ft) to inches (in).

D = 16,000 ft.

D = 16,000 ft. x 12 inches/ft. = 192,000 inches

Now we can use the equation

S = 𝒅𝑫

S = 𝟖 𝒊𝒏𝟏𝟗𝟐,𝟎𝟎𝟎 𝒊𝒏

Because we are dividing the same unit in the numerator as the denominator, the units (inches) cancel out.

S = 𝟖𝟏𝟗𝟐,𝟎𝟎𝟎

Now we need to simplify the equation so that our numerator is a 1. We can do this by dividing both the numerator and the denominator by 8.

S = 𝟖/𝟖𝟏𝟗𝟐,𝟎𝟎𝟎/𝟖

S = 𝟏𝟐𝟒,𝟎𝟎𝟎

This ratio can also be written as 1:24,000.

Example 2: Calculate the scale of a map in which the distance between two features is 6” on the map (d) and 12 miles on the ground (D).

Again, to calculate the scale, we first need to convert distances into the same units. There are 63,360 inches in a mile. If we multiply 12 miles by 63,360 we can convert D into inches

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D = 12 miles

D = 12 miles x 63,360 inches/mile = 720,360 inches

Now we can use the equation

S = 𝒅𝑫

S = 𝟔 𝒊𝒏𝟕𝟐𝟎,𝟑𝟔𝟎 𝒊𝒏

= 𝟔

𝟕𝟐𝟎,𝟑𝟔𝟎

Because we are dividing the same unit in the numerator as the denominator, the units (inches) cancel out.

Now we need to simplify the equation so that our numerator is a 1. We can do this by dividing both the numerator and the denominator by 6.

S = 𝟔/𝟔𝟕𝟐𝟎,𝟑𝟔𝟎/𝟔

= 𝟏

𝟏𝟐𝟔,𝟕𝟐𝟎

This ratio can also be written as 1:126,720

Notice that Examples 1 and 2 have different map scales. The map scale in Example 1, at 1:24,000, is larger than the map scale in Example 2, at 1:126,760.

Large-scale maps are more zoomed in and therefore show more detail, but less area. Conversely, small scale maps are more zoomed out and therefore show less detail but more area. Figures 2 and 3 illustrate larger and smaller map scales.

Figure 2. Map with a 1:24,000 scale (larger scale map) (USGS)

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Example 3. What is the distance on a map (d) in centimeters between two features if they are 5km apart on the ground (D) and the map has a scale (S) of 1:100,000?

First, we need to rearrange our equation so that we are solving for map distance rather than scale.

S = 𝒅𝑫

rearranged to d = S * D

Because Scale (S) is unitless, we do not have to worry yet about converting units. To note, the Scale ratio of 1:100,000 can be rewritten as 1/100,000.

d = S * D

d = 𝟏𝟏𝟎𝟎,𝟎𝟎𝟎

* 5km = 𝟓𝒌𝒎𝟏𝟎𝟎,𝟎𝟎𝟎

d = 0.00005km

Because we are solving for map distance (d), it is unlikely that the final answer will be in kilometers, and far more likely to be in centimeters. So, we convert km to cm.

d = 0.00005km * 𝟏𝟎𝟎,𝟎𝟎𝟎 𝒄𝒎

𝟏𝒌𝒎

d = 5cm

Example 4. What is the distance on the ground in kilometers between two features if they are 5cm apart on the map and the map has a scale of 1:50,000?

Figure 3. Map with 1:62,500 scale (smaller scale map) (USGS)

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First, we need to rearrange our equation so that we are solving for map distance rather than scale.

S = 𝒅𝑫

rearranged to D = 𝒅𝑺

Next, we solve the equation.

D = 𝒅𝑺 = 𝟓𝒄𝒎𝟏 𝟓𝟎,𝟎𝟎𝟎⁄

= 𝟓𝒄𝒎∗𝟓𝟎,𝟎𝟎𝟎𝟏

= 250,000cm

Because we are solving for ground distance (D), it is unlikely that the final answer will be in centimeters, and far more likely to be in kilometers. So, we convert cm to km.

D = 𝟐𝟓𝟎,𝟎𝟎𝟎𝒄𝒎𝟏𝟎𝟎,𝟎𝟎𝟎𝒄𝒎 𝟏𝒌𝒎⁄

= 2.5km

Question 13. Using Figure 4, calculate the distance on the ground, in miles, between Mill Point and Oak Point. Assume we measured 5 inches as the map distance, and know that the map scale is 1:63,360.

Figure 4. Mill and Oak Points (USGS)

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A. 5 inches * 63,360 inches = 316,800 inches = 60 miles B. 5 inches * 63,360 inches = 316,800 inches = 5 miles C. 5 inches / 63,360 inches = .0000799 miles = 41.7 feet D. 63,360 inches / 5 inches = 12,672 inches = 2.4 miles

Question 14: What is the distance on a map in centimeters between two features if they are 7.6 km apart on the ground and the map has a scale of 1:125,000?

A. 7.6 km * (1/125,000) = 0.0000608 cm B. 7.6 km * (1/125,000) = 6.08 cm C. 7.6 km / (1/125,000) = 95 cm D. 7.6 km / (1/125,000) = 950,000 cm

Google Earth does not provide scale as a ratio, representative fraction, or a verbal scale. It does, however, provide a bar scale, found in the lower left hand corner of the screen. If it is not active, select View > Scale Legend.

Even if it seem counterintuitive, remember! the larger the distance on the bar scale, the smaller the map scale. Likewise, the smaller the distance on the bar scale, the larger the map scale.

Double-click and select Squirrel Island 1.

Question 15: What is the approximate distance, in feet, represented by the scale bar?

A. ~ 4000 ft B. ~ 5800 ft C. ~ 6600 ft D. ~ 7400 ft

Uncheck Squirrel Island 1. Double-click and select Squirrel Island 2.

Question 16:What is the approximate distance, in feet, represented by the scale bar?

A. ~ 1150 ft B. ~ 1350 ft C. ~ 1550 ft D. ~ 1950 ft

Question 17: Which bar scale represents the smaller map scale – Squirrel Island 1 or Squirrel Island 2?

A. Squirrel Island 1 B. Squirrel Island 2

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C. They are the same D. Unable to determine from information provided

Collapse and uncheck MAP SCALES.

CONTOURS

Contours are lines that connect places of equal elevation. A contour interval (CI) is the elevation difference between two consecutive contour lines, and is commonly provided in the margin of a map. In Figure 5, the CI is 10 feet, meaning each consecutive contour line represents a 10 foot change in elevation.

Index contours are typically labeled and are have a heavier line weight than regular contour lines. In Figure 5, the index contours are found every 50 feet (every 5 contour lines). The Index contours at 50, 100, and 150 feet are labeled on the contour map.

There some rules regarding contour lines:

• Contour lines always form a closed polygon (see A in Figure 5). However, on some maps, contour lines might run off the margin.

• Contour lines spaced closer together depict a steeper slope (see B in Figure 5). In contrast, contour lines spaced farther apart (wider spacing) depicts a gentler slope or flat area.

• Contour lines might touch where there is a steep elevation change, like a steep slope or cliff. Contour lines never cross unless the cliff face has an overhanging ledge (hidden contours are then depicted as dashed lines).

• Concentric, closed contours denote a hill or summit (see C in Figure 5); whereas closed contours with hachure marks on the downslope side depicts a depression.

Figure 5. Contours (USGS)

A

C

D

B

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• Wherever contour lines cross a river point, the lines point upstream and create a V-shaped pattern (see D in Figure 5).

Double-click and expand CONTOURS.

Double-click and select Boothbay Harbor. (Note: The topographic map might take a few seconds to display). To close the citation, click the X in the top right corner of the window.

A USGS 7.5” map will appear near Georgetown, Maine. You might have to pan and zoom in or out to answer the following questions.

Question 18: What is the contour interval of this map?

A. 10 meters B. 24,000 feet C. 10 feet D. 24,000 meters

Double-click and select MacMahan Island.

Question 19: What is the index contour interval shown on MacMahan Island?

E. Every 20 feet F. Every 40 meters G. Every 50 feet H. Every 100 meters

Unselect MacMahan Island. Double-click and select Red Squares.

Question 20: What is the highest elevation within the two squares?

A. 150 meters B. 150 feet C. 175 feet D. 93 feet

Question 21: Within the right red square, determine the general downstream direction of the river.

A. North B. East C. South

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D. West

Question 22: Explain what contour rule helped you answer Question 22.

A. Contours are spaced close together B. Contours form closed polygons C. Contours form a V shape that points upstream D. Contours form a V shape that points downstream

Question 23: Within these two red squares, where is the steepest slope located?

A. Left edge of right square B. Left edge of left square C. Middle of right square D. Middle of left square

Question 24: Within these two red squares, where is the flattest area?

A. Left edge of left square B. Upper right corner of right square C. Upper center of left square D. Upper center of right square

Uncheck Red Squares.

Double-click and select Slope 1. Next, change the elevation exaggeration to 2 (see GETTING STARTED lab module on how to change exaggeration). Double-click and select Perspective view to see the landscape in three dimensions.

Question 25: As you move from left to right across the yellow line, is the elevation increasing or decreasing?

A. Increasing B. Decreasing C. Remaining flat D. Unable to determine from information provided

Right-click on Slope 1 and select Show Elevation Profile.

At the bottom of the screen is a cross section of the terrain for the yellow line. The X axis of the elevation profile chart is the distance of the line, while Y axis of the charge represents the elevation over the line distance. As you run the cursor along the line, the corresponding

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location along the profile is identified. Additional information regarding elevation, distance, and slope is found immediately above the elevation profile.

Question 26: What is the approximate length of the profile line (distance), in feet?

A. ~ 131 feet B. ~ 161 feet C. ~ 966 feet D. ~ 5280 feet

Question 27: What is the change in elevation (the relief) from one end of the line to the other, in feet?

A. ~ 131 feet B. ~161 feet C. ~ 966 feet D. ~ 5280 feet

Question 28: Slope is the rise (relief of the line) divided by the run (distance of the line). Using your answers from the previous two questions, calculate the percent slope of the line to the nearest integer.

𝑹𝒊𝒔𝒆𝑹𝒖𝒏

*100 = (________ /_______) *100 = ______________

A. (131 feet / 161 feet) * 100 = 81% B. (161 feet / 966 feet) * 100 = 17% C. (966 feet / 5280 feet) * 100 = 18% D. (966 feet / 161 feet) * 100 = 600%

Collapse and uncheck CONTOURS.

REMOTE SENSING

Remote sensing is the art and science of acquiring information about a feature or phenomenon without being in direct contact of that feature or phenomenon. In this part of the lab, you will explore land use and land cover change using satellite imagery. For the rest of this lab, you will be working with Landsat satellite imagery, which is considered the longest continuous global record of Earth’s surface.

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Expand REMOTE SENSING and click NASA Landsat Flyby. Note: Some Mac users might have to click the following URL to view the Flyby video: https://www.youtube.com/watch?v=ZZx1xmNGcXI

Question 29: How long has Landsat been collecting data on Earth?

A. Since 1968 B. Since 1953 C. Since 1977 D. Since 1972

Question 30: Natural disasters like the Mount St. Helens eruption and urban growth in places like Las Vegas are two uses of Landsat data. Based on the video, name two additional physical geography topics – and their example locations – for which Landsat imagery has been used.

A. Mosquito habitat, Mississippi & Oil exploration, Canada B. Climate change, Antarctic & Flooding, North Carolina C. Ecosystems, North Carolina & Mosquito habitat, Yemen D. Oil exploration, Yemen & Farmland, Kansas

Uncheck NASA Landsat Flyby.

Click Landsat Viewer. (Note: if the webpage does not open or takes too long to load, open the web browser outside of Google Earth by choosing the browser icon at the top left corner of the Google Earth Viewer.)

In the ESRI web site, go to the top right hand corner and select View larger. The default image should be Mount St. Helens, in Washington, USA. If it is not, type Mount St. Helens in the search field and then press Enter. To zoom in or out, use any slider found in the top left-hand corner of an image area. Assume North is at the top of these remotely sensed images.

The images in the left (1975) and center (2000) panels are called false color composite images. The satellite sensors collect data from the non-visible portion of the electromagnetic spectrum (that is to say, wavelengths outside of the visible portion of the electromagnetic spectrum we see with our eyes). Specifically, the images are displaying reflected infrared energy; these are wavelengths longer than visible light. Vegetation reflects a great amount of this energy, and appears red in these images. The image to the far right shows change or difference between the 1975 and 2000 images. For a further interpretation of colors, see the legends found below the images.

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Question 31: What direction was most impacted by the 1980 Mount St. Helen’s eruption?

A. North B. East C. South D. West

Question 32: How did you determine this from the remote sensing imagery?

A. The significant decrease in vegetation B. The Swift Reservoir is smaller in the 2000 image C. Spirit Lake in 1975 is now 2 separate lakes in 2000 D. Forests have grown back.

Type Las Vegas, Nevada in the search field and then press Enter. You can pan or zoom in or out of the image to answer the following questions.

Question 33: What does the “white” in the change detection image (right panel) represent?

A. Increased vegetation B. Decreased vegetation C. No change D. Clouds

Question 34: In which direction has the majority of urban growth occurred between 1975 and 2000?

E. North F. East G. South H. All directions

Question 35: What are the bright red (green in the change detection image) rectangle features that are predominately found on the west side of Las Vegas?

A. New casinos B. New subdivisions C. New golf courses D. New water parks

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Question 36: Is urbanization in this region linked to an overall increase, decrease, or no change in vegetation land cover?

A. Increase B. Decrease C. Roughly the same D. Unable to tell from information provided

Question 37: Present in both 1975 and 2000, what is the diagonal strip running NE to SW through the middle of the city?

A. Dried river bed B. Airport runway C. The famous Las Vegas “Strip” D. A major interstate highway

Collapse and uncheck REMOTE SENSING. You have completed Lab Module 2.