how to lie with maps mr. keller ap human geography september 2006

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How to Lie with Maps Mr. Keller AP Human Geography September 2006

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Page 1: How to Lie with Maps Mr. Keller AP Human Geography September 2006

How to Lie with Maps

Mr. Keller

AP Human Geography

September 2006

Page 2: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Introduction

• A map is a generalization or representation of the real world.

• All maps lie. They contain distortions. You cannot represent the three-dimensional Earth on a flat surface without distorting reality.

• Any useful map is selective in what is put in and left out. Example, road or subway map.

Page 3: How to Lie with Maps Mr. Keller AP Human Geography September 2006
Page 4: How to Lie with Maps Mr. Keller AP Human Geography September 2006
Page 5: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Three sources of map distortion

• Map scale – most maps are smaller than the reality they represent. Map scales tell us how much smaller.

• Map projection – this occurs because you must transform the curved surface of Earth on a flat plan.

• Map type – you can display the same information on different types of maps

Page 6: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Map scale – tells us relationship between distance on map and distance on Earth’s surface

• Ratio scale = ratio of map distance to Earth distance.– 1:10,000 means that one inch on the map equals 10,000

inches on Earth’s surface, one centimeter represents 10,000 centimeters, one foot equals 10,000 feet.

– Recall a small fractions has a large denominator so that 1:100,000 is smaller scale than 1:25,000.

– A large-scale map depicts a small area with great detail. A small-scale map depicts a larger area with little detail.

Page 7: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Ratio scale

Page 8: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Which is the large-scale map?

Page 9: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Map scale continued:

• Verbal scale – translates the representative fraction into words– One inch represents one mile conveys more meaning

than 1:63,360

– Used little in places where people use metric system. People familiar with centimeters and kilometers have little need for verbal scales to tell them that 1:100,000 means that one centimeter equals one kilometer or that 1:250,000 means that four centimeters represent one kilometers.

Page 10: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Map Scale Continued:

• Graphic scale – is a simple bar scale that portrays distance on the map.

Page 11: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Map projection is the way we fit Earth’s three-dimensional surface

onto flat paper or a screen.

Page 12: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Mercator Projection

Page 13: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Mercator Projection

• Stretches the poles from on length to the size of the equator. The north-south scale is constant, but east-west scale increases to twice the north-south scale at 60 degrees N and infinitely at the poles

• Shapes are correct for all areas, and map has correct directional relationships.

• Look at the size of Greenland and Antarctica.• Map exaggerates the distance between Chicago

and Stockholm, both in northern latitudes.

Page 14: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Equal Area Projection

Page 15: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Equal Area Projection

• Represents areas correctly but distorts shapes.

• If South America is 8 times larger than Greenland on the globe, it will be 8 times bigger on the map.

Page 16: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Robinson Projection

Page 17: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Robinson Projection

• Frequently used.

• Distorts both size and shape, but not too much.

Page 18: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Map Type -- you can display the same information on different

maps• A thematic maps depicts a single feature, for

example, climate, population, landform, or land use.

• Types of thematic maps:– Isoline – connects points of equal value– Choropleth – puts features into classes and then maps

classes for each region– Proportional symbol – size of the symbol corresponds

to the magnitude of the mapped feature– Dot – each dot represents some frequency

Page 19: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Map types

Page 20: How to Lie with Maps Mr. Keller AP Human Geography September 2006

What kind of map is this?

Page 21: How to Lie with Maps Mr. Keller AP Human Geography September 2006

What kind of map is this?

Page 22: How to Lie with Maps Mr. Keller AP Human Geography September 2006

What kind of map is this?

Page 23: How to Lie with Maps Mr. Keller AP Human Geography September 2006

What kind of map is this?

Page 24: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Other types of visual images: Mental map=map of an area in

your mind.

Page 25: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Satellite Images – data are collected and processed from satellites over Earth’s surface

Page 26: How to Lie with Maps Mr. Keller AP Human Geography September 2006

Bottom Line: Hundreds of decisions are made in the making of a map, including scale, projection, and type. These decisions ultimately determine the map’s message.