Map Types & Projections: Notes Why do we use maps? – Many can be stored at once – Easier (than a globe) to carry – Can have special purposes – Scales allow different levels of detail What are the limitations of maps? – Globe is 3D, maps are 2D. – 2D will lead to distortion for shapes, distances, sizes, and directions VS. What do you think?

Different Types of Maps Different types of maps try to protect from different distortions Conformal Conformal The shapes of places are accurate. Distance Distance Measured distances are accurate. Area/Equivalence Area/Equivalence The areas represented on the map are proportional to their area on the earth. Direction Direction Angles of direction are portrayed accurately.

Maps from Different Shapes Planar Planar – Good: polar maps, minimal distortion at the center, show directions & distance well – Bad: edges have distorted area, shape; only shows half of the world at once Cylindrical Cylindrical – Good: navigation, show direction and distance well, showing the whole world – Bad: distort shape & area near the poles (check out Greenland & Antarctica) Conic Conic (a compromise) – Good: mid-latitude maps like the US and Europe, showing a smaller area – Bad: adds distortion of all aspects, but attempts to keep each at a minimum

Planar Map

Cylindrical Map

USA: Cylindrical Map

Conic Map

USA: Conic Map

USA: Conic & Cylindrical

Draw the Map Types On your note-sheets, draw the map types to the best of your ability.

Describe if the following are Planar, Cylindrical, or Conic

Interrupted Projection These types of maps try to depict the continents as accurately as possible by leaving blank space in the less important areas of the map.

Common Map Projections types projections Even the same types of maps can become different projections (or representations)

Azimuthal Equal-Area Mercator Azimuthal Equidistant Robinson

Robinson Projections

How do these map projections differ? Azimuthal Equal-Area Mercator Azimuthal Equidistant Robinson Changes a sphere to a disk -Shows the size of areas correctly -Does not represent angles correctly Standard map for nautical purposes b/c easy to plot a course across an ocean. -Shows shape of areas correctly -Accurate near the equator but becomes distorted along the poles (distorts these areas) Map for showing airline distances -Attempts to show distances, & direction accurately -Useful for polar projections but distorts area & shapes the fuller you get from the center point. Projection used to show the whole world at once (the compromise map) -Tries to reduce all types of distortion in size, shape, direction, & distance. -Distortion at the poles

Projections: Discussion Questions So, what map projections should we use most often? So, what map projections should we use most often? How do map projections affect our perception of the world? How do map projections affect our perception of the world?

Mercator Projection Mercator Projection (Google maps uses this)

Peters Map Projection

The Controversy Over Projection Types The Controversy Over Projection Types What’s an accurate map?Mercator Cons: – Centers the world on Europe – Inflates the northern areas at the expense of the equatorial regions Pros: – Easy to travel across an ocean: represents lines of constant course Peters Cons: – Created for political purposes, not cartography (lacks data) – Distorts the shape of continents Pros: – Peters: "the Mercator projection overvalues the white man and distorts the picture of the world to the advantage of the colonial masters of the time“ What can you conclude from this comparison? Summarize each projection in your own words.

How big is Greenland? How big is Greenland? On this Mercator projection Greenland and South America appear similar in size. The inset map shows that South America is actually about 15 times larger than Greenland.

How big is Africa? Greenland appears to be the same size as Africa, yet the land mass of Africa is actually 14 times larger: How big is Europe? And compare Europe vs. South America (3.8 million square miles vs. 6.9 million square miles):

The Mercator map distorts the relative size of the north and the south. The south is actually more than twice as large (38.6 million square miles to 18.9 million square miles) Why were cartographic decisions made this way?

Where are the majority of third world nations located?

Why does the ‘Northern’ hemisphere HAVE to be at the top of the map? Could we change the world by changing our map?

Special Purpose Maps Also called thematic maps – they cover one theme in a region – Train lines, postal codes, population density, precipitation, elevation, etc.

Special Purpose Maps: Types Choropleth: different colors are used to show different values Choropleth Isarithmic/contour: have lines that connect regions with similar values & themes Isarithmic/contour Dot: each dot represents a certain number of some occurrence or feature Dot Proportional symbol: varying sizes of a symbol represent the real difference in some occurrence or feature Proportional symbol

Choropleth Isarithmic/contour Dot Proportional Symbol

A Special Purpose Example: Topography A map with lines and symbols representing the natural and man-made features of a part of the earth’s surface. They show the location and shapes of mountains, valleys, plains, etc. Why would this be a useful map for hikers, or engineers?

Maps: Reflection Describe two (2) ways that a special purpose map could be used to represent something from the state of Connecticut. Describe two (2) ways that a special purpose map could be used to represent something from the state of Connecticut.