Maps—The Geographer’s Maps—The Geographer’s ToolTool

Cartography: The art and Cartography: The art and science of making mapsscience of making maps

A 2-D View of a 3-D WorldA 2-D View of a 3-D World

Globe vs. MapGlobe vs. Map

All flat maps distort shape or size or directionWe can hold one constant, but not all three

Map ProjectionsMap Projections Trying to take something round and Trying to take something round and

make it flat isn’t easy (especially if make it flat isn’t easy (especially if you’re trying to make it into a you’re trying to make it into a rectangle)!rectangle)!

Map projections attempt to do this by Map projections attempt to do this by “projecting” an image of Earth’s “projecting” an image of Earth’s surface onto a piece of papersurface onto a piece of paper

Cylindrical Projection

Imagine a light bulb in the center of a globe, with a sheet of paper wrapped around it in the form of a cylinder. Meridians and parallels would be "projected'' onto the cylinder as straight, parallel lines. Meridians on these projections do not meet at the poles, so these maps are increasingly stretched and distorted toward the poles. 

Azimuthal or Planar Projection

A perfectly flat piece of paper (a plane) would touch the globe at a point (the tangent). This projection is a good choice for maps with circular or square shapes. When the point of tangency is one of the poles, meridians are shown as straight lines radiating from the pole. If parallels are then drawn as equally spaced concentric circles, this projection would be equidistant (scale is true along any line radiating from the center point, in this case the pole).

Conic Projection

A cone of paper placed over a globe would touch its surface along one standard line (usually a parallel). A cone that sliced through the globe would intersect it twice, creating two standard parallels. Such a projection is well-suited for showing areas in the middle-latitudes with a mostly east-west extent (like the United States). 

Pseudocylindrical (or elliptical) projections normally have straight parallels and curved meridians (usually equally spaced). The Robinson Projection is a popular example. It was created to make the world "look" right by keeping angular and areal distortions to a minimum.

Pseudocylindrical Projection

Interrupted ProjectionInterrupted Projection

Conformal vs. Equivalent ProjectionsConformal vs. Equivalent Projections

““Reading” MapsReading” Maps

In order to find your way around a map, In order to find your way around a map, you need to know how standard map you need to know how standard map

coordinates are written:coordinates are written:

As in:3721’41”N 1227’41”W

(Lat.) (min') (sec”) (N/S) (Long.) (min') (sec”) (E/W)

Quick Quiz:Quick Quiz:Which of the following is written incorrectly?Which of the following is written incorrectly?

a)a) 0º0º0º0ºb)b) 0º180º0º180ºc)c) 38ºS 120ºE38ºS 120ºEd)d) 89º56’62”W 179º01’59”N89º56’62”W 179º01’59”N

Elements of a Good MapElements of a Good Map

All maps need certain characteristics in order to be easily readable.

So what is it that makes a mapa “good” map?

Elements of a Good MapElements of a Good Map TitleTitle DateDate Legend/KeyLegend/Key DirectionDirection LocationLocation IndexIndex Data SourceData Source Projection TypeProjection Type ScaleScale Relief and TopographyRelief and Topography DesignDesign

Topographic MapsTopographic Maps

USGS—United USGS—United States Geological States Geological SurveySurvey

How a Topographic Map is MadeHow a Topographic Map is Made

IsolinesIsolines Four basic characteristics:Four basic characteristics: 1. Isolines always form closed shapes. The connecting 1. Isolines always form closed shapes. The connecting

section may be cut off at the edges of the map, but at section may be cut off at the edges of the map, but at some point all isolines meet and close.some point all isolines meet and close.

2. Except in rare cases (such as an overhanging cliff), 2. Except in rare cases (such as an overhanging cliff), isolines do not cross.isolines do not cross.

3. The elevation difference between one isoline and the 3. The elevation difference between one isoline and the next is called an “interval”. Intervals may differ between next is called an “interval”. Intervals may differ between maps, but are usually the same throughout any one map.maps, but are usually the same throughout any one map.

4. Where isolines are close together, there is a steep 4. Where isolines are close together, there is a steep gradientgradient, or slope, or a rapid change of some sort. Where , or slope, or a rapid change of some sort. Where they are further apart, there is a gentle gradient, slope, or they are further apart, there is a gentle gradient, slope, or slow change.slow change.

USGS Topo MapsUSGS Topo Maps

Take one and check it out!Take one and check it out!

ScaleScale

Maps Illustrate and Reinforce Our Maps Illustrate and Reinforce Our Ideas about the World Around UsIdeas about the World Around Us

What we see, what we don’t see, and What we see, what we don’t see, and what we’re not willing to see…what we’re not willing to see…

How we think about the world around How we think about the world around us…us…

What is important to us and what is What is important to us and what is not…not…

These things all “appear” on our These things all “appear” on our mapsmaps

1600’s

1700’s

1800’s

G.I.S.G.I.S.

Geographic Information Geographic Information Systems has Systems has revolutionized the way revolutionized the way we make mapswe make maps

However, the computer However, the computer program only depicts program only depicts what we tell it to…what we tell it to…

3838

A Simplification or a Lie?A Simplification or a Lie?““A more subtle form of cartographic censorship usually occurs A more subtle form of cartographic censorship usually occurs as silences--as features or conditions ignored.as silences--as features or conditions ignored.““Hence basic maps of most cities show streets, landmark Hence basic maps of most cities show streets, landmark structures, elevations, parks, churches, and large museums--structures, elevations, parks, churches, and large museums--but not dangerous intersections, impoverished neighborhoods, but not dangerous intersections, impoverished neighborhoods, high crime areas, and other zones of danger and miser that high crime areas, and other zones of danger and miser that could be accommodated without sacrificing information about could be accommodated without sacrificing information about infrastructure and terrain.infrastructure and terrain.““By omitting politically threatening or aesthetically unattractive By omitting politically threatening or aesthetically unattractive aspects of geographic reality...our topographic ‘base maps’ are aspects of geographic reality...our topographic ‘base maps’ are hardly basic to the concerns of public health and safety hardly basic to the concerns of public health and safety officials, social workers, and citizens rightfully concerned about officials, social workers, and citizens rightfully concerned about the well-being of themselves and others.the well-being of themselves and others.““In this sense, cartographic silences are indeed a form of In this sense, cartographic silences are indeed a form of geographic disinformation.geographic disinformation.

--Monmonier, How to Lie with Maps, p. 1223838