Maps and Map Skills

Why we use different maps.

Types of Maps

• •

General Reference Maps

• Provide the reader general information about an area or place.

Thematic Maps

• Provide more specific information about an area or place than general reference maps.

General reference

Thematic Map

• • Maps are important tools for geographers.

A globe is a better model of Earth than a map, but a globe has disadvantages that a map does not have

Common Features

• • Map Parts • Title • • Legend or Key Grid System • • Direction Scale Map orientation – This has to do with direction

Title Scale Compass

Large Scale and Small Scale Maps

• • A large-scale map shows a small area such as a neighborhood street in great detail.

A small-scale map shows a large area such as a country or a continent in comparatively lesser detail.

Small Area = Large Scale Large Area = Small Scale

Large Scale Small Scale

Small Area = Large Scale Large Area = Small Scale

Compass

• Is used to orient a map toward north

Making Maps

• • • • • Gathering Information Problem of Distortion Map Properties Map Projections Cartographers (Mapmakers)

Gathering Information

• • • Surveying Aerial Photography (Air Planes) Remote Sensing (Satellites)

Problem of Distortion

• Features are stretched to put Earth’s information onto a map.

Map Properties

• No map can have all of the properties at once • Equal areas • Conformality • • Consistent Scale True-Compass Directions

•

Equal areas

• Places shown have the same proportions as they do on Earth. • Example: Greenland 1/8 land area of S. America

•

Conformality

• Having correct shapes.

• • Shows true shapes.

Can show larger areas as closely as possible to their true shapes

•

Consistent Scale

• Uses the same scale for all parts of the map .

• Shows the true distances between places on Earth • In most Cases maps showing large areas cannot be consistent-scale maps.

•True-Compass Direction

• Parallels and meridians appear as straight lines .

• By following these lines you will be following the cardinal directions of N,S,E,&W.

• Straight line between two points on map determines exact directions and set course. (Navigators use these maps)

Map Projections

• • • • • •

Cylindrical Projections Conic Projections Flat Plane Projections Gnomonic Projection Robinson Projection Goode’s Interrupted

• • •

Cylindrical Projections

Straight lines of latitude and Longitude are Perpendicular Little distortion near the equator Best Known: •

Mercator –

• conformal and true-compass direction map, but distortion near poles makes size of land and water areas inaccurate. Land shapes correct – areas distorted – valuable to navigator

• • •

Conic Projections

Cannot map the entire world.

Used for middle latitudes between 30

0

latitudes, and between 30

0

and 60

0

and 60 0 north south latitudes Best Known: •

Lambert Conformal Conical

• Important because it shows the true shapes of areas.

•

Albers Equal Area Conical

• Consistent scale and is used when the size of land and water areas must be accurate. (military and engineering maps)

Flat Plane Projections

• Used to map areas of the North and South poles. Areas near that point show little distortion • • Farther away from the point the greater the distortion of area, shape, and scale .

Shows no more than ½ of the Earth at one time.

• Also called

Azimuthal Projection

•

Gnomonic Projection

Circles of latitude lines and straight longitude lines form a wheel-like pattern.

• Especially useful to navigators because the shortest distance between two places on the map is found by drawing a straight line between them {this line is actually a part of a

great circle

– any imaginary line that circles Earth and divides it into 2 equal parts • Navigators use these along with true-compass direction maps to make their travel plans.

•

Robinson Projection

Equal areas – shown with high degree of accuracy • Conformal except near edges of map where distortion increases • Valuable for showing entire world .

Goode’s Interrupted

• • • High degree of accuracy in area and shape Distorted direction and scale .

Valuable for showing Land masses.

Points to Remember

• • • The projection one chooses to use depends on the information one wants.

All Maps are projections – they transfer Earth’s features from the globe to a flat surface (map).

• When large areas of Earth are mapped, distortion is more serious .

When mapping small areas like cities, distortion is not usually evident .