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

Compass Title Scale

Grid System

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

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

Cylindrical

Conic Projections Cannot map the entire world. Used for middle latitudes between 300 and 600 north latitudes, and between 300 and 600 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)

Conic

Albers Equal Area Conical

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

Flat Plane Map

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.

Gnomonic Projection

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.