How to read & use a map

First Coast High SchoolA.P. World HistoryWorld History HonorsWorld History

By Michael Aiken

CartographyCartography is the art and science of expressing the

known physical features of the earth graphically by maps and charts.

Old World Map c.1629

Compass HeadingsOne of the basic features of a map is the directional markings known as

compass headings. These headings are reference points for the orientation of the map or globe enabling the reader to navigate from “point A” to “point B” by way of an the imaginary line linking directional compass points such as north, south, east, or west.

These compass points for north, south, east, and west form a perfect circle connecting a 360 degree arc whereas true north is 0 degrees, east is 90 degrees, south is 180 degrees, and west is 270 degrees.

Hemispheres

A world map or global projection is usually broken into four hemispheres: eastern, western, northern, and southern.

Western Hemisphere

Eastern Hemisphere

The Equator & The Prime MeridianThe eastern and western hemisphere is divided by

the prime meridian located at 0 degrees longitude.

The equator divides the northern & southern hemisphere at 0 degrees latitude.

Map Legends & Symbols

Cartographic symbology has been developed in an effort to portray the world accurately and effectively convey information to the map reader. A legend explains the pictorial language of the map, known as its symbology.

Globes vs. Flat Maps

A globe is a three-dimensional scale model of Earth. It is the only geographical representation that has a negligible distortion over large areas.

A flat map is created using a map projection that inevitably introduces an increasing amount of distortion the larger area that the map shows.

AtlasAn atlas is a collection of maps of Earth or a region of

Earth. They have traditionally been bound into book form, but today many atlases are in multimedia formats. In addition to presenting geographic features and political boundaries, many atlases often feature geopolitical, social, religious and economic statistics.

Of Meridians & EquatorsA meridian (or line of longitude) is an imaginary arc on the Earth's surface from the North Pole to the South Pole that connects all locations

running along it with a given longitude. The position of a point on the meridian is given by the latitude. Each meridian is perpendicular to all circles of latitude at the intersection points. Each is also the same size, being half of a great circle on the Earth's surface and therefore measuring 20,003.93 km.

Since the meridian that passes through Greenwich, England, establishes the meaning of zero degrees of longitude, or the Prime Meridian, any other meridian is identified by the angle, referenced to the center of the earth as vertex, between where it and the prime meridian cross the equator. As there are 360 degrees in a circle, the meridian on the opposite side of the earth from Greenwich (which forms the other half of a circle with the one through Greenwich) is 180° longitude, and the others lie between 0° and 180° of West longitude in the Western Hemisphere (west of Greenwich) and between 0° and 180° of East longitude in the Eastern Hemisphere (east of Greenwich). Most maps show the lines of longitude.

The term "meridian" comes from the Latin meridies, meaning "midday"; the sun crosses a given meridian midway between the times of sunrise and sunset on that meridian. The same Latin stem gives rise to the terms a.m. (ante meridiem) and p.m. (post meridiem) used to disambiguate hours of the day when using the 12-hour clock.