Map, representation of a geographic area, usually a portion of the earth's surface, drawn or printed on a flat surface. In most instances a map is a diagrammatic rather than a pictorial representation of the terrain; it usually contains a number of generally accepted symbols, which indicate the various natural, artificial, or cultural, features of the area it covers.
TYPES OF MAPS
Maps may be used for a variety of purposes, and as a result a number of specialized types of maps have been developed.
A Topographic Maps
The basic type of map used to represent land areas is the topographic map. Such maps show the natural features of the area covered as well as certain artificial features, known as cultural features. Political boundaries, such as the limits of towns, countries, and states, are also shown. Because of the great variety of information included on them, topographic maps are most often used as general reference maps.
B Special-Purpose, or Thematic, Maps
Among the most important of the special-purpose maps are hydrographic and aviation charts. Hydrographic charts are used for the navigation of ships and cover the surface of the oceans and other large bodies of water and their shores. Over the water portion of a chart, depths are shown at frequent intervals by printing the number of fathoms of water at low tide. Shoal areas are circled or shaded to give them greater visibility, and the limits of channels are shown by lines. The type of bottom, such as sand, mud, or rock, is also indicated. An important feature of such charts is the exact location of lighthouses, buoys, and other aids to navigation. The only other shore features shown on a chart are such landmarks as tall buildings or prominent peaks on which a navigator may wish to take a bearing. Aviation charts for use over land somewhat resemble topographic maps but bear in addition the location of radio beacons, airways, and the areas covered by the beams of radio range stations.
Other special-purpose maps include political maps, which show only towns and political divisions without topographic features; geologic maps, showing the geologic structure of an area; and maps indicating the geographic distribution of crops, land use, rainfall, population, and hundreds of other kinds of social and scientific data. Another useful type of map is the relief map, which is a three-dimensional model of the terrain of an area. Such maps are usually carved out of clay or plaster of paris. To emphasize relief, the vertical scale of relief maps is usually several times the horizontal scale. Such maps can also be manufactured by stamping plastic sheets in a mold. Relief maps are extensively used in military and engineering planning. 05 October 2010Comment