<P> Many of the symbol feature on maps of the earth will be shown by straight, curved, dashed, or solid lines . They may also be colored to represent different classes of information . The typical color standard for topographic maps depicts contours in brown, bodies of water in blue, boundaries in black, and grids and roads in red . Topographic maps may use different colors to represent area features . Most topographic maps will use green for vegetation or national parks and wildlife management areas . They will also use blue for rivers, lakes, or other bodies of water . Red may also be used to represent areas of significant importance . </P> <P> A map is a smaller representation of an area on the earth's surface; therefore, map symbols are used to represent real objects . Without symbols, maps would not be possible . Both shapes and colors can be used for symbols on maps . A small circle may mean a point of interest, with a brown circle meaning recreation, red circle meaning services, and green circle meaning rest stop . Colors may cover larger areas of a map, such as green representing forested land and blue representing waterways . To ensure that a person can correctly read a map, a map legend is a key to all the symbols used on a map . It is like a dictionary so you can understand the meaning of what the map represents / </P> <P> There are certain rules to follow with map symbols . The representative symbols should always be placed on the left and defined to the right . This allows for the reader to view the symbol first, then its definition, which is customary in English dictionaries . In most cases, representative symbols should be vertically displayed and the symbols should be horizontally centred . The symbols should be vertically centred with the definitions . The definitions are supposed to be horizontally centred to the left . </P> <P> Symbols are used to represent geographic phenomena . Most phenomena can be represented by using point, line, or area symbols . It is necessary to consider the spatial arrangement of the phenomena to determine what kind of symbolization it will require . Discrete phenomena occur at isolated points, whereas continuous phenomena occur everywhere . Both of these can also be broken down into either smooth or abrupt . For example, rainfall and taxes for states are both continuous in nature, but rainfall is smooth because it does not vary at state boundaries, leaving the tax to be considered abrupt . It is important to distinguish between real world and the data we use to represent it . There are basically five types of spatial dimensions that are used to classify phenomena for map symbolization . Point phenomena are assumed to have no spatial extent and are said to be zero - dimensional . These use point symbols on a map to indicate their location . An example of these would be fire hydrants or trees in a park . Linear phenomena are one - dimensional and have a length . This would include any line feature on a map like roads or sidewalks . Areal phenomena are 2 - D that has both a length and a width . The best example of this would be a lake or other body of water . When volume comes into consideration, it is broken down into two types, 2 1⁄2 dimensions and 3 - D. A good example of 2 1⁄2 D would be the elevation of a place above sea level, while 3 - D being any three - dimensional objects . </P>

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