Every map is drawn using a set of symbols. A map symbol is any graphic or visual sign or mark used on a map to represent and communicate information about a geographical feature. The symbols are used to code or set data and present it in form of a diagram or illustration. Symbols are part of the sign language of the map. The symbols used on a map are usually defined in the map’s legend or key.
Types of Map Symbol
There are different types of symbols that can be used to produce a map. However, using dimension as a parameter we can conveniently group the different symbols into three broad categories namely point symbols, line symbols and area symbols. Notice that this grouping is also in line with our grouping of geographical features into point features, line features and area features in Unit 1 above. Nonetheless, we also have conventional symbols, pictorial symbols, and literal or textual symbols.
Point symbols are used to map point or zero-dimensional features. On the map point symbols are shown as individual discrete dots existing at single spots or locations. The dots, however, are not always circular. In other words, point symbols could be of various shapes and sizes too (Figure 2.0(a)). More so, a point symbol can be used to represent a qualitative value or a quantitative value. As shown in Figure 2.0(a), when used as a qualitative symbol, a point symbol simply shows us where individual features are located. For example, a symbol showing a building, settlement, petrol station, trigonometric station, spot height or benchmark. On the other hand, if used as a quantitative symbol it indicates the quantity or amount of the feature it represents. For instance, as illustrated in Figure 2.0(b), one dot can be used to represent 5000 people in a dot map showing the distribution of human population in a region(s).
Line symbols are used to represent one-dimensional or linear features such as roads, rivers, railways, pipelines, and power or telecommunication cables. Like point symbols, some line symbols (e.g. ones showing rivers or roads) are used to show qualitative values (Figure 2.1(a)), while some (e.g. contour lines) are used to show quantitative values (Figure 2.1(b)). Line symbols (e.g. flow maps) can also be used to show the movement or flow of people, goods, energy, animals etc. from one location to another. Line symbols that show movement can indicate both the direction of the movement and the quantity involved in the movement (Figure 2.1(c)). There are different patterns of line symbols.
Area (or areal) symbols are used to map two-dimensional or polygonal features; that is, features that significantly cover a wide area of land. Examples of areal features include lakes, lagoons, farmlands, school compounds, state, country, and so on. There are qualitative area symbols as well as quantitative area symbols. Figure 2.2(a) shows different land use types in a place; the area symbols used here are qualitative. On the other hand, Figure 2.2(b) is composed of quantitative area symbols showing the distribution of population density. The area symbol can also be in form of a colour or pattern.
These are commonly recognised and used map symbols
Literal or Textual Symbols
These are symbols that are derived from the abbreviation of some words; hence they are in form of texts or letters. They are used to indicate the locations of the features they represent.
These are symbols that look very similar to what they represent; they are like a picture or diagrammatic illustration of the feature they stand for aid of a legend or key. Hence, pictorial symbols are mostly used in producing maps for children and non-literate adults.