Map Scales are used to represent the relative size of objects and relative distances on the map as compared to the actual size of objects and actual distances on the ground. Map scales and classifications are important to read and interpret a map. The scale used in a map is always stated on the map so that it can be interpreted easily. In general, the map scale is given as a ratio of the map distance to the actual distance. The map scales help to represent an extensive area on the map as compared to the ground. The representative fraction is one of the most commonly used scales and is expressed as a ratio. For example, a map scale of 1 inch to 1 mile states that 1 mile on the ground is represented as 1 inch on the map.
Classification of Maps
To understand what is a map scale let us go through a few classifications of maps and map scales, first. As per the common classification of maps, there are about five types of maps that are to be understood. They are thematic maps, general maps, navigation charts, topographic maps, series maps, cadastral, and plans. The types of map scale representations are discussed below.
The basic type of representation of actual distance on maps is done by bar scales and lexical scales. In the bar scales used in maps, the distance ratio is expressed visually whereas, in lexical scales, the ratio is stated in words. There are 3 ways of representing the scale of a map, namely, representative fraction, verbal, and graphic. Of these three, the representative fraction is the most commonly used scale. For example, the topographic maps help to understand the contour and general landforms of an area and most have the scale stated in representative fraction. In topographic maps, various colours are used to represent the contour of landforms, water bodies, settlements.
Map projections are used to draw the parallels and meridians of the Earth systematically, on a flat surface. Various map projections are used to represent the landforms on maps. There are certain map projections that have equal-area properties. Also, projections that have the feature of conformal delineations are devised to represent the landforms on maps. In certain cases, the outlined shape of very small regions is nearly represented in the same way on the map as it is on the ground. It is not possible to completely avoid distortions of shapes of land areas on large-scale maps. The only way to reduce the distortions is to devise the most suitable for the purpose of the particular map.
In general, the Mercator projection is devised on the navigational charts. The charts for the polar regions and the great circle charts do not devise the ordinary Mercator projections. The Great Circle charts that represent large map areas are generally depicted on quite small scales devising gnomonic projection. For example, the navigational chart for the Pacific Ocean. The navigators use these charts to lay a track between two ports and calculate the shortest distance between the ports.
Symbols are the graphical representations of landforms, water bodies, winds, ocean currents, settlements, transport, and communication systems for maps. It may be said that symbols make a graphical language for maps and charts. The symbols were originally ordinary pictograms, which have now developed into conventional signs and symbols for the representation and interpretation of maps.
Standardization of symbols has been brought about by the joint efforts of the UN, NATO, International Map of the World agreements, and the international technical societies. It helped to reduce the confusion that used to arise in the interpretation of maps. The symbols can be classified as hypsographic and planimetric. These symbols can also be grouped on the basis of conventional colours. For example, the blue colour is used to represent water bodies, black colour is used to represent occupation, cultures, and names of population, green colour is used to depict vegetation, brown colour is used to depict relief features, and red colour is used to depict types of roads and other special information. This is the standard use of colours, but there may be variations for geologic and soil maps. Planimetric features are used to represent the slopes, heights, and shapes of the land, on a map.
To enhance the utility of maps, all the possible features and places are identified and labeled on a map. However, for the small-scale maps, only the important features and places are labeled, so as to enhance legibility. The nomenclature of maps has various parts. The geographic names are among the most troublesome part of map nomenclature. The large-scale maps permit the naming of the minor features like streams, hilltops, ridges, etc. While making a topographic map, extensive research and documentation are carried out. Also, the local records are referred to for identifying and labeling all the parts of the area under concern. When a topographical map is published and distributed, it is used as an official document that eliminates confusion regarding the nomenclature of the local areas. The basic types of lettering that are used in the maps are Roman style, Italic, Gothic style.
Importance of Map Scale
The map scale helps readers to get an understanding of the size of the land area represented on the map. With the help of map scales, the demographic information of an area can be expressed on the basis of distance relationships. The denominator of the map scales helps to give readers an idea of the area being represented on a map.
The common map scale examples discussed above will provide a brief idea of how various regions are represented on maps. Knowledge of the classification of maps in geography will help readers understand the reason behind plotting various maps. For example, the physical features, rivers, cities, vegetation, etc. are the common types of maps that are generally covered in the school-level academic curriculum.