What is a Map Scale?
Map scales are useful to understand the sizes of objects and distances between objects (their relative sizes) in comparison to the actual sizes of objects and distances between them. This means that on a map it is not possible to denote the actual distances between objects or their sizes since then the map would need to be as big as the objects being measured. This would defeat the purpose of having a map in the first place.
This is what it means when it is said that maps are drawn to scale. Scales are always mentioned on the maps so that whoever looks at them can get an idea of how to navigate through them. The scale represents how much the area on the map corresponds to the actual area on the ground that it shows. For example, if a map is drawn to a scale of one inch to one kilometre, it would mean that one inch on the map is equivalent to one kilometre on the ground.
Classification of Maps
To understand what a map scale is, 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 - 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. Out 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
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.
Symbolization
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 based on 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.
Nomenclature
To enhance the utility of maps, all the possible features and places are identified and labelled on a map. However, for the small-scale maps, only the important features and places are labelled, to enhance legibility. The nomenclature of maps has various parts. The geographic names are among the most troublesome parts 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 labelling 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, and Gothic style.
What is the Significance of the Map Scale?
Map scales give people an accurate idea about how the distances mentioned are plotted on the map. This is useful in understanding how to go from one place to another, especially if one is a traveller or engaged in a similar profession.
For academics, a map scale is useful to measure exact distances between objects and base their work on that. This is useful in calculating operations such as measuring the demographics of an area, measuring the geographical faults of an area, keeping a note of all physical features of the area and its vegetation, and so on. Measuring and making a note of all detailed features of an area on a map is only possible through map scales. If maps were not drawn to scale then no one would be able to navigate through an unknown place all on their own.
FAQs on Map Scales
1. What is a map scale and why is it needed?
A map scale shows the relationship between a distance on a map and the corresponding distance on the ground. Since it's impossible to draw a map at its real size, scales are used to shrink everything down proportionally. For example, a scale might show that 1 centimetre on the map represents 1 kilometre in the real world.
2. What are the three main types of map scales used in Geography?
The three main types of scales you will find on maps are:
- Verbal or Statement Scale: This uses words to describe the relationship, such as "1 cm to 10 km".
- Representative Fraction (RF): This uses a ratio, like 1:50,000. This means one unit on the map represents 50,000 of the same units on the ground.
- Graphical or Bar Scale: This is a printed ruler on the map that allows you to directly measure distances visually.
3. What is the difference between a large-scale map and a small-scale map?
The main difference is the level of detail and the size of the area covered. A large-scale map (e.g., 1:25,000) shows a small area, like a neighbourhood, with a lot of detail. In contrast, a small-scale map (e.g., 1:2,500,000) shows a very large area, like an entire country, but with much less detail.
4. How do you read a map scale like 1:100,000?
A scale written as 1:100,000 means that one unit of measurement on the map is equal to 100,000 of the same units on the ground. For instance, 1 centimetre on the map would represent 100,000 centimetres (which is 1,000 metres or 1 kilometre) in reality. This ratio format is useful because it works with any unit of measurement.
5. Why is choosing the right map scale so important?
Choosing the right scale is crucial because it determines the map's purpose and usefulness. If you need to plan a local delivery route, you need a large-scale map to see individual streets. If you just want to plan a flight between two countries, a small-scale map is more appropriate. The wrong scale would make the map either too cluttered or not detailed enough.
6. When would you use a large-scale map in a real-life situation?
You would use a large-scale map for any activity that requires high detail in a small area. For example, an architect uses a large-scale site plan to design a building, a town planner uses one to map out utilities, or a tourist might use one to navigate a historical city centre or a large park.
7. How does a graphical scale stay accurate even if the map is resized?
A graphical or bar scale is very clever because it changes size along with the map. If you enlarge or shrink the map using a photocopier or a computer, the bar scale also gets proportionally larger or smaller. This means it remains a true measure of distance for the resized map, unlike a verbal scale (e.g., "1 cm = 1 km"), which would become incorrect.
8. Are small-scale maps in an atlas less accurate than large-scale maps?
It's not about being less accurate, but about showing less detail due to a process called generalisation. A small-scale map of a continent is drawn to a precise mathematical scale, but it must omit small features like local roads to remain clear. A large-scale map of a town is also accurate, but it can show those details because it covers a much smaller area. Both are accurate for their specific purpose.
