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Maps are the most important and indispensable tool for geographers to use. They help people understand and explore “relationships” on our planet. A map shows a representation of various phenomenons over all the earth or of a specific area of the land, in a visual graphic format. The earliest maps were drawn on rock surfaces, clay tablets, metal plates, papyrus linen or constructed of sticks. Today maps are usually rendered on a flat surface such as paper or on a computer monitor. Maps are the most successful means of recording and communicating information about the location and spatial characteristics of the natural world and of different societies and cultures. Maps are not perfect, but as technology has improved, so have the quality and accuracy of maps. The science of map making is known as cartography. As maps are so commonly used to convey information, it is important to be able to read and interpret them correctly.
Drawn to Scale
A map is a reducer; it shrinks an area to a manageable size. The amount of reduction is known as the scale. In order for maps to be useful they are scaled down so that they are small enough to be handled by an individual and so that they fit on the available paper or screen. When scaling down a map, every part of the map is scaled by the same amount. This ensures that every object on the map is the same proportion as everything else on the map. As the earth is round and maps are flat it is impossible to create a map with a perfect scale, some parts of the map will be big and others small. The larger a territory represented by a map, the greater the distortion in the scale. The smaller the area the map represents, the more accurate it is. It is important that we recognise how to read, understand and utilize scale as we examine the different maps we encounter. The scale on the map is used to convert distances on the maps to distances in reality and the scale is depicted on the map as three common methods. They are referred to as the graphic (linear) method, the verbal (word) method and the fractional (ratio) method.
The graphic method depicts scale using a line with separations marked by smaller interesting lines, similar to a ruler. One side of the scale represents the distance on the map, while the other side represents the true distance of objects in real life. By measuring the distance between two objects on a map and then referring to the graphic scale it is easy to calculate the actual distance between those same items.
The verbal method simply uses words to describe the ratio between the map’s scale and the real world. Simply measure the distance on the map and then follow the verbal directions to calculate the actual distance.
[“Once centimetre on the map equals one hundred and fifty meters on the ground”]
The fractional method portrays the scale of a map using a representative fraction to describe the ratio between the map and the real world.
1:24 000, in this example, 1cm on the map represents 2,4km on the ground
Large Scale VS Small Scale
A map which depicts a relatively small area is referred to as a large scale map. The visual representation is shown in more detail. This is because the area of land being represented by the map has been scaled down less, in other words, the scale is larger. 1:10000 is a relatively large fraction.
A map depicting a large area, such as an entire country, is considered a small scale map. In order to show the entire country, the map must be scaled down until it is much smaller. This map is less detailed as it shows a relatively vast area. 1:50000 is a small fraction. Large Scale Map VS Small Scale Map
Maps are very effective in conveying information about space and location.
Relative location defines a place in relation to other places. It is a basic reference tool. It is part of your basic geographic knowledge and critical thinking. Directions such as south, west, next door or down the road are used.
Absolute location is crucial for referencing maps and is also known as mathematical location. Coordinate systems are used where as grids consisting of horizontal (parallels of latitude) and vertical lines (meridians of longitude) covering the entire globe are used. The interceptions of these lines create addresses in a global coordinate system giving each location a specific, unique and mathematical placement.
Longitude and Latitude
Measuring latitude – the North Pole and the South Pole provide two natural reference points because they mark the opposite positions of the Earth’s axis. The equator, halfway between the poles, forms a circle that divides the planet into the Northern hemisphere and the Southern hemisphere. The equator is the reference line for measuring latitude in degrees north or south of the equator = 0’ latitude. From the equator, the angles and their arcs increase until we reach the North and South Pole at the maximum latitudes of 90’ North and 90’ South.
Measuring longitude – to describe an east or west position, we need a starting line. Longitude lines run from pole to pole. The global position of the 0’ east-west line for longitude was established by international agreement. The longitude line passing through Greenwich, England (near London) was accepted as the prime meridian, known as the Greenwich Meridian.
Grid referencing occurs when you use the lines of latitude and longitude to locate a place or an object. It is measured in degrees, minutes and seconds. When writing down the grid reference, remember to quote the latitude numbers first (numbers on the side of the map) and write South or North afterwards. These are the lines going across the map. Then quote the longitude (numbers from the bottom or top of the map) and write East or West afterwards. Always have 6 digits in your reference and any one digit number must then have a 0 written in front of it.
Projecting Our Globe onto a Flat Surface
Over the centuries, many different ways of representing the round earth on flat paper have been developed. Each of these methods is referred to as map projections. There are thousands of projections but no “single” or “correct” projection. Today it is still impossible to draw a flat map that is 100% accurate. This is due to the impossibility of recreating the surface of a round planet on a flat map. Distortions are common but there mathematical attempts to minimise the distortions. Distortion occurs in area, shape, scale, distance and direction. Map projections are an attempt to correct distortions.
The types of projections are cylindrical, conical and planar (Mercator, Lamberts, Universal Transverse Mercator and the Gauss Conformal Projection).
Cylindrical projection maps are the most common type of map that we see. The area close to the equator has very little distortion, however the closer to the poles that one travels, the more distorted the map becomes.
Conical projection maps display a more accurate map then the cylindrical map. However, the further we travel down the map, the more distorted and less accurate the map becomes.
Planar projection maps are not commonly used.
There are many different types of interrupted projection maps. They depict the continents as accurately as possible by leaving out less important blank spaces of the map, such as the ocean.
Properties of Map Projections
Each of the map projections must consider shape, area, distance, size and direction when depicting the maps. The two most important factors that need to be considered is Shape Vs Size. The challenge is that the more accurate you depict the shape of objects, the less accurate the size of the objects will be and vice versa. Map projections are classified as follows: conformal and equivalent.
Conformal maps portray shape accurately. This type of map has many negative aspects that it can get quiet distorted, especially towards both the top and bottom of the map. This creates problems with scale.
Equivalent maps portray size accurately. These maps are very useful as no matter what part of the map we examine, the scale will remain accurate. Although the sizes of the objects are accurate their shapes may become distorted.
By blending both conformality and equivalency map projections, we create a map that balances the distortion of both size and shape. By compromising these projections a hybrid map between conformal and equivalent is formed.
The Key to Understanding Maps
Maps can be drawn to represent a variety of information. Cartographic abstraction is when important details are chosen to convey the map’s information, while less relevant details are often not shown. This indicates that the map is not “complete” as details are simplified or omitted to keep the map legible. Geographic features shown on maps are represented by symbols such as: lines, shapes, colours, dots and units. This information might include things such as roads, churches, diggings and monuments. The objects on a map are represented using symbols. A symbol is a picture on the map that represents something in the real world. Understanding these symbols requires the use of a key/legend. It usually shows a small picture of each of the symbols used on the map, along with a written description of the meaning.
Maps are important tools in geography and geography students must be able to identify and distinguish between different maps. Maps convey spatial information, through graphic symbols, “a language of location” that must be able to be read and understood to appreciate and comprehend the rich store of information maps display. Scale, coordinate systems, projections and symbolization are some of the main concepts of the “language” found on maps.