What is a map?
The map is a scaled representation of the earth’s surface or part of the earth’s surface on the flat surface
Types of maps
There are two types of map
topographical map and statistical map
this is a type of map drawn to show both natural and artificial features.
Examples of natural features are hills, mountains, valleys, and rivers
Examples of artificial features are roads, railways, and buildings
Statistical or distribution map
This is a type of map that is drawn to show the distribution of data or information.
For example, the map of California shows the distribution of people
According to Scale size;
1) Large scale maps
Are those maps drawn to large scale size e.g. 1:10000
These maps gives a larger representation of small area, they are also more detailed (shows a lot of information). They represent areas like cities, towns and villages.
2) Medium scale maps
Are those maps drawn to medium scale size e.g. 1:100000
They show a moderate amount of details. They represent areas like districts, regions and countries.
3) Small scale maps
Are those maps drawn to small scale size e.g. 1:1000000
They give a small presentation of a large area; they show little content (little information) They represent areas like continents and the world.
What is map reading?
Map reading and interpretation is an essential part of our daily life because at one point in your life you will need a map to give you direction in the new city or help you to locate a restaurant or bus station.
By definition map reading and interpretation is the ability to understand symbols and signs in the map and derive important information such as settlement distribution and type of vegetation from the map.
It is the ability to see the information which the map maker wanted you to see and use it to solve various problems using the information.
Map reading and interpretation are old skills that have been around for hundreds of years and have helped navigators and explorers to explore the furthest parts of the world and to find important pieces of information throughout human history.
Map reading and interpretation are very important, especially for tourists visiting new destinations and people wishing to explore new cities and towns.
Nowadays you can use apps such as google maps to explore the world but it may be less useful if you lack the skills to lead and interpret the map.
map reading and interpretation skills can be acquired through studying geography and through exploring various websites on the internet.
IMPORTANCE OF MAP READING
i) They provide basis for description of geographical phenomenon
ii) They are useful for traveling purpose i.e. they guide people to reach their destination
iii) Maps are useful for storage of geographical information
iv)They are important for field studies
v) They are important for land use planningvi) They are useful for military purposes e.g. during wars.
how to do map enlargement and map reduction
IN REDUCING ANY MAP TO A GIVEN SIZE, THE FOLLOWING STEPS SHOULD BE FOLLOWED:
- Measure the length and width of the map.
- Divide the length and width by 2 or 4 if you are asked to reduced the map to half or a fourth of its original size. For example, if the length and width of a map are 24cm and 20cm respectively, such a map should measure 12cm by 10cm if seduced to half its size and 6cm by 5cm if reduced to a fourth of its size and so on.
- Having reduced the original map, it is obvious that the scale would equally change. Therefore, if a map has a scale of 1:50,000, the scale of the map changes to 1:100,000 if the size has been reduced to half, and 1:200,000 if the size of the map has been reduced to a fourth of its original size.
- The features to be shown on the reduced map should also be proportional to the required size of the map.
- When you have finished drawing the reduced map, remember to write its title and the new horizontal scale
IN ENLARGING ANY MAP THE FOLLOWING STEPS SHOULD BE TAKEN
- Measure the length and width of the original map.
- Multiply the length and width by 2 or 4 respectively if you intend to enlarge the map to twice or thrice its original size.For example, if the length and width of a map are 5cm and 3cm respectively, such a map would measure 10cm by 6cm if enlarged to twice its size and 20cm by 12cm if enlarged four times its size and so on.
- Having enlarged the original map, it is equally obvious that the scale would change. Therefore, if a map has a scale of 1:60,000, the scale of the map changes to 1:30,000 if the size has been enlarged twice and 1:15,000 if the size of the map has been enlarged to four times its original size.
- The features to be shown on the enlarged map should also be proportional to the required size of the map.
- When you have finished drawing the enlarged map, write its title and the new horizontal scale.
Before one can know whether to reduce or enlarge a map, it may be necessary to divide the initial scale (scale of the original map) by the scale of the new map to be drawn.
For example, if the scale of a map is 1:50,000 and is to be reproduced to a scale of 1:200,000, divide the former scale with the latter as follows:
50000/200000=1/4 Therefore the new map should be 1/4 times the size of the original map.
10 map essentials
Maps come in an infinite variety of sizes and styles and serve a limitless diversity of purposes.
Regardless of type, however, every map should contain a few basic components to facilitate its use
Omission of any of these essential components decreases the clarity of the map and may make it more difficult to interpret.
the following are 10 map essentials
This should be a brief summary of the map’s content or purpose. It should identify the area covered and provide some indication of content, such as “Road Map of Kenya,” or “River Discharge in Northern Europe.”
This should indicate the time span over which the information was collected. In addition, some maps also give the date of publication of the map.
Most maps depict conditions or patterns that are temporary or even momentary. For a map to be meaningful, therefore, the reader must be informed when the data were gathered, as this information indicates how timely or out of date the map is.
Although the grid system of latitude and longitude is the most common system of location seen on maps, other types of reference grids may also be used on maps.
For example, some large-scale maps (such as road maps) use a simple x- and y-coordinate grid to locate features, and some maps display more than one coordinate system.
Most maps use symbols, colors, shadings, or other devices to represent features or the amount, degree, or proportion of some quantity.
Some symbols are self-explanatory, but it is usually necessary to include a legend box in a corner of the map to explain the symbolization.
any map that serves as more than a pictogram must be drawn to scale, at least approximately. a graphic, verbal or fractional scale is, therefore, necessary
a map should indicate which way is north (and/or south, east, and west). Commonly this is done by a north arrow or compass rose.
Orientation may also be shown by graticule or grid marks (e.g. lines of latitude and longitude).
By convention, north is towards the top of the page (thus some maps do not have north arrows), but the orientation must still be given for a ‘proper’ map.
map data source
For most thematic maps, it is useful to indicate the source of the data.
map projection type
On many maps, particularly small-scale ones, the type of map projection is indicated to help the user assess the kinds of distortions on the map.
a border identifies exactly where the mapped area stops.
The border is often the thickest line on the map and should be close to the edges of the mapped area.
The distance between the map and the border should be the same on all sides (balanced).
purpose of the map
All maps have a purpose that should influence every element of the map and the map layout.
A cartographer should be able to clearly articulate the purpose of their map and should keep the audience and the client in mind.
Difference between Signs and Symbols
The natural and artificial landscape features are represented on maps by means of symbols and signs.
Symbols and signs are the alphabet or language of maps.
As symbols and signs are important in giving information on a map they should have the following qualities. They should be.
- Easy to read;
- Easy to understand;
- Easy to interpret; and
- Correctly and clearly shown and presented on any map.
Symbols and signs are commonly shown at the key or reference or legend of the map. With the aid of a key, reference or legend we can read and interpret a map.
Symbols that are used in maps usually look like the natural and artificial features they represent. Signs usually do not look like the features they represent.
Also, most of the symbols are pictorial while most signs are not. The symbols and signs used on maps are used to improve the appearance and readability of the map.
Various symbols are used to depict features such as buildings, mines, forests, water bodies,
meaning of map scale
before understanding the map scale first you need to understand what is scale? The scale is the ratio that is used to calculate the actual size or area of items which has been reduced in size.
The map scale is the ratio of a distance on the map with the actual or corresponding distance on the ground.
Remember, the map is a scaled representation of the part of the earth’s surface.
3 types of map scale representation
Map scale can be expressed in three ways
- Using linear and this is known as a linear scale
- using ratio this is known as ratio fraction or RF
- using a statement where the scale is expressed in words, for example, I cm on the map represent 10 kilometers on the ground
The statement scale
The statement scale is when you make a statement saying what the distance on the map represents on the ground.
You may say 1 centimeter measured on the map represents 1 kilometer measured on the ground or 1 centimeter to 1 kilometer.
Notice that the statements mention two distances. The smaller distance refers to the map and the larger distance refers to the ground.
For the statement scale, the distance on the ground is always given in kilometers or meters.
Thus, in this case, the distance of 1 cm on the map represents a distance of 1 kilometer on the ground.
The Representative Fraction (R. F.)
The scale is given as a fraction: 1/10 or as a ratio: 1:10. What it means is that one unit measured on the map stands for ten of the same units on the ground. You can use any units that you are familiar with.
So, you can say 1 centimeter represents 10 cm. On most maps, the Representative Fraction is given as a ratio, which is usually 1:50,000 on topographic maps.
Note that the larger the Representative Fraction denominator, the smaller the scale and the less detail that can be shown.
A scale of 1:25 000 will show more detail than a scale of 1:100000.
The smaller the denominator of the Representative Fraction, the larger the scale, and more detail can be shown for a given area.
The linear scale or line-scale
this is the most common scale used for maps and you need to really know how to use it.
This is a special ruler that is drawn below a map that can be used to measure an area or distance. It is divided into a number of equal parts.
The divisions on the line scale measure map distances and the labeling will give you the distance on the ground.
To the right of zero – each scale division represents a distance of 1 kilometer. To the left of zero – the distance representing 1 km is shown.
how to convert statement scale into representative fraction scale (step by step guide)
convert the given statement scale of I centimeter representing 10 kilometers into a representative fraction (R.F)
the given statement scale may be converted into a representative fraction using the following steps
1 centimeter represents 10 kilometers
1 centimeter represents 10*100,000 centimetres (1 kilometre=100,000 centimetres)
I centimeter represent 1,000,000 centimeters
we can now replace the character centimeters into units and read it as
one unit represents 1000000 units
how to convert representative fraction scale (R.F SCALE) into statement of scale (step by step guidance)
convert R.F 1:100,000 into a statement of scale
the given R.F scale of 1:100,000 may be converted into statement of scale using the following steps:
- 1:100,000 mean that
- 1 unit on the map represent 100,000 unit on the ground
- 1 cm represent 100,000/100,000 (1 km=100000cm)
- 1 centimeter represent 1 kilometre
1 cm represent 1 km
3 factors to consider when choosing a map scale
The map content
Some special themes can not have various scales, but only the most logical ones.
For example, population density maps cannot be larger than 1:100 000 otherwise the mapped people are not representative (commuters, day labourer, etc.).
The map purpose
The map scale must be adapted to the purpose of the map and not to the first design or aesthetic idea of the author. Here you should think about how wide will the earth area be mapped be?
The map precision
With what measuring and counting will the map be built? Here you should think about how detailed the information you display on the map will be.
With large-scale maps, the information is precisely because they are less generalized.
Large scale maps are on the whole not economic, not easy to handle, and sometimes misleading.
And, small scales make the whole map difficult to read, complicated, and sometimes are meaningless.
Which scale is selected for a given map design problem will finally depend on the map purpose and physical size.
The amount of geographical detail necessary to satisfy the purpose of the map will also act as a constraint in scale selection.
is topographical map similar to road map?
both types of maps show roads, water features, cities, and parks, but that is where the similarity ends
topographical maps show contours, elevation, forest cover, marsh, pipelines, power transmission lines, buildings, and various types of boundary lines such as international, regional and administrative.
topographical maps show a universal transverse Mercator (UTM) grid, allowing the user to determine precise position.
in other words, topographical maps allow the user to see the three-dimensional landscape on the two-dimensional surface
Importance or advantages of map scale
- The map scale is used to measure the distance of actual ground represented by the map. As we said in our introduction that map scale is used to translate map distance to actual ground distance therefore you can know the actual ground from the map using the map scale through the formula shown above.
- Scale help in calculating the area on the map. This is because it helps the map reader to measure various dimensions in the map such as width and length.
- The scale is used in map enlargement and reduction
- Scale help to determine the amount of content/feature that a map will contain
Classification of scales based on their sizes
Based on sizes, the scales are classified into three categories:
- Small scales
- Medium scales
- Large scales
A map drawn using a small scale is called a small-scale map. A small-scale map has the
It represents a large area of the earth’s surface on a piece of paper.
The features on a small scale map appear crowded and closer to each other than they
really are. As a result, they are not seen clearly.
The map shows fewer details as it covers a large area on a piece of paper e.g. an atlas
map of the world, Africa or Tanzania. It only gives a general picture of the area represented.
Examples of small scales are: 1:10,000,000 or 1 cm:100 km; 1:1,000,000 or 1 cm:10 km
This is a scale ranging between a small scale and a large scale.
Examples of medium scales are: 1:500,000 or 1 cm:5 km; 1:250,000 or 1 cm:2.5 km
A map drawn using a large scale is called a large-scale map. A large-scale map has the following
The map shows many details of a small area on a piece of paper, e.g. a map drawn to
represent a small area such as a town, a certain location or village etc. Therefore, more features
can be represented on a large scale map.
The map appears large in size though it represents a small part of the earth’s surface.
The features on the map are large in size, so they can be seen quite clearly.
Examples of large scales are: 1:50,000 or 1cm:.0.5km; 1:25,000 or 1cm:.0.25km
Usefulness and setback of using maps
The following are the usefulness of maps:
- Maps are used for recreational purposes such as traveling, hiking, and orienteering
- Maps are used by government and industry to assist with urban planning, mining, emergency management, and establishment of legal boundaries and land ownership
- Maps are very important in field studies
- Maps are used as storage of geographical facts of represented. this makes the map capable of giving insight into the previous appearance of the area
- The map is used in conducting a wide range of project like; building design, construction of roads, and others of the same reflection
- Maps can be used to show relationships of various geographic phenomena like the relationship between population and landscape
The setback or disadvantages or limitation of using maps
- Maps use symbols and signs to represent various features on the earth’s surface
- Maps are selective since they show only selected information to appear on the maps
- Maps are more expensive to make compared to other geographic tools like the photograph
- The map takes a long time to make compared to other geographic tools like a photograph
- The reading and interpretation of the map need high skills
- The map is not capable of recording and keeping instant data
HOW TO DRAW CROSS-SECTION FROM TOPOGRAPHICAL MAP
A cross-section is a profile of the area under discussion. It is a diagram showing the change in height along a line drawn between 2 points on a map.
In an exam, the vertical scale will always be indicated – you must not change it. e.g. 1 cm represents 50 meters on the Y-axis (vertical axis) Remember: the Horizontal Scale remains 1:50 000 (this will be map scale)
Procedure for drawing cross-sections
- BEFORE starting, study the area of the cross-section to the general shape or lie of the land, that is always have an idea of the shape BEFORE you begin plotting heights or drawing the section.
- Join the 2 points, making sure the FROM point is on the left.
- On a “magic” piece of paper, delimit the cross-section on the map and match it to the “given” graph. Mark off the right hand extreme on the graph and draw a vertical line to delimit it.
- On the map, place the piece of paper, and (holding it steady) mark off EVERY contour that cuts it, ACCURATELY numbering each mark vertically. Eg. 2 2 2 2 0 2 4 6 0 0 0 0
- Now place the “magic” piece of paper along the base line of the graph – ensure that the 2 extremes are accurately lined up. Matching the vertical scale to the marked contour height, mark a small “x” to show the position of each contour on the graph.
- YOUR EDGES OF THE GRAPH MUST COINCIDE WITH THE LIMITS OF THE GRAPH – nowhere on earth does a piece of land end in mid air!!!
- Join these points free hand, taking care to show valleys or hills where 2 or 3 adjacent points are at the same height.
- Write a FULL heading on your cross-section eg. Cross section from • 96 to r 281 on 3326 BC Grahams town map extract 1 : 50 000 Topographical Series
- Mark in the horizontal scale ,Mark in the vertical scale showing the units of measurement Label the edges of the cross-section using the designated points (NOT just A and B
This is used as the vertical scale must be exaggerated because, if the horizontal scale were used for the vertical, the relief would show as an almost flat line on a cross-section. Formula:
Vertical Exaggeration = Vertical Scale (Given on the cross-section)/Horizontal Scale (1cm represent 50000cm)
Eg Vertical Scale = 1 cm represent 20 metres Convert to cms (an RF) by multiplying by 100 i.e. 1 : 2 000 VE = 1:2000/1:50000 VE=50000/2000/ VE = 25 times
This is the concept of whether one place on a map can be seen from another. It is decided upon by studying the heights between the 2 places. Any ground which cannot be seen behind a higher height is known as DEAD GROUND.
If a convex slope is between the 2 places, the second cannot be seen. A rough cross-section sketch shows this more easily.
Intervisibility can also be affected by the presence of buildings or vegetation.
frequently asked questions on map reading and interpretation
topography is the surface features both natural and man-made, collectively depicted on a topographical map
these are roads for which the surface is unidentified
bearing is the horizontal angle at a given point, measured clockwise from magnetic north or true north to a second point
these are roads for which surface type, width, and use are identified
this is the vertical distance from a datum (usually mean sea level) to a point or object on the earth’s surface
this is the average height of the surface of the sea for all stages of tides, used as a reference surface from which elevation is measured
this is the positional reference or the basis for the geographic location of features on the map
this is an orderly index system suitable for a series of maps of different scales for the coverage of Canada
this is the physical configuration of the earth’s surface, depicted on the topographical map
spot elevation is the point on a map where height above mean sea level is noted, usually by a dot and elevation value; it is shown wherever practical for example road intersection, summit, lakes, large flat areas, and depression