Geography SS 1
Topic : Map Work / Introduction to Map Reading
A map can be said to be a representation of the earth’s surface as it is seen from above on a paper.
Hence map reading therefore involves the ability to recognize conventional signs on a map and interprete the same.
Types of Map
There different types of map, namely
- Topographical maps
- Atlas maps
- Plan maps
- Sketch maps
*Topographical maps are specifically used for map reading.
Map Scale / The Scale of a Map
The scale of a map indicates the relationship between the distance of two points on a map and the actual or equivalent distance on ground.
In other words, it is the ratio, proportion or relationship between measurements on the map and the actual measurements on ground. Thus if, for instance, the scale of a map is 2cm to 1km, it simply means that 2 centimetres on a map represent one kilometre on ground.
Types of Scale
There are three types of scale, namely Statement scale, Linear scale and Representative fraction (R. F)
- Statement scale: this expresses the map scale in form of statement and figures. Below are some examples of statement scale;
- One centimetre represents two kilometres or 1cm to 2km
- Two centemetres represent one kilometre or 2cm to 1km
- One centimetre to half kilometre or 1cm to ½kkm
*Note: the centimetre (cm) part of the scale represents measured distance on the map, while the kilometre (km) part represents the equivalent ground distance.
- Linear scale: this type of scale uses a line to represent the relationship between the distance on the map and the actual distance on ground. It is usually divided into two parts viz, primary division and secondary division.
- Representative Fraction (R. F) : this expresses the map and ground distances as a fraction or ratio; while the numerator shows map distance, the dinominator represents distance on ground.
Examples of Representative fraction are shown below;
- 1:100,000 is the same as 1cm to 1km
- 1:25,000 is the same as 4cm to 1km or 1cm to ¼km
- 1:50,000 is the same as 1cm to ½km