1. Understanding maps
Geographical Data Skills (Part 1)

2. What are maps?
Maps are pictures or graphical representations of all or a part of the Earth’s surface and its features.
Examples of maps:
Atlas
World map
Street directory
Dot maps
Isobars, Isotherms, contour maps, etc

3. Functions of Maps
Different types of maps would represent different data variables, or perspectives of the map-maker.
For example, all maps of the world will be distorted to a certain degree, depending on their intended use.

4. Functions of Maps
Standard World Map (Mercator Projection)

5. Functions of Maps
Peters Projection

6. Different Types of maps
Dot Density maps
The features of a polygon theme are displayed with a number of dots corresponding to a value.
Used for:
Showing how particular things are distributed throughout an area

7. Different Types of maps
Topographic maps
Shows the shape and elevation of terrain.
Used for:
To understand the earth’s terrain
To plan routes and buildings
To establish evacuation routes and flood control maps.
For hazard mapping.

8. Different Types of maps
Remotely sensed images
Geographic information gathered by means of a sensor.
The common remote sensing images include aerial photographs, radar images, and satellite images.
Used for:
These images are important sources for producing digital maps and are useful for monitoring environmental changes and human activities.

9. Key Parts of a Map Names of Features Names of Features Names of
Title
Grid Lines
Scale
Scale
Scale
Directional
Indicator
Symbols and
Legends

10. Title The title of the map states what the map shows
It usually appears on top of the map
On topographical maps, the title is usually the name of the largest settlement on the map

11. Name of Features Features include:
Roads
Settlements
Rivers
Naming them helps us to identify these features.

12. Scale
The scale shows the size of the map as compared to the actual size of the area that the map represents.
Purpose:
Allows the user to calculate exactly how big or small a features is on the earth’s surface.

13. Grid Lines
Grid lines are a series of numbered vertical lines drawn on a map.
They are used to locate features on a map.

14. Directional Indicator
It shows where
North
South
East
West lies
North (Never)
East (Eat)
South (Sour)
West
(Watermelon)

15. Symbols and Legends
Symbols are used to represent the different physical or man- made features found on the surface of the Earth.
Symbols are used because it is possible to fit a lot of information into a small space.
Legend lists all the symbols used in the map and explains what each of them mean or represent.

16. So, HOW do we read a map?

17. Measuring Distance 1 cm represents 2 km 1:200000
A scale can be shown on a map in 3 ways:
As a statement
As a representative or fraction
As a line or linear scale
1 cm represents 2 km
1:200000

18. Measuring Distance (cont)
Measuring a straight line:
Use a ruler to measure the length between two points.
Use the scale of the map to find out the actual distance on the ground.
Eg if the scale of the map is 1:10000, then a length of 1cm on the map is equivalent to 10000cm(0.1km / 100 metres)

19. Measuring Distance (cont)
Measuring distance along a curve
Place one end of the string at the starting point. Hold this end down firmly with your finger.
Use the string to follow the path with your fingers slowly.
When you reach the end, use a pencil to mark the string.
Remove the string and measure the distance against a ruler.
Use the scale to convert the length to actual distance on the ground.

20. Finding Location 1) By Latitudes and Longitudes
Latitudes and longitudes are imaginary lines which cannot be seen on the actual surface of the Earth
Expressed as degrees of a circle measured from the centre of the Earth
Measured in degrees(°), minutes(‘) and seconds(“)
1° = 60’
1’ = 60”
Latitude is always read 1st before longitude.
very much like in mathematics – (x, y)
Eg. Singapore is located at 1°17’N 103°51’E

21. Finding Location Latitude (parallels, x)
Imaginary horizontal lines running in an east- west direction around the world
Numbered from 0 to 90°N and 90°S

22. Finding Location Longitude (meridians, y)
Imaginary lines that run in a north-south direction from North Pole to South Pole
Numbered from 0° at Greenwich to 180°E and 180°W
Longitude 180°E and 180°W are the same line.

23. Use of Latitude and Longitude
Clue: (x, y)
30°N 10°E

24. Finding Location 2) Locations can also be found using grid references.
There are basically 2 types of grid references
Four figure grid references
Six figure grid references

25. 1391

26. Finding Direction N NW NE W E SW SE S
Cardinal Points are points marked on a compass.
Besides the basic North, South, East, West, there are additional points marked North East, South East, South West, North West. N NW NE W E SW SE S

27. Finding direction using cardinal points.
Find the direction of X from Y
Draw a line joining the two places or feature
Draw a mini vertical and horizontal line, which intersects at X
Look at X and use one of the cardinal points to describe the position of Y from X.

28. Bearings (Angles!) Measure the bearing of B from A
Draw a line to join the two points
Place the protractor at A. The 0° on the protractor must point to North
The point on the outer edge of the protractor where the line joining A and B crosses show the bearing of B from point A.

29. QUICK ACTIVITY! Pg 23 of your Geography workbook Q1 – 5

30. Contours

32. Using Contours to represent relief
A contour is an imaginary line joining places of the same height above sea level
Besides showing us the height, contours also tell us about the
Shape
Slope

33. Using Contours to represent relief
Some points to remember about contours:
Contour lines that are close together denote steep slopes.
Contour lines that are far apart indicate gentle slopes.
When there are no contours, it means that the land is almost flat.

34. Contours joined in a circular form, with contour lines increasing in height towards the centre can indicate a hill or a mountain.

35. A ridge is a linear or elongated upland area.

36. A plateau is similar to a ridge but it has a steep slope and flat summit.

37. A valley’s contours point towards higher ground forming an inverted ‘V’

38. Gradient Gradient = Vertical Distance Horizontal Distance
The gradient of a feature refers to the steepness of the slope of that feature.
Usually expressed as a ratio between vertical distance risen in relation to horizontal distance covered.
Gradient =
Vertical Distance
Horizontal Distance

39. Horizontal Distance
Gradient
Of AB =
Vertical Distance
20 m
10000 m 1
500
1:500
Both values in
same units,
Make numerator 1

40. Drawing a cross-section
Draw a line joining the two points
On a sheet of paper, draw 2 axes
Label the height of the contour on the y-axis
Place the piece of paper below and from the left, drop a perpendicular line from where each contour line cuts its corresponding height
Draw horizontal lines for all contour
Join the points together to make a smooth and even outline