What makes a good map?
A map shows a place from above, drawn smaller, on a flat surface. Map-making is called cartography.
Every map needs TODALSS
- Title – what the map shows
- Orientation – a north arrow
- Date – when it was made
- Author – who made it
- Legend (key) – what each symbol and colour means
- Scale – how much smaller than real life
- Source – where the data came from
Types of maps
Topographic maps show relief, rivers, roads and settlements in detail. Thematic maps show one topic, like rainfall or population. An atlas is a book of maps; use its index to find a place, then its page and grid square or latitude/longitude.
Scale, distance and direction
Scale
Scale can be shown three ways:
- Statement: 1 cm represents 1 km.
- Ratio (representative fraction): 1 : 50 000, so 1 cm on the map = 50 000 cm = 500 m on the ground.
- Line (bar) scale: a ruler drawn on the map.
Distance = map distance × scale. For a curved road, lay a string along it, then measure the string.
A large-scale map (1 : 10 000) shows a small area in great detail. A small-scale map (1 : 10 000 000) shows a big area with little detail.
Direction
The four cardinal points are N, E, S and W; between them are NE, SE, SW and NW. A bearing is an angle measured clockwise from north in three figures: east = 090°, south = 180°, west = 270°.
Latitude and longitude
On a globe or atlas, places are found with latitude (degrees north or south of the Equator) and longitude (degrees east or west of the Prime Meridian). For example, New Delhi is about 28.6° N, 77.2° E.
Grid references
Maps are covered by a grid of numbered lines. Eastings are the vertical lines, numbered along the bottom; the numbers increase to the east. Northings are the horizontal lines, numbered up the side; they increase to the north.
4-figure grid reference (a square)
Take the easting on the left edge of the square, then the northing on the bottom edge. Easting 23 and northing 32 give square 2332.
6-figure grid reference (a point)
Imagine each side of the square split into 10 tenths. Add the tenths: 5 tenths across and 5 tenths up gives 235 325. This points to a spot within about 100 m on a 1 : 50 000 map.
Rule: always along the corridor, then up the stairs.
Showing height: contours and relief
Contour lines join points of equal height above sea level. The contour interval is the height difference between lines (for example 20 m or 100 m).
- Lines close together = steep slope.
- Lines far apart = gentle slope.
- Rings getting smaller towards the middle = a hill or peak.
- V shapes pointing uphill = a river valley.
Other ways to show height: spot heights (a dot with a number), trig points (triangles), and layer colouring (green for low land, brown for high).
A cross-section is a side view of the land drawn from contour lines; it shows the shape of hills and valleys.
Digital maps, GPS, remote sensing and GIS
GPS (Global Positioning System): a phone receives signals from at least four satellites and works out its latitude, longitude and height. India's own system is NavIC.
Remote sensing: satellites and drones photograph the Earth. Comparing images from different years shows change, such as forests cut down, cities growing or floods spreading.
GIS (Geographic Information System): computer software that stores map data in layers (roads, rivers, heights, population, schools) and lets you stack and query them. Example question: "Which villages are more than 5 km from a hospital?"
Using geographic data wisely
Check the source, the date and the scale of any map or data set. Maps choose what to show and what to leave out, so compare more than one source. Geographers also think at different scales of analysis – local, regional and global – and look at how places are connected.
Key formulas and definitions
- Real distance = map distance × scale denominator
- 1 : 50 000 → 1 cm = 500 m; 2 cm = 1 km
- 4-figure ref = easting (2 digits) + northing (2 digits)
- 6-figure ref = easting + tenths, then northing + tenths
- Bearing: clockwise from north, 3 figures (E = 090°)
- Close contours = steep; far apart = gentle
Worked examples
1. On a 1 : 25 000 map, two villages are 6 cm apart. How far apart are they really?
6 × 25 000 = 150 000 cm = 1500 m = 1.5 km.
2. A school is in the square whose bottom-left corner is easting 45, northing 18. Give the 4-figure reference.
Eastings first: 4518.
3. A temple is 7 tenths across and 2 tenths up in square 4518. Give the 6-figure reference.
Easting 457, northing 182 → 457 182.
4. What is the bearing of south-west?
SW is halfway between S (180°) and W (270°), so 225°.
5. The contour lines on the east side of a hill are close together; on the west side they are far apart. Which side is easier to climb?
The west side, because widely spaced contours mean a gentle slope.
6. A 1 : 50 000 map shows a road 9 cm long. How long does a cyclist ride at 15 km/h to cover it?
9 × 50 000 = 450 000 cm = 4.5 km. Time = 4.5 ÷ 15 = 0.3 h = 18 minutes.
Common mistakes
- Reading the northing before the easting. Always along the corridor first, then up the stairs.
- Using the easting on the right side of the square. Use the line on the left (west) edge and the bottom (south) edge.
- Forgetting to convert units: 1 : 50 000 in cm must be changed to m or km (100 cm = 1 m, 1000 m = 1 km).
- Thinking close contour lines mean a high place. They mean a steep slope; height is read from the numbers on the lines.