GeographyICSE Class 10 · Interpretation of Topographical Maps

Grid References, Contours and Landforms: Reading a Survey of India Toposheet (ICSE Class 10)

Updated 17 October 2026 · Draft, not yet fact-checked

Locate a feature with a four-figure reference (easting then northing of the grid square) or a six-figure reference (add tenths of the square east and north). A contour is a line joining places of equal height above mean sea level, and the contour interval is the constant vertical difference between successive contours. Close contours show a steep slope, wide contours a gentle slope; closed rings with rising values are a hill, and a slope that is steep on one side and gentle on the other is an escarpment.

Give the easting first, then the northing: square 7418, and the tank at 3 tenths east and 6 tenths north is 743186.

Illustration drawn for QuestionBuddy.

Understand Grid References, Contours and Landforms on a Toposheet

1. The grid. A topographical map is covered by numbered grid lines. Eastings run vertically (north to south) and their numbers are printed along the top and bottom edges; they increase to the east. Northings run horizontally (east to west) and their numbers are printed on the left and right edges; they increase to the north. On the 1:50,000 sheets used for ICSE, the lines are drawn at 1 km intervals.

2. Four-figure reference (a grid square).

Take the number of the easting line on the left (west) side of the square and the number of the northing line along the bottom (south) side.
Always write the easting first, then the northing. A useful memory line is "along the corridor, then up the stairs".
Example: a square whose west edge is easting 74 and whose south edge is northing 18 is square 7418.

3. Six-figure reference (a point inside the square). Imagine the square divided into ten equal parts in each direction. The third figure is the number of tenths east of the easting line, and the sixth figure is the number of tenths north of the northing line.

Example: a tank that lies 3 tenths east of easting 74 and 6 tenths north of northing 18 has the reference 743186.
Easting digits come first (74 and 3), northing digits second (18 and 6).

4. Contours. A contour is an imaginary line joining places of the same height above mean sea level; on the sheet it is drawn in brown with height figures along it. The contour interval is the constant difference in height between two consecutive contours (on many ICSE sheets it is 20 m, but read the value from the sheet).

5. Landforms from the contour pattern.

Steep slope: contours very close together. Gentle slope: contours far apart.
Hill: closed (ring-shaped) contours, values rising towards the centre, often topped by a height figure.
Ridge: a long, narrow, raised area; elongated contours that are close on both sides of the crest.
Escarpment: a slope that is steep on one side (contours crowded) and gentle on the other (contours well apart).

6. Heights shown on the map.

Triangulated height: found by a triangulation survey, shown by a small triangle with the height figure.
Spot height: the height of a surveyed point, shown by a dot with the figure.
Relative height or depth: the height of a feature (a mound, an embankment) above, or the depth (a well, a dry tank) below, the ground around it. The sheet's legend shows how this is printed.
A height not exactly on a contour can be placed between the two nearest contour values.

7. How many contour lines lie between two heights. Divide the difference by the interval, taking care to count only contours that actually fall between them. Example: between 300 m and 412 m with an interval of 20 m, the contour lines are at 320, 340, 360, 380 and 400 m, which is 5 lines.

Grid References, Contours and Landforms on a Toposheet: key facts

Grid reference rule: Easting first, then northing
Four figures: a square
Six figures: a point within the square
Four-figure reference: West edge easting + south edge northing | Example: 74 and 18 gives 7418
Six-figure reference: Easting + tenths east, then northing + tenths north | Example: 74 and 3, 18 and 6 gives 743186
Contour interval: The constant vertical difference between two consecutive contours | Read it from the sheet (often 20 m)
Slope from contours: Close together steep
Far apart gentle
Steep one side and gentle the other escarpment
Closed rings with rising values hill
Height symbols: Triangle with figure triangulated height
Dot with figure spot height
Relative height or depth shown as in the legend

Close together	steep
Far apart	gentle
Steep one side and gentle the other	escarpment
Closed rings with rising values	hill

Triangle with figure	triangulated height
Dot with figure	spot height
Relative height or depth	shown as in the legend

How to answer Grid References, Contours and Landforms on a Toposheet questions

For a reference or landform item on the toposheet, work in a fixed order.

1Locate the feature inside the square named in the question; do not name features from other squares.
2For a four-figure reference, read the easting line to the left of the feature and the northing line below it.
3For a six-figure reference, estimate the tenths across and up, and add them as the third and sixth digits.
4Check the order: easting first, then northing, with no digits swapped.
5For landforms, read the spacing and shape of the brown contours: close means steep, wide means gentle, rings with rising values mean a hill.
6For heights, state the value with its unit in metres, and for contour interval give a full definition.

Grid References, Contours and Landforms on a Toposheet in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Planning a trek from a map

Suppose a school group wants to walk from a village at height 120 m to a temple on a hilltop marked 412 m on a toposheet. The map shows contours crowded on the west of the hill and well spaced on the east.

Which side should the group climb and what does the pattern tell them?

Try it first, then show the solutionSolution

Contours crowded together on the west show a steep slope, so the climb on that side would be hard.
Contours spaced widely on the east show a gentle slope, so the east side is the easier route.

Answer: They should climb from the east, where the gentle slope is shown by widely spaced contours.

Memory hook: Crowded contours: tough climb.

Tricks to remember Grid References, Contours and Landforms on a Toposheet

Short memory aids. Say each one aloud once, then use it on a question the same day.

Along the corridor, up the stairs
Read the easting (along) first and then the northing (up).
Use it when: Avoiding the swapped-digit error in references.
Left and bottom
For a four-figure reference use the line to the left and the line at the bottom of the square.
Use it when: Choosing the correct lines.
Close = steep
When contours huddle together the ground rises quickly; when they spread out the ground is almost level.
Use it when: Slope questions.

Grid References, Contours and Landforms on a Toposheet: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Six-figure reference · 1 mark · Map workBoard level

A well lies in grid square 7136. It is 4 tenths of the way east of easting line 71 and 8 tenths of the way north of northing line 36. Give its six-figure reference.

Try it first, then show the solutionSolution

Easting part: 71 with 4 tenths gives 714.
Northing part: 36 with 8 tenths gives 368.
Join them: 714368.

Answer: 714368.

Example 2: Slope from contours · 2 marks · Map workBoard level

In one grid square the brown contours are drawn very close together, and in the next square they are far apart. State what each pattern shows about the slope.

Try it first, then show the solutionSolution

Closely spaced contours show a steep slope.
Widely spaced contours show a gentle slope.

Answer: The first square has a steep slope; the second has a gentle slope.

Example 3: Identify the landform · 2 marks · Map workHarder board level

A set of contours with values 280, 300, 320 and 340 m forms closed rings around a central point marked by a triangle with the figure 352. (a) Name the landform. (b) What is the triangle called and what does it represent?

Try it first, then show the solutionSolution

(a) Closed rings with values rising towards the centre are a hill.
(b) The triangle with a height figure is a triangulated height: the surveyed height of 352 m above mean sea level.

Answer: (a) A hill. (b) A triangulated height of 352 m.

Example 4: Counting contours · 3 marks · Map workHarder board level

The foot of a hill lies on the 240 m contour and its top is a triangulated height of 396 m. The contour interval is 20 m. (a) How many contour lines (with values) lie strictly between the two heights? (b) What is the height of the hill above its foot?

Try it first, then show the solutionSolution

(a) Contour values above 240 up to 396: 260, 280, 300, 320, 340, 360 and 380, which is 7 lines.
(b) Height above foot = 396 - 240 = 156 m.

Answer: (a) 7 contour lines (b) 156 m.

Example 5: Escarpment or ridge? · 4 marks · Map workHOTS / competency

Two features on a sheet: Feature X has crowded contours on its northern side and widely spaced contours on its southern side. Feature Y is a long, narrow area where contours are elongated and close on both sides of the crest. (a) Name X and Y. (b) Suggest which side of X is easier to farm and give one reason.

Try it first, then show the solutionSolution

(a) X is an escarpment (steep one side, gentle on the other). Y is a ridge.
(b) The southern side, because its gentle slope is easier to plough and holds soil and water better than the steep north side.

Answer: (a) X: escarpment; Y: ridge. (b) The southern side, which has the gentle slope.

Where students lose marks in Grid References, Contours and Landforms on a Toposheet

The slips examiners see most often, and what to write instead.

Mistake: Swapping easting and northing
Candidates write the northing digits first, so the reference points to a completely different place.
Wrong working
Temple at 186743 (northing first).
Right working
Temple at 743186 (easting 74 + 3 tenths, northing 18 + 6 tenths).
Do this: Easting first; remember "along the corridor, up the stairs".
Usually costs: 1 mark per item.
Mistake: Writing only four figures when six are asked
The question says "six-figure grid reference" and the third and sixth digits are left out.
Do this: Count the figures before you finish: easting two digits plus one, northing two digits plus one.
Usually costs: 1 mark.
Mistake: Quoting the contour interval as a number only
A question that says "define" needs a sentence, not just 20 m.
Do this: Write: the constant vertical difference between two consecutive contours.
Usually costs: 1 mark.
Mistake: Naming a landform from the wrong square
Features from outside the stated square are named.
Do this: Look only in the stated grid square.
Usually costs: 1 mark.

Exam tips

Mark the stated square with a pencil outline on the question sheet before answering.
For six-figure answers, check there are exactly six digits and the order is easting then northing.
Describe landforms by naming the pattern (close, wide, closed rings) as well as the name.
Always give metres (m) with a height and km or km² with distance and area.

Practice questions on Grid References, Contours and Landforms on a Toposheet

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
In a six-figure grid reference, the first three figures represent the:
(a) northing
(b) easting
(c) height
(d) scale
Hint
Easting comes first.
Answer
(b) easting.
Q2 · 1 mark · MCQBoard level
Contours on a topographical map are drawn in:
(a) blue
(b) black
(c) brown
(d) green
Hint
Colour used for relief on the sheet.
Answer
(c) brown.
Q3 · 1 mark · Very short answerBoard level
Define contour interval.
Hint
Difference in height between successive contours.
Answer
The constant vertical difference in height between two consecutive contour lines on a map.
Q4 · 2 marks · Map workHarder board level
A school lies at the point 5 tenths east of easting 56 and 2 tenths north of northing 79 on the same sheet. (a) Give its four-figure reference. (b) Give its six-figure reference.
Hint
Four figures use only the lines; six add the tenths.
Answer
(a) 5679 (b) 565792.
Q5 · 2 marks · Short answerHarder board level
Explain how contours distinguish a spur-shaped ridge from a hill.
Hint
Shape of the closed lines.
Answer
A hill has roughly circular closed contours with values rising to the centre. A ridge is elongated: contours are long and narrow, close on both sides of a crest line.
Q6 · 1 mark · Assertion-reasonHarder board level
Assertion (A): The contour interval on a given toposheet remains the same throughout the map.
Reason (R): The vertical difference between any two consecutive contours is constant by definition.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Hint
Interval is fixed by definition.
Answer
(a).
Q7 · 3 marks · Map workHarder board level
A spot height on the map reads 347 m and a triangulated height reads 412 m. The contour interval is 20 m. (a) Find the difference between the two heights. (b) Between which two contour values does the spot height lie? (c) Name the symbol used for each height.
Hint
Subtract; check the nearest multiples of 20.
Answer
(a) 412 - 347 = 65 m. (b) Between 340 m and 360 m. (c) Spot height: dot with figure; triangulated height: triangle with figure.
Q8 · 4 marks · Long answerHOTS / competency
A village lies on a gentle slope; a hill rises steeply to its west and a stream flows east of it. State how the contours would be drawn in the three places, and explain why a village on the gentle slope has a better site than one on the steep slope.
Hint
Compare spacing of contours.
Answer
Gentle slope: widely spaced contours. West hill: crowded closed contours with values rising westwards. Near the stream: contours that bend in V-shapes pointing upstream. A village on the gentle slope has easier building and farming and is nearer to the stream for water, while the steep slope is hard to build on and prone to soil loss.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.In a grid reference, are the vertical lines called eastings or northings?Show answer
Eastings; they are quoted before the northing.
2.Digits in a six-figure reference?Show answer
Six.
3.What do close contours show?Show answer
A steep slope.
4.Symbol for a spot height?Show answer
A dot with the height figure.
5.Colour of contours?Show answer
Brown.

Grid References, Contours and Landforms on a Toposheet: frequently asked questions

How do I give a four-figure grid reference?

Read the easting line to the left of the square and the northing line below it, easting first.

What is a contour?

An imaginary line joining places of equal height above mean sea level.

How do I recognise a hill on a map?

Closed rings of contours with values rising towards the centre.

What is an escarpment?

A long slope that is steep on one side and gentle on the other.