Maharashtra Board Class 7 Geography Chapter 11 Contour Maps and Landforms PDF Download

Contour Maps And Landforms

In Standard V, you have gathered some information about how height and relief are shown on a map. Now carry out the following activity on the same topic under the guidance of your teacher.

Try This

Take a large oblate shaped potato and other required items as shown above.

Observe how a potato appears when seen from the front and when seen from above? Draw an outline of the potato in your note book.

Cut the potato into two parts so that each part has a flat base.

Rest the cut half on its flat base and measure its height in millimetres.

Do not separate the slices. Insert a toothpick or a piece of pointed stick through the slices vertically.

This is our 'potato hill'. The tapering side of the potato is the hill top.

Draw two circles, each going round the hill, one near the top, and the other close to the base. Keep sufficient distance between the circles. The circle near the top will be smaller.

Without removing the toothpick, place the sliced potato on a piece of paper. Moving a pencil along the edge of the lowest slice draw, its outline. It will be nearly circular in shape.

Now the teacher will slice the potato on these circles.

After drawing the outline, pull the toothpick upwards. Remove the lowest slice delicately and keep it aside. Repeat the same procedure for the other two slices.

Observe the figure that is formed after the exercise is complete. You will note that you have drawn three concentric circles.

Write the height of the potato that you had measured earlier in the centre of the innermost circle. Measure the thickness of all the slices you have kept side. Give value '0' (zero) to the outermost circle. How will you give the values to the other lines? Think about it. Do you think that the thickness of each slice that you have measured can help you?

After assigning values to each circle, our sketch of the potato hill will be complete.

Teacher's Note

This activity teaches children how to show 3D shapes on flat paper. In India, surveyors use similar methods to make maps of our mountains and hills.

Exam Trick

Remember: Concentric circles = closer lines mean steeper slope, farther lines mean gentle slope. Just like staircase steps! This helps you find slopes on contour maps.

Points to Remember

A potato hill shows how real hills look when drawn on flat paper.
Concentric circles show the height of the land at different levels.
Each slice thickness tells us how much the height changes.
This 3D to 2D method is the basic idea behind contour maps.
Close circles mean steep slopes, far circles mean gentle slopes.

Think About It

What did we achieve in this activity? We have transferred a three dimensional object – the potato – into a two dimensional picture.

In reality it is not possible to make the slices of a mountain or any other landform and place them on paper or on the ground to draw a two dimensional picture of that landform. For this, mathematical and survey methods are applied. You will learn about these methods if you study Geography as a special subject at a later stage.

Teacher's Note

Contour maps are used to show real mountains like the Himalayas. Surveyors in India use special tools to measure land and create these maps for planning roads and dams.

Exam Trick

Remember: Contour lines = like drawing rings around a potato! The numbers on lines show height in metres. Just memorise this and you will understand all contour maps.

Points to Remember

Contour maps show land height using circles and numbers.
They help mountaineers, soldiers, and farmers plan their work.
Close contour lines mean the land goes up or down quickly.
Far apart contour lines mean gentle slopes.
You are looking at the land from above when reading a contour map.

This is a preview of the first 3 pages. To get the complete book, click below.