Contour Maps and Landforms Class 7 Geography Notes Maharashtra State Board
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. Outline the potato in your notebook.
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 millimeters
This is our ‘potato hill’. The tapering side of the potato is the hilltop.
Draw two circles, each going around the hill, one near the top, and the other close to the base. Keep a sufficient distance between the circles. The circle near the top will be smaller.
Now the teacher will slice the potato into these circles.
Do not separate the slices. Insert a toothpick or a piece of pointed stick through the slices vertically.
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.
After outlining, 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 center of the innermost circle. Measure the thickness of all the slices you have kept aside. Give the 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.
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 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.
While studying different landforms on the surface of the earth, one has to take into consideration various facets of landforms like altitude, relief, slope, direction of slope, and drainage. For this, maps prepared using particular methods are used. These are known as contour maps. These maps help us to understand the above characteristics of the landforms. These maps are of immense use to mountaineers, trekkers, soldiers, defense officers, etc. These maps prove to be of great use in the planning for a region too.
A 3D model is given in the figure. The northern part of the model shows the basin of the rivers Mula-Mutha. To its south is the Katraj-Diveghat range extending from the west to the east. Beyond that, some portion of the Karha basin is seen.
Contour lines join places with the same altitude on a map. Therefore, generally, they do not cross each other.
Good Maharashtra State Board Class 7 Geography Notes Contour Maps and Landforms can simplify complex concepts and make studying more efficient.