Topographical Forms MCQs Quiz | Class 9
This is a multiple-choice quiz for Class 9 NCC (Code 076), based on Army Unit 3: Map Reading. The questions cover essential topics like Landforms and the introductory concept of contours. Answer all questions, submit your quiz to see your score, and download the PDF answer sheet for future reference.
Understanding Topographical Forms and Contours
In map reading, understanding topographical forms is crucial for navigating and interpreting the terrain. Topographical maps use contour lines to represent the three-dimensional shape of the Earth’s surface on a two-dimensional map. This introductory guide covers the fundamental concepts of landforms and contours.
What are Contour Lines?
A contour line is an imaginary line on a map that connects points of equal elevation (height) above sea level. By studying these lines, one can visualize the shape and steepness of the ground.
- Contour Interval: The constant vertical distance between two adjacent contour lines. This value is usually printed on the map margin.
- Index Contours: Every fifth contour line is typically drawn thicker and is labeled with its elevation. These are called index contours.
- Intermediate Contours: The thinner lines between index contours.
Identifying Major Landforms using Contours
The pattern, spacing, and shape of contour lines help in identifying various landforms:
| Landform | Contour Representation |
|---|---|
| Hill or Mountain | A series of closed, concentric contour lines with increasing elevation towards the center. |
| Valley | U-shaped or V-shaped contour lines. The ‘V’ points towards higher ground, indicating the direction from which a stream flows. |
| Ridge | A line of high ground, represented by U-shaped or V-shaped contours pointing away from high ground (downhill). |
| Saddle or Col | A low point between two hills or peaks, often represented by an hourglass shape formed by two sets of contours. |
| Depression | A low area or hole in the ground, shown by closed contours with small tick marks (hachures) pointing inwards. |
Understanding Slopes from Contours
The spacing of contour lines indicates the steepness of a slope:
- Steep Slope: Contour lines are very close together. This means elevation changes rapidly over a short horizontal distance.
- Gentle Slope: Contour lines are widely spaced. This indicates a gradual change in elevation.
- Uniform Slope: Contour lines are evenly spaced.
- Concave Slope: Contour lines are widely spaced at the top and closely spaced at the bottom. The slope is gentle at the top and steep at the bottom.
- Convex Slope: Contour lines are closely spaced at the top and widely spaced at the bottom. The slope is steep at the top and gentle at the bottom.
Quick Revision Points
- Contour lines never cross or divide.
- The closer the contour lines, the steeper the slope.
- A hill is represented by closed contours with increasing values inside.
- A valley’s V-shaped contours point upstream (towards higher elevation).
- Contour interval is the vertical difference in height between two consecutive lines.
Practice Questions
1. What does a closed contour line with hachures pointing inward represent?
Answer: A depression or a pit.
2. If you are walking along a single contour line, are you moving uphill, downhill, or on level ground?
Answer: On level ground, as you are staying at the same elevation.
3. How would a cliff be represented on a topographical map?
Answer: Several contour lines would merge or be very close together, appearing as a single thick line.
4. What is the difference between a ridge and a valley in terms of contour shapes?
Answer: For a ridge, the U or V shapes point downhill. For a valley, they point uphill.
5. If the contour interval of a map is 20 meters, what is the height difference between an index contour and the next intermediate contour?
Answer: 20 meters.
