Which of the following is not a mathematical method for representation of relief?

Question

Accepted Answer

Option 3 is the correct answer because hachures are a qualitative method of representing relief, relying on short lines drawn in the direction of the steepest slope. The thickness and density of the lines indicate the steepness of the slope; thicker and denser lines represent steeper slopes. This method is subjective and does not provide precise elevation values. Therefore, it is not considered a mathematical method.

Here's why the other options are incorrect:

*   **Option 1 (Spot height):** Spot heights are points on a map or chart that have a known elevation. These are numerical values representing the height above a datum (usually sea level). They are a direct mathematical representation of relief.

*   **Option 2 (Bench mark):** Benchmarks are surveyed points with precisely known elevations, permanently marked and recorded. Like spot heights, they provide specific numerical elevation data, making them a mathematical representation of relief.

*   **Option 4 (Form lines):** Form lines are lines drawn on a map to approximate contours. While they are not based on precise survey data like contours, they still represent elevation changes and are often derived using some form of estimation or interpolation based on available elevation data, making them a more quantitative (and therefore closer to mathematical) representation of relief than hachures.