Question

What were the different scales on which topography sheets were initially drawn in India?

Answer 1

Hint: A topographic map or a topographic sheet is a kind of map that characterises large-scale detail and provides a quantitative representation of relief using contour lines. It shows both natural and artificial features. Large scale surveys were conducted of areas to draw topographical maps which showed a variety of elevation and landforms. Historically, they were prepared to assist the military in planning for battle and defensive emplacements and now they are used for planning infrastructure and resource exploitation.

Complete answer: The initial maps in India were drawn by the British East India Company, starting in 1802, under the project The Great Trigonometric Survey of India. After 1857, it was passed on to the Survey of India under the British Crown and was completed in 1871. It started with the measurement of a baseline near Madras and it had an enormous scientific impact being one of the first accurate measurements of a geodesic anomaly. The topographical maps of India are prepared on 1 : 10,00,000, 1 : 250,000, 1 : 1,25,000, 1 : 50,000 and 1: 25,000 scale providing a latitudinal and longitudinal coverage of 4° x 4°, 1° x 1°, 30' x 30', 15' x 15' and 5' x 7' 30", respectively taken from the initial series itself.

Note: Relief representation on topographical maps are done through contours which are imaginary lines joining places having the same elevation above mean sea level which helps exhibit gentle slope, steep slope, plateau, conical hills, v-shaped valley, u-shaped valley and other such features.