Geography [3 Mark Question Answer]

Marginal Information can be obtained from the margin of the sheet. The name of the state to which the area belongs is given at the top of the sheet. The year when the area was surveyed is also mentioned. The number of the sheet is given in the right hand top comer. The direction of the magnetic variation and true north position is also given in the right hand top corner.

A town, which is at the junction of many routes is usually very important and is known as a nodal centre. A nodal centre has generally a dense settlement. Big towns, having dense settlements, reflect the availability of industry and commerce. The availability of minerals can also cause the growth big towns.

Six colours are used in a survey map to show various features. They are as follows:
Black: All names, river banks, broken grounds, dry streams, surveyed trees, heights and their numbering, railway tracks, telephone and telegraph lines.
Yellow: All cultivated areas.
Green: All wooded/forested areas, scattered trees and scrubs.
Brown: Contour lines, their numbering, stony waste, sand features.
Blue: All water bodies, where they contain water.
Red: Grid lines and their numbering, roads, cart tracks, settlements, huts and other buildings. Note: Sometimes we find white patches here and there to show barren lands.

The position of a certain feature on the sheets is indicated eastward and southward. The eastward lines of the grid are known as Northings. The northward lines of the grid are known as Eastings. These have been named Eastings and Northings because they indicate distances eastward and northward respectively from the point of origin.

(i) To measure the straight distance:
To measure the shortest distance between two points on the topographic map along a straight line can be done easily with the help of a pair of divider. Keep the two pointed ends of the divider over line or two points which has to be measured and then carefully keep on scale. Note down the distance on the map in centimetres; then either with the help of the graphical scale which is provided below the toposheet or by using the statement scale distance can be measured in kilometres and metres.
e.g., two places are 5.6 km., apart on the map.
The scale is given 2 cm. = 1 km.
1 cm. = 1/2 km.
5.6 cm. = 1/2 × 5.6
= 2.8 km.
(ii) To measure winding course:
To measure a winding course route is complicated. It has to be measured with the help of a strip of paper or thread e.g., to measure a river in a toposheet take a piece of thread make a knot on one end. At the end of thread (close to knot) mark the point with pen at which you will begin to measure (point A). Put the thread along the line touching as far as possible to measure and keep on marking with ink at turns till the last point. Stretch the thread on the scale line, you will get the ground distance in kilometres and metres, writing the unit of measurement is always important e.g., if the distance calculated between two points is 3.3 km. If asked in kilometres the answer would be 3km., 300m. If asked in metres the answer would be 3300 metres.