Representation of Geographical Features

The large-scale maps, prepared by the Survey of India, based on actual field surveys are called the topographical maps or topo sheets.

The topo sheets are categorized into three main groups:

1. Million sheets
2. Quarter sheets
3. Quadrant sheets

Three features of arbitrary grid system are:

1. The south-west corner or the bottom-left corner of topo sheet is always taken as the starting point or the point of reference for the grid.
2. The vertical grid lines, drawn from north to south, are called the eastings. The eastings are so called because they lie towards the east of the south-west corner.
3. The horizontal grid lines, drawn from east to west, are called the northings. The northings are so called because they lie towards the north of the south-west corner.

Contour — Contours are lines, drawn on a map, which join the places that have the same height above the mean sea level.

Contour Interval —The difference between the values of any two successive contours is known as the contour interval (vertical interval).

Two characteristics of contours are:

1. They are shown in brown.
2. They are marked with a number called the contour value. It shows the height of the land, in metres, above the mean sea level.

Steep slope — It is shown by closely-spaced contours.

Ridge — It is shown by elliptical contours.

Bench Mark — It is shown by a black dot followed by BM and a number.

The factors suitable for the growth and development of a settlement are:

1. Fertile river valleys and plains
2. Source of water
3. Presence of market or industrial sites
4. Connectivity (presence of roads and railways)

Two examples of areas where compact settlements are found are:

1. Fertile Area
2. Industrial area

The two information that are included under drainage are:

1. Drainage patterns
2. Prominent water bodies

The two roads that connect Abu city are:

1. Abu road (from the south-east)
2. Oriya road (from north-east)

1. Lighthouse
2. Tehsil boundary
3. Palmyra
4. Unmetalled Road
5. Tidal river

The extent of each quarter sheet is 1° of latitude and 1° of longitude. Thus, the quarter sheets are also called 1° x 1° sheets or degree sheets.

Contours are the lines, drawn on the map, which join the places that have same height above the mean sea level. The contours are marked with a number, known as contour value, which shows the height of the land in metres. Thus the difference between two successive contours (contour interval) depicts the difference in heights of two points on land. Thus, contour interval being same, widely spaced contours will depict a gentle slope while closely-spaced contours will depict a steep slope.

False, Topo sheets show the details of a very small area.

million

quadrant sheet

The eastings and the northings intersect to form a network of squares called the arbitrary grid system. Each square in the arbitrary grid system is called the grid square.

The grid lines are numbered in order to locate places and features on topo sheets.

The contour interval on a topo sheet is 20 metres.

steep

saddle

True

The spot height is shown by a black dot followed by a number. The number shows the height of the spot in metres.

Temporary settlements

The different types of settlement on the basis of their shape are:

1. Compact
2. Scattered
3. Linear

Scattered settlement

False

The major possible occupations in the region are written under economic activities.

Northings

Valley

Profile or Cross Section

Linear Settlements

Sipu Nadi

36

brown

dendritic

settlements

Gujarat