# Contours

## Give the terms used in contours for each of the following

#### Question 1

A number preceded by a dot.

Spot height

#### Question 2

The numerical difference between two contour lines.

Vertical interval

#### Question 3

A number preceded by a triangle.

Triangulation point

#### Question 4

The difference between maximum and minimum height in areas of steep slope.

Relative height

#### Question 5

The accurate height of some point marked above the ground.

Spot height

## Describe the following terms

#### Question 1

Contour Interval

Contour interval means the difference of height between two consecutive contours. For example, if one thick contour shows the height 300 metres and the next thin contour depicts the height of 320 metres. Then, the contour interval is 20 metres.

#### Question 2

Vertical Interval

The vertical distance between any two contour lines is called vertical interval.

#### Question 3

Horizontal Equivalent

The actual distance between two points on two contour lines is called horizontal equivalent.

#### Question 4

The ratio between the vertical height and the horizontal distance of a slope of land measured along the ground is called gradient.

## Explain how would you distinguish between the following on the basis of contours

#### Question 1

Gentle Slope and Steep Slope

Gentle SlopeSteep Slope
In gentle slopes, the change of elevation is gradual. Normally about 1:25 gradient of elevation is gradual.Steep slope suddenly slopes up or down.
The contours are placed wide apart in gentle slope.For steep slopes, the contours are drawn close to one another.

#### Question 2

Scarp and Dip

ScarpDip
A scarp has a narrow top with a steep slope.A dip has a narrow top with a gentle slope.
The contour lines are closer to each other.The contour lines are spread far apart.

#### Question 3

Ridge and Water Divide

RidgeWater Divide
It is a long and narrow highland sloping steeply downwards on its sides.A line which separates two adjacent drainage basins is known as water divide.
Contours showing a ridge are elongated and are closely spaced.The side on which the ridge is steeper, the contours are drawn closely together, whereas the side on which the ridge is gentle, the contours are drawn far apart.

#### Question 1

What is a 'contour'?

Contour lines are imaginary lines which are drawn on a map to join places having the same height above the mean sea level.

#### Question 2

Give two points of difference between Bench Mark and Spot Height.

Bench MarkSpot Height
These are marks etched on stone or a building to indicate the accurate height determined by surveys.It refers to the height of a point on the ground above the mean sea level.
It is written as "BM" followed by a number.It is represented by a dot followed by a number on the map.

#### Question 3

What do you understand by V.I. and H.E.?

V.I. stands for vertical interval. It is the vertical distance between any two contour lines.

H.E. stands for horizontal equivalent. It is the actual distance between two points on two contour lines.

#### Question 4

Hill shading and hachuring only give an impression of the slope but do not indicate the heights of the land above sea level, whereas the contours show both impression of the slope as well as the heights of the land above the sea level.

#### Question 5

Why two contours never intersect each other?

Two contours never intersect each other because each line represents a separate elevation, and we can't have two different elevations at the same point.

## Structured Questions

#### Question 1

What is meant by relief?

Relief refers to actual configuration of land which includes its altitude and slope. The relief features found on the earth's surface include mountains, valleys, hills, plains and plateaus.

#### Question 2

State the three methods used to show the earth's relief features.

The three methods used to show the earth's relief features are-

1. hachures
3. contours

#### Question 3

What do the contour lines represent?

Contour lines are imaginary lines joining places which have the same height above mean sea level.

#### Question 4

How do contour lines show different slopes of land?