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NCERT Solutions for Class 7 Social Science Geography Chapter 3 - Our Changing Earth

NCERT Solutions for Class 7 Geography Chapter 3 - Our Changing Earth are provided here. Download the best answers for easy and quick preparations for the exams.

Jun 30, 2020 16:57 IST
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NCERT Solutions for Class 7 Social Science Geography Chapter 3 - Our Changing Earth
NCERT Solutions for Class 7 Social Science Geography Chapter 3 - Our Changing Earth

NCERT Solutions for Class 7 Social Science Geography Chapter 3 Our Changing Earth are provided here to help you in easy and active learning of the concepts. We have provided here the best and accurate answers to all the questions given in chapter 3 of the latest NCERT Book for Class 7 Geography. All the answers are provided here in a readable and downloadable format.

NCERT Solutions for Class 7 Social Science Geography Chapter 3 - Our Changing Earth:

1. Answer the following questions.

(i) Why do the plates move?

Answer: 

The movement of molten magma inside the earth causes the plates to move.

(ii) What are exogenic and endogenic forces?

Answer: 

Exogenic forces: The forces that work on the surface of the earth are called as exogenic forces.

Endogenic forces: The forces that act in the interior of the earth are called as endogenic forces.

(iii) What is erosion?

Answer: 

The wearing away of the landscape by different agents like water, wind, ice, etc. is called erosion.

(iv) How are flood plains formed?

Answer: 

When a river overflows its banks, it results in the flooding of the nearby areas. When it floods, it deposits layers of fine soil and other material called sediments along its banks. This leads to the formation of a flat fertile plains named as floodplains.

(v) What are sand dunes?

Answer: 

In deserts, the fast moving winds lift and transport sand from one place to another. When the wind stops blowing, the sand falls and gets deposited in the low hill-like structures. These structures are known as sand dunes.

(vi) How are beaches formed?

Answer: 

The sea waves deposit sediments along the seashores. This leads to the formation of beaches.

(vii) What are the ox-bow lakes?

Answer: 

As the river enters the plain it twists and turns forming large bends known as meanders. Due to continuous erosion and deposition along the sides of the meander, the ends of the meander loop come closer and closer. Eventually, the meander loop cuts off from the river and forms a cut-off lake, known as the ox-bow lakes.

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2. Tick the correct answer.

(i) Which is not an erosional feature of sea waves?

(a) Cliff

(b) Beach

(c) Sea cave

Answer: (b) Beach

(ii) The depositional feature of a glacier is:

(a) Flood plain

(b) Beach

(c) Moraine

Answer: (c) Moraine

(iii) Which is caused by the sudden movements of the earth?

(a) Volcano

(b) Folding

(c) Flood plain

Answer: (a) Volcano

(iv) Mushroom rocks are found in:

(a) Deserts

(b) River valleys

(c) Glaciers

Answer: (a) Deserts

(v) Ox bow lakes are found in:

(a) Glaciers

(b) River valleys

(c) Deserts

Answer: (b) River valleys

3. Match the following.

(i) Glacier

(a) Sea shore

(ii) Meanders

(b) Mushroom rock

(iii) Beach

(c) River of ice

(iv) Sand dunes

(d) Rivers

(v) Waterfall

(e) Vibrations of earth

(vi) Earthquake

(f) Sea cliff

 

(g) Hard bedrock

 

(h) Deserts

Answer:

(i) Glacier

(c) River of ice

(ii) Meanders

(g) Rivers

(iii) Beach

(a) Sea shore

(iv) Sand dunes

(h) Deserts

(v) Waterfall

(d) Hard bedrock

(vi) Earthquake

(e) Vibrations of earth

4. Give reasons.

(i) Some rocks have the shape of a mushroom.

Answer: 

Some rocks have a shape of a mushroom because, in desserts, wind erodes the lower section of rock more than the upper section. Due to this, the lower part of the rock becomes narrow and the upper part becomes wide, giving it the shape of a mushroom.

(ii) Flood plains are very fertile.

Answer: 

When river water overflows, it results in the flooding of the neighbouring areas. This deposits a layer of fine soil and other sediments on the river banks, which leads to the formation of fertile flood plains.

(iii) Sea caves are turned into stacks.

Answer: 

The sea waves strike at the rocks and form the cracks in the rocks. These cracks become bigger over time forming the hollow caves on the rocks. They are called sea caves. Further erosion by the waves breaks the roof, leaving only the walls. These wall like features are called stacks. Thus, through continuous erosion, sea caves are turned into stacks.

(iv) Buildings collapse due to earthquakes.

Answer: 

During an earthquake, vibrations are produced within the earth’s surface as a result of the movement of the Lithospheric plates. When these vibrations travel outwards from the epicentre as waves, this leads to a sudden movement of the Earth's surface which results in the collapse of buildings.

Download all the NCERT Solutions for Class 7 Geography Chapter 3 from the following link:

NCERT Solutions for Class 7 Geography Chapter 3 - Our Changing Earth

 

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