NCERT Solutions Class 7th Geography Social Science Chapter – 3 Our Changing Earth Question & Answer

May 11, 2022

NCERT Solutions Class 7th Geography Social Science Chapter – 3 Our Changing Earth

Textbook	NCERT
Class	7^th
Subject	Geography Social Science
Chapter	Chapter – 3
Chapter Name	Our Changing Earth
Category	Class 7th Social Science Geography
Medium	English
Source	Last Doubt

NCERT Solutions Class 7th Geography Social Science Chapter – 3 Our Changing Earth Question & Answer What is our changing earth? What is erosion?What are sand dunes ? Why is our Earth changing? What are the 3 changes of Earth? What changes Earth for kids? How we are changing the planet? Why is Earth important? How can kids save Earth? What are the 5 lines on Save Earth?What are 10 ways to save Earth? Why save the earth? How can we save the earth life? How can we save the world? What is the earth essay? What is Earth 10 lines? What is called a Earth? Why is it called Earth? Who first named Earth? Who gave Earth its name? What are 5 facts about Earth?

NCERT Solutions Class 7th Geography Social Science Chapter – 3 Our Changing Earth

Chapter – 3

Our Changing Earth

Question &Answer

Answer the following questions briefly:

Question. 1.Why do the plated move?

Answer– Plates move due to the movement in the molten magma found in the interior of the earth.

• Exogenic Forces
• Exogenic forces are those forces which act on the surface of the earth and cause
• changes on the surface of the earth.

Examples– Weathering, gradation, erosion, deposition.

Question. 2.What are exogenic and endogenic forces?

Answer- Endogenic Forces Endogenic forces are those forces which originate in the interior of the earth and
cause changes on the surface of the earth.

Examples– Volcanoes and Earthquakes.

Question. 3.What is erosion?

Answer- Erosion
Erosion is the wearing away of the landscape by different agents like running water, glacier, wind, ground water and sea waves.

Question. 4.How are flood plains formed?

Answer- Flood plains are formed in the following manners:

• During rains rivers overflow their banks.
• This leads to the flooding of the nearby areas.
• After the flood has receded, a layer of fine material and other material is deposited over the plain in the form of sediments.
• This leads to the formation of the flood plain.

Question. 5.What are sand dunes?

Answer- Sand Dunes
Sand dunes are heaps of sand deposited at a place by the wind’s action in the desert areas.

Question. 6. How are the beaches formed?

Answer- Formation of Beaches

• Sea waves strike the coasts.
• They erode the coasts and carry the eroded material in the form of silt and other material.
• When they withdraw they deposit the silt and other material (sediments) along the shore, forming wide beaches.

Question. 7.What are the ox-bow lakes?

Answer- Ox-Bow Lakes

• When the meander loop is cut-off from the main river, it forms a cut-off lake.
• Its shape is like an ox-bow.
• Hence, the cut-off lake is called ox-bow lake.

Question. 2. Tick the correct answer:

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

(a) Cliff
(b) Beach
(c) Sea cave.

Answer- (a) Cliff

(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

Question. 3. Match the skill:

Column A	Column B
(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 bed rock
	(h) Deserts

Answer

Column A	Column B
(i) Glacier	(c) River of ice
(ii) Meanders	(g) Hard bed rock
(iii) Beach	(a) Sea shore
(iv) Sand dunes	(h) Deserts
(v) Waterfall	(d) Rivers
(vi) Earthquake	(e) Vibrations of earth

Question. 4. Give reasons:

1.Some rocks have the shape of a mushroom.
2. Flood plains are very fertile.
3. Sea caves are turned into stacks.
4. Buddings collapse due to earthquakes.

Answer- (1) Some rocks have the shape of a mushroom, because of the following reasons:

• When’ rocks fall in the course of running dust-storms, the suspended particles of sand strike the lower portion of the rocks and erode them.
• The upper portions of the rocks remain unaffected/uneroded.
• In course of time the rocks take up the shape of a mushroom.

(2) Flood plains are very fertile because of the following reasons:

• They are made of the silt and other material brought by floods.
• Due to spread of the new silt, the flood plains are fertile areas.

(3) Sea caves are turned into stacks because of the following reasons:

• The sea waves strike the coasts and erode the soft rocks. Hard rocks remain uneroded. This action results in the formation of sea caves.
• In course of time the roofs of the caves also come down due to erosion and the arms/walls of the caves remain standing like pillars. • These pillars-like formations are termed as stacks.

(4) Buildings collapse due to earthquakes because of the following reasons:

• Most buildings are not built/made earthquake-proof.
• When the earthquakes strike, the buildings are not capable of resisting the
vibrations of the earthquakes.
• They tear apart due to shallow foundation, sub-standard interior material, and lack of adequate steel.
• They collapse and fall down like a pack of papers/cards.