NCERT Solutions for Class 7 Geography Chapter 3 Our Changing Earth Social Science
In this page NCERT Solutions for Class 7 Geography Chapter 3 Our Changing Earth will help in building a strong foundation of concepts from the very beginning thus students will be given an easy and straightforward learning path. These NCERT Solutions for students help them with their research in analyzing problems and answering it with precision and the right concepts. You will experience the wonder and beauty in all that you are learning.
Chapter 3 Our Changing Earth NCERT Solutions for Class 7 Geography
1. Answer the following questions.
(i) Why do the plates move?
Solution
The plates move because of the movement of the molten magma inside the earth.
(ii) What are exogenic and endogenic forces?
Solution
The forces that work on the surface of the earth are called as exogenic forces. The forces which act in the interior of the earth are called endogenic forces.
(iii) What is erosion?
Solution
Erosion is the wearing away of the landscape by different agents like water, wind and ice.
(iv) How are flood plains formed?
Solution
During floods, layers of fine soil and other material called sediments are deposited on the river bank. This leads to the formation of a flat fertile flood plains.
(v) What are sand dunes?
Solution
The low hill-like structures formed due to deposition of sand at one place by the wind in the desert is called sand dunes.
(vi) How are the beaches formed?
Solution
The sea waves deposit sediments along the shores which leads to the formation of beaches.
(vii) What are oxbow lakes?
Solution
2. Tick the correct answer.
(i) Which is not an erosional feature of sea waves?
(a) Cliff
(b) Beach
(c) Sea cave
Solution (b) Beach
(ii) The depositional feature of a glacier is:
(a) Flood plain
(b) Beach
(c) Moraine
Solution (c) Moraine
(iii) Which is caused by the sudden movements of the earth?
(a) Volcano
(b) Folding
(c) Flood plain
Solution (a) Volcano
(iv) Mushroom rocks are found in:
(a) Deserts
(b) River valleys
(c) Glaciers
Solution (a) Deserts
(v) Oxbow lakes are found in:
(a) Glaciers
(b) River valleys
(c) Deserts
Solution (b) River valleys
3. Match the following.
(i) Glacier | (a) Seashore |
(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) Seacliff |
(g) Hard bedrock | |
(h) Deserts |
Solution
(i) Glacier | (c) River of ice |
(ii) Meanders | (d) Rivers |
(iii) Beach | (a) Seashore |
(iv) Sand dunes | (h) Deserts |
(v) Waterfall | (f) Seacliff |
(vi) Earthquake | (e) Vibrations of earth |
4. Give reasons.
(i) Some rocks have the shape of a mushroom.
Solution
In deserts, the wind is a natural cause of erosion which erodes the lower section of rocks more than the upper portion. Therefore, some rocks have a distinctive shape of a mushroom with a narrow base and wider top.
(ii) Flood plains are very fertile.
Solution
Flood plains are very fertile because floods deposit layers of fine soil and other material called sediments which is ideal for cultivation.
(iii) Sea caves are turned into stacks.
Solution
When cavities in sea caves become bigger and bigger, the roof of the caves is all that remains. The remaining roof is eroded, breaking into a stack of walls.
(iv) Buildings collapse due to earthquakes.
Solution
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