Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature

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Kerala State Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature

By the Hands of the Nature Textual Questions and Answers

Question 1.
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature 1
Observe the diagram. Haven’t you seen how rainwater carries away the loose rock particles from elevated regions and deposits elsewhere? What all changes take place on the surface of the earth as a result of both the process mentioned above?
Answer:
Carries loose material away – erosion
Deposits in low lying regions – deposition

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Question 2.
What are the different process of weathering?
Answer:
Weathering is the process where rock is dissolved, worn away or broken down into smaller and smalleds pieces. There are three different weathering processes such as mechanical, chemical and organic/biological.

Question 3.
Varied features are seen in the river course at every stage. Observe the diagram and answer the following questions by analyzing the features of these three courses.
i) In which stage is the intensity of erosion more?
ii) Which process results in the landforms in the lower course?
iii) In which stage of the river is the amount of sediments more?
Answer:
i) Upper course
ii) Active depositional process
iii) Middle course

Question 4.
What could be the reason behind the round shape and polished surface of pebbles?
Answer:
The rock particles are carried by the river rub against the rocks along the bed and both the sides of the river. This results in the wearing down of rocks. Such erosion is known an abrasion or corrosion. Through these processes, the river can polish even the hard rocks along its course.

Question 5.
Why are gullies formed along steep slopes?
Answer:
Gullies are formed through intense erosion resulting from an increase in the velocity of water flow.

Question 6.
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature 2
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature 3
Observe the pictures to understand how oxbow lakes take birth from meanders.
Answer:
Meanders are usually formed in the middle and lower courses of wide rivers. The transformation happening to the meanders through further erosion and deposition: Meanders may further curve through continuous erosion and deposition. Finally, the river takes a straight course. The curves may get detached from the main river to form isolated water bodies. Such water bodies are called oxbow lakes.

Question 7.
Prepare notes by discussing the agricultural importance of flood plains.
Answer:
The deposition of alluvium along both the flooded banks may cause the formation of plains called flood plains. Flood plains contain rich and fertile soil suitable for cultivation. Agricultural improvement is possible in flood plains. This has historically led to the development of various civilizations along the flood plains. Flood plains are along the banks of rivers. Thus the area is rich in water availability. The physiography of flood plains is suitable for both agricultural activities and settlement.

Question 8.
Complete the table based on what you have learnt about the landform created by rivers.
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature 4
Answer:

Landforms Course of formation Erosional/ Depositional
Waterfall Upper course Erosional
Meanders Middle and lower course Erosion and deposition

Question 9.
Why is water is called universal solvent?
Answer:
Water is called as universal solvent because most of the mineral present in the rocks gets dissolved as water pass through them.

Question 10.
Identify the landform created by the merging of stalacticles and stalagmites.
Answer:
Limestone pillars

Question 11.
Name the districts in which the tourism-oriented beaches in Kerala can be found? )
Answer:
Thiruvananthapuram, Alappuzha, Kannur, Kozhikode, Kasaragod, and Kollam

Question 12.
Which is the major geomorphic agent creating landforms in deserts?
Answer:
Rock pedestals, Deflation hollows, Oasis, Sand dunes, Yasdangs and Desert Pavements.

Question 13.
What could be the reason for the increased erosion at the bottom of the rocks as shown in the figure?
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature 5
Answer:
Mushroom rocks are created by wind blowing material and eroding the rocks to form a mushroom rock. It also can be formed by glacial erosion. This can happen when a glacier retreats and leaves behind rocks causing the rock on the bottom to erode faster leaving behind a mushroom rock. One day, erosion will weaken the base of these rocks and the top part will come tumbling down.

By the Hands of the Nature Model Questions and Answers

Question 14.
What are glaciers?
Answer;
Thick masses of ice slowly move downhill in snow-clad region are called glaciers.

Question 15.
Define geomorphology
Answer:
Geomorphology is the branch of geography which deal with the study of origin and evolution of landforms.

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Question 16.
What are geomorphic processes?
Answer:
The processes that help in the formation of landforms are called geomorphic processes.

Question 17.
Distinguish between erosion and deposition.
Answer;
The transfer of rock particles framed by chemical, physical or biological weathering processes from one place to another by external agencies such as running water, wing, glaciers, sea waves, etc. is called erosion. These materials will be deposited in low lying regions and this process is called deposition.

Question 18.
Identify the external agencies that help in erosion?
Answer:
Running water, wing, glaciers, sea waves.

Question 19.
Place of origin of river is called
Answer:
Source

Question 20.
The place at which river discharges into the sea or water bodies called ……………
Answer:
River mouth.

Question 21.
Complete the flow chart
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature 6
Answer:
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature 7

Question 22.
Match the following

A B
Upper course Oxbow lakes
Deltas
Valleys

Answer:

A B
Upper course Oxbow lakes
Middle course Deltas
Lower course Valleys

Question 23.
Point out the features of upper course
Answer:

  • Place of origin of the river
  • River flows through steep slopes
  • Intense rate of erosion
  • Less amount of sediments
  • No deposition
  • Landforms such as valley, waterfall, etc. are seen

Question 24.
What are the features of middle course?
Answer:

  • Flows through the foothills
  • Both erosional and depositional processes are active
  • More sediments are carried down
  • Features such as meanders and oxbow lakes are seen

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Question 25.
Mention important peculiarities of lower course.
Answer:

  • Flows through the plains
  • Active depositional process
  • The quantity of water, as well as sediments, is high
  • Depositional landforms such as flood plains are deltas are seen

Question 26.
Point out the factors affecting the intensity of river erosion.
Answer:

  • Velocities of water flow
  • Slope of the terrain
  • Rock structure

Question 27.
Explain the process of abrasion or corrosion.
Answer;
The rock particles like gravel, sand, pebbles, etc. carried by the river rub against the rocks along the bed and the sides of the river. This results in the wearing down of rocks. Such erosion is known as abrasion or corrosion. Through these processes, the river can polish even hard rocks along its course.

Question 28.
River bed erosion is more prevalent in ………..
a) Upper course of the river
b) Middle course of the river
c) Lower course of the river
Answer:
a) Upper course of the river

Question 29.
Examine the process that results in waterfalls.
Answer:
Waterfalls are generally formed at the upper course of rivers as a result of erosion. Soft rocks are easily eroded in the valleys where soft and hard rocks are found intermingled. This results in the formation of waterfalls.

Question 30.
What do you mean by flood plains?
Answer:
Rivers overflowing their banks during rainy seasons. Flood water may cover extensive areas on both sides of the river. The deposition of alluvium along both the flooded banks may cause the formation of plains. Such plains are called flood plains.

Question 31.
How is deltas formed?
Answer:
Velocity of the river decreases when it nears the river mouth. Most rivers branch out to distributaries at this stage where the volume of both water and sediments is high. The sediments brought by the river are deposited between these distributaries forming almost triangular-shaped landforms called deltas. These features are called as they resemble the Greek alphabet A (Delta).

Question 32.
Name the largest delta in the world.
Answer;
The Sundarbans in West Bengal

Question 33.
Why are the erosional and depositional landforms of underground water mainly confined to limestone region?
Answer;
Rocks like limestone easily dissolve in rainwater which percolates to form underground water. Hence the erosional and depositional landforms of underground water are mainly confined to limestone regions.

Question 34.
Categorize the following based on their formation.
1. Limestone caves
2. Stalactites
3. Stalagmites
4. Limestone Pillars
Answer:
Erosion:
Limestone caves
Depositions:

  • Stalactites
  • Stalagmites
  • Limestone Pillars

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Question 35.
Give an example of limestone caves.
Answer;
The Borra caves near Visakhapatnam in Seemandhra

Question 36.
What are coastlines? Give different types of coastlines.
Answer:
Coastal landforms are created by the erosional and depositional processes carried out by the waves. There are two types of coastlines namely.

  • Rocky coasts
  • Non-rocky coasts

Question 37.
Define sea cliff.
Answer:
The steep hillocks facing the sea are called sea cliffs.

Question 38.
Give an example of sea cliff in Kerala.
Answer:
Varkala beach

Question 39.
Landforms created by wind are mostly seen in
a) Valleys
b) Beaches
c) Deserts
d) Farmlands
Answer:
c) Deserts

Question 40.
What is the process of deflation?
Answer:
The strong whirlwind carry away the dry desert sands from one place to another. This process of wind erosion is called deflation.

Question 41.
What do you mean by barchans?
Answer;
The sand dunes formed in the deserts are as a result of the deposition by wind. The sand dunes commonly formed in crescent shapes are called barchans.

Let Us Assess

Question 42.
Describe the characteristic of different stages in a river’s course.
Answer;
The course of a river can generally be divided into three stages based on the difference in slope from its source to mouth.

  • Upper course
  • Middle course
  • Lower course

Upper course is that part of the river where it rapidly flows down along steep slopes from the place of origin. The intensity of erosion is severe in this course. Middle course is that stage of the river where it flows through gently sloping foothills. As the velocity of the flow decreases, the intensity of erosion declines and deposition begins.
Lower course is the stage where the river flows through the plains. The rate of deposition will be higher due to the slow pace of the river and the increase in the amount of sediments during this stage.

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Question 43
Compare the ‘v-shaped’ valleys with ‘u shaped’ valleys based on processes of formation.
Answer:
Deepening of gullies occurs through intense erosion resulting from an increase in the velocity of water flow. The valleys take a distinct shape as a result of the intensity of erosion along the river bed. Such valleys are called V-shaped valleys.

The rate of erosion along the river bed decreases as the river leaves the upper course. However lateral erosion dominates, the river flowing through comparatively gentle slopes takes deviations when the sediments or rock forms create obstruction to the flow. Such bending course of a river is leading to u shaped valleys.

Question 44.
List with example the agricultural and environmental significance of deltas and flood plains.
Answer:
The deposition of alluvium along both the flooded banks may cause the formation of plains called flood plains. Flood plains contain rich and fertile soil suitable for cultivation. Agricultural improvement is possible in flood plains. This has historically led to the development of various civilizations along the flood plains. Flood plains are along the banks of rivers. Thus the area is rich in water availability. The physiography of flood plains is suitable for both agricultural activities and settlement.

HSSLive.Guru

Question 45.
Illustrate the formation of mushroom rocks with the help of a diagram
Answer:
As a result of the continued erosion caused by sand and other rock particles carried by strong winds, rocks in deserts get worn down. This process of wind erosion is called abrasion. Figure given below shows here is of a rock formed in this manner. Such rocks seen in deserts resembling mushrooms are called mushroom rocks.
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature 8

Question 46.
Explain the formation of any two erosional landforms created by glaciers.
Answer:
Glacial landforms are generally confined to the high mountain ranges and the poles. The movement of a glacier along the mountain slope is depicted in the given picture.
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature 9
Observe the changes happening to the valley at different stages. Different types of valleys as shown in the pictures are formed by glacial erosion. Armchair like valleys so formed are called cirques.
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature 10
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature 11

Question 47.
Prepare a table showing the erosional and depositional landforms created by any three external forces.
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature 12
Answer:
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature 13

Question 48.
Identify the landforms shown in the pictures and explain how they are formed
Kerala Syllabus 9th Standard Social Science Solutions Part 2 Chapter 4 By the Hands of the Nature 14
Answer:
A — Oxbow lakes:
Meanders are usually formed in the middle and lower courses of wide rivers. The transformation happening to the meanders through further erosion and deposition. Meanders may further curve through continuous erosion and deposition. Finally, the river takes a straight course. The curves may get detached from the main river to form isolated water bodies. Such water bodies are called oxbow lakes.
B — Mushroom Rocks:
As a result of the continued erosion caused by sand and other rock particles carried by strong winds, rocks in deserts get worn down. This process of wind erosion is called abrasion. Figure given below shows here is of a rock formed in this manner. Such rocks seen in deserts resembling mushrooms are called mushroom rocks.

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