7th Std Social Science Term 1 Solution | Lesson.6 Landforms

Lesson.6 Landforms

Lesson.6 Landforms

I. Choose the correct answer

1. _________ is a deposition of river sediments along the foot-hills.

1. Plunge pool
2. Alluvial fan
3. Flood plain
4. Delta

Ans : Alluvial fan

2. Courtallam falls is located across the _________ river.

1. Cauvery
2. Pennar
3. Chittar
4. Vaigai

Ans : Chittar

3. The landform created by glacial deposition is _________.

1. Cirque
2. Arete
3. Moraine
4. Tarn lake

Ans : Moraine

4. Large deposits of loess are found in _________.

1. USA
2. India
3. China
4. Brazil

Ans : China

5. _________ are not associated with wave erosion.

1. Cliff
2. Sea arch
3. Stack
4. Beaches

Ans : Clif

II. Fill in the Blanks.

1. The process of breaking and crumbling of rocks is _________.

Ans : weathering

2. The place where the river joins a lake or a sea is known as _________.

Ans : river mouth

3. Inselbergs are found in the _________ desert in South Africa.

Ans : Kalahari

4. A cirque is known as _________ in Germany.

Ans : Kar

5. The first longest beach in the world is _________.

Ans : Miami beach

III. Match the following

IV. Consider the following statement and tick ( √ ) the appropriate answer. 

1. Assertion (A) : The deltas are formed near the mouth of the river

Reason (R) : The velocity of the river becomes slow when it approaches the sea.

1. Both A and R are correct
2. A is correct and R is wrong
3. A is wrong and R is correct
4. Both A and R are wrong

Ans : Both A and R are correc

2. Assertion (A) : Sea arches in turn become Sea Stacks.

Reason (R) : Sea Stacks are the results of wave deposition.

1. Both A and R are correct
2. A is correct and R is wrong
3. A is wrong and R is correct
4. Both A and R are wrong

Ans : A is correct and R is wrong.

V. Answer the following. 

1. Define s erosion.

Erosion is the wearing away of the landscape by different agents live water, wind, ice and sea waves.

2. What is a plunge pool?

Plunge pool is a hollow feature at the base of a waterfall. Which is formed by cavitation.

3. How are Ox – bow lakes formed?

In due course of time the meander loop cuts off from the rivers and forms a cut off lake, also called an Ox – bow lake.

4. Name the major landforms formed by glacial erosion.

Cirque, Aretes, Moraine.

5. Give a note on Mushroom rocks.

Some rocks have a shape of a mushroom. Because the winds erode the lower section of the rock more than upper part. So commonly called mushroom rocks.

6. What is a lagoon? Give an example.

Lagoon is a shallow stretch of water partially or completely separated from the sea.

Eg: Chilka lake in Odisha.

Puilcat lake in TamilNadu and Andhra, Vembanad lake in Kerala

VI. Distinguish between.

1. Tributary and Distributary.

2. ‘V’ shaped valley and ‘U’ shaped valley.

3. Active volcano and dormant volcano.

VII. Give reason.

1. The ends of the meander loops come closer and closer.

Due to continuous erosion and deposition along the sides of the meander, the ends of the meander loops comes closer and closer.

2. Flood plains are very fertile.

As the river floods, it deposits layers of fine soil and other material called sediments along its banks. This leads to the formation of a flat fertile flood plain.

3. Sea caves are turn into stacks.

The cavities of sea caves become bigger and bigger only the roof of the caves remains. Thus forming sea Arches, Further erosion breaks the roof and only walls are left. These wall like features are called stacks.

VIII. Answer in a paragraph.

1. Explain different landforms produced by river erosion.

The processes of erosion and deposition create different river land forms.

• ”V” shaped valley
• Water fall
• Plunge pool
• Alluvial fan
• Food hills
• Meanders
• Ox-bow lake

“V” shaped valley:

The running water erodes the landscape, which creates a steep-sided valley like the letter “V” known as “V” shaped valley.

Water fall:

Falling of river over a vertical step in the river bed is called waterfall.

Plunge pool:

It is a hollow feature at the base of a water fall which is formed by cavitation.

Alluvial fan:

It a deposition of sediment occurs at which the river enters a plains or the food hills.

Meanders:

As the river enters the plains it twists and turns forming large bends known as meanders.

Ox-bow lake:

In due course of time the meander loop cuts off from the river and founds a cut-off lake, also called an Ox-bow lake.

2. Describe the landforms associated with wind.

An active agent of erosion and deposition in the deserts is wind.

• Mushroom rocks
• Inselbergs
• Sand dune
• Barchans
• Loess

Mushroom rocks:

The winds erode the lower section of the rock more than the upper part. So some rocks have a shape of a mushroom rocks.

Inselbergs:

An isolated residual hill, standing like a pillar with rounded tops are called Inselbergs.

Eg: Inselbergs in the Kalahari Desert of South Africa.

Sand dunes:

When the wind blows, it lifts and transport sand from one place to another, when it stops blowing the sand falls and gets deposited in low hill- like structures. These are called sand dunes.

Barchans:

The crescent shaped sand dunes are called Barchans.

Loess:

When the grain of sand are very fine and light the wind can carry it over a very long distance and deposited in large area is called loess.

Eg: Large deposits of loess are found in china.

3. How are aretes formed?

• The ice melts, they get filled up the cirque with water and become beautiful lakes in the mountain called as Tarn lake.
• When two adjacent cirques erode towards each other the previously rounded landscape is transformed in to a narrow rocky, steep-sided ridge called Aretes.

சில பயனுள்ள பக்கங்கள்

• 9th Standard All Books – Download

• 8th Standard All Books – Download

• 7th Standard All Books – Download

• Lesson 5 (Interior of the Earth) Answers – More