9th Social Science Geography Guide Unit 2 Lithosphere – II Exogenetic Processes

9th Standard Social Science Geography Unit 2 Lithosphere – II Exogenetic Processes Book Back Answers History Lesson 2 Geography Lithosphere – II Exogenetic Processes Book Back Answers English Medium. 9 all Subject Book Answers. Class 9 Social Science All Unit Book in Answers TM & EM.

• 9th Social Science ( All Units ) – English Medium – Guide – Book Back Answers

9th Social Science Guide – Geography Lithosphere – II Exogenetic Processes

I. Choose the correct answer.

1. The disintegration or decomposition of rocks is generally called as …………………

(a) weathering

(b) erosion

(c) transportation

(d) deposition

Answer:(a) weathering

2. The process of the levelling up of land by means of natural agents.

(a) aggradation

(b) degradation

(c) gradation

(d) none

Answer:(c) gradation

3. ……………. is seen in the lower course of the river.

(a) Rapids

(b) Alluvial fan

(c) Delta

(d) Gorges

Answer:(c) Delta

4. Karst topography is formed due to the action of ………………

(a) Glacier

(b) Wind

(c) Sea waves

(d) Ground water

Answer:(d) Ground water

5. Which one of the following is not a depositional feature of a glacier?

(a) cirque

(b) Moraines

(c) Drurrtlins

(d) Eskers

Answer:(a) cirque

6. Deposits of fine silt blown by wind is called as …………….

(a) Loess

(b) Barchans

(c) Hamada

(d) Ripples

Answer:(a) Loess

7. Stacks are formed by …………….

(a) Wave erosion

(b) River erosion

(c) Glacial erosion

(d) Wind deposion

Answer:(a) Wave erosion

8. ……………… erosion is responsible for the formation of cirque.

(a) wind

(b) glacial

(c) river

(d) underground water

Answer:(b) glacial

9. Which one of the following is a second order land form?

(a) Asia

(b) Deccan Plateau

(c) Kulu valley

(d) Marina Beach

Answer:(b) Deccan Plateau

II. Match the following.

1. Distributaries – glacial action
2. Mushroom rock – action of sea wave
3. Eskers – Lower course of river
4. Stalactites – Aeolian process
5. Cliff – karst topography

Answer:

1. (c)
2. (d)
3. (a)
4. (e)
5. (b)

III. Answer the following Questions in brief.

1. Define weathering.

• Weathering is the disintegration and decomposition of materials of the earth’s crust by their exposure to the atmosphere.
• Weathering is affected and controlled by the factors such as temperature, rock structure, land slope, and vegetation.

2. What do you mean by biological weathering?

• Biological weathering occurs due to the penetration and expansion of plant roofs, earth worms, burrowing animals (rabbits, rats) and same human activities.

3. Mention the three courses of a river with any two land forms associated to each course.

The course of a river is divided into

1. The Upper course – V-shaped valleys, gorges
2. The middle course – Alluvial fans, flood plains
3. The lower course – Delta and Estuary.

4. What are Ox-bow lakes?

1. Meanders in due course of time become almost a complete circle with narrow necks.
2. This in turn gets abandoned and forms a lake. This is called an Ox-bow lake.

5. How does a cave differ from a sea arch?

Answer:

Sea cave	Sea Arch
Prolonged wave attack on the base of a cliff erodes rock materials which result in the formation of caves.	When two caves approach one another from either side of a headland and Unite, they form an arch, e.g., Neil Island, Andaman & Nicobar.

 

6. List out any four karst topographical areas found in India.

Answer:

1. Guptadham caves – Western Bihar
2. Pandav caves Pachmuri – Madhya Pradesh
3. Kutumsar – Bastar district in Chattisgarh
4. Borra caves of Visakhapatnam – Andhra Pradesh

7. What do you mean by a hanging valley?

Answer:

• These are valleys eroded by tributary glacier and that hangs over the main valley.

8. Define: (a) Moraine (b) Drumlin (c) Esker.

Answer:

(a) Moraine:

• Landforms formed by the glacial deposits of valley (or) continental glaciers are termed as moraines.
• They are of various shapes and sizes, like ground, terminal and lateral moraines, etc.

(b) Drumlin:

• Drumlins are deposits of glacial moraines that resemble giant inverted teaspoons (or) half cut eggs.

(c) Esker:

• Long narrow ridges composed of boulders gravel and sand deposited by streams of melting water which run parallel to a glacier are called eskers.

9. Mention the various features formed by wind erosion.

Answer:

• The erosional landforms of wind: Mushroom rocks, Inselbergs and Yardangs
• The Depositional Landforms of wind: Sand dunes, Barchans and loess.

10. What are wave cuLplatforms?

Answer:

• Flat surface found at the foot of the sea cliffs are called as wave cut platforms,
• wave cut platform is also referred as beach, shelf, terrace and plain.

IV. Distinguish between:

1. Physical and chemical weathering

Answer:

S.No.	Physical weathering	Chemical weathering
(i)	It is the breakdown of rocks without changing their chemical composition through the action of physical forces.	Disintegration and. decomposition of rocks due to chemical reactions is called Chemical weathering.
(ii)	Cracks are formed and disintegration occurs eventually.	Chemical weathering takes place through the processes of oxidation, carbonation solution and hydration.
(iii)	Exfoliation, block disintegration, granular disintegration, etc., are the different types of weathering.	The agents of Chemical weathering are oxygen, CO2 and Hydrogen.

2. Delta and Estuary

Answer:

S.No.	Delta	Estuary
(i)	A triangular shaped low lying area formed by the river at its mouth is called Delta.	Deltas have fine deposits of sediments enriched with minerals.
(ii)	Estuary is formed where the rivers meet the sea.	Deposition of silt by the river is not possible in the estuaries like Delta as if the waves keep on eroding the deposits e.g. River Narmada, River Tapti.

3. Stalactite and stalagmite

Answer:

Stalactite	Stalagmite
When the water containing dissolved calcite gradually drips from the ceiling of the caves, water evaporates and the remaining calcite hangs from the ceiling and thus Stalactites are formed.	When the calcite deposits rises upward like a pillar Stalagmites are formed.

4. Longitudinal and Transverse sand dunes

Answer:

Longitudinal	Transverse sand dunes.
Longitudinal dunes are long narrow ridges of sand, which extend in a direction parallel to the prevailing winds. These dunes are called Seifs in Sahara.	Transverse dunes are asymmetrical in shape. They are formed by alternate slow and fast winds that blow from the same direction.

5. Inselbergs and yardangs

Answer:

S.No.	Inselbergs	Yardangs
(i)	Certain hard rocks like igneous rocks are more resistant to wind action.	In arid regions, certain rocks .have hard and soft layers arranged vertically.
(ii)	Isolated residual hills rising abruptly from their surroundings are termed as inselbergs. e.g., Uluru (or) Ayers Rock – Australia.	When winds blow over these rocks, the soft layers get eroded leaving irregular crests. These are called Yardangs.

6. Spit and bar

Answer:

Spit	Bar
A spit is a ridge (or) embankment of sediment, attached to the land on one end and terminating in open water on the other end. Spits are common at the mouth of estuaries, e.g., Kakinada Spit.	A bar is an elongated deposit of sand, shingle (or) mud found in the sea almost parallel to the shoreline

V. Give Reasons.

1. Chemical weathering is predominant in hot and humid zones.

Answer:

1. Chemical is predominant in hot and humid zones because the warm temperature and rainfall increases the chemical weathering.
2. It encourages the decomposition of plant matter to produce chemicals such as humic acids and CO2

These chemicals increases the rate of weathering.

2. Slit deposits are less at estuaries than deltas.

Answer:

• Silt deposits are less at estuaries than deltas because the waves keep on eroding the deposits e.g., River Narmada & Tapti.

3. The snow line is at the sea level in Polar regions.

Answer:

• The snow line is at the sea level in Polar regions because higher the latitude lower the snow line from sea level.

4. Wind can possibly erode the rocks from aO sides.

Answer:

• Wind erosion can occur in any area where the Soil (or) Sand is not compacted (or) if it is finely granulated in nature.
• Wind can loosen the materials and send it in all directions.

5. In limestone regions, surface drainage is rarely found.

Answer:

• The rain water mixes with CO2 and enters into limestone region it dissolves and destroys much of the lime stone.
• Subterranean drainage may limit surface water with few to no rivers.
• The ability of water to penetrate the rock lowers. Joints and bedding planes make the rock permeable.So surface drainage is rarely found.

VI. Answer in Paragraph.

1. Write a note on weathering classify and explain.

Answer:

Weathering is the disintegration and decomposition of materials of the earth’s crust by their

exposure to atmosphere. There are three types of weathering,

(a) Physical weathering,

(b) Chemical weathering

(c) Biological weathering

Physical weathering:

• It is the breakdown of rocks without changing their chemical composition, through the action of physical forces.
• The constant freezing and thawing of rocks during the night and day leads to the expansion and contraction of rocks. Cracks are formed and disintegration occurs eventually.
• Exfoliation, block disintegration, granular disintegration etc., are the different types of weathering.

Chemical weathering:

• Disintegration and decomposition of rocks due to chemical reactions is called Chemical Weathering.
• This is predominantly high in the hot and humid regions such as the equatorial, tropical and sub tropical zones.
• Chemical weathering takes place through the processes of oxidation, carbonation, solution, and hydfation. The agents of Chemical weathering are Oxygen, Carbon-dioxide and H
• Biological weathering: Biological weathering occurs due to the penetration and expansion of plant roots, earthworms, burrowing animals (rabbits, rats) and some human activities.

2. Explain the erosional landforms formed by underground water.

Answer:

Most erosion takes plaice due to the process of solution. When rain water mixes with carbon- di-oxide and enters into a limestone region, it dissolves and destroys much of the limestone. As a result, landforms suph as Terra rossa, Lappies, sinkholes, swallow holes, dolines, uvalas, poljes, caves and caverns are formed.

Terra Rossa (Italian term for Red soil): Deposition of red clay soil on the surface of the Earth is due to the dissolution of limestone content in rocks. The redness of the soil is due to the presence of iron oxide.

Lappies: When the joints of limestone rocks are corrugated by groundwater, long furrows are formed and these are called LAPPIES.

Sinkhole: A funnel shaped depressions formed due to dissolution of limestone rock is called sinkholes. Their average depth ranges between three and nine meters.

Caves and Caverns: Caves and caverns are subterranean features of karst topography. Caves are hollows that are formed by the dissolution of limestone rocks when carbon di oxide in air turns into carbonic acid after its reaction with water. They vary in size and shape. Caverns are the caves with irregular floors, e.g., Guptadham caves in Western Bihar.

All types of deposits in the caves and caverns are collectively called speleothems which includes travertines, tufa, dripstones.

Swallow Holes, Uvalas, Dolines, Poljis are other erossional Features of karst regions predominant in other parts of the world.

3. What is a glacier? Explain its types.

Answer:

• A Glacier is a large mass of ice that moves slowly over the land, from its place of accumulation. It is also known as ‘River of ice’. The place of accumulation is called snowfield. The height above which there is a permanent snow cover in the higher altitude or latitude is called snowline. Higher the latitude, lower the snowline from sea level.
• The gradual transformation of snow into granular ice is called ‘firn’ or ‘ neve’ and finally it becomes solid glacial ice.

Movement of Glacier:

The large mass of ice creates pressure at its bottom and generates heat. Due to this, the glacier melts a little and starts to move The rate of movement of a glacier varies from a few centimetres to several hundred meters a day. The movement of glaciers depends on slope, volume of the glacier, thickness, roughness at the bottom (friction) etc., and Temperature. Like the rivers, glaciers also carry out erosion, transportation and deposition.

Types of Glacier:

Glaciers are broadly divided into two types based on the place of occurrence, such as Continental glacier and valley glacier.

4. Describe the depositional work of winds.

• Deposition occurs when the speed of wind is reduced by the presence of obstacles like bushes, forests and rock structures. The sediments carried by wind get deposited on both the wind ward and leeward sides of these obstacles.
• Some of the depositional landforms are sand dunes, barchans and loess.
• Sand Dune: In deserts, during sandstorms, wind carries loads of sand. When the speed of wind decreases, huge amount of sand gets deposited. These mounds or hills of sand are called sand dunes. There are different types of sand dunes.
• Barchan: Barchans are isolated, crescent shaped sand dunes. They have gentle slopes on the windward side and steep slopes on the leeward side.
• Transverse Dunes: Transverse dunes are asymmetrical in shape. They are formed by alternate slow and fast winds that blow from the same direction.
• Longitudinal Dunes: Longitudinal dunes are long narrow ridges of sand, which extend in a direction parallel to the prevailing winds. These dunes are called Seifs in Sahara.
• Loess: The term loess refers to the deposits of fine silt and porous sand over a vast region. Extensive loess deposits are found in Northern and Western China, the Pampas of Argentina, in Ukraine and in the Mississippi Valley of the United States.

5. Give a detailed account on the three orders of land forms.

Answer:

Major land forms:

(i) First order landforms : Continents & Oceans

(ii) Second order landforms : Mountains, Plateaus, and plains minor land forests

(iii) Third order landforms : Deltas, Fjords coasts, Sand dimes, Beaches, Valleys, Cirques, Mushroom rocks, Limestone rocks.

First order land forms:

Continents: (i) It is a very large area of land.

(ii) One of the seven large land masses on the earth’s surface, surrounded by sea.

Asia, Africa, Europe, North America, South America, Australia and Antarctica.

Oceans: A very large expanse of sea, Atlantic ocean, Arctic ocean, Pacific ocean, Indian ocean and Antarctic ocean.

Second order land forms: Mountains, Plateaus and Plains.

1. Mountains: A large natural elevation of the earth’s surface, rising abruptly from the surrounding level, e.g., Himalayas.
2. Plateaus: An area of fairly level high ground, e.g., Tibetean plateau.
3. Plains: A large area of flat land, e.g., Coastal plains.

Third order land forms: Deltas, Fjords, Sand dunes, Beaches, Valleys, Cirques, Mushroom rocks, Limestone rocks.

1. Deltas: A triangular shaped low lying area formed by the river at its mouth is called Delta. Fjords: These are glacial valleys that are partly submerged in the sea.
2. Sand Dunes: In deserts, huge amount of sand gets deposited. These mounds (or) hills of sand are called sand dunes.
3. Beaches: Sand and gravel are moved and deposited by waves along the shore to form Beaches. Valleys: A low area of land between hills (or) mountains typically with a river (or) stream flowing through it.
4. Cirques: The glacier erodes the steep side walls of the mountain and farms bowl shaped arm chair. It is termed as cirque.
5. Mushroom rocks: By the constant wearing down action of wind the bottom of the rock gets eroded away to form a mushroom like structure. ,
6. This is called Mushroom rock (or) Pedestal rock.
7. Limestone rocks: The underground water creates distinct landforms in limestone regions called Karst Topography. It consists of calcite, argonite.

VII. Consider the given statements and choose the right option given below.

Question (i).

1. ‘I’ shaped valley is an erosional feature of the river.
2. ‘U’ shaped valley is an erosional feature of the glacier.
3. ‘V’ shaped valley is an erosional feature of the glacier.

(a) (i), (ii) and (iii) are right

(b) (i) and (ii) are right

(c) (i) and (iii) are right

(d) only (i) is right

Answer:

(d) only (ii) is right

Question (ii).

Statement I: Running water is an important agent of gradation.

Statement II: The work of the river depends on the slope of land on which-it flows.

(a) Statement I is false II is true

(b) Statement I and II are false

(c) Statement I is true II is false

(d) Statement I and II are true

Answer:

(a) Statement I is false II is true

Question (iii).

Statement: Limestone regions have less underground water.

Reason : Water does not percolate through limestone.

(a) The statement is right reason is wrong.

(b) The statement is wrong Reason is right.

(c) The statement and reason are wrong.

(d) The statement and reason are right.

Answer:

(d) The statement and reason are right.

 

VIII. HOTS

1. Is wind the only gradational agent in the desert?

Answer:

1. Yes, wind is the only gradational agent in the desert.
2. g., Erosional activity: Yardung
3. Depositional activity: Sand Dimes.

2. Underground water is more common in limestone areas than surface run off. Why?

Answer:

The chief constituent of limestone is calcium carbonate which is soluble in pure water and easily soluble in carbonate water.

3. The river channels in the lower course are wider than the upper course.

Answer:

The reasons are,

1. The river splits into a number of channels called distributaries.
2. The river brings down loads of debris from its upper and middle.
3. The river deposits and develop typical landforms like Delta and Estuary.

In-text HOTs Questions

1. Is weathering a pre-requisite in the formation of soil?

Answer:

1. Yes, weathering a pre-requisite in the formation of soil.
2. The rock materials in due course of time are weathered further to form soil.
3. Soil is a mixture of disintegrated rock material.

2. Snowline of Alps’is 2700 metre where as the snowline of Greenland is just 600 mts. Find out the reason.

Answer:

On tropical mountains the snowline may be as high as 500 mts, but when traced poleward it descends to 2700 mts in the European Alps to 600 meters in Greenland and just to se-a level near the poles. –

IX. Map Skill.

1. On the given outline map of the world, mark the following.

1. Any two deltas
2. A Karst region
3. Any two hot and cold deserts

 

X. Give geographical terms for the following:

Question 1.

(a) Chemical alternation of carbonate rocks on lime stone region.

(b) Flat surfaces near cliffs.

(c) Erosion + Transportation + Deposition =

(d) The bottom line of a snow field.

Answers:

(a) Carbonation

(b) Plateau

(c) Gradation

(d) The snowline

 

Lithosphere – I Endogenetic Processes Additional Questions

I. Choose the correct answer.

Question 1.

The process of dissolution of rock substances in water is …………….

(a) oxidation

(b) solution

(c) gradation

(d) hydration

Answer:(b) solution

Question 2.

This generally originate from mountains.

(a) lake

(b) sea

(c) river

(d) ocean

Answer:(c) river

Question 3.

The cylindrical holes drilled vertically in the river bed are …………….

(a) Pot holes

(b) canyons

(c) rapid

(d) Gorge

Answer:(a) Pot holes

Question 4.

The largest Delta in the world is …………….

(a) The Nile River Delta

(b) The Ganga – Brahmaputra Delta

(c) The Yellow river Delta

(d) The Indus Delta

Answer:(b) The Ganga – Brahmaputra Delta

Question 5.

The redness of the red clay soil is due to. the presence of ……………

(a) iron oxide

(b) carbon

(c) copper

(d) magnesium

Answer:(a) iron oxide

Question 6.

The most powerful agents of gradation are ……………

(a) Rivers

(b) Glaciers

(c) Sea waves

(d) Streams

Answer:(c) Sea waves

 

III. Answer in brief.

Question 1.

Define Granular Disintegration.

Answer:

Granular disintegration takes place in crystalline rocks where the grains of the rocks become loose and fall out. This is due to the action of temperature & frost.

Question 2.

Mention the land features carved by a river in its upper course.

Answer:

‘V’ shaped valleys, Gorges, Canyons, rapids, pot holes, spurs and waterfalls.

Question 3.

What are “Pot Holes”?

Answer:

Due to the river action, cylindrical holes are drilled vertically in the river bed with varying depth and diametre.

Question 4.

State the other erosional features of Karst regions in other parts of the world.

Answer:

Swallow Holes, Uvalas, Dolines, Poljis are the other erosional features.

Question 5.

What are Transverse Dunes?

Answer:

1. Transverse Dunes are asymmetrical in shape.
2. They are formed by alternate slow and fast winds that blow from the same direction.

Question 6.

What are wave cut Platforms?

Answer:

Flat surface found at the foot of the sea cliffs are called as wave Cut platform. It is also referred as Beach, shelf, terrace and plain.

 

IV. Distinguish between.

Question 1.

Oxidation and Carbonation.

Answer:

S.No.	Oxidation	Carbonation
(i)	Oxygen in the atmosphere reacts with the Iron found in rocks thus leading to the formation of Iron oxide. This process is known as oxidation.	Carbonation is the mixing of water with the atmospheric CO2 forming carbonic acid.
(ii)	Oxidation weakens the rocks.	It is important in the formation of caves, in limestone region.

Question 2.

Alluvial Plain and Flood Plain.

Answer:

S.No.	Alluvial Plain	Flood Plain
(i)	A fan shaped deposition made by the river at the foothills is called an alluvial plain.	Fine sediments are deposited on river banks when a river floods and is called flood plain.
(ii)	These deposits are rich and fertile useful for cultivation.	These sediments make the region rich and fertile.

Question 3.

Arete and Matterhorn.

Answer:

Arete	Matterhorn
Aretes are narrow ridges formed when two cirque walls joined together back to back and forms narrow knife like ridges.	The pyramidal peaks formed when three (or) more cirques meet together are referred as matterhoms.

Question 4.

Sea Cave and Sea Arch.

Answer:

Sea Cave	Arch
Prolonged wave attack on the base of a cliff erodes rock materials which result in the formation of caves.	When two caves approach one another from either side of a headland and Unite, they form an arch, e.g., Neil Island, Andaman Nicobar.

V. Give reasons.

Question 1.

Why do the Biological weathering occur?

Answer:

Biological weathering occurs due to the penetration and expansion of plant roots, earth worms, burrowing animals (rabbits and rats) and some human activities.

Question 2.

Why is Karst Topography formed?

Answer:

Karst Topography is formed due to the dissolution of soluble rocks such as limestone, dolomite and Gypsum.

Question 3.

Why do the Pedestal rock look like mushroom?

Answer:

By the constant wearing down action of wind, the bottom gets eroded away to form a mushroom like structure. So the Pedestal rock looks like mushroom.

VI. Answer in a Paragraph.

Question 1.

Explain the origin of the river and its course.

Answer:

Rivers generally originate from mountains and end in a sea or lake. The whole path that a river flows through is called its course. The course of a river is divided into:

(i) The upper course

(ii) The middle course and

(iii) The lower course

(i) The Upper Course: Erosion is the most dominant action of river in the upper course. In this course, a river usually tumbles down the steep mountain slopes. The steep gradient increases the velocity and the river channel performs erosion with great force to widen and deepen its valley. The land features carved by a river in its upper course are V-shaped valleys, gorges, canyons, rapids, pot holes, spurs, and waterfalls.

(ii) The Middle Course: The river enters the plain in its middle course. The volume of water increases with the confluence of many tributaries and thus increases the load of the river. Thus, the predominant action of a river is transportation. The deposition also occurs due to the sudden decrease in velocity. The river in the middle course develops some typical landforms like alluvial fans, flood plains, meanders, ox-bow lakes etc.,

(iii) The Lower course: The river, moving downstream across a broad, level plain is loaded with debris, brought down from its upper and middle courses. Large deposits of sediments are found at the level bed and the river, splits into a number of channels called distributaries. The main work of the river here is deposition and it develops typical landforms like delta and estuary.

Question 2.

Describe the Erosional landforms of Sea.

Answer:

Some of the erosional landforms of sea waves are sea cliff, sea cave, arch, stack, beach, bar and spit and wave cut platform.

• Sea Cave: Prolonged wave attack on the base of a cliff erodes rock materials, which result in the formation of caves.
• Sea Arch: When two caves approach one another from either side of a headland and unite, they form an arch, e.g., Neil Island, Andaman and Nicobar.
• Sea Stack: Further erosion by waves ultimately leads to the total collapse of the arch. The seaward portion of the headland will remain as a pillar of rock known as stack. Eg the Old man of Hoy in Scotland.
• Sea Cliffs: Sea cliffs are steep rock faces formed when sea waves dash against them. The rocks get eroded to form steep vertical walls.
• Wave Cut Platforms: Flat surface found at the foot of sea cliffs are called as wave cut platforms. Wave cut platform is also referred as beach, shelf, terrace and plain.

 

VII. Consider the given statements and choose the right option given below.

Question 1.

(i) The nature and magnitude of weathering differs from place to place and region to region.

(ii) Granular disintegration takes place due to the action of volcanoes.

(iii) Weathering is a pre-requisite in the formation of soil.

Which of the above statement is/are the right statement.

(a) (i), (ii) and (iii) are right

(b) (i) & (ii) are right

(c) (i) & (iii) are right

(d) only (i) is right.

Answer:(c) is right

Question 2.

(i) Small streams that join the main river is tributary.

(ii) River Gangas is a tributary.

Which of the above statement is/are the right statement.

(a) The statement is right reason is wrong

(b) The statement is wrong reason is right

(c) The statement & reason are wrong

(d) The statement & reason are right

Answer:(a) is right.