Chapter 4 – Geomorphic Processes and Landforms of the Earth | Class 9 School Geography Solution

Book Name	: School Geography
Subject	: Geography
Class	: 9 (Madhyamik)
Publisher	: Bengal Book Syndicate (P) Ltd.
Chapter Name	: Geomorphic Processes and Landforms of the Earth

Identify the correct answers

Question 1 (a)

The study that deals with landforms and the processes that shape them is called, Biology/Geomorphology/Physics/Chemistry.

Answer

Geomorphology

Explanation:

Geomorphology is the study of landforms and the processes that shape them. Biology is the study of living organisms, Physics is the study of matter and energy, and Chemistry is the study of the composition and properties of matter.

Question 1 (b)

The geomorphic processes which are active on the earth’s surface are called, Photosynthesis/Earthquake/Terrestrial processes/ Volcanism.

Answer

Terrestrial processes

Explanation:

Terrestrial processes are the geomorphic processes that are active on the Earth’s surface. These include processes such as weathering, erosion, deposition, mass wasting, and soil formation. Photosynthesis is the process by which plants convert sunlight into chemical energy.

Question 1 (c)

The Geomorphic processes that act at the interior of the earth are called, Endogenous/Exogenous/degradation/ aggradation.

Answer

Endogenous

Explanation:

Endogenous processes are the geomorphic processes that act at the interior of the Earth. These include processes such as tectonic uplift, volcanic activity, and mountain building.

Question 1 (d)

The exogenetic force derives energy from, moon/sun/slope/running water.

Answer

Exogenetic forces

Explanation:

Exogenetic forces are processes that act at the Earth’s surface and are powered by external sources of energy. Among the given options, running water is the source of energy that drives exogenetic forces such as erosion, transportation, and deposition of sediment.

Question 1 (e)

The mountain building movement is known as : Epeirogenic movement / weathering/Orogenic movement/Volcanism.

Answer

Orogenic movement

Explanation:

Orogenic movement is the process of mountain building. It involves the folding, faulting, and uplift of rock layers due to tectonic activity, which can result in the formation of mountain ranges.

Question 1 (f)

Mountains are those landforms that rise above : 1000 m/600 m/300 m /200 m from the sea-level.

Answer

600 meters

Explanation:

Mountains are generally defined as landforms that rise at least 600 meters (about 2000 feet) above the surrounding terrain. However, the specific height or elevation that constitutes a mountain may vary depending on the region and context.

Question 1 (g)

The plate Tectonic theory advocates the formation of : relict mountain/fold mountain/volcanic mountain/block mountain.

Answer

Fold mountain

Explanation:

The Plate Tectonic Theory advocates that fold mountains are formed by the collision of two tectonic plates. When two continental plates converge, neither is dense enough to be subducted (forced under) the other, so they are both compressed and uplifted, forming a mountain range.

Question 1 (h)

An example of an old fold mountain is Alps/Himalayas/Aravalli/Rockies.

Answer

Aravalli

Explanation:

The Aravalli Range is a mountain range in western India, and it is one of the oldest fold mountain ranges in the world, dating back to the Proterozoic Era (about 2.5 billion years ago).

Question 1 (i)

An example of Block mountain is : Himalayas/Aravalli/Black Forest/Nilgiri.

Answer

Black Forest

Question 1 (j)

The plateaus which have mountains surrounding them are called : Lava plateau/ intermontane plateau/Dissected plateau/Continental plateau.

Answer

Intermontane plateaus

Explanation:

Intermontane plateaus are plateaus that are surrounded by mountains on all sides. They are often formed by the uplift and tilting of a block of land between two parallel faults, with the surrounding mountains formed by the same tectonic activity.

Question 1 (k)

The plains which are formed by the deposition of rivers near their mouths are called: flood plain/karst plain/Deltaic plain/Loess plain.

Answer

Deltaic plains

Explanation:

Deltaic plains are formed by the deposition of sediment carried by a river near its mouth, where the river flows into an ocean or sea. As the river enters the ocean, the velocity of the water slows down, and the sediment it carries is deposited, forming a fan-shaped deltaic plain.

Question 1 (l)

Vale of Kashmir is an example of Flood Plain/Lacustrine plain/Loess plain/Till plain.

Answer

Lacustrine plain

Explanation:

The Vale of Kashmir is an example of a Lacustrine plain, which is a type of plain that is formed by the infilling of a former lake bed with sediment.

If the sentence is true write T and if false write F against the following

1. Volcanism is a type of exogenetic process.
2. Up folds or anticlines are found in Block mountains.
3. The geomorphic process responsible for the formation of alluvial plains is aggradation.
4. The Chhotanagpur plateau is an example of dissected plateau.
5. The plates which form the ocean beds are called continental plates.

1. True; Volcanism is an exogenetic process because it involves the release of magma, ash, and other materials onto the Earth’s surface from deep within the Earth.
2. False; Block mountains are formed by the uplift and tilting of large blocks of rock along faults, but they do not typically have up folds or anticlines.
3. True; Alluvial plains are formed by the deposition of sediment carried by rivers, which is a type of aggradation.
4. True; The Chhotanagpur plateau in eastern India is an example of a dissected plateau because it has been extensively eroded by rivers, resulting in a dissected landscape of ridges, valleys, and waterfalls.
5. False; The plates which form the ocean beds are called oceanic plates, while continental plates form the Earth’s continents.

Fill in the blanks with appropriate words

1. The mountains have ____ slopes and ____ ____ peaks.
2. The young fold mountains were formed about ____ million years ago.
3. ____ is the dome-shaped mass of igneous rock formed by intrusion of magma.
4. The African plateau, Austrian plateau, Antarctic plateau are parts of ancient ____.
5. ____ is one of the features seen on a flood plain.

1. steep, and jagged, pointed
2. 65
3. Batholith.
4. Cratons.
5. Oxbow.

Answer in word or words

Question 4 (a)

Which is the highest plateau in the world?

Answer

The highest plateau in the world is the Tibetan Plateau.

Question 4 (b)

Which plateaus result from tectonic movements?

Answer

Most plateaus result from tectonic movements.

Question 4 (c)

Name the mountains formed due to tensile forces and faulting.

Answer

Mountains formed due to tensile forces and faulting are called Horst Mountains.

Question 4 (d)

Name a residual mountain which was also an old fold mountain.

Answer

The Appalachian Mountains is an example of a residual mountain which was also an old fold mountain.

Short answer type questions

Question 5 (a)

What are Endogenic processes? 

Answer

Endogenic processes are geomorphic processes that occur within the Earth’s crust and are powered by internal sources of energy. These processes are driven by tectonic activity, which involves the movement of the Earth’s crustal plates.

Question 5 (b)

What are Exogenic processes?

Answer

Exogenic processes are geomorphic processes that occur at or near the Earth’s surface and are powered by external sources of energy, such as the Sun, wind, and water. These processes are primarily driven by the Earth’s external agents, including weathering, erosion, transportation, and deposition.

Question 5 (c)

What is Plate tectonic theory?

Answer

The Plate Tectonic Theory explains how the Earth’s lithosphere is divided into plates that move and interact with one another due to convection currents in the mantle. It is widely accepted among scientists and is responsible for many of the Earth’s geological processes, including mountain building, earthquakes, and volcanic activity.

Question 5 (d)

What is a Block mountain?

Answer

A Block mountain is a type of mountain that is formed by the uplift and tilting of large blocks of rock along faults. One side of the mountain range is raised up relative to the other side, creating a steep escarpment or cliff on one side and a gentle slope on the other side.

Question 5 (e)

What is Intermontane plateau? 

Answer

An Intermontane plateau is a type of plateau that is surrounded by mountains on all sides. These plateaus are often formed by the uplift and tilting of a block of land between two parallel faults, with the surrounding mountains formed by the same tectonic activity.

Question 5 (f)

What is a Flood plain?

Answer

A flood plain is a flat, low-lying area adjacent to a river that is periodically flooded when the river overflows its banks. Flood plains are formed by the deposition of sediment carried by the river during floods, which creates a fertile, flat area that is ideal for agriculture.

Question 5 (g)

What is a Residual mountain?

Answer

A Residual mountain is a mountain that remains standing after erosion has worn away the surrounding rock. These mountains are typically composed of hard, resistant rock that is more resistant to weathering and erosion than the surrounding rock.

Question 5 (h)

What is Orogenic movement?

Answer

Orogenic movement is the geological process of mountain building through the collision and/or compression of two or more tectonic plates.

Question 5 (i)

What is a Peneplain?

Answer

A Peneplain is a near-level land surface that has been eroded for a long period of time and is essentially a plain of low relief. It is formed by the process of prolonged erosion, in which the land is worn down by processes such as weathering, erosion, and mass wasting to the point where it becomes nearly flat.

Question 5 (j)

What are the features of a volcanic mountain?

Answer

Volcanic mountains, also known as stratovolcanoes or composite volcanoes, typically have the following features:

1. A conical shape, with steep sides and a pointed summit.
2. A central vent or caldera, through which magma, ash, and gas are erupted.
3. Layers of solidified lava, volcanic ash, and other volcanic materials that have been deposited during past eruptions.

Answer the following questions

Question 6 (a)

Classify Terrestrial processes and write a brief note on any one of them.

Answer

Terrestrial processes are classified into Endogenic (internal) and Exogenic (external) processes. Mountain building is an Endogenic process that involves the uplift and deformation of the Earth’s crust, driven by tectonic activity. This can create various types of mountains, such as block, fold, and volcanic mountains, which can impact the landscape and create habitats for diverse flora and fauna. The Himalayan Mountains are an example of a prominent mountain range that is home to rare and endangered species like the snow leopard and Himalayan tahr.

Question 6 (b)

Describe the characteristics of a fold mountain (any 3)

Answer

Fold mountains are formed by the folding and deformation of rock layers as a result of tectonic activity. Some of their characteristics include:

1. Fold mountains have a long, linear shape, often stretching for hundreds of kilometers.
2. They typically have a series of parallel ridges and valleys, with the ridges formed by the upfolding of rock layers and the valleys formed by the downfolding of rock layers.
3. The rock layers in fold mountains are often highly folded and deformed, and may be tilted or overturned in some places.

Question 6 (c)

How is a dissected plateau formed ?

Answer

A dissected plateau is formed by the erosion of a plateau by rivers and streams over time. It starts as a flat surface created by tectonic or volcanic activity, which is gradually eroded by rivers and streams, forming deep valleys and ridges. The process takes millions of years and is influenced by factors like rock type, climate, and rate of erosion. Dissected plateaus are characterized by dramatic scenery and are important habitats for diverse plant and animal species.

Question 6 (d)

How are erosional plains formed on Earth?

Answer

Question 6 (e)

Distinguish between a horst and a graben.

Answer

Horst	Graben
Forms when two parallel faults move away from each other, causing the central block to be uplifted.	Forms when two parallel faults move towards each other, causing the central block to be downfaulted.
Has uplifted blocks of land that are separated by steeply dipping faults.	Has downfaulted blocks of land that are separated by steeply dipping faults.
Often creates linear mountain ridges or plateaus.	Often creates linear valleys or basins.

Correct the following

Question 7 (a)

The Orogenic movement causes the formation of shields, plateaus etc.

Answer

The Orogenic movement causes the formation of mountains, not shields or plateaus.

Question 7 (b)

Residual mountains are called mountains of accumulation.

Answer

Residual mountains are not called mountains of accumulation.

Question 7 (c)

Columbia snake plateau is an example of Intermontane plateau.

Answer

Columbia Basin is an example of an Intermontane plateau.

Question 7 (d)

Loess plain is formed of glacial boulders and rocks.

Answer

Loess plain is formed by windblown dust and silt, known as loess.

Draw and label the following

Question 8

1. A Block mountain (Horst),
2. Intermontane plateau,
3. Deltaic plain,
4. Dissected plateau,
5. Residual mountain.

Answer

(a) A Block mountain (Horst)

(b) Intermontane plateau

(c) Deltaic plain

(d) Dissected plateau

(e) Residual mountain

Cross-Word

Question 9

Clues

Across-

(1) A high landform about 1000 m from the sea-level

(2) The down-thrown block between two parallel faults.

(3) A landform is also called a tableland.

Down-

(4) The force that acts externally.

(5) The plateau surrounded by mountains

Answer

Across:

(1) Mountain

(2) Graben

(3) Plateau

Down:

(4) Exogenic

(5) Intermontane

Essay-type or Long answer-type questions

Question 10 (a)

Describe the geomorphic processes.

Answer

Geomorphic processes are natural processes that shape the Earth’s surface. These processes can be broadly classified into two categories: endogenic and exogenic processes.

• Endogenic processes are powered by internal energy sources and are responsible for the formation of landforms such as mountains, plateaus, and volcanoes. These processes are driven by tectonic activity, which involves the movement of the Earth’s plates, and include mountain building, volcanic activity, and earthquakes.
• Exogenic processes, on the other hand, are powered by external energy sources such as the sun, wind, and water. These processes are responsible for the weathering, erosion, and deposition of sediments, and include processes such as fluvial erosion, glacial erosion, wind erosion, and coastal erosion.

Question 10 (b)

Describe the processes that produce the initial landforms (mountains, plateaus etc.), on earth.

Answer

The processes that produce the initial landforms on Earth are known as endogenic processes. These processes are powered by internal energy sources and are responsible for the formation of landforms such as mountains, plateaus, and volcanoes. The main processes that produce these landforms include:

1. Plate tectonics: The movement of the Earth’s plates causes the crust to buckle and fold, leading to the formation of mountains and plateaus. This process also creates volcanic activity along the boundaries of the plates.
2. Volcanism: The eruption of magma from the Earth’s mantle can create new landforms such as volcanic mountains, lava plateaus, and volcanic islands.
3. Faulting: The movement of the Earth’s crust along fault lines can create uplifted areas known as horsts and downfaulted areas known as grabens, which can eventually form plateaus.
4. Epeirogeny: This refers to broad, regional uplift or subsidence of the Earth’s crust, which can lead to the formation of plateaus or basins.

Question 10 (c)

How are fold mountains formed? Explain in the light of plate tectonics.

Answer

Here are the key points explaining how fold mountains are formed in the light of plate tectonics:

1. Fold mountains are formed by the process of orogenesis, which involves the folding and uplift of the Earth’s crust.
2. This process is driven by plate tectonics, which describes the movement of the Earth’s plates.
3. When two plates collide, one plate is forced under the other in a process known as subduction.
4. The subducting plate is forced deep into the Earth’s mantle, causing it to melt and form magma.
5. This magma rises to the surface, where it can erupt and create volcanic activity.
6. The collision between the two plates also causes the crust to buckle and fold, leading to the formation of fold mountains.
7. The folding process is caused by compressional forces, which push and squeeze the crust, causing it to deform and fold upwards.
8. Over time, erosion and weathering can wear away the surface of the mountains, exposing the layers of rock that were folded during the orogeny.
9. These layers can provide geologists with important information about the geological history of the area.
10. Examples of fold mountains include the Himalayas, the Rocky Mountains, and the Andes, which are formed by the collision of two continental plates.

Question 10 (d)

Write the differences between Volcanic mountains and Residual mountains.

Answer

Volcanic Mountains	Residual Mountains
Formed by volcanic activity	Formed by erosion and weathering
Found near tectonic plate boundaries	Can be found in a variety of locations
Typically conical in shape	Have a more irregular shape
Made up of volcanic rocks	Made up of pre-existing rock formations
Usually relatively young	Can be much older

Question 10 (e)

Classify plateaus and write an account on any one of them.

Answer

Plateaus can be classified into the following types:

1. Intermontane Plateaus
2. Piedmont Plateaus
3. Continental Plateaus

Intermontane plateaus are located between mountain ranges and are often surrounded by steep mountain slopes on one or more sides. They are formed by tectonic uplift and can vary in size from a few hundred square kilometres to tens of thousands of square kilometres.

One example of an Intermontane plateau is the Tibetan Plateau, which is located in central Asia and covers an area of approximately 2.5 million square kilometres. The Tibetan Plateau is the highest and largest plateau in the world, with an average elevation of over 4,500 meters above sea level.

Question 10 (f)

Describe the depositional plains with examples.

Answer

Depositional plains are low-lying areas that have been formed by the deposition of sediments by rivers, wind, or ocean currents. These plains are typically flat or gently sloping and are often characterized by fertile soils, making them important agricultural regions.

Some examples of depositional plains include:

1. River floodplains: These plains are formed by the deposition of sediments by rivers during floods. One example is the Indo-Gangetic plain in India, which is formed by the deposition of sediments by the Ganges, Brahmaputra, and Meghna rivers.
2. Deltaic plains: These plains are formed by the deposition of sediments by rivers as they flow into the ocean or a lake. One example is the Nile delta in Egypt, which is formed by the deposition of sediment by the Nile River as it flows into the Mediterranean Sea.
3. Alluvial plains: These are depositional plains that are formed at the base of mountain ranges by the deposition of sediment carried by rivers. One example is the Bhabhar plain in northern India, which is formed by the deposition of sediment carried by the Sutlej and Yamuna rivers.
4. Glacial outwash plains: These plains are formed by the deposition of sediments carried by glacial meltwater as it flows out of a glacier. One example is the Great Plains of North America, which are formed by the deposition of sediment carried by meltwater from the Laurentide Ice Sheet.

Question 10 (g)

Discuss the importance of mountains in the life of people.

Answer

The importance of mountains in the life of people

1. Mountains provide a source of freshwater for many people through rivers, lakes, and groundwater.
2. They offer unique habitats for a wide range of plant and animal species, many of which are endemic and found nowhere else in the world.
3. Mountains provide recreational opportunities for activities such as hiking, camping, and skiing, which are important for tourism and local economies.
4. They often have cultural and spiritual significance for indigenous communities who have lived in the mountains for generations.
5. Mountains are also important for their mineral resources, such as gold, silver, and copper, which are used in many industries.

Question 10 (h)

Why do people like to live in plains?

Answer

People like to live in plains for several reasons:

1. Fertile soil: Plains often have fertile soil, which is good for agriculture. Many crops, such as wheat, corn, and rice, are grown in plains, providing food for millions of people.
2. Easy transportation: Plains have flat terrain, which makes it easier to build roads, highways, and railroads. This makes transportation of people and goods faster and more efficient.
3. Access to water: Many rivers flow through plains, providing a source of water for drinking, irrigation, and other purposes. This makes it easier to establish settlements and build infrastructure.
4. Mild climate: Plains often have a mild climate, with relatively stable temperatures throughout the year. This can be more comfortable for people compared to areas with extreme weather conditions, such as deserts or mountains.
5. Economic opportunities: Plains are often home to large cities and industrial centers, providing job opportunities for people. Many people also choose to live in plains to be closer to these economic opportunities.