Selina Concise Solutions for ICSE Class 9 Geography Chapter 5 Landforms of the Earth

Exercises

I. Short answer questions.

Question 1. What is meant by a landform ?
Answer: A landform is a natural feature on the surface of the earth with a particular shape.
In simple words: A landform is just a fancy name for the different shapes of the Earth's surface, like a mountain, a flat plain, or a high plateau. It is like the "natural architecture" of our planet.

📝 Teacher's Note: Help students understand that landforms are created by both internal forces (like volcanoes) and external forces (like wind and water). Use a physical map to point out different shapes.

🎯 Exam Tip: When defining landform, use the keywords "natural feature" and "particular shape" to ensure a precise answer.

Question 2. Why are the fold mountains called so ?
Answer: Fold mountains are called so because of the result of large- scale earth movements caused by stresses in the earth’s crust. Such stresses may be caused by weight of the overlying rocks, movements in the mantle, the expansion or contraction of some part of the earth, etc. These stresses subject the rocks to compressive forces, producing wrinkling or folding along the lines of weakness. This is shown in fig. the raising of folds makes the fold mountains.

In simple words: Imagine pushing the ends of a tablecloth together—it wrinkles and creates waves. Fold mountains are the Earth's "wrinkles" formed when giant pieces of the ground push against each other and squeeze the rock layers upward.

📝 Teacher's Note: Use a sponge or a stack of papers to demonstrate compression. Show how the top of the wave is the "anticline" and the bottom is the "syncline."

🎯 Exam Tip: "Compressive forces" is the technical term for the pressure that creates these mountains. Remember that most of the world's highest mountains are fold mountains.

Question 3. Give two chief characteristics of the fold mountains.
Answer:
1. The fold mountain system has parallel ranges.
2. A fold mountain region is also a region of sudden forces such as of volcanoes and earthquakes.
In simple words: These mountains usually grow in long, side-by-side rows like giant ripples. Because the ground is still being squeezed, these areas often have earthquakes and volcanoes.

📝 Teacher's Note: Use the Himalayas as an example. Explain that because the Indian plate is still pushing into the Eurasian plate, the region is "unstable" and prone to quakes.

🎯 Exam Tip: If asked for characteristics, always mention their "parallel ranges" and "geological instability."

Question 4. Give one example of each :
(a) Young fold mountains;
(b) Old fold mountain. Why they are called so
Answer:
(a) These mountains are made of light sedimentary rocks of recent tertiary age and are the highest mountain system which are still increasing their heights due to gradual upthrust force. The Himalayas are called young fold mountains.
(b) The Alpine-Himalayan system and Circum Parific mountain belt are the ‘Old Fold Mountains’ which existed as geosynclines 50-60 million years ago.
In simple words: "Young" mountains like the Himalayas are the tallest and still growing. "Old" mountains formed many millions of years ago and have been worn down by rain and wind over time.

📝 Teacher's Note: Note that "Young" in geography still means millions of years old! The main difference is height and sharpness—young ones have sharp peaks, while old ones have rounded tops.

🎯 Exam Tip: The Himalayas are the most common example of Young Fold mountains. For Old Fold, the Aravallis (India) or Urals (Russia) are also excellent examples.

Question 5. Give example of residual mountains.
Answer: Examples of Residual mountains are Nilgiri, Parasnath and Rajmahal Hills in India and the Catskill range in the USA.
In simple words: These are "leftover" mountains. They were once parts of big plateaus or mountains, but everything around them was washed away by rain and rivers, leaving only the toughest rocks standing.

📝 Teacher's Note: Explain that "residual" means "remaining." They are relict features of a landscape that was once much higher.

🎯 Exam Tip: Mentioning the Nilgiri Hills is important for exams focusing on Indian geography.

Question 6. How is a rift valley formed ? Give one example of a rift valley.
Answer: A rift valley is formed by the submergence of a big landmass between two high block mountains, e.g. the Rhine river flows through a rift valley in its middle course.
In simple words: Think of a giant crack opening in the Earth. The middle piece of ground between two cracks sinks down, creating a long, steep valley.

📝 Teacher's Note: Use the "trapdoor" analogy. If two faults move away from each other, the block in the middle loses support and drops down.

🎯 Exam Tip: The "Rhine Rift Valley" is the classic textbook example. The "East African Rift Valley" is another major one you can use.

Question 7. Give a brief definition of a plateau.
Answer: The Himalayas are an important form of folding being the highest mountain range in the world.
In simple words: (Note: The provided answer in the source describes a mountain range instead of a plateau). A plateau is actually a large area of flat land that is raised high above the ground around it, like a giant natural table.

📝 Teacher's Note: Note to students: The answer provided in the textbook snippet for Question 7 is incorrect for the definition of a plateau. A plateau is an upland with a flat top.

🎯 Exam Tip: A better definition for an exam is: "A plateau is an elevated area of more or less level land which rises abruptly from the surrounding region."

Question 8. Give one example of each :
(a) Intermontane plateau
(b) Volcanic plateau and
(c) Piedmont plateau
Answer:
(a) The Tibetan plateau
(b) The Plateau of Peninsular India.
(c) The Patagonian plateau of South America.
In simple words: Plateaus are sorted by where they are. Tibetan is "inside" mountains, Peninsular India was made by lava, and Patagonian is at the "foot" of mountains.

📝 Teacher's Note: Tibet is the "Roof of the World"—it is the highest and largest intermontane plateau, surrounded by the Himalayas.

🎯 Exam Tip: Learn the specific definitions: Intermontane (between mountains), Piedmont (between mountains and plains), and Volcanic (made of lava).

Question 9. Give two points of importance of landforms.
Answer: Various landforms display the internal and external forces of the earth, different climatic effects and features, forests, snow lands giving birth to rivers, coasts and islands as fishing regions. All these together make the earth beautiful and ideal for living and various activities.
In simple words: Landforms matter because they give us resources. Mountains give us fresh water from snow, plateaus provide minerals, and coastal landforms give us places to fish and live.

📝 Teacher's Note: Connect landforms to human livelihoods. Mountains are good for tourism, plateaus for mining, and plains for farming.

🎯 Exam Tip: Mention how landforms influence "climate" and "human occupations" to score high marks.

Question 10. What are known as epeirogenic movements ?
Answer: The movements such as uplift and submergence working in vertical direction are known as epeirogenic movements. ‘Epeiros’ in Greek means continent ‘genic’ means building. As this movement created continents coming out higher from the oceans.
In simple words: These are slow "up and down" movements of the Earth's crust. They are responsible for lifting huge pieces of land out of the sea to make whole continents.

📝 Teacher's Note: Contrast epeirogenic (vertical) with orogenic (horizontal/mountain building) movements. Epeirogenic forces act slowly over vast areas.

🎯 Exam Tip: Use the term "vertical direction" to define epeirogenic movements clearly.

Question 11. Name two landforms created by epeirogenic movements.
Answer:
1. Block mountains.
2. Rift valleys and basins are produced by epeirogenic movements.
In simple words: When the ground moves vertically, it can snap the crust into big blocks. This makes mountains with flat tops and long sunken valleys.

Question 12. Why are the sudden forces described as ‘Constructive forces ?
Answer: Earthquakes and volcanic activities are described as sudden forces. These forces are described as ‘Constructive Forces’ because they create relief features on the surface of the earth. As volcanic eruptions result in the formation of volcanic mountains, extensive plateaus and also plains.
In simple words: Even though they seem scary and destructive, we call them "constructive" because they build new things. A volcano "constructs" a brand new mountain or plateau with the lava it spills.

📝 Teacher's Note: This is a common point of confusion for students. Destructive forces (erosion) tear things down; constructive forces (volcanoes) build things up.

🎯 Exam Tip: Focus on the creation of "relief features" like volcanic mountains and lava plateaus.

Question 13. What are called endogenic forces ?
Answer: Endogenic forces are the internal diastrophic forces working inside the interior of the earth related to the tectonic forces.
In simple words: These are "inner powers." They are the forces deep underground, like heat and pressure, that move the giant tectonic plates and change the surface from below.

Question 14. Name four relief features on the surface of the earth.
Answer: The four major landforms are mountains, plateaus, plains, valleys and basins.
In simple words: These are the "big four" shapes of nature: high peaks, flat highlands, flat lowlands, and low-lying hollows.

Question 15. What are known as exogenic forces ?
Answer: Exogenic forces work on the surface of the earth through water, wind and ice, resulting in changing the shape of landforms slowly.
In simple words: These are "outer powers." They are forces like wind, rain, and ice that wear down mountains and carve out valleys from the outside.

📝 Teacher's Note: Explain that exogenic forces are the "sculptors" of the Earth. They smooth out the sharp shapes built by endogenic forces.

Question 16. Name the two land forms produced by exogenic forces.
Answer:
1. Alluvial and erosional plains
2. Glacial landforms.
In simple words: Rivers leave behind silt to make flat farming plains, and slow-moving ice (glaciers) grinds the rocks into U-shaped valleys.

Question 17. Give one chief characteristic of the fold mountains.
Answer: The fold mountains are formed by the lateral compression of sedimentary rocks as seen by the different layers of various types of rocks one upon another.
In simple words: These mountains are made of squashed layers of rock. If you cut into one, you would see layers of ancient sand and mud stacked up like a many-layered cake.

🎯 Exam Tip: Use the term "lateral compression" to explain how the horizontal pressure folds the rock strata.

Question 18. Give one example of volcanic mountains.
Answer: Volcanic mountains are formed by erupting magma from the inner core on the surface e.g. Mt. Krakatoa is an active volcano on the western side of Java.
In simple words: Mt. Krakatoa is a famous example. It was built up layer by layer from hot liquid rock spilling out of a hole in the ground.

Question 19. How is a rift valley formed ? Give one example.
Answer: A rift valley is formed by the submergence of a big landmass between two high block mountains, e.g. the Rhine river flows through a rift valley in its middle course.
In simple words: (Repeat of Question 6). It's a valley that drops down like a basement between two high walls of rock.

Question 20. Give a brief definition of a plateau.
Answer: A plateau is a higher tableland between mountain and valley, lower than mountain and higher than valley.
In simple words: Imagine a table standing on the floor. It is higher than the floor (plains) but lower than the ceiling (mountains).

Question 21. Give one example of each
(a) Intermontane plateau
(b) Piedmont plateau
(c) Volcanic plateau.
Answer:
(a) The Tibetan plateau.
(b) The Patagonian plateau of South America.
(c) The Plateau of Peninsular India.
In simple words: (Repeat of Question 8). These are different types of flat highlands found around the world.

Question 22. How are erosional plains formed ?
Answer: Erosional plains are formed by the agents of erosion in millions of years, when the higher landforms are eroded into level plain areas, e.g. Lorraine plain in France.
In simple words: Nature works like a giant piece of sandpaper. Over millions of years, rain and wind rub down high hills until they are almost perfectly flat.

📝 Teacher's Note: These are sometimes called "Peneplains" (almost-plains). They represent the final stage of landform evolution.

Question 23. Give two points of importance of landforms.
Answer: Various landforms display the internal and external forces of the earth, different climatic effects and features, forests, snow lands giving birth to rivers, coasts and islands as fishing regions. All these together make the earth beautiful and ideal for living and various activities.
In simple words: (Repeat of Question 9). Landforms create the environments where we live, farm, and find water.

II. Distinguish between each of the following

Question 1. Fold Mountain and Block Mountain.
Answer:
Fold Mountain :
1. Fold mountains is built by the tectonic forces folding the sedimentary rocks.
2. These are formed of light sedimentary rocks e.g. the Himalayas
Block Mountain :
1. Block mountain is built after the submergence of a landmass leaving behind the big blocks on the both sides.
2. These are formed by solid rocks standing on the both sides of a rift valley. e.g. Vosges mountain in France.
In simple words: Fold mountains are made by "squeezing" the ground into waves. Block mountains are made by the ground "snapping" into giant slabs.

📝 Teacher's Note: Emphasize that fold mountains involve "folding" of rock layers, while block mountains involve "faulting" (cracking and shifting).

Question 2. Intermontane plateau and Volcanic plateau.
Answer: Intermontane plateau : These are the highest and most extensive types on the globe surrounded by hills and mountains. The plateau of Tibet is the highest plateau as well as most extensive intermontane plateau. Other examples are Columbian Plateau, North Americal Cordillera, Bolivian, Peruvian and Mexican plateaus.
Volcanic Plateau : In places where fissure eruptions have taken place magma erupts quietly through narrow fissures several kilometres in length. This magma spreads on the surface and cools down as a sheet of lava covering the surface of the land. Eruptions at intervals lead to the piling up of lava sheets one over the other in a series of steps. The Deccan trap region of Peninsular India has several lava sheets having a maximum thickness of about 200 metres. This region forms a lava plateau. Other examples are South African plateau, Columbian Plateau and Ethiopian plateau.
In simple words: Intermontane plateaus are like a high floor inside a house of mountains. Volcanic plateaus are built up by layers of "liquid stone" spilling out of cracks and hardening.

Question 3. Structural plain and Depositional plains.
Answer: Structural plain : It is formed by the uplift of landmass by Diastrophic forces creating an extensive lowland. The Missouri – Mississippi plain of U.S.A. is an example, which came out of ocean by uplift force.
Depositional plains : These plains are formed by the deposition of materials which have been brought by various agents of transportation, eg.
1. River Deposition : The most widespread of these are alluvial plains like the Northern Plains of India; the flood plains like the Mississippi Plains in the USA, deltaic plains in Egypt and India
2. Wind Deposition : Most of such plains are sandy deserts like the Sahara in Africa and the Thar desert in India. They have irregular and undulating surface made by existence of sand dunes and hallows.
3. Marine Deposition : These plains are found in coastal regions. Examples are the east coast of India, the estuarine banks in the Netherlands, coast of Germany and Denmark.
In simple words: Structural plains are just pieces of the sea floor that got lifted up into the air. Depositional plains are made of "rubbish" like sand or mud that rivers and wind piled up over time.

📝 Teacher's Note: Point out that depositional plains (especially river ones) are the most fertile lands on Earth, which is why ancient civilizations started there.

Question 4. Tectonic mountain and Volcanic mountain.
Answer: Tectonic mountain :
1. It is built by the tectonic force working on the crust of the earth.
2. It is the result of upthrust force of the tectonic movement.
3. It may be built by sedimentary or metamorphic rocks.
Volcanic mountain :
1. It is built by the volcanic eruption from the interior of the earth.
2. It is the result of upthrust force of magma coming up on the earth surface.
3. It may be built by crystalline igneous rocks of particular composition.
In simple words: Tectonic mountains are made by the solid crust moving and pushing. Volcanic mountains are made by liquid rock from deep inside the Earth exploding onto the surface.

III. Give one technical term for each of the following

Question 1. Block mountains with flattened summits.
Answer: Horst Mountains.
In simple words: A Horst is a giant flat-topped block of land that was pushed up between two cracks in the Earth.

Question 2. Plateaus surrounded by hills and mountains on all sides.
Answer: Intermontane plateaus.
In simple words: "Intermontane" literally means "inside mountains."

Question 3. Plateaus formed by lava.
Answer: Volcanic plateaus.
In simple words: These are the "hardened lava pools" of the world.

Question 4. An extensive area of lowland with a level or gently undulating surface.
Answer: Plain.
In simple words: A plain is just a large, flat, low-lying field.

Question 5. The compressional forces that cause folding of rocks and formation of fold mountains.
Answer: Diastrophic forces.
In simple words: This is the scientific name for the slow, giant forces that bend and break the Earth's crust.

Question 6. The vertical movements which are the result of faults and cracks in the surface of the earth.
Answer: Epeirogenic forces.
In simple words: These are the powers that lift land up or let it sink down vertically.

Question 7. The forces operating on the surface of the earth.
Answer: Exogenic forces.
In simple words: The "outside" forces like rain and wind.

Question 8. Plateaus surrounded by mountains on one side and plains on the other.
Answer: Piedmont plateaus
In simple words: "Piedmont" means at the foot of the mountains.

P Q. Fill in the blanks with suitable words.

1. Volcanic activity is a sudden movement.
2. The upfolds of the rock strata are called anticlines.
3. The Mid-Atlantic Ridge rises 3 km above the floor of the Atlantic.
4. The Great Plain of the USA was formed by Diastrophic forces.
5. The Great Northern plains of India were formed by River Deposition.

IV. Long Answer Questions.

Question 1. Describe the formation of mountains and their types.
Answer: Mountains are classified into three main types depending on the forces that have formed them. Three main types of mountains are
1. Fold Mountains : Fold mountains are the result of large-scale earth movements caused by stresses in the earth’s crust. Such stresses may be caused by weight of the overlying rocks, movements in the mantle, the expansion or contraction of some part of the earth, etc. These stresses subject the rocks to compressive forces, producing wrinkling or folding along the lines of weakness. This is shown in fig. The raising of folds makes the fold mountains.
2. Residual Mountains : Mountains which are subjected to weathering and erosion for a longtime, are lowered down and called residual or relict mountains. Denudation and erosion by natural agents like winds, water, snow etc., cause the mountains to be lowered but some resistant areas may remain and form residual mountains. They may also be formed on plateaus that are dissected by rivers. For example the hills and valleys in the Deccan plateau. Some examples of Residual mountains are Nilgiri, Parasnath and Rajmahal Hills in India and the Catskill range in the USA.

3. Block Mountains : Horst or a block mountain is an uplifted land mass situated between two adjacent faults. The central block is upthrown or land on the outer sides of the faults is downthrown so that the central mass appears like a highland. Its surface is like a plateau, but it has steep edges. The Vosges mountains to the west of the Rhine Rift Valley and the Black Forest mountain to the east of the Rhine Rift Valley are good examples of Horsts.

In simple words: Mountains are formed in different ways: folding the crust (Fold), leaving strong rock behind while softer rock washes away (Residual), or pushing huge slabs of rock upward (Block).

📝 Teacher's Note: Use the "Block Mountain" diagram to explain how a "Horst" is the high part and a "Graben" is the low part. This is essential for students to visualize topography.

Question 2. Describe the characteristics of four different types of plateaus.
Answer: Intermontane plateaus are the highest plateaus between highest mountains, e.g. Tibetan plateau. Piedmont plateaus lie between mountains and plains with steep slopes towards plains due to the force of flowing water downwards, e.g. Appolochian plateau of U.S.A., Patagonia plateau of South America Volcanic plateaus are created by volcanic eruption and Lava flows, e.g. Deccan plateau of peninsular India Uplifted plateaus are caused by the endogenic forces resulting in the dome shaped plateaus e. g. Chhotanagpur plateau in India
In simple words: Plateaus are flat highlands. They can be trapped between mountains (Intermontane), sit at the base of mountains (Piedmont), be built by cooled lava (Volcanic), or just be a giant "bubble" of ground pushed up from below (Uplifted).

Question 3. Describe the characteristics of structural plains.
Answer: Structural plains are created by uplifting of a large landmass due to Diastrophic movements, e.g. plainofU.S.A. Erosionalplains are formed by eroding highlands into plain areas, e.g. Lorraine plain in France. Srinagar Valley of Kashmir is the result of glacial erosion, Sahara desert plain is the result of wind erosion. Karst plains are created by erosion of limestone rocks by ground water, e.g. Karst plain of Yugoslavia. Depositional plains are caused by large scale deposition of debris and silt deposited by the running water or rivers, e.g. Northern plain of India.
In simple words: Structural plains were once part of the ocean floor that got pushed up flat. Other plains are made by ice carving the land (Glacial), wind blowing away sand (Wind), or water dissolving soft rock (Karst).

Question 4. Explain the chief characteristics of depositional plains and their types.
Answer: Depositional plains These plains are formed by the deposition of materials which have been brought by various agents of transportation, eg.
1. River Deposition : The most widespread of these are alluvial plains like the Northern Plains of India; the flood plains like the Mississippi Plains in the USA, deltaic plains in Egypt and India
2. Wind Deposition : Most such plains are sandy deserts like the Sahara in Africa and the Thar desert in India. They have irregular and undulating surface made by existence of sand dimes and hallows.
3. Marine Deposition : These plains are found in coastal regions. Examples are the east coast of India, the estuarine banks in the Netherlands, coast of Germany and Denmark.
In simple words: These plains are made by nature "dropping" mud, sand, or dirt in a low spot. Rivers make the best farming land this way, wind makes big sandy deserts, and the sea makes flat coastal areas.

Question 5. Give a brief account of importance of landforms on the surface of the earth.
Answer: Landforms play an important role for human activities by providing different aspects of landscapes, climatic variety, natural gifts of snowclad ranges, glaciers and rivers etc., various vegetation zones imparting innumerable forest’ products, agriculture and other occupations related to different types of landforms, natural beauty and tourism all these making this earth fascinating living world.
In simple words: Landforms are like different "rooms" on Earth. One room is good for farming, another is for mining gold, and another is for beautiful vacations and skiing. They give us all the variety we need for life.

Practice Questions (Solved)

Question 1. Describe the direction in which the following mountain systems lie and also point out the continents where they are found.
(a) Alpine Himalayan System
(b) Rocky-Andean System
Answer:
(a) Alpine and Himalayan System both run from West to East direction in Europe and Asia continents respectively.
(b) Rocky-Andean System both run from North to South in the western margins of North America and South America continents.
In simple words: The big mountains in Europe and Asia go side-to-side (West to East). The big mountains in the Americas go up-and-down (North to South).

Question 2. Describe the different stages in the growth of mountains.
Answer: There are three different stages in the growth of mountains.
1. The geosyncline stage : The deposition of sediments in the sea-bed to form large geosynclines.
2. The Orogenic stage : The tectonic forces working horizontally push and press there geosynclines to form various folds.
3. Epeirogenic stage : When the whole mass of geosynclines is raised and buckled up and form a distinct series of troughs (synclines) and arcs (auticlines) i.e. Mountains and Valleys.
In simple words: First, a deep puddle of mud forms in the sea (Geosyncline). Then, giant plates push that mud from the sides (Orogenic). Finally, the whole mess gets pushed high into the air to become mountains (Epeirogenic).

Question 3. What are the different types of Geosynclines ?
Answer: There are three types of Geosynclines
1. Monogeosynclines : Long, narrow geosynclines along narrow water bodies take the shape of narrow mountains such as Appalachian mountains of North America.
2. Polygeosynclines : Geosynclines laid down in wide and long water basin take the shape of broad and long mountain ranges like Rockies in North America.
3. Mesogeosynclines : The geosynclines lying between Europe and Africa continents resulted in various mountain ranges e.g. Alps and Pyrenees in Europe, Atlas in Africa.
In simple words: These are the different types of "underwater basins" that eventually got pushed up into mountains. Some were skinny, some were huge, and some were trapped between whole continents.

Question 4. Write a note on the characteristics of folded mountains.
Answer: Folded mountains are formed by the forces of compression and contortion resulting in a series of synclines and anticlines, later on undergoing various erosive forces. All the highest mountain systems are example of folded mountains made of sedimentary rocks.
In simple words: These mountains are like giant "rock waves." They are made from layers of rock that used to be at the bottom of the sea, which is why we find sea fossils on top of Mount Everest!

Question 5. What are Block mountains ? How are they formed ?
Answer: Block mountains are formed on the both sides of a rift valley, which is formed by deep submergence of a large landmass leaving behind two raised platform type blocks known as Block mountains. These landforms are created by displacement of landmass along fault lines known as faulting.
In simple words: Imagine a giant slab of rock. If cracks (faults) appear and the middle piece falls down, the two high pieces left standing on the sides are the Block mountains.

Question 6. How can mountains be classified according to their different size and arrangement ? Describe in detail two of the classes of such mountains.
Answer: Simply the mountains can be divided into 4 groups:
1. Folded mountains
2. Block mountains
3. Volcanic mountains
4. Relict mountains
Volcanic mountains : are formed by the eruption and deposition of magma from the interior core to the land surface. According to their construction these are Cinder or Ash cones, Lava cones and composite cones, e.g. Fujiyama in Japan.
Relict mountains : These are formed by the continuous erosion of the original materials and giving birth to the hills of rounded peaks made of high density rocks, which have undergone excessive pressure and denudation by natural agents. One of the best example is Vindhyanchal mountain.
In simple words: Volcanic mountains are "fire mountains" built from the inside out. Relict mountains are "survivor mountains"—they are what's left after millions of years of rain washed their neighbors away.

Question 7. What are Block mountains ? How are they formed ?
Answer: Horst or a block mountain is an uplifted land mass situated between two adjacent faults. The central block is upthrown or land on the outer-sides of the faults is downthrown so that the central mass appears like a highland. Its surface is like a plateau, but it has steep edges. The Vosges mountains to the west of the Rhine Rift Valley and the Black Forest mountains to the east of the Rhine Rift Valley are good examples of Horsts.

In simple words: (Repeat description). A Horst is a "hill" made by faults, and a Graben is the "hole" or valley between those hills.

Question 8. How can mountains be classified according to their different size and arrangement ?
Answer: Mountains can be classified according to their different size and arrangement as given below :
1. Cordilleras: These are large regions of mountains topography which are characterised by a large number of chains and ranges.
2. System: It is formed of several associated ranges. These ranges should be similar in position, form and structure although trenches or basins may separate them.
3. Chain: It is a series of ridges in one line although separated by trough like valleys.
4. Range: It is a linear arrangement consisting of a large number of peaks and ridges separated by valleys. The different mountains possess a unity of form and structure.
5. Group: It is a circular or massive arrangement of peaks and ridges. Group formations often result from the erosion of laccoliths.
6. Ridge: It is the individual arch or block that results from folding and faulting. It may be of various types according as the slope is steep on one side or the other.
7. Peaks: These are formed by the less regular beds resisting denudation. They may be dome-like or pyramidical or needle-shaped. Their shape depends upon the rock structure and joint planes of the region.
In simple words: This is the "dictionary" for mountain shapes. A range is a line of peaks, a chain is a very long line, and a peak is just the very top point of a mountain.

Question 9. What are plateaus ? How are they different from mountains ? Give suitable examples.
Answer: Plateaus or table lands are elevated uplands, extensive in size and descending steeply to the surrounding regions. On the other hand, a portion of land surface rising considerably above the surroundings either as a single eminence or in a range of chain is called a mountain.
Examples of Plateaus :
1. Deccan Plateau of India.
2. Tibetan Plateau (called the roof of the world)
In simple words: A mountain has a sharp peak at the top. A plateau is also high up, but its top is flat and big enough to build a city on. It looks like a giant's table.

Question 10. What is a Piedmont Plateau ? How is it different from a Continental plateau ? Give suitable examples to illustrate.
Answer: Piedmont Plateaus: The plateaus which lie at the foot of the mountains are called Piedmont plateaus. These are flanked on one side by the plains or seas. The chief examples are the Colorado plateau or North America and the Patagonia Plateau of South America.
Continental Plateaus: The extensive and massive tablelands which rise abruptly from the bordering lowlands or from the sea are called continental plateaus. On most of their margins, there is sea. They seldom have mountainous rims. The major portion of Africa, Arabia, Spain, Australia, Peninsular India, Greenland and Antarctica are continental plateaus.
In simple words: A Piedmont plateau is like a step-stool right next to a giant mountain. A Continental plateau is like a massive stage that takes up almost a whole country and is surrounded by oceans.

Question 11. Write short notes on the following :
(a) Coastal plains
(b) Karst plains
(c) Peneplain
(d) Cuestiform plains.
Answer:
(a) Coastal plains : The plains situated near a sea coast are called coastal plains. They are formed by the sea waves after sea bottoms have emerged. Many coastal plains increased in width towards the sea because the sea waves continue adding matter to it.
(b) Karst plains : These plains are formed by the action of underground water, dissolving the regions made of chalk or limestone. They are often flat-bottomed. Due to wind erosion and differential weathering, the topography is etched and rounded or even polished.
(c) Peneplains : Very low undulating plains are called peneplains. They are almost plains.
(d) Cuestiform plains : The plains marked by a concentric arrangement of ridges and lowlands are called Cuestiform plains. Paris and London are the typical examples. They are made by river action on hard and soft rocks.
In simple words: Coastal plains are the beaches' giant cousins. Karst plains are made by water "eating" away soft white rocks. Peneplains are "nearly-finished" flat lands. Cuestiform plains are rolling lands with gentle ridges.

Question 12. Why and how are the plains the centres of all human activity ?
Answer: The plains are the centres of great economic advancement. The alluvial plains have been the cradles of civilisation from the earliest time. They have the following advantages to man:
1. Railways, roads and waterways can be easily laid.
2. They are the granary of the world.
3. Due to fine climate, fertile soil and facilities for movement, the plains have become thickly populated and most of the big cities and towns are situated in the plains.
In simple words: Life is easier on flat land. You can build straight roads, farm big fields, and build huge cities without having to climb up and down mountains every day. That's why most people in the world live on plains.

Question 13. Differentiate between Young fold mountains and Old fold mountains.
Answer: Old fold mountains : The fold mountains which were formed about more than 250 million years ago are called old fold mountains. For example, the Urals in Russia, the Appalachians in North America and the Aravalli range in India are old fold mountains. These mountain ranges are of low altitude and have gentle slopes.
Young fold mountains : The most recent phase of mountain building took place about 25 million years ago. The world’s highest mountain ranges were formed during this period. These are known as young fold mountains. They have rugged relief features because they have been subjected to denudation for a comparatively short period only.
In simple words: It's like comparing a new, sharp pencil to one that has been used until it's just a tiny stub. Young mountains are sharp and tall; old ones are low and smooth.

Question 14. Give reasons for the following :
1. Old fold mountains have low altitude and gentle slopes.
2. Young fold mountains have rugged relief features.
3. Young fold mountains are liable to Earthquakes and Volcanic action.
Answer:
1. Old fold mountains have low altitude and gentle slopes because they have been subjected to denudations for million of years.
2. Young fold mountains have rugged relief features because they have been subjected to denudation for a comparatively short period only.
3. Young fold mountains are liable to Earthquakes and volcanic action because these mountain regions are areas of crustal instability.
In simple words: Old ones are small because nature has been "sanding them down" for a very long time. Young ones are sharp because they haven't been worn down yet and they are still "alive" and moving deep underground.

Question 15. State two evidences that the Earth movements have taken place in the past.
Answer:
1. The basins containing sedimentary rocks indicate that such basins must have been below sea level in the past. The coalfields of the Damodar valley occur in such basins.
2. Oilfields occur in basins containing old sedimentary rocks. Such basins are now occurring on the land. This shows that the portion of the crust which was once depressed must have been uplifted later.
3. The Himalayas provide another evidence of the recent effect of Earth movements.
In simple words: We find coal and oil (which are made under the sea) on top of high dry land. This proves the ground must have moved upward over time!

Question 16. What causes Orogenic movements ?
Answer: Orogenic movements are caused by compressional or tensional forces.
In simple words: These are "mountain-building" forces. They happen when the ground is squeezed together or pulled apart.

Question 17. What are the effects of Epeirogenic movements ?
Answer: Effects of epeirogenic movements :
1. They cause rising or sinking of the crust. They may cause the elevation of broad areas as extensive as those of a continent or lowering of the sea level.
2. These movements are responsible for the formation of plateaux.
In simple words: These forces act like a giant elevator for the Earth's crust, lifting up whole plateaus or pushing land down under the sea.

📝 Teacher's Note: Remind students that these movements are so slow that we can't feel them happening, but over millions of years, they change the entire map of the world.

🎯 Exam Tip: Epeirogenic = Continent building (vertical); Orogenic = Mountain building (horizontal). Keep these two separate in your mind.