Landforms of the Earth ICSE Class 9: Mountains, Plateaus and Plains

What Landforms of the Earth is about

Weightage: CISCE publishes no chapter weightage and no question-paper layout for ICSE Class 9 Geography. Class IX is examined by your school: one 80-mark paper of 2 hours plus 20 marks of internal assessment (a record file and one project). Landforms of the Earth is topic 2(b), Structure of the Earth, of the 2028 syllabus.Source: CISCE ICSE 2028 Geography syllabus, Class IX

Key concepts

Mountains: meaning

A mountain is a natural elevation of the earth's surface rising steeply to a great height (generally more than about 600 m above the surrounding area), with a narrow summit and steep slopes. A series of mountains is a range; a group of ranges is a mountain system or chain.

The syllabus covers three types by mode of formation:

• fold mountains: formed by folding of rock layers;
• block mountains: formed by faulting;
• residual mountains: remnants left after long erosion.

(Volcanic mountains exist too but are studied under volcanoes.)

Worked example

(2 marks) What is a mountain? Name the three types of mountains in your syllabus.

Try it first, then show the solutionSolution

1. A steep natural elevation rising high above the surrounding land, with a narrow summit - 1 mark.
2. Fold, block and residual mountains - 1 mark.

Answer: A mountain is a natural elevation rising steeply high above the surrounding area, with a narrow summit and steep slopes. The three types studied are fold, block and residual mountains.

Fold mountains

Formation: layers of sedimentary rock deposited in a shallow sea (geosyncline) are squeezed by compressional forces when two plates move towards each other. The layers bend into folds. The upfolds are called anticlines and the downfolds synclines. Continued compression lifts the folded layers into high mountain ranges.

Features: long, high ranges with sharp peaks; often found along the edges of continents; contain fossils of sea creatures, showing their marine origin.

Types and examples:

• Young fold mountains, formed in the last tens of millions of years, high and rugged: the Himalayas (India), the Alps (Europe), the Rockies (North America) and the Andes (South America).
• Old fold mountains, formed hundreds of millions of years ago and worn down: the Appalachians (USA) and the Urals (Russia); in India the Aravallis are among the oldest fold mountains, now largely worn down.

Worked example

(3 marks) How are fold mountains formed? Give one example each from India and the world.

Try it first, then show the solutionSolution

1. Sediments deposited in a shallow sea are compressed when plates move towards each other - 1 mark.
2. The layers bend into anticlines (upfolds) and synclines (downfolds) and are uplifted - 1 mark.
3. Examples: Himalayas (India); Alps / Rockies / Andes (world) - 1 mark.

Answer: Sedimentary layers laid down in a shallow sea are squeezed by compressional forces as plates converge, bending into anticlines and synclines and rising as lofty ranges. Examples: the Himalayas in India; the Alps, Rockies or Andes in the world.

Block mountains

Formation: when tensional (or compressional) forces act on the crust, rocks crack along lines of weakness called faults. Blocks of land between faults may be raised or the land on either side may sink.

• The raised block between two faults is a block mountain, also called a horst.
• A block that sinks between two faults forms a rift valley, also called a graben.

Features: steep sides along the faults and a flat or gently sloping top.

Examples: the Vosges (France) and the Black Forest (Germany), with the Rhine rift valley between them; the Sierra Nevada (USA). In India, the Satpura range is often cited as a block mountain, with the Narmada flowing through a rift valley to its north.

Worked example

(3 marks) Explain the formation of block mountains and rift valleys, with examples.

Try it first, then show the solutionSolution

1. Forces in the crust cause cracks called faults - 1 mark.
2. A block raised between two faults is a block mountain (horst); a block sunk between faults is a rift valley (graben) - 1 mark.
3. Examples: Vosges and Black Forest with the Rhine rift valley between them - 1 mark.

Answer: Forces in the crust break rocks along faults. A block pushed up between two faults stands as a block mountain or horst; a block that sinks between faults forms a rift valley or graben. The Vosges and Black Forest are block mountains with the Rhine rift valley between them.

Residual mountains

Formation: residual (relict) mountains are the remains of older mountains or high plateaus that have been worn down over very long periods by agents of erosion such as rivers, wind, ice and weathering. The harder rocks resist erosion and are left standing as low, rounded hills or ranges while softer rocks around them are removed.

Features: low height, rounded tops, gentle slopes, often broken into separate hills.

Examples in India: the Aravallis (remnants of very old fold mountains), the Eastern Ghats and Parasnath hill. In the world: isolated hills such as Mount Monadnock (USA), from which the term 'monadnock' for a residual hill comes.

Worked example

(2 marks) What are residual mountains? Give one example from India.

Try it first, then show the solutionSolution

1. Remnants of older mountains or plateaus worn down by long erosion; hard rocks remain - 1 mark.
2. Example: the Aravallis (or Eastern Ghats, Parasnath) - 1 mark.

Answer: Residual mountains are the worn-down remains of older mountains or plateaus, where harder rocks have resisted erosion. Example: the Aravalli range.

Plateaus: intermont and volcanic

A plateau is an extensive elevated area with a fairly flat top and at least one steep side rising sharply above the surrounding land. It is often called a tableland.

Intermont plateau: a plateau partly or fully enclosed by mountain ranges ('inter-montane' means between mountains). It forms when the land between ranges is uplifted along with the mountain-building process.
Examples: the Tibetan Plateau, between the Kunlun and the Himalayas, the highest and largest such plateau; the Bolivian Plateau (Altiplano) in the Andes; the Mongolian Plateau.

Volcanic (lava) plateau: formed when very fluid basaltic lava pours out quietly through long cracks (fissures) in the crust, spreading over a large area in successive layers; when the lava cools, it forms a high, level surface.
Examples: the Deccan Traps in the north-western part of the Deccan Plateau, India (giving fertile black soil); the Columbia-Snake Plateau in the USA.

Worked example

(3 marks) Distinguish between an intermont plateau and a volcanic plateau, with one example each.

Try it first, then show the solutionSolution

1. Intermont: enclosed by mountain ranges, uplifted with mountain building - 1 mark.
2. Volcanic: built up by layers of fluid lava from fissure eruptions - 1 mark.
3. Examples: Tibetan Plateau (intermont); Deccan Traps / Columbia Plateau (volcanic) - 1 mark.

Answer: An intermont plateau is enclosed by mountains and raised during mountain building, like the Tibetan Plateau. A volcanic plateau is built by successive sheets of fluid lava from fissure eruptions, like the Deccan Traps of India or the Columbia Plateau of the USA.

Plains: structural and depositional

A plain is an extensive area of flat or gently rolling low land, usually not more than a few hundred metres above sea level.

Structural plains: formed by earth movements, mainly the uplift of a part of the sea floor or continental shelf, so that horizontal layers of rock are raised above sea level without being folded. They are broad and level.
Examples: the Great Plains of the USA and the Russian Platform (the plains of European Russia).

Depositional plains: formed by the deposition of material brought by agents such as rivers, wind, glaciers and lakes.

• River (alluvial) plains: the Indo-Gangetic plain of India; the plains of the Mississippi.
• Delta plains at river mouths: the Ganga-Brahmaputra delta.
• Loess plains, of fine wind-blown dust: north China around the Hwang Ho.
• Glacial (till) plains, of material left by ice sheets: parts of northern Europe and North America.
• Lacustrine plains, of filled-up lakes: the Kashmir Valley.

Depositional plains, especially alluvial ones, are very fertile and densely populated.

Worked example

(3 marks) Explain how depositional plains are formed, naming two types with examples.

Try it first, then show the solutionSolution

1. Formed by deposition of sediments carried by rivers, wind, glaciers or lakes - 1 mark.
2. Alluvial (river) plain: Indo-Gangetic plain - 1 mark.
3. Loess plain: north China / delta: Ganga-Brahmaputra / lacustrine: Kashmir Valley - 1 mark.

Answer: Depositional plains are built up by layers of sediment laid down by rivers, wind, ice or in lakes. Alluvial plains such as the Indo-Gangetic plain are formed by rivers; loess plains such as those of north China are formed by wind-blown dust.

Landforms of the Earth in real life

Each concept, met in an everyday situation. Read the situation, answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Topics in this chapter

• Mountains, Plateaus and Plains: Types and Formation

Landforms of the Earth: key facts

Fold mountains

Compression → anticlines and synclines

Himalayas, Alps, Rockies, Andes (young); Appalachians, Urals, Aravallis (old).

Block mountains

Faulting → horst (up) and graben/rift valley (down)

Vosges, Black Forest, Rhine rift; Sierra Nevada; Satpura often cited.

Residual mountains

Long erosion of older highlands

Aravallis, Eastern Ghats, Parasnath.

Intermont plateau

Enclosed by mountains

Tibet, Bolivia, Mongolia.

Volcanic plateau

Fissure eruptions of fluid basaltic lava

Deccan Traps, Columbia-Snake Plateau.

Plains

Structural: uplift of sea floor; depositional: rivers, wind, ice, lakes

Great Plains (USA); Indo-Gangetic plain; north China loess; Kashmir Valley.

How the school exam asks Landforms of the Earth

The question patterns to expect, and the method that works for each.

Tricks to remember Landforms of the Earth

Short memory aids. Say each one aloud once, then use it on a question the same day.

• Fold = Force from both sides

  Compression folds; tension faults.

  Use it when: Fold vs block mountains.

• Horst is High, Graben is Grave

  Horst rises; graben sinks.

  Use it when: Block mountain terms.

• Intermont = in the middle of mountains

  Tibet sits between the Kunlun and the Himalayas.

  Use it when: Plateau types.

Landforms of the Earth: exam-level solved questions

Ordered from exam level to HOTS. Cover the solution, write your own, then compare step by step.

Case-study practice (Section B style)

Read the situation, then answer every part. In a school exam set on the board pattern this is a 8-mark question split into 2 + 3 + 3 marks.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

Where students lose marks in Landforms of the Earth

The slips examiners see most often, and what to write instead.

• ✗Mistake: Giving the Aravallis as young fold mountains

  They are fold in origin.

  ✓Do this: The Aravallis are very old fold mountains, now residual.

  Usually costs: 1 mark.

• ✗Mistake: Describing block mountains as formed by folding

  Mixing processes.

  ✓Do this: Block mountains: faulting; fold mountains: folding.

  Usually costs: 1-2 marks.

• ✗Mistake: Writing examples outside the syllabus types

  E.g. erosional plains or dome plateaus.

  ✓Do this: Stick to fold, block, residual; intermont, volcanic; structural, depositional.

  Usually costs: Marks for irrelevant points.

• ✗Mistake: No example from India when asked

  Students give only world examples.

  ✓Do this: Learn India-world pairs.

  Usually costs: 1 mark.

Practice questions on Landforms of the Earth

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

1. Q1 · 1 mark · MCQExam level

   The Tibetan Plateau is an example of:
   (a) a volcanic plateau
   (b) an intermont plateau
   (c) a structural plain
   (d) a residual mountain

   Hint

   Enclosed by mountains.

   Answer

   (b) an intermont plateau.

2. Q2 · 1 mark · MCQHarder exam level

   A sunken block between two faults is called a:
   (a) horst
   (b) anticline
   (c) graben
   (d) syncline

   Hint

   Rift valley.

   Answer

   (c) graben.

3. Q3 · 1 mark · Very short answerExam level

   Name one structural plain of the world.

   Hint

   North America.

   Answer

   The Great Plains of the USA (or the Russian Platform).

4. Q4 · 2 marks · Very short answerExam level

   What is an anticline and a syncline?

   Hint

   Up and down folds.

   Answer

   An anticline is an upfold (arch) in folded rock layers; a syncline is a downfold (trough).

5. Q5 · 2 marks · Very short answerHarder exam level

   Name two depositional plains and the agent that formed each.

   Hint

   River, wind, lake.

   Answer

   Indo-Gangetic plain (rivers); loess plains of north China (wind) (also Kashmir Valley, lake).

6. Q6 · 2 marks · Very short answerHarder exam level

   Why are residual mountains low and rounded?

   Hint

   Age and erosion.

   Answer

   They are the remains of very old highlands that have been worn down by weathering and erosion over millions of years, leaving only the harder, rounded remnants.

7. Q7 · 2 marks · Very short answerHOTS / competency

   Why do young fold mountains experience frequent earthquakes?

   Hint

   Plates still moving.

   Answer

   They lie along active plate boundaries where plates are still converging; continuing movement and stress cause frequent earthquakes, as in the Himalayas.

8. Q8 · 3 marks · Short answerExam level

   Explain the formation of a volcanic plateau.

   Hint

   Fissure eruption.

   Answer

   Very fluid basaltic lava flows out quietly through long cracks (fissures) in the crust; it spreads over a vast area in successive sheets, which cool and solidify into a high, level surface: a lava plateau, such as the Deccan Traps.

9. Q9 · 3 marks · Short answerHOTS / competency

   The Narmada flows westwards through a narrow valley between two highlands. Which landform process might explain this, and why?

   Hint

   Faulting.

   Answer

   Faulting: the Narmada valley is regarded as a rift valley, formed when a block of land sank between faults, while adjacent blocks remained high (the Satpura often cited as a block mountain). A river naturally follows such a long, straight depression.

10. Q10 · 3 marks · Short answerHarder exam level

    Distinguish between structural and depositional plains on three points.

    Hint

    Origin, material, example.

    Answer

    (1) Structural plains form by uplift of the sea floor or continental shelf; depositional plains by the deposition of sediments. (2) Structural plains are made of raised horizontal rock layers; depositional plains of alluvium, loess or glacial material. (3) Examples: Great Plains of the USA; Indo-Gangetic plain.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1. 1.Upfold in rock layers?Show answer

   Anticline.

2. 2.Raised block between faults?Show answer

   Horst (block mountain).

3. 3.Example of an intermont plateau?Show answer

   Tibetan Plateau.

4. 4.Example of a volcanic plateau in India?Show answer

   Deccan Traps.

5. 5.Example of a lacustrine plain in India?Show answer

   Kashmir Valley.

6. 6.Which rift valley lies between the Vosges and Black Forest?Show answer

   The Rhine rift valley.

Quick revision checklist

The night before the exam: can you do each of these without looking?

• ☐Mountain: steep high elevation; fold, block, residual.
• ☐Fold: compression; anticline and syncline; Himalayas, Alps, Rockies, Andes (young); Appalachians, Urals, Aravallis (old).
• ☐Block: faulting; horst and graben; Vosges, Black Forest, Rhine rift, Sierra Nevada.
• ☐Residual: worn-down remnants; Aravallis, Eastern Ghats, Parasnath.
• ☐Plateau: flat-topped tableland; intermont (Tibet, Bolivia); volcanic (Deccan Traps, Columbia).
• ☐Plains: structural (uplift: Great Plains, Russian Platform); depositional (Indo-Gangetic, Mississippi, deltas, loess, glacial, lacustrine).

Landforms of the Earth: frequently asked questions