Mountains, Plateaus and Plains: Types by Origin, Situation and Formation, ISC Class 11

What Mountains, Plateaus and Plains is about

Weightage: CISCE gives no Class XI unit weightage for ISC Geography. Mountains, Plateaus and Plains is topic 5 of the Class XI syllabus (Changing Face of the Earth) and can be asked anywhere in the 70-mark Paper I (Theory, 3 hours). Class XI is examined by the school, so your school sets the paper and decides how many marks each topic carries.Source: CISCE ISC Geography (853) syllabus, examination year 2028, Class XI

Key concepts

Fold mountains

Formation: horizontal compressional forces, often where plates converge, squeeze thick layers of sediment deposited in long troughs (geosynclines) into folds; the layers are uplifted, folded, overturned and thrust into ranges.

Features
1. Long, high, often parallel ranges with steep slopes and sharp peaks (young fold mountains).
2. Made mainly of folded sedimentary rocks, often containing marine fossils.
3. Associated with earthquakes and, where oceanic plates subduct, volcanoes.

Types

• Young fold mountains: formed in the last major mountain-building period (the Alpine orogeny, within the last tens of millions of years): Himalayas, Alps, Andes, Rockies, Atlas. They are high and rugged.
• Old fold mountains: formed in earlier periods and much worn down: Aravallis (among the oldest), Appalachians, Urals. They are lower and rounded.

Importance: sources of rivers, forests, minerals, hydroelectric power; climatic barriers (the Himalayas block cold winds and cause monsoon rain).

Worked example

[4] Explain the formation and features of young fold mountains, with examples. (Understanding)

Try it first, then show the solutionSolution

1. Horizontal compression at convergent plate boundaries folds sediments - 1 mark.
2. Thick sediments from troughs uplifted, folded, thrust - 1 mark.
3. Features: high, rugged, sharp peaks; sedimentary rocks with marine fossils; earthquakes - 1 mark.
4. Examples: Himalayas, Alps, Andes, Rockies - 1 mark.

Answer: Young fold mountains form where plates converge and horizontal compression squeezes thick sediments from long ocean troughs, folding, uplifting and thrusting them into ranges. They are high and rugged with sharp peaks, are made largely of folded sedimentary rocks containing marine fossils, and are prone to earthquakes. Examples are the Himalayas, Alps, Andes and Rockies.

Block, volcanic and residual mountains

Block mountains

• Formed by faulting, usually under tension: a block of land is raised between faults (horst) or left standing when the land on either side sinks.
• Features: steep sides along fault scarps, flat or gently sloping tops.
• Examples: the Vosges (France) and Black Forest (Germany) on either side of the Rhine rift valley; the Sierra Nevada (USA); the Salt Range (Pakistan).

Volcanic mountains

• Built by the accumulation of lava, ash and other material ejected from vents.
• Features: conical shape, often with a crater at the summit; may be active, dormant or extinct.
• Examples: Fujiyama (Japan), Kilimanjaro (Tanzania), Vesuvius (Italy), Mauna Loa (Hawaii), Cotopaxi (Ecuador).

Residual (relict) mountains

• Remnants of older highlands or plateaus that have been worn down by long erosion; harder rocks survive as hills and ridges.
• Features: low, rounded summits; often made of hard, ancient rocks.
• Examples: the Aravallis and the Eastern Ghats in India.

Worked example

[4] Distinguish between block mountains and volcanic mountains with examples. (Analysis)

Try it first, then show the solutionSolution

1. Block: faulting under tension; volcanic: accumulation of erupted material - 1 mark.
2. Block: steep fault scarps, flat tops; volcanic: conical with crater - 1 mark.
3. Block examples: Vosges, Black Forest, Sierra Nevada - 1 mark.
4. Volcanic examples: Fujiyama, Kilimanjaro, Mauna Loa - 1 mark.

Answer: Block mountains form by faulting, when a block is raised between faults or left standing as the land around it sinks; they have steep scarp sides and flat tops, like the Vosges, the Black Forest and the Sierra Nevada. Volcanic mountains are built up by erupted lava and ash into cones, often with a summit crater, like Fujiyama, Kilimanjaro and Mauna Loa.

Plateaus by situation

A plateau is an extensive upland with a broad, fairly level top and at least one steep side rising above the surrounding land.

1. Intermontane plateaus

• Enclosed wholly or partly by mountain ranges; formed during mountain building when land between ranges was uplifted.
• They are the highest and often largest plateaus.
• Examples: Tibet (the highest and largest), Bolivia (Altiplano), Mexico, Iran, Anatolia.

2. Piedmont plateaus

• Lie at the foot of mountains, bounded on one side by mountains and on the other by a plain or the sea; often formed by erosion or deposition from the nearby mountains.
• Examples: Patagonia (Argentina), the Piedmont plateau of the eastern USA (Appalachians), the Malwa plateau (India).

3. Continental plateaus

• Broad tablelands that rise abruptly from lowlands or the sea, far from mountains; formed by uplift of large areas or by extensive lava flows.
• Examples: the Deccan plateau (India), the Western Australian plateau, the Arabian plateau, the Brazilian plateau, the plateaus of Antarctica and Greenland.

Importance: plateaus are storehouses of minerals (Chotanagpur, Western Australia), have waterfalls with hydroelectric potential, and some have fertile lava soils (Deccan).

Worked example

[4] Classify plateaus by situation, with two examples of each type. (Recall)

Try it first, then show the solutionSolution

1. Intermontane: enclosed by mountains - Tibet, Bolivia - 1 mark.
2. Piedmont: at the foot of mountains - Patagonia, Malwa - 1 mark.
3. Continental: rise from lowlands or sea - Deccan, Western Australia - 1 mark.
4. Correct description of formation for each - 1 mark.

Answer: Intermontane plateaus are enclosed by mountains and were uplifted during mountain building, such as Tibet and Bolivia; piedmont plateaus lie at the foot of mountains between them and a plain or sea, such as Patagonia and Malwa; and continental plateaus are broad tablelands rising from lowlands or the sea, formed by uplift or lava flows, such as the Deccan and the Western Australian plateau.

Depositional plains

Plains are extensive areas of flat or gently undulating low land. Depositional plains are built up by material laid down by rivers, ice, wind or in lakes.

1. Riverine (alluvial) plains: formed by deposition of silt by rivers, especially during floods.

• Flood plains and alluvial plains: Indo-Gangetic plain, Mississippi plain, North China (Hwang Ho) plain.
• Delta plains: at river mouths, e.g., the Ganga-Brahmaputra (Sundarbans) delta, Nile delta.

2. Glacial plains: formed by deposits of ice sheets (till plains) and meltwater (outwash plains), e.g., the North European Plain, parts of the Canadian prairies.
3. Aeolian (loess) plains: formed by deposits of fine wind-blown dust, e.g., the loess plateau and plains of northern China.
4. Lacustrine (lake) plains: formed when lakes filled with sediment dry up, e.g., the Kashmir valley (Karewa deposits), the Red River valley of North America.

For contrast, erosional plains (peneplains) are formed by long erosion of uplands.

Importance: fertile soils, easy farming, transport and settlement make plains the most densely populated regions; the Indo-Gangetic plain is among the world's most populous regions.

Worked example

[4] Explain the types of depositional plains with examples. (Understanding)

Try it first, then show the solutionSolution

1. Riverine: alluvial and delta plains - Indo-Gangetic, Mississippi, Nile delta - 1 mark.
2. Glacial: till and outwash - North European Plain - 1 mark.
3. Aeolian (loess): northern China - 1 mark.
4. Lacustrine: Kashmir valley - 1 mark.

Answer: Riverine plains are built by river silt, as in the alluvial Indo-Gangetic and Mississippi plains and the Nile delta; glacial plains by till and outwash from ice sheets, as in the North European Plain; aeolian loess plains by wind-blown dust, as in northern China; and lacustrine plains by sediments of former lakes, as in the Kashmir valley.

Importance of the three landforms

Mountains

• Sources of rivers and water (glaciers), hydroelectric power, forests, minerals and medicinal plants.
• Climatic barriers and influence on rainfall (orographic rain).
• Tourism and pilgrimage; natural frontiers.
• Limitations: steep slopes, thin soils and harsh climate limit farming and settlement.

Plateaus

• Rich in minerals (iron, coal, manganese, gold); hydroelectric sites at waterfalls; grazing; some fertile volcanic soils.
• Limitations: rugged edges and poor transport in some areas.

Plains

• Fertile alluvial soils, flat land for farming and irrigation, easy construction of roads and railways, dense population and large cities.
• Limitations: floods and, in deltas, cyclones and salinity.

India has all three: the Himalayas, the Peninsular plateau and the Northern Plains, each supporting distinct economies.

Worked example

[4] Explain the economic importance of plateaus, with Indian examples. (Understanding)

Try it first, then show the solutionSolution

1. Storehouses of minerals: Chotanagpur (coal, iron) - 1 mark.
2. Waterfalls and hydroelectric power - 1 mark.
3. Fertile lava soils: Deccan black soil for cotton - 1 mark.
4. Grazing, forests and pleasant climate in some areas - 1 mark.

Answer: Plateaus such as Chotanagpur are storehouses of coal, iron ore and other minerals; their rivers fall steeply over waterfalls that can generate hydroelectric power; the Deccan lava plateau has fertile black soil for cotton; and plateaus also support grazing and forests.

Mountains, Plateaus and Plains 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 by Origin: Fold, Block, Volcanic and Residual
• Plateaus and Depositional Plains

Mountains, Plateaus and Plains: key facts

Mountains by origin

$Fold,block,volcanic,residual$

Himalayas; Vosges; Fuji; Aravallis.

Young and old fold

$Young:Himalayas,Alps,Andes,Rockies;Old:Aravallis,Appalachians,Urals$

Young are high and rugged.

Block mountains

Horst between faults

Vosges, Black Forest, Sierra Nevada.

Plateaus by situation

$Intermontane,piedmont,continental$

Tibet; Patagonia, Malwa; Deccan.

Depositional plains

$Riverine(alluvial,delta),glacial,aeolian(loess),lacustrine$

Indo-Gangetic; North European; N. China; Kashmir.

Erosional plains

$Peneplain$

For contrast only.

How the school exam asks Mountains, Plateaus and Plains

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

Tricks to remember Mountains, Plateaus and Plains

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

• Mountains: 'F-B-V-R'

  Fold, Block, Volcanic, Residual: 'Five Big Volcanic Ranges'.

  Use it when: Four types by origin.

• Plateaus: 'In, At the foot, Alone'

  Intermontane (inside mountains), Piedmont (at the foot), Continental (alone, from lowland or sea).

  Use it when: Plateau types.

• Plains by agent: 'Water, Ice, Wind, Lake'

  Riverine, glacial, aeolian, lacustrine.

  Use it when: Depositional plains.

Mountains, Plateaus and Plains: 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 D 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 3 + 2 + 1 + 2 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 Mountains, Plateaus and Plains

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

• ✗Mistake: Wrong plateau type for Tibet or the Deccan

  The situation-based classes are confused.

  Wrong working

  The Deccan is an intermontane plateau.

  Right working

  Tibet is intermontane; the Deccan is continental.

  ✓Do this: Ask: is it enclosed by mountains, at their foot, or alone?

  Usually costs: 1 mark.

• ✗Mistake: Examples only from India

  The syllabus asks for examples from the world.

  ✓Do this: Give a world example for each type (Alps, Vosges, Fuji, Patagonia).

  Usually costs: 1 mark per type.

• ✗Mistake: Calling block mountains folded

  Process confusion.

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

  Usually costs: 1 mark.

• ✗Mistake: Listing plain types without the agent

  Formation is the basis of classification.

  ✓Do this: Name the agent: river, ice, wind or lake.

  Usually costs: 1 mark.

• ✗Mistake: Treating residual mountains as volcanic

  Old hills may look volcanic.

  ✓Do this: Residual = remnants after long erosion.

  Usually costs: 1 mark.

Practice questions on Mountains, Plateaus and Plains

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 · Very short answerExam level

   What is a residual mountain?

   Hint

   Left after erosion.

   Answer

   A mountain that is the remnant of an older highland worn down by long erosion, such as the Aravallis.

2. Q2 · 1 mark · Very short answerExam level

   Give one example of a piedmont plateau.

   Hint

   Argentina or India.

   Answer

   Patagonia (or Malwa).

3. Q3 · 1 mark · MCQExam level

   Kilimanjaro is an example of a:
   (a) Fold mountain
   (b) Block mountain
   (c) Volcanic mountain
   (d) Residual mountain

   Hint

   Cone with crater.

   Answer

   (c) Volcanic mountain.

4. Q4 · 1 mark · Very short answerHarder exam level

   What type of plain is the Kashmir valley?

   Hint

   Former lake.

   Answer

   A lacustrine (lake) plain.

5. Q5 · 4 marks · Short answerHarder exam level

   [4] Distinguish between young and old fold mountains.

   Hint

   Age, height, shape, examples.

   Answer

   (1) Young fold mountains formed in the recent Alpine period; old ones much earlier. (2) Young are high; old have been lowered by erosion. (3) Young have sharp peaks and steep slopes; old have rounded tops. (4) Young: Himalayas, Alps, Andes; old: Aravallis, Appalachians, Urals.

6. Q6 · 4 marks · Short answerHarder exam level

   [4] Explain the formation of glacial and loess plains.

   Hint

   Till and outwash; wind-blown dust.

   Answer

   (1) Ice sheets deposit unsorted till as they melt, forming till plains. (2) Meltwater spreads sand and gravel as outwash plains; example: the North European Plain. (3) Loess plains form from fine dust carried by wind and deposited far away. (4) Example: northern China, where loess is very thick and fertile.

7. Q7 · 4 marks · Short answerHarder exam level

   [4] Explain the importance of mountains to human beings.

   Hint

   Water, power, forests, climate.

   Answer

   (1) Sources of rivers and glaciers that supply water for irrigation and drinking. (2) Steep rivers provide hydroelectric power. (3) Forests, minerals and medicinal plants. (4) Climatic barriers that cause rain and block cold winds; also tourism and pilgrimage.

8. Q8 · 4 marks · Short answerHOTS / competency

   [4] Why is the Deccan called a continental plateau, while Malwa is often called a piedmont plateau?

   Hint

   Position relative to mountains.

   Answer

   (1) The Deccan is a broad tableland rising from the coastal lowlands and the sea, not enclosed by mountains. (2) It was formed largely by extensive lava flows and uplift of a large area. (3) Malwa lies at the foot of the Aravallis and Vindhyas, between the hills and lower land. (4) Position next to mountains makes it piedmont, while the Deccan's independence from mountains makes it continental.

9. Q9 · 4 marks · Short answerHOTS / competency

   [4] 'Plains are not always gifts; they can also be hazards.' Discuss.

   Hint

   Floods, cyclones, salinity.

   Answer

   (1) Plains offer fertile soil and easy settlement. (2) But river plains flood frequently (Bihar, Assam). (3) Delta plains face cyclones, storm surges and salinity (Sundarbans). (4) Dense population increases the damage, so plains need flood control and planning.

10. Q10 · 7 marks · Long answerHarder exam level

    [7] (a) Explain the formation of fold mountains. [4]
    (b) Explain the types of depositional plains with examples. [3]

    Hint

    (a) four steps; (b) three types.

    Answer

    (a) (1) Sediments accumulate in long troughs (geosynclines). (2) Plates converge, causing horizontal compression. (3) Layers are folded, uplifted, overturned and thrust. (4) Young ranges like the Himalayas and Alps form; erosion later lowers them into old fold mountains like the Aravallis. (b) (1) Riverine: alluvial and delta plains (Indo-Gangetic, Mississippi, Nile delta). (2) Glacial: till and outwash (North European Plain). (3) Aeolian loess (northern China) and lacustrine (Kashmir valley).

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.Name two young fold mountains.Show answer

   Himalayas and Alps (also Andes, Rockies).

2. 2.Name two block mountains on either side of the Rhine.Show answer

   The Vosges and the Black Forest.

3. 3.Which is the highest plateau in the world?Show answer

   The Tibetan plateau.

4. 4.Which plain is formed by wind-blown dust?Show answer

   A loess plain (northern China).

5. 5.Give an example of a delta plain.Show answer

   The Ganga-Brahmaputra delta (or the Nile delta).

6. 6.Which Indian range is among the oldest fold mountains?Show answer

   The Aravallis.

Quick revision checklist

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

• ☐Fold: compression; young (Himalayas, Alps, Andes, Rockies), old (Aravallis, Appalachians, Urals).
• ☐Block: faulting; Vosges, Black Forest, Sierra Nevada.
• ☐Volcanic: Fuji, Kilimanjaro, Vesuvius, Mauna Loa; residual: Aravallis, Eastern Ghats.
• ☐Plateaus: intermontane (Tibet, Bolivia), piedmont (Patagonia, Malwa), continental (Deccan, Western Australia, Arabia).
• ☐Depositional plains: riverine (Indo-Gangetic, Mississippi, deltas), glacial (North European), loess (N. China), lacustrine (Kashmir).
• ☐Importance: mountains (water, power), plateaus (minerals), plains (farming, population).

Mountains, Plateaus and Plains: frequently asked questions