Skip to content

Geological Divisions, Himalayas, Northern Plains Class 11

questionbuddy.in/cbse/class-11/geography/structure-and-physiography/geological-divisions-northern-mountains-and-northern-plains

GeographyCBSE Class 11 · Structure and Physiography

Geological Divisions, the Northern Mountains and the Northern Plains of India (Class 11 Geography, India: Physical Environment, Chapter 2)

Updated 17 October 2026 · Fact-checked

India has three geological divisions: the ancient rigid Peninsular Block, the young and flexible Himalayas and other Peninsular mountains, and the Indo-Ganga-Brahmaputra plain, a geosynclinal depression filled with 1,000 to 2,000 m of alluvium. Physiography has six divisions; the northern mountains form a 2,500 km wall and the Northern Plains (3,200 km) have bhabar, tarai, bhangar and khadar zones.

Read left to right: young folded mountains, then the alluvial plain in four zones, then the old rigid Peninsular Block.

Illustration drawn for QuestionBuddy.

Understand Geological Divisions of India, the Northern and North-eastern Mountains and the Northern Plains

Why this topic matters. The comparison of the three geological divisions, the zones of the plain and the features of the northern mountains are repeated Board items and map work.

1. Peninsular Block. Very ancient gneisses and granites, a rigid block since the Cambrian period. Its northern boundary runs from Kachchh along the western flank of the Aravalis near Delhi, roughly parallel to the Yamuna and Ganga to the Rajmahal hills and the Ganga delta, with extensions in Karbi Anglong and the Meghalaya plateau (separated by the Malda fault) and under Rajasthan's desert. Relict and residual mountains (Aravali), rift valleys of the Narmada, Tapi and Mahanadi, block mountains such as the Satpura, shallow valleys with low gradients and deltas on the east coast.

2. Himalayas and other Peninsular mountains. Young, weak and flexible, tectonic, still affected by faults, folds and thrusts, with youthful rivers forming gorges, V-shaped valleys, rapids and waterfalls.

3. Indo-Ganga-Brahmaputra plain. A geosynclinal depression that reached its maximum development in the third phase of Himalayan formation, about 64 million years ago, filled by Himalayan and Peninsular rivers with alluvium 1,000 to 2,000 m deep.

4. Physiography. The outcome of structure, process and stage of development. Six divisions: Northern and North-eastern Mountains, Northern Plain, Peninsular Plateau, Indian Desert, Coastal Plains and Islands.

5. Northern and North-eastern Mountains. A series of parallel ranges, the Greater Himalayan range and the Shiwalik among them. Ranges run north-west to south-east in north-western India, east-west in Darjiling and Sikkim, and north-south in Nagaland, Manipur and Mizoram. The central axial range is about 2,500 km long and 160 to 400 km wide. It is a wall between the subcontinent and Central and East Asia, and a physical, climatic, drainage and cultural divide. Peaks: K2, Kanchenjunga, Nanda Devi, Nanga Parbat, Namcha Barwa. Passes: Shipki La, Nathu La.

6. Northern Plains. Alluvial deposits of the Indus, Ganga and Brahmaputra; about 3,200 km long, 150 to 300 km wide, at 50 to 150 m above sea level. Zones from north to south: Bhabar (8 to 10 km, along the Shiwalik foothills, where streams drop boulders and sink), Tarai (10 to 20 km, where streams re-emerge to form marshy land), Bhangar (old alluvium) and Khadar (new alluvium). Mature landforms: sand bars, meanders, oxbow lakes and braided channels. Haryana and Delhi form the water divide between the Indus and Ganga systems. The plain supports wheat, rice, sugarcane, jute and a large population.

Geological Divisions of India, the Northern and North-eastern Mountains and the Northern Plains: key facts

Geological divisions
Peninsular Blockgneisses and granites, rigid since Cambrian
Himalayasyoung, weak, flexible
Indo-Ganga-Brahmaputra plainalluvium 1,000 to 2,000 m, about 64 million years ago depression
Three divisions.
Six physiographic divisions
  • Northern and North-eastern Mountains
  • Northern Plain
  • Peninsular Plateau
  • Indian Desert
  • Coastal Plains
  • Islands
Structure + process + stage.
Northern Plains
  • Length about 3,200 km
  • Width 150 to 300 km
  • Bhabar 8 to 10 km
  • Tarai 10 to 20 km
  • Bhangar old, Khadar new
Zones north to south.
Himalayan axis
  • Central axial range about 2,500 km long
  • 160 to 400 km wide
  • Wall and physical, climatic, drainage, cultural divide
Northern Mountains.

How to answer Geological Divisions of India, the Northern and North-eastern Mountains and the Northern Plains questions

A zone comparison answer is best given as a table with width, position and feature.

  1. 1List the zones in the order north to south.
  2. 2Give width and the feature that identifies each zone.
  3. 3Explain the process (break of slope, re-emergence of streams).
  4. 4End with the importance of the plain for agriculture and population.

Geological Divisions of India, the Northern and North-eastern Mountains and the Northern Plains in real life

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

Disappearing stream

Suppose a stream coming from the foothills carries heavy gravel and seems to vanish into the ground, and reappears 10 km further south in a marshy patch.

Which two zones are involved?

Try it first, then show the solutionSolution
  1. Streams sink in the bhabar along the foothills.
  2. They re-emerge in the tarai, making the land marshy.

Answer: Bhabar then tarai.

Memory hook: Sink then spring.

Old and new soil

Suppose a farmer notes that the higher, older soil above the floods differs from the fresh silt near the river that gets renewed every flood.

Which two kinds of alluvium are these?

Try it first, then show the solutionSolution
  1. Old alluvium is bhangar.
  2. New alluvium is khadar.

Answer: Bhangar (old) and khadar (new).

Memory hook: B for before, K for kal (new).

Tricks to remember Geological Divisions of India, the Northern and North-eastern Mountains and the Northern Plains

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

  • B-T-B-K

    Bhabar, Tarai, Bhangar, Khadar from north to south

    Use it when: Order of zones.

  • 64 million

    Third phase of Himalayan formation filled the plain

    Use it when: Depression.

  • 3,200 and 2,500

    Plain 3,200 km, Himalaya 2,500 km

    Use it when: Lengths.

Geological Divisions of India, the Northern and North-eastern Mountains and the Northern Plains: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Bhabar · 1 mark · MCQBoard level

Streams disappear along the foothills of the Shiwalik in a zone called:
(A) tarai
(B) khadar
(C) bhabar
(D) bhangar

Try it first, then show the solutionSolution
  1. Streams drop boulders and sink in the bhabar (1 mark).

Answer: (C)

Example 2: Himalayan significance · 2 marks · Very short answerBoard level

State two ways in which the Himalayas are more than a physical barrier. (2 marks)

Try it first, then show the solutionSolution
  1. Climatic divide (1 mark).
  2. Drainage and cultural divide (1 mark).

Answer: The Himalayas are also a climatic divide, a drainage divide and a cultural divide between the subcontinent and Central and East Asia.

Example 3: Peninsular Block versus Himalayas · 3 marks · Short answerHarder board level

Contrast the Peninsular Block with the Himalayas in age, rigidity and rivers. (3 marks)

Try it first, then show the solutionSolution
  1. Peninsular: ancient gneisses and granites, rigid since Cambrian; Himalayas: young, weak and flexible (1 mark).
  2. Peninsular rivers: shallow valleys, low gradients; Himalayan rivers: youthful with gorges, V-shaped valleys, rapids (1 mark).
  3. Peninsular has relict and residual mountains; Himalayas are tectonic and still affected by faults, folds and thrusts (1 mark).

Answer: The Peninsular Block is very ancient, made of gneisses and granites and has been rigid since the Cambrian, whereas the Himalayas are young, weak and flexible. Peninsular rivers flow in shallow valleys with low gradients; Himalayan rivers are youthful with gorges, V-shaped valleys and rapids. Peninsular mountains are relict and residual, while the Himalayas are tectonic and still affected by faults, folds and thrusts.

Example 4: Assertion and reason: plain depression · 1 mark · Assertion-reasonHarder board level

Assertion (A): The Indo-Ganga-Brahmaputra plain is filled with thick alluvium.
Reason (R): It is a geosynclinal depression filled by Himalayan and Peninsular rivers.
(A) Both true, R explains A
(B) Both true, R does not explain A
(C) A true, R false
(D) A false, R true

Try it first, then show the solutionSolution
  1. The depression was filled by river deposits to a depth of 1,000 to 2,000 m (1 mark).

Answer: (A)

Example 5: HOTS: from Shiwalik to the delta · 5 marks · Long answerHOTS / competency

Describe what a traveller would see walking south from the Shiwalik foothills across the Northern Plains to the delta, naming zones, the nature of rivers and one human use, and explain why the plain is densely populated. (5 marks)

Try it first, then show the solutionSolution
  1. Foothills: bhabar of boulders where streams sink (1 mark).
  2. Then the marshy tarai with dense vegetation and wildlife (1 mark).
  3. Then bhangar and khadar alluvium with meanders, oxbow lakes, braided channels (1 mark).
  4. Rivers form large deltas such as the Sunderbans at their mouths (1 mark).
  5. Fertile alluvium supports wheat, rice, sugarcane and jute, hence a large population (1 mark).

Answer: Starting at the Shiwalik foothills the traveller crosses the bhabar, where rivers drop boulders and sink, then the marshy tarai where streams re-emerge. Further south lie the bhangar (old alluvium) and khadar (new alluvium) with mature features such as meanders, oxbow lakes and braided channels, ending in large deltas such as the Sunderbans. The fertile alluvium supports wheat, rice, sugarcane and jute and so a large population.

Where students lose marks in Geological Divisions of India, the Northern and North-eastern Mountains and the Northern Plains

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

  • Mistake: Reversing the order of the plain zones

    Direction confusion.

    Wrong working

    Tarai lies north of bhabar.

    Right working

    Bhabar is nearest the foothills, then tarai, bhangar and khadar south.

    Do this: Remember B-T-B-K.

    Usually costs: 1 mark.

  • Mistake: Calling bhangar new alluvium

    Terms swapped.

    Wrong working

    Bhangar is new alluvium.

    Right working

    Bhangar is old alluvium; khadar is new.

    Do this: Link khadar with flood renewal.

    Usually costs: 1 mark.

  • Mistake: Mixing the length of the plain and the Himalaya

    Both are thousands of km.

    Wrong working

    Himalaya 3,200 km, plain 2,500 km.

    Right working

    Himalaya (central axis) about 2,500 km; plain about 3,200 km.

    Do this: Pair values.

    Usually costs: 1 mark.

Exam tips

  • Use a table for bhabar, tarai, bhangar and khadar.
  • Mention the 64 million years for the depression.
  • On maps mark K2, Kanchenjunga, Nanda Devi, Nanga Parbat and Namcha Barwa.

Practice questions on Geological Divisions of India, the Northern and North-eastern Mountains and the Northern 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 · MCQBoard level

    The Peninsular Block has been rigid since the:
    (A) Cambrian period
    (B) Pleistocene
    (C) Miocene
    (D) Eocene

    Hint

    Very ancient.

    Answer

    (A)

  2. Q2 · 2 marks · Very short answerBoard level

    Name the six physiographic divisions of India. (2 marks)

    Hint

    List.

    Answer

    Northern and North-eastern Mountains, Northern Plain, Peninsular Plateau, Indian Desert, Coastal Plains and Islands.

  3. Q3 · 3 marks · Short answerHarder board level

    Describe the tarai and its importance. (3 marks)

    Hint

    Re-emergence.

    Answer

    The tarai is a 10 to 20 km belt south of the bhabar where streams re-emerge without defined channels and create marshy, swampy land. It has luxuriant vegetation and a variety of wildlife.

  4. Q4 · 3 marks · Short answerHarder board level

    Explain the direction of the Himalayan ranges in different parts of India. (3 marks)

    Hint

    Four regions.

    Answer

    In north-western India the ranges run north-west to south-east, in Darjiling and Sikkim east-west, in Arunachal Pradesh south-west to north-east, and in Nagaland, Manipur and Mizoram north-south.

  5. Q5 · 4 marks · Short answerHOTS / competency

    The Meghalaya plateau, though part of the Peninsular Block, lies far from the main plateau. Explain with the role of the Malda fault and the plain. (4 marks)

    Hint

    Fault.

    Answer

    The Peninsular Block has extensions in Karbi Anglong and the Meghalaya plateau, separated from the Chotanagpur plateau by the Malda fault. The gap was filled by river deposits of the plain, so the Meghalaya plateau appears detached though it is geologically part of the block.

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.Width of bhabar?Show answer

    8 to 10 km.

  2. 2.Which fault separates Meghalaya from Chotanagpur?Show answer

    The Malda fault.

  3. 3.Which two passes are in map work?Show answer

    Shipki La and Nathu La.

  4. 4.What divides the Indus and Ganga systems?Show answer

    Haryana and Delhi.

Geological Divisions of India, the Northern and North-eastern Mountains and the Northern Plains: frequently asked questions

Is physiography the same as geology?

No; physiography results from structure, process and stage of development.

Where does the Brahmaputra turn south?

About 90 degrees south at Dhubri into Bangladesh.

What is a geosynclinal depression?

A long trough that fills with sediments; the plain filled with alluvium.