Landforms and their Evolution, Class 11 Geography: Running Water and Wind

What Landforms and their Evolution is about

Weightage: This chapter is part of Unit III, Landforms, of Fundamentals of Physical Geography, which carries 6 of the 70 theory marks in the school annual exam together with Geomorphic Processes. Map work carries a further 5 marks for each book.Source: CBSE Geography (029) syllabus 2026-27, Class XI course structure

Key concepts

Landforms, landscapes and evolution

NCERT section Landforms and their Evolution (introduction)

• Landform: small to medium tract of the earth's surface, with its own shape, size and materials, produced by certain processes and agents.
• Landscape: a large tract made of several related landforms.
• Most processes are slow, so landforms take a long time to shape. Every landform has a beginning, and once formed it changes slowly or fast as processes continue.
• Changes in climate and vertical or horizontal movements of landmasses can change the intensity of processes or the processes themselves, modifying landforms.
• Evolution = stages of transformation, either of a part of the surface from one landform into another, or of an individual landform after it forms. Every landform has a history of development.
• A landmass passes through stages comparable to life: youth, mature, old.

Two aspects of evolution (the chapter's question): transformation of one landform into another, and change in an individual landform over time.

Worked example

Distinguish between a landform and a landscape with an example of each. (2 marks)

Try it first, then show the solutionSolution

1. A landform is a small to medium part of the surface with its own shape, e.g. a natural levee or an alluvial fan.
2. A landscape is a large tract made of several related landforms, e.g. a river floodplain with levees, point bars, meanders and oxbow lakes together.

Answer: Landform: one feature (levee); landscape: a set of related features (a floodplain).

Work of running water and the stages of a river landscape

NCERT section Running Water

Two components: overland flow (sheet over the general surface) and linear flow (streams and rivers in valleys).

Erosion and deposition with slope: most erosional landforms belong to vigorous, youthful rivers on steep gradients. Continued erosion makes channels gentler; velocity falls and deposition increases: the gentler the channel, the greater the deposition. As beds become gentle, down-cutting weakens and lateral erosion of banks increases, reducing hills and valleys to plains.

From sheet flow to valleys: sheet flow causes sheet erosion; flow concentrates along irregularities, friction removes material, forming rills → gullies → network of valleys.

Peneplain: early stages: down-cutting removes waterfalls and cascades; middle stages: slower down-cutting, severe lateral erosion; valley sides and divides are lowered until almost flat. What remains is a lowland of faint relief with low resistant remnants (monadnocks): a peneplain ('almost plain').

	Youth	Mature	Old
Streams	Few, poorly integrated, on original slopes	Plenty, well integrated	Few small tributaries, gentle gradients
Valleys	Shallow V-shaped; no or very narrow floodplains	V-shaped but deep; wider floodplains with meanders confined in the valley	Vast floodplains; free meanders, natural levees, oxbow lakes
Divides	Broad, flat, with marshes, swamps, lakes; meanders may form and later entrench	Sharp; youthful marshes disappear	Broad, flat, with lakes, swamps, marshes
Waterfalls/rapids	May exist where hard rock is exposed	Disappear	None
Level	-	-	Most land at or slightly above sea level

Worked example

In which stage of a river landscape does downward cutting dominate, and what features show it? (2 marks)

Try it first, then show the solutionSolution

1. Down-cutting dominates in the youth (early) stage, when streams flow over steep original slopes.
2. It produces shallow but sharp V-shaped valleys with little or no floodplain, and waterfalls and rapids where hard rock is exposed.

Answer: Youth stage: V-shaped valleys, no floodplains, waterfalls and rapids.

Erosional landforms of running water

NCERT section Erosional Landforms

Valleys: start as rills, grow into gullies, which deepen, widen and lengthen into valleys. Types depend on dimensions and shape and on rock type and structure:

	Gorge	Canyon
Sides	Very steep to straight	Steep, step-like
Width	About equal at top and bottom	Wider at top than bottom
Rock	Hard rocks	Horizontally bedded sedimentary rocks
NCERT example	Kaveri near Hogenakkal (Dharmapuri, Tamil Nadu)	Colorado river, USA

A canyon is a variant of a gorge.

Potholes: more or less circular depressions on rocky beds of hill streams, formed by stream erosion aided by abrasion; pebbles and boulders collect in a shallow hollow and are rotated by the water, enlarging it; a series of potholes joins and deepens the valley.
Plunge pools: large, deep potholes at the foot of waterfalls, formed by the sheer impact of water and rotation of boulders.

Incised (entrenched) meanders: normally, fast streams on steep gradients erode mostly downwards, and meanders form on gentle slopes through lateral erosion (floodplains, delta plains). But very deep and wide meanders cut into hard rock are incised or entrenched meanders. (They indicate meanders that began on a gentle surface and were later cut down into the rock.)

River terraces: surfaces marking old valley-floor or floodplain levels; may be bare bedrock or alluvial (stream deposits). Basically products of erosion: the stream cuts vertically into its own floodplain. Several terraces at different heights mark former bed levels; terraces at the same elevation on both sides are paired terraces.

Worked example

A valley has steep, step-like sides and is much wider at the top than at the bottom; it is cut in flat-lying sedimentary rock. Name it and give the NCERT example. (2 marks)

Try it first, then show the solutionSolution

1. Steep step-like sides and a top wider than the bottom describe a canyon (a variant of a gorge).
2. Canyons form in horizontally bedded sedimentary rocks; NCERT shows the Colorado river, USA.

Answer: A canyon, e.g. the Colorado river valley.

Depositional landforms of running water

NCERT section Depositional Landforms

Alluvial fans: form where streams from higher levels break onto foot-slope plains of low gradient; the very coarse load is too heavy for the gentler gradient and is dumped as a broad, low-to-high cone. Streams on fans shift and form many channels called distributaries. Humid areas: low cones, gentle slope from head to toe. Arid/semi-arid: high cones, steep slopes. (NCERT photo: on the way to Amarnath, Jammu and Kashmir.)

Deltas: like fans but formed where rivers dump load into the sea; if not carried away or spread along the coast, it builds a low cone. Unlike fans, delta deposits are very well sorted with clear stratification: coarsest first, finer silt and clay carried seaward. As the delta grows, distributaries lengthen and it builds out into the sea (Krishna delta, Andhra Pradesh).

Floodplains: the major depositional landform (deposition makes floodplains as erosion makes valleys). Large material settles first where the channel meets a gentle slope; fine sand, silt and clay are carried by slow water in plains and laid on the bed and, during floods, above the banks.

• Active floodplain: river bed made of river deposits.
• Inactive floodplain: above the banks; has channel deposits (coarse, in abandoned or cut-off channels) and flood deposits (finer silt and clay from spilled water).
• In a delta, floodplains are delta plains.

Natural levees: low, linear, parallel ridges of coarse deposits along the banks of large rivers, often cut into mounds.
Point bars (meander bars): on the concave side of meanders of large rivers; sediments laid in a linear fashion along the bank; almost uniform in profile and width, mixed sizes.

Meanders: loop-like channel patterns on flood and delta plains. A meander is not a landform but a channel pattern, because of: (i) the tendency of water on very gentle gradients to work laterally; (ii) unconsolidated alluvial banks with irregularities; (iii) Coriolis force deflecting the water. Small bank irregularities grow into curves by deposition on the inside and erosion on the outside. In large rivers: deposition on the convex bank (long, gentle slip-off profile) and undercutting on the concave bank (steep scarp, the cut-off bank). Deep loops may be cut off at the inflection points, leaving oxbow lakes (Burhi Gandak near Muzaffarpur, Bihar).

Worked example

How do natural levees differ from point bars? (2 marks)

Try it first, then show the solutionSolution

1. Natural levees are low, linear ridges of coarse deposits running parallel along the banks of large rivers, often broken into mounds.
2. Point bars (meander bars) are linear deposits of mixed sizes along the bank on meander curves (NCERT: the concave side of meanders), almost uniform in profile and width.

Answer: Levees: coarse ridges along the banks; point bars: mixed-size deposits laid along meander curves.

Work of wind in deserts

NCERT section Winds

Why wind is strong in hot deserts: dry, barren floors heat up too much and too quickly; the air above is heated and rises with turbulence; obstructions create eddies, whirlwinds, updrafts and downdrafts; winds also sweep the floors at great speed. Storm winds are very destructive.

Three actions of wind:

• Deflation: lifting and removal of dust and small particles from rock surfaces.
• Abrasion: sand and silt carried by wind act as tools that wear the surface.
• Impact: sheer force of momentum when sand is blown against rock; like sand-blasting.

Wind is not the only agent: many desert features owe their origin to mass wasting and running water as sheet floods. Rain is scarce but torrential for short periods; bare rocks decay fast through mechanical and chemical weathering under drastic diurnal temperature changes; torrential rain removes the debris. So wind moves fine material, while general mass erosion is mainly by sheet floods (sheet wash). Desert stream channels are broad, smooth, indefinite and flow briefly after rain.

Worked example

Is wind the only agent shaping desert landforms? Explain. (2 marks)

Try it first, then show the solutionSolution

1. No: rain in deserts is rare but torrential; sheet floods remove weathered debris and do most of the mass erosion.
2. Wind moves the fine material by deflation, abrasion and impact; mass wasting also contributes.

Answer: No; sheet floods and mass wasting do much of the work, wind moves the fine material.

Erosional landforms of deserts

NCERT section Winds

Pediments and pediplains:

• Landscape evolution in deserts is mainly the formation and extension of pediments.
• Pediment: gently inclined rocky floor at the foot of mountains, with or without a thin debris cover, formed by lateral erosion of streams and sheet flooding of the mountain front.
• Erosion starts along steep margins; once a pediment forms with a steep wash slope and a free face (cliff) above it, both retreat backwards: parallel retreat of slopes through backwasting.
• Pediments extend at the expense of the mountain front until only a remnant, an inselberg, is left.
• High relief is reduced to low featureless plains: pediplains.

Playas: in basins ringed by mountains, drainage goes to the centre, and deposition from the margins builds a nearly level plain. With enough water it becomes a shallow lake, a playa, which holds water only briefly because of evaporation and often has thick salt deposits. A salt-covered playa plain is an alkali flat.

Deflation hollows and caves: persistent one-directional winds blow away weathered mantle or bare soil, creating shallow deflation hollows and small pits on rock surfaces. Impact and abrasion of wind-borne sand create shallow blow-outs, some of which deepen and widen into caves.

Mushroom, table and pedestal rocks: outcrops susceptible to deflation and abrasion wear quickly, leaving resistant remnants polished into a mushroom (slender stalk, broad rounded pear-shaped cap), a table (broad flat top) or pedestals.

Worked example

What is an inselberg, and how does it form? (2 marks)

Try it first, then show the solutionSolution

1. Pediments spread backwards as the wash slope and free face retreat in parallel (backwasting), eating into the mountain front.
2. Eventually only an isolated remnant of the mountain is left standing above the pediplain: an inselberg.

Answer: A residual hill left when parallel slope retreat has consumed most of a desert mountain.

Depositional landforms of wind: sand dunes

NCERT section Winds

Wind as a sorting agent: grains move by rolling or saltation along the floor or in suspension; they are sorted during transport. As wind slows, grains settle according to size and critical velocity, so wind deposits are well sorted. With a good sand source and constant wind directions, such features can form anywhere in arid regions.

Sand dunes need dry hot deserts and obstacles to start forming (Figure 6.14).

Dune	Conditions	Shape
Barchan	Constant, moderate wind; nearly uniform surface	Crescent; points/wings directed downwind
Parabolic	Sandy surface partly covered with vegetation	Reversed barchan (same wind direction)
Seif	A shift in wind conditions	Like a barchan but with only one wing, which can grow very long and high
Longitudinal	Poor sand supply, constant wind	Long ridges of great length, low height
Transverse	Constant wind; sand source an elongated feature at right angles to the wind	Aligned perpendicular to wind; very long, low

With plenty of sand, regular dunes coalesce and lose their shapes. Most desert dunes shift; a few get stabilised, especially near human settlements.

Worked example

A crescent dune has its wings pointing away from the wind. If the same area's sand is partly covered by grass, what dune would you expect instead? (2 marks)

Try it first, then show the solutionSolution

1. A crescent dune with wings pointing downwind is a barchan, formed under constant, moderate wind on a uniform surface.
2. Where vegetation partly covers the sand, parabolic dunes form: reversed barchans with the same wind direction.

Answer: Barchan; with partial vegetation, a parabolic dune.

Landforms and their Evolution 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

• Landforms of Running Water: Valleys, Meanders, Fans, Deltas and Floodplains
• Wind Action and Desert Landforms: Pediments, Playas and Sand Dunes

Landforms and their Evolution: key facts

Valley development

1. 1.Sheet flow
2. 2.rills
3. 3.gullies
4. 4.valleys
5. 5.(lateral erosion)
6. 6.peneplain with monadnocks

Down-cutting early, lateral erosion later.

Gradient rule

1. 1.Steeper gradient
2. 2.more down-cutting; gentler gradient
3. 3.more lateral erosion and deposition

'The gentler the channel, the greater the deposition.'

Gorge vs canyon

Gorge: equal width, hard rock | Canyon: wider top, step-like sides, horizontal sedimentary rock

Canyon is a variant of a gorge.

Fan vs delta

Fan: foot of mountains, coarse, poorly sorted | Delta: at the sea, well sorted, stratified

Both have distributaries.

Meander banks

$Concavebank=undercut,steep(cut-offbank)|Convexbank=deposition,gentle(slip-off)$

Point bars on the concave side of meanders (as NCERT words it); oxbow lakes from cut-offs.

Why meanders

Lateral work on gentle gradients + unconsolidated banks + Coriolis force

A meander is a channel pattern, not a landform.

Wind actions

Deflation (lift) + abrasion (sand as tools) + impact (sand-blasting)

Sheet floods do most mass erosion in deserts.

Desert erosion sequence

1. 1.Pediment
2. 2.parallel retreat (backwasting)
3. 3.inselberg
4. 4.pediplain

Playa → alkali flat when salt-covered.

Dune types

Barchan	crescent, wings downwind
parabolic	vegetation
seif	one wing
longitudinal	poor sand
transverse	perpendicular

Wind deposits are well sorted.

Landforms and their Evolution: diagrams to practise

Practise each one on paper: draw it from the checklist, then tick off every label.

How the school exam asks Landforms and their Evolution

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

Tricks to remember Landforms and their Evolution

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

• Valley birth

  'Rain Ripples Grow Valleys': Rills → Gullies → Valleys.

  Use it when: Valley formation.

• Stages

  'Youth Falls, Mature Sharpens, Old Wanders': waterfalls in youth, sharp divides in maturity, free meanders in old age.

  Use it when: Stages of landscape.

• Meander banks

  'Cave in on the conCAVE side': undercutting on the concave bank; convex bank grows.

  Use it when: Meander diagrams.

• Wind actions

  'DAI': Deflation, Abrasion, Impact.

  Use it when: How wind works.

• Dunes

  'Big Planes Shift Long Trains': Barchan, Parabolic, Seif, Longitudinal, Transverse.

  Use it when: Listing dune types.

Landforms and their Evolution: 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 E style)

Read the situation, then answer every part. In a school exam set on the board pattern this is a 4-mark question split into 1 + 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 Landforms and their Evolution

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

• ✗Mistake: Swapping gorge and canyon

  Both are deep valleys.

  Wrong working

  A gorge has step-like sides and is wider at the top.

  Right working

  A canyon has step-like sides and is wider at the top; a gorge has straight sides and nearly equal width.

  ✓Do this: Canyon = Colorado = steps.

  Usually costs: 1 mark per MCQ.

• ✗Mistake: Calling a meander a landform

  It looks like a feature.

  Wrong working

  A meander is a depositional landform.

  Right working

  A meander is a channel pattern; point bars and oxbow lakes are the landforms associated with it.

  ✓Do this: Meander = pattern.

  Usually costs: 1 mark.

• ✗Mistake: Drawing barchan horns upwind

  Confusing barchans with parabolic dunes.

  Wrong working

  Barchan wings point towards the wind.

  Right working

  Barchan wings point downwind; parabolic dunes are the reverse.

  ✓Do this: Barchan horns run away from the wind.

  Usually costs: 1-2 marks in a diagram.

• ✗Mistake: Writing that wind alone shapes deserts

  The 'deserts = wind' shortcut.

  Wrong working

  All desert landforms are made by wind.

  Right working

  Mass erosion in deserts is mainly by sheet floods; pediments are cut by lateral stream erosion and sheet flooding; wind moves fine material.

  ✓Do this: Deserts: water does the heavy lifting.

  Usually costs: 1-2 marks in a 3-5 mark answer.

• ✗Mistake: Answering glacier or coastal landforms

  They are printed in the same NCERT chapter.

  Wrong working

  Long answer on cirques and sea stacks.

  Right working

  The 2026-27 CBSE content names only running water and wind for this chapter.

  ✓Do this: Prepare rivers and deserts thoroughly.

  Usually costs: Time lost on unassessed content.

NCERT exercise guide: Landforms and their Evolution

What each exercise in the NCERT chapter tests, how to approach it, and a question of the same kind solved step by step. Questions here are written in our own words.

Practice questions on Landforms and their Evolution

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

   A river basin has few, poorly connected streams, shallow V-shaped valleys with hardly any floodplain, and broad flat divides with marshes and lakes. Which stage of landscape development does it show?
   (a) Youth
   (b) Mature
   (c) Old
   (d) Peneplain

   Hint

   Few streams, original slopes, marshy divides.

   Answer

   (a) Youth.

2. Q2 · 1 mark · MCQExam level

   A seif differs from a barchan because it:
   (a) forms only with vegetation
   (b) has only one wing
   (c) is perpendicular to the wind
   (d) forms with poor sand supply

   Hint

   A shift in wind conditions.

   Answer

   (b) Has only one wing.

3. Q3 · 1 mark · Assertion-reasonHarder exam level

   Assertion (A): A meander is not a landform.
   Reason (R): A meander is only a channel pattern caused by lateral work of water, unconsolidated banks and Coriolis force.
   Choose (a)-(d).

   Hint

   NCERT's own reasoning.

   Answer

   (a). Both true; R explains A.

4. Q4 · 2 marks · Short answerHarder exam level

   Why are river terraces called products of erosion even when they are made of alluvium? (2 marks)

   Hint

   What creates the step?

   Answer

   Terraces form when a river cuts vertically into its own depositional floodplain, leaving the old floor standing as a step. The step is created by erosion, even if the surface is made of earlier deposits.

5. Q5 · 2 marks · Short answerExam level

   Compare alluvial fans in humid and arid climates. (2 marks)

   Hint

   Cone height and slope.

   Answer

   Humid areas: low cones with a gentle slope from head to toe. Arid and semi-arid areas: high cones with steep slopes.

6. Q6 · 3 marks · Short answerHarder exam level

   Distinguish between active and inactive floodplains and the two kinds of deposits in the inactive floodplain. (3 marks)

   Hint

   Bed versus above the banks.

   Answer

   Active floodplain: the river bed made of river deposits. Inactive floodplain: above the banks. It has channel deposits (coarse, in abandoned or cut-off channels) and flood deposits (finer silt and clay from spilled flood water).

7. Q7 · 3 marks · Short answerHOTS / competency

   Suppose a farmer's field lies on the outer (concave) bank of a river bend, and his neighbour's on the inner (convex) bank. Over twenty years, how will each field change, and why? (3 marks)

   Hint

   Undercut versus slip-off bank.

   Answer

   The outer (concave) bank is undercut by erosion, so the first field will lose land as the bank retreats as a steep scarp. The inner (convex) bank receives deposition, so the neighbour's land grows with a gentle slip-off slope. Over time the bend deepens and could be cut off as an oxbow lake.

8. Q8 · 5 marks · Long answerHarder exam level

   Describe the erosional landforms produced in deserts. (5 marks)

   Hint

   Pediments, pediplains, playas, deflation hollows, caves, mushroom rocks.

   Answer

   Pediments: rocky floors at the mountain foot from lateral stream erosion and sheet floods; extended by parallel retreat to leave inselbergs and pediplains. Playas: shallow temporary lakes in basin centres; alkali flats when salt-covered. Deflation hollows: depressions from persistent one-way winds. Blow-outs and caves: from impact and abrasion. Mushroom, table and pedestal rocks: resistant remnants polished by deflation and abrasion.

9. Q9 · 2 marks · Short answerHOTS / competency

   Why would potholes be rare on a gentle, sandy lowland river? (2 marks)

   Hint

   Where do potholes form?

   Answer

   Potholes form on rocky beds of hill streams where fast water rotates pebbles and boulders in hollows (abrasion). A gentle lowland river on sand has no rocky bed, slow water and fine load, so it deposits rather than drills.

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.What is a peneplain?Show answer

   An almost plain left by long stream erosion, with resistant remnants called monadnocks.

2. 2.Where do plunge pools form?Show answer

   At the base of waterfalls.

3. 3.What are paired terraces?Show answer

   River terraces at the same elevation on both sides of a river.

4. 4.What is the steep outer bank of a meander called?Show answer

   The cut-off (undercut) bank.

5. 5.Name the three actions of wind.Show answer

   Deflation, abrasion and impact.

6. 6.What is an alkali flat?Show answer

   A playa plain covered with salts.

7. 7.Which dune forms where sand is partly covered by vegetation?Show answer

   Parabolic dune.

8. 8.What is parallel retreat of slopes called?Show answer

   Backwasting.

Quick revision checklist

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

• ☐Landform = small/medium tract; landscape = related landforms; evolution = stages of change.
• ☐Running water: sheet flow and stream flow; most important agent in humid areas.
• ☐Rills → gullies → valleys; down-cutting early, lateral erosion later → peneplain with monadnocks.
• ☐Youth: few streams, V valleys, waterfalls. Mature: many streams, sharp divides. Old: free meanders, oxbow lakes.
• ☐Gorge: hard rock, straight sides. Canyon: sedimentary rock, step-like sides, wider top.
• ☐Potholes on rocky hill-stream beds; plunge pools below waterfalls; terraces from down-cutting into old floodplains.
• ☐Fans (coarse, unsorted, at hill foot) vs deltas (sorted, stratified, at the sea).
• ☐Levees: coarse ridges along banks; point bars on meander curves; meander = channel pattern.
• ☐Wind: deflation, abrasion, impact; sheet floods do most mass erosion in deserts.
• ☐Pediment → backwasting → inselberg → pediplain; playa, alkali flat; mushroom rocks; dunes: barchan, parabolic, seif, longitudinal, transverse.

Landforms and their Evolution: frequently asked questions