Geomorphic Processes, Class 11 Geography: Weathering, Mass Movements and Soil

What Geomorphic Processes 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 Landforms and their Evolution. Map work carries a further 5 marks for each book.Source: CBSE Geography (029) syllabus 2026-27, Class XI course structure

Key concepts

Endogenic and exogenic forces; geomorphic processes and agents

NCERT section Geomorphic Processes

	Endogenic	Exogenic
Origin	Inside the earth	Earth's atmosphere
Energy	Radioactivity, rotational and tidal friction, primordial heat (via geothermal gradients and heat flow)	Sun (atmosphere) + gradients created by tectonic factors
Role	Land-building	Land-wearing (degradation and aggradation)
Processes	Diastrophism, volcanism	Weathering, mass wasting, erosion, deposition

Gradation: wearing down of relief through erosion.

Geomorphic process: a force applied on earth materials that changes the configuration of the surface.
Geomorphic agent: a mobile medium (running water, groundwater, glaciers, wind, waves and currents) that removes, transports and deposits earth materials. Exogenic elements become mobile because of gradients and move material from higher to lower levels.

Gravity: a directional force that activates all downslope movement and causes stress in materials; it indirectly drives wave- and tide-induced currents and winds. Without gravity and gradients, no erosion, transportation or deposition would be possible. All movements happen along gradients: from higher to lower levels, from high to low pressure.

Why the original crust is uneven: geothermal gradients, heat flow, crustal thickness and strength vary, so endogenic forces act unevenly.

Worked example

Is a river a geomorphic process or a geomorphic agent? Explain. (2 marks)

Try it first, then show the solutionSolution

1. A process is a force acting on earth materials (e.g. erosion); an agent is a mobile medium that removes, transports and deposits material.
2. Running water in a river is a mobile medium, so the river is an agent; the erosion it carries out is the process.

Answer: An agent (running water); erosion and deposition are the processes it performs.

Diastrophism and volcanism

NCERT section Endogenic Processes

Diastrophism: all processes that move, elevate or build up portions of the crust:
1. Orogenic processes: mountain building through severe folding, affecting long, narrow belts.
2. Epeirogenic processes: uplift or warping of large parts of the crust; continental building; simple deformation.
3. Earthquakes: local, relatively minor movements.
4. Plate tectonics: horizontal movement of crustal plates.

These can fault and fracture the crust and cause pressure, volume and temperature (PVT) changes, which induce metamorphism of rocks.

Orogeny	Epeirogeny
Mountain building	Continental building
Severe folding	Simple deformation, uplift or warping
Long, narrow belts	Large parts of the crust

Volcanism: movement of molten rock (magma) onto or towards the surface, and the formation of intrusive and extrusive volcanic forms. (Volcano = the vent and landform; volcanism = the whole set of processes.)

Worked example

Cite two differences between orogeny and epeirogeny. (2 marks)

Try it first, then show the solutionSolution

1. Orogeny builds mountains by severe folding of long, narrow belts; epeirogeny builds continents by uplift or warping of large areas.
2. Orogeny deforms the crust severely; epeirogeny causes simple deformation.

Answer: Mountain vs continent building; severe folding of narrow belts vs simple warping of large areas.

Exogenic processes and denudation

NCERT section Exogenic Processes

Energy: from the atmosphere, determined ultimately by the sun, plus slopes created by tectonic factors.

Stress: force per unit area; produced in a solid by pushing or pulling; causes deformation. Shear stresses act along faces of materials (separating forces); they break rocks and cause angular displacement or slippage. Molecular stresses come from temperature changes, crystallisation and melting. Chemical processes loosen bonds between grains and dissolve soluble minerals or cements. So the basic cause of weathering, mass movement and erosion is stress in earth materials.

Denudation: the general term for all exogenic processes ('denude' = strip off, uncover): weathering, mass wasting, erosion and transportation. Each has its own driving force (Figure 5.1).

Why exogenic processes vary:

• Between regions: climates differ (latitude, season, land-water spread); vegetation density and type depend on temperature and precipitation.
• Within a region: altitude, aspect (north/south versus east/west facing slopes receive different insolation), wind, kind and intensity of precipitation, precipitation-evaporation balance, daily temperature range, freeze-thaw frequency, frost depth.
• Rock type and structure: folds, faults, bed orientation and inclination, joints, bedding planes, mineral hardness, chemical susceptibility, permeability. A rock may resist one process but not another, so processes work at different rates and create differences in topography.
• Effects are small and slow but, through continued fatigue, severe in the long run.

Worked example

If the sun suddenly stopped heating the earth unevenly, which geomorphic processes would slow down or stop, and which would carry on? Give a reason. (2 marks)

Try it first, then show the solutionSolution

1. Uneven solar heating creates the temperature, pressure and moisture differences that drive weathering, winds, rain, running water and ice, so exogenic processes would largely slow down or stop (gravity-driven mass movements on existing slopes could continue for a while).
2. Endogenic processes would carry on, as they draw energy from inside the earth (radioactivity, rotational and tidal friction, primordial heat).

Answer: Exogenic processes, which depend on the sun's heat, would slow or stop; endogenic processes would continue.

Weathering: types, special effects and significance

NCERT section Weathering

Definition: mechanical disintegration and chemical decomposition of rocks by elements of weather and climate. Very little or no motion: an in-situ (on-site) process. Climate controls both the processes and the depth of the weathering mantle (Figure 5.2).

Three groups (rarely alone, often one dominates):
1. Chemical: solution, carbonation, hydration, oxidation and reduction decompose, dissolve or reduce rocks to a fine state through reactions with oxygen, surface/soil water and acids. Water, air (oxygen and carbon dioxide) and heat speed reactions; decaying plants and animals add carbon dioxide underground.
2. Physical (mechanical): applied forces: (i) gravitational (overburden pressure, load, shearing stress); (ii) expansion (temperature changes, crystal growth, animal activity); (iii) water pressure from wetting and drying. Most are caused by thermal expansion and pressure release; repeated expansion and contraction cause fatigue.
3. Biological: adding or removing minerals and ions, and physical changes by organisms. Burrowing and wedging (earthworms, termites, rodents) expose new surfaces; humans disturb vegetation and plough; decaying matter produces humic, carbonic and other acids; plant roots exert great pressure.

Special effect: exfoliation. A result, not a process: curved sheets flake off rock, leaving smooth, rounded surfaces. Caused by unloading, thermal expansion-contraction and salt weathering. Exfoliation domes result from unloading; tors from thermal expansion.

Significance:

• Prepares the way for regolith and soils, erosion and mass movements (erosion cannot be significant without weathering).
• Biodiversity: biomes depend on forests, which depend on the depth of the weathering mantle.
• Enrichment: leaching by groundwater removes some materials, concentrating valuable ores of iron, manganese, aluminium, copper, making them economically viable.

Worked example

Explain how weathering leads to the enrichment of ores. (2 marks)

Try it first, then show the solutionSolution

1. During weathering, some materials are removed by chemical or physical leaching by groundwater.
2. The remaining valuable materials (iron, manganese, aluminium, copper ores) become more concentrated, enough to be worth mining and refining.

Answer: Leaching removes unwanted material, concentrating valuable ores: enrichment.

Mass movements and landslides

NCERT section Mass Movements

Mass movements transfer rock debris down slopes under the direct influence of gravity. Air, water or ice do not carry the debris; instead the debris may carry air, water or ice with it. Range: slow to rapid; shallow to deep; include creep, flow, slide and fall.

• Not erosion: no geomorphic agent (running water, glaciers, wind, waves) takes part.
• Weathering is not a pre-requisite (gravity acts on bedrock too), but mass movements are most active on weathered slopes.
• Material moves only when force exceeds its shearing resistance.

Favourable conditions: loose or weak material, rocks in thin beds, faults, beds dipping steeply, steep slopes and vertical cliffs, plenty of rain or torrential downpours, and little vegetation.

Activating causes (nine): removal of support from below; increased slope gradient and height; overloading by added material or artificial filling; overloading by heavy rain, saturation and lubrication; removal of load from the original slope; earthquakes, explosions or machinery; excessive natural seepage; heavy drawdown of water from lakes, reservoirs and rivers; indiscriminate removal of vegetation.

Three forms: heave (heaving of soil by frost growth and other causes), flow, slide.

Landslides: relatively rapid and perceptible; material relatively dry; size and shape depend on rock discontinuities, degree of weathering and slope.

Type	Movement
Slump	One or several units slip with backward rotation
Debris slide	Rapid rolling or sliding of debris without backward rotation
Debris fall	Nearly free fall of debris from a vertical or overhanging face
Rockslide	Individual rock masses slide down bedding, joint or fault surfaces; planar failure; fast and destructive on steep slopes; affects material to substantial depth
Rock fall	Free fall of rock blocks from superficial layers, keeping away from the slope

India: debris avalanches and landslides are very frequent in the Himalayas (tectonically active; sedimentary and unconsolidated rocks; very steep slopes). The Nilgiris and Western Ghats are tectonically stable with hard rocks, yet landslides occur because of near-vertical cliffs and escarpments, strong mechanical weathering from temperature changes, and heavy rain in short spells, so rock falls are frequent.

Worked example

Why are mass movements not counted as erosion, even though material moves? (2 marks)

Try it first, then show the solutionSolution

1. Erosion needs a geomorphic agent (running water, glaciers, wind, waves) to acquire and transport debris.
2. In mass movements, gravity alone moves the debris; no agent carries it, so it is not erosion.

Answer: Because gravity, not an agent, moves the debris.

Erosion and deposition

NCERT section Erosion and Deposition

Erosion: acquisition and transportation of rock debris by agents (running water, groundwater, glaciers, wind, waves), aided greatly by abrasion from the debris they carry. Relief is degraded (worn down). Weathering aids erosion but is not a pre-condition. Weathering, mass wasting and erosion are degradational processes; erosion is largely responsible for the earth's continuous surface changes. Erosion and transportation are controlled by kinetic energy.

Climatic and non-climatic agents:

• Climate-controlled: wind (gas), running water (liquid), glaciers (solid): the three states of matter.
• Not climate-controlled: waves (work decided by location at the land-sea interface, the coast) and groundwater (decided by lithology; karst develops only where rocks are permeable and soluble and water is available).

Deposition: a consequence of erosion, not the work of any agent as such. Agents lose velocity and energy on gentler slopes; their load settles, coarser first, finer later; depressions are filled. The same agents act as aggradational agents.

Worked example

Why do coarse pebbles settle before fine silt when a river slows down? (2 marks)

Try it first, then show the solutionSolution

1. Deposition happens when an agent loses velocity and energy on gentler slopes.
2. Heavier, coarser material needs more energy to stay in motion, so it settles first; finer material is carried further before settling.

Answer: Loss of energy drops coarse material first, fine material later.

Soil formation and soil-forming factors

NCERT section Soil Formation

Soil: a dynamic medium of constant chemical, physical and biological activity; a result of decay and a medium for growth; it changes with the seasons.

Process (pedogenesis): depends first on weathering: the weathering mantle is the basic input.
1. Weathered or transported material is colonised by bacteria, mosses and lichens; minor organisms shelter in it.
2. Dead remains build humus.
3. Grasses and ferns grow, then bushes and trees from seeds brought by birds and wind.
4. Roots penetrate, burrowing animals bring particles up; the mass becomes porous and sponge-like, holding water and passing air.
5. A mature soil, a complex mixture of mineral and organic products, forms.

Five factors (acting together):

Factor	Type	Role
Parent material	Passive	In-situ debris (residual soils) or transported deposits (transported soils); texture, structure, mineral and chemical composition, rate and depth of weathering. Young soils and some limestone soils show strong links to parent rock
Topography	Passive	Exposure to sunlight and drainage; thin soils on steep slopes, thick on flat uplands; gentle slopes ideal; flat areas may form thick dark clay rich in organic matter
Climate	Active	Moisture: water moves components down (eluviation) and deposits them below (illuviation); wet equatorial areas lose bases and silica (desilication); dry climates bring salts up by capillary action forming hardpans; intermediate tropical rainfall forms kankar (calcium carbonate nodules). Temperature: chemical activity rises with heat, falls in cold (except carbonation), stops when frozen; tropical soils deeper, tundra soils mechanically broken
Biological activity	Active	Adds organic matter, moisture retention, nitrogen; humus; organic acids decompose minerals. Cold climates: slow bacteria, humus and peat accumulate (sub-arctic, tundra). Humid tropics: intense bacteria, low humus. Nitrogen fixation: Rhizobium in root nodules of legumes. Ants, termites, earthworms, rodents rework soil
Time	Passive	Decides maturity and profile development; young soils on fresh alluvium or glacial till have no or poor horizons; no fixed absolute time

Worked example

Why does a humid equatorial forest soil have low humus, while tundra soils have peat? (2 marks)

Try it first, then show the solutionSolution

1. In humid tropical and equatorial climates bacterial action is intense, so dead vegetation is rapidly oxidised and little humus remains.
2. In cold sub-arctic and tundra climates bacterial growth is slow; organic matter stays undecomposed and builds up as peat.

Answer: Fast bacterial decay in the tropics removes humus; slow decay in cold regions lets peat accumulate.

Geomorphic Processes 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

• Endogenic and Exogenic Forces, Weathering and Mass Movements
• Erosion, Deposition and Soil Formation (Pedogenesis)

Geomorphic Processes: key facts

Forces

$Endogenic=land-building;exogenic=land-wearing(degradation+aggradation)$

Relief persists while both act.

Endogenic energy

Radioactivity + rotational and tidal friction + primordial heat

Acts through geothermal gradients and heat flow.

Diastrophism

Orogeny + epeirogeny + earthquakes + plate tectonics

Causes faulting, fracturing and PVT changes (metamorphism).

Denudation

Weathering + mass wasting + erosion + transportation

'Denude' = strip off.

Weathering groups

$Chemical(solution,carbonation,hydration,oxidation,reduction)|physical|biological$

Weathering is in situ.

Landslide types

• •Slump (backward rotation)
• •debris slide
• •debris fall
• •rockslide
• •rock fall

Rock fall: superficial layers; rockslide: substantial depth.

Erosion agents by state

Wind (gas), running water (liquid), glacier (solid): climate-controlled; waves and groundwater: not

Erosion = acquisition + transportation.

Soil-forming factors

$Soil=f(parentmaterial,topography,climate,biologicalactivity,time)$

Active: climate, biology. Passive: parent material, topography, time.

Climate in soils

Eluviation (down-wash) → illuviation (deposit below); desilication (wet tropics); hardpan (dry); kankar (intermediate)

Chemical activity rises with temperature, except carbonation.

Geomorphic Processes: diagrams to practise

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

How the school exam asks Geomorphic Processes

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

Tricks to remember Geomorphic Processes

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

• Endogenic energy

  'RRP': Radioactivity, Rotational and tidal friction, Primordial heat.

  Use it when: Sources of endogenic energy.

• Chemical weathering

  'SCHOR': Solution, Carbonation, Hydration, Oxidation, Reduction.

  Use it when: Listing chemical processes.

• Landslide types

  'Sly Dogs Dig Rocks Rapidly': Slump, Debris slide, Debris fall, Rockslide, Rock fall.

  Use it when: Landslide types.

• Soil factors

  'CLORPT' style: Climate, Organisms (biology), Relief (topography), Parent material, Time.

  Use it when: Five soil-forming factors.

• Active versus passive

  'Climate and Critters act; Rock, Relief and Clock wait'.

  Use it when: Classifying soil factors.

Geomorphic Processes: 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 Geomorphic Processes

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

• ✗Mistake: Calling deposition a gradational process

  Students lump all exogenic work together.

  Wrong working

  Deposition is gradation because it changes relief.

  Right working

  Gradation is wearing down by erosion; deposition fills depressions (aggradation).

  ✓Do this: Grade down = erode; aggrade = fill.

  Usually costs: 1 mark per MCQ.

• ✗Mistake: Saying mass movements are a type of erosion

  Both move material.

  Wrong working

  Landslides are erosion by gravity.

  Right working

  Mass movements are gravity-driven with no agent; erosion needs an agent such as running water or wind.

  ✓Do this: No agent, no erosion.

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

• ✗Mistake: Calling exfoliation a process

  It sounds like an action.

  Wrong working

  Exfoliation is a weathering process.

  Right working

  Exfoliation is a result of physical weathering processes (unloading, thermal expansion and contraction, salt weathering).

  ✓Do this: Exfoliation = result.

  Usually costs: 1 mark.

• ✗Mistake: Classing climate as passive

  Students learn the factor list without the active/passive tag.

  Wrong working

  Passive factors: climate, topography, time.

  Right working

  Active: climate, biological activity. Passive: parent material, topography, time.

  ✓Do this: Living and weather things act; rock, slope and clock wait.

  Usually costs: 1 mark.

• ✗Mistake: Writing that weathering involves transport

  Weathered grains sometimes shift a little.

  Wrong working

  Weathering breaks and carries rock away.

  Right working

  Weathering is in situ: little or no motion; transport belongs to erosion.

  ✓Do this: Weathering stays home.

  Usually costs: 1 mark in a definition.

NCERT exercise guide: Geomorphic Processes

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 Geomorphic Processes

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

   Which of these is NOT a mass movement?
   (a) Slump
   (b) Debris avalanche
   (c) Solifluction
   (d) Deflation by wind

   Hint

   Mass movements are aided by gravity alone; no agent carries the material.

   Answer

   (d) Deflation: removal of material by wind is erosion by an agent, not a mass movement.

2. Q2 · 1 mark · MCQExam level

   Which soil-forming factor is active?
   (a) Parent material
   (b) Topography
   (c) Time
   (d) Climate

   Hint

   Three are passive.

   Answer

   (d) Climate.

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

   Assertion (A): Deposition is not actually the work of any agent.
   Reason (R): Agents lose velocity and energy on gentler slopes and their load settles.
   Choose (a)-(d).

   Hint

   Deposition is a consequence.

   Answer

   (a). Both true; R explains A.

4. Q4 · 2 marks · Short answerHarder exam level

   Distinguish between rock fall and rockslide. (2 marks)

   Hint

   Depth affected and contact with the slope.

   Answer

   Rock fall: free fall of blocks from the superficial layers, keeping away from the slope. Rockslide: rock masses slide down bedding, joint or fault surfaces, affecting material to substantial depth.

5. Q5 · 3 marks · Short answerHarder exam level

   What are exfoliation domes and tors, and how do they form? (3 marks)

   Hint

   Exfoliation is a result, not a process.

   Answer

   Exfoliation is flaking of curved sheets from rock, leaving smooth rounded surfaces. Exfoliation domes result from unloading (pressure release); tors result from thermal expansion. Both are results of physical weathering.

6. Q6 · 3 marks · Short answerExam level

   A coastal village sees its cliffs cut back by waves, while a nearby desert village sees dunes move and a hill village sees its stream deepen its valley. Name the agents at work, state the prime job all of them share, and say which of them are mainly controlled by climate. (3 marks)

   Hint

   Mobile agents: running water, groundwater, glaciers, wind, waves and currents.

   Answer

   Waves (coast), wind (desert) and running water (hills). Like groundwater, glaciers and currents, their prime job is erosion: acquiring and transporting earth materials and depositing them, degrading relief. Wind, running water and glaciers are controlled by climate; waves depend on the location of the coast rather than on climate.

7. Q7 · 3 marks · Short answerHOTS / competency

   Suppose a town draws water from a lakeside reservoir very quickly during a drought, and soon cracks appear on the lake's steep banks. Using the chapter, explain why. (3 marks)

   Hint

   One of the nine activating causes.

   Answer

   Heavy drawdown of water from lakes or reservoirs is an activating cause of mass movement: water trapped in the banks flows out slowly from under the slopes, reducing support and shearing resistance. On steep banks this can trigger slides, shown first by cracks.

8. Q8 · 5 marks · Long answerHOTS / competency

   Soil on a slope in the humid tropics and soil on a flat tundra surface have formed from the same kind of rock. Explain why they differ, separating the process of soil formation from the soil-forming factors and focusing on climate and biological activity. (5 marks)

   Hint

   Process = what happens step by step; factors = the controls.

   Answer

   Process (pedogenesis): weathered material is colonised by bacteria, mosses and lichens; their remains add humus; grasses, ferns and then bushes and trees grow; roots and burrowing animals open the material until a porous, mature soil develops. Factors: parent material, topography, climate, biological activity and time control the result. Same rock means parent material is not the cause. Climate: moisture and temperature differ, so in the humid tropics heavy leaching (eluviation, desilication) and fast chemical activity occur, while in the tundra cold slows chemical activity. Biological activity: in the humid tropics intense bacterial action oxidises dead vegetation rapidly, leaving little humus; in the tundra low bacterial activity leaves undecomposed matter as peat. Topography also matters: the slope loses soil while flat land retains it.

9. Q9 · 2 marks · Short answerHOTS / competency

   Is weathering essential for soil formation? Is it enough? (2 marks)

   Hint

   Pedogenesis 'depends first' on weathering.

   Answer

   Yes, it is essential: the weathering mantle is the basic input for soil. It is not enough: colonisation by organisms, humus, plants, burrowing animals, climate and time are needed to turn weathered material into mature soil.

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 gradation?Show answer

   Wearing down of relief variations through erosion.

2. 2.Name the four processes under diastrophism.Show answer

   Orogeny, epeirogeny, earthquakes, plate tectonics.

3. 3.What does 'denude' mean?Show answer

   To strip off or uncover.

4. 4.What is enrichment?Show answer

   Concentration of valuable ores after leaching removes other materials during weathering.

5. 5.What are the three forms of mass movement?Show answer

   Heave, flow and slide.

6. 6.What is desilication?Show answer

   Removal of silica from soil in wet equatorial climates.

7. 7.What are kankar nodules?Show answer

   Calcium carbonate nodules formed in tropical areas of intermediate precipitation.

8. 8.Which bacterium fixes nitrogen in legume root nodules?Show answer

   Rhizobium.

Quick revision checklist

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

• ☐Endogenic = land-building; exogenic = land-wearing; relief remains while both act.
• ☐Agent = mobile medium; process = force; gravity switches on downslope movement.
• ☐Endogenic energy: radioactivity, rotational and tidal friction, primordial heat.
• ☐Diastrophism: orogeny, epeirogeny, earthquakes, plate tectonics; PVT changes cause metamorphism.
• ☐Denudation = weathering + mass wasting + erosion + transportation.
• ☐Weathering is in situ: chemical (SCHOR), physical (thermal expansion, pressure release), biological.
• ☐Exfoliation is a result; domes from unloading, tors from thermal expansion.
• ☐Mass movement: gravity only, no agent; landslides: slump, debris slide, debris fall, rockslide, rock fall.
• ☐Erosion needs agents; deposition: coarse first, fine later.
• ☐Soil factors: parent material, topography, time (passive); climate, biology (active).

Geomorphic Processes: frequently asked questions