Geomorphic Processes

1.Geomorphic Processes

• Endogenic and Exogenic ForcesImportance 4/5UPSC 2013
  Why is the earth's surface uneven? Be clear how internal (endogenic) and external (exogenic) forces differ in origin and in their main effect. Do their actions oppose each other, and what follows from that? Also understand, briefly, how human misuse affects the surface.
• Degradation, Aggradation and GradationImportance 3/5
  Remember what degradation, aggradation and gradation each mean, and which forces bring about each. How does gradation relate to degradation and aggradation? Note that usage varies: some treat gradation as wearing down by erosion only, others include deposition as well.
• Meaning of Geomorphic ProcessesImportance 3/5
  Be clear what geomorphic processes are, and which of them are endogenic (internal) and which exogenic (external).
• Geomorphic Agents and Geomorphic Processes DistinguishedImportance 2/5
  Is a geomorphic process the same as a geomorphic agent? Understand the difference between a force applied on earth materials and a mobile medium that carries them. Remember which natural elements count as agents.
• Role of Gravity and GradientsImportance 3/5
  Why would there be no erosion, transport or deposition without gravity and gradients? Understand gravity as a directional force that also causes stress. Remember how gravity indirectly drives wave- and tide-induced currents and winds.

2.Endogenic Processes

• Sources of Energy for Endogenic ProcessesImportance 3/5
  Remember the main sources of the energy behind endogenic processes. Understand why endogenic action is uneven from place to place (think of geothermal gradients, heat flow, and the thickness and strength of the crust).
• Meaning and Types of DiastrophismImportance 4/5
  What is diastrophism? Remember its meaning and the four processes it includes, with the basic idea of each. Which of the four involves only local, relatively minor movements?
• Orogeny and Epeirogeny DistinguishedImportance 4/5
  How do orogeny and epeirogeny differ in the area they affect, the kind of deformation, and what each builds? Remember an example of uplift of a large land area (the Colorado Plateau) and understand what subsidence means here.
• Faulting, Fracturing and Metamorphism (PVT Changes)Importance 2/5
  How do diastrophic movements lead to faulting and fracturing of the crust? Understand how they bring changes in pressure, volume and temperature (PVT), and how these changes lead to metamorphism of rocks.
• Folds and FaultsImportance 3/5
  How do folding and faulting differ? Which stresses produce folds, and which produce the main types of fault (normal, reverse or thrust, and strike-slip)? Understand what a dip-slip fault is, and how slip along a fault causes earthquakes.
• Fold, Block and Residual MountainsImportance 4/5UPSC 2024
  How does each of these three mountain types form? Remember examples of each, and how young fold mountains differ from old ones. Understand horst and graben (for example the Vosges and the Rhine Valley), and tilted versus lifted block mountains. Why are young fold mountains seismically active?
• IsostasyImportance 2/5
  What is isostasy? Understand the balance between the lithosphere and the asthenosphere, and how the crust rises or sinks when load is added or removed (for example by erosion or mountain building).
• Meaning of VolcanismImportance 2/5
  What does volcanism include? Remember the movement of magma and the intrusive and extrusive forms it produces. What do the words "volcanism" and "volcanoes" each indicate?
• Volcanic MountainsImportance 2/5
  How do volcanic mountains form, and why are they called mountains of accumulation? In which belt are they most common? Remember examples such as Mt. Fuji, Mt. Mayon and Mt. Etna.
• Igneous RocksImportance 2/5
  How do igneous rocks form? Why are they called primary rocks, and do they contain fossils? Distinguish plutonic (intrusive) from volcanic (extrusive) igneous rocks.
• Sedimentary RocksImportance 3/5UPSC 2001
  Understand how denudation, deposition and lithification make sedimentary rocks. Remember their traits (layering, fossils, porosity), the mechanical, organic and chemical classes with examples, and which fuel resources they hold. Note that limestone can form in more than one way.
• Metamorphic Rocks and Types of MetamorphismImportance 3/5UPSC 2001
  How do heat and pressure turn existing rocks into metamorphic rocks? Understand recrystallisation, foliation and banding, and how PVT changes cause them. Distinguish thermal from dynamic metamorphism. Remember standard parent and metamorphic pairs (for example, what sandstone becomes).
• Rock CycleImportance 2/5
  What is the rock cycle? Understand how each of the three rock types can change into the others, and why the process is continuous.

3.Exogenic Processes

• Energy Source of Exogenic ProcessesImportance 3/5UPSC 2013
  Where do exogenic processes get their ultimate energy from? Understand how conditions in the atmosphere pass that energy on, and why the slopes (gradients) these processes need arise from tectonic factors.
• Stress in Earth MaterialsImportance 2/5
  Remember what stress, shear stress and molecular stress mean. Understand what can cause molecular stress, and why stress lies behind weathering, mass movement and erosion.
• Denudation and Its Driving ForcesImportance 3/5
  What is denudation, and which processes does it include? Does each process have its own driving force? Be able to pair each process with its force.
• Climatic Controls on Exogenic ProcessesImportance 3/5
  Which two climatic elements control exogenic processes? Understand why one process varies from region to region and even locally (altitude, north- and south-facing slopes versus east- and west-facing slopes, frost, wind, rainfall intensity). How does vegetation influence them indirectly?
• Rock Type and Structure as ControlsImportance 3/5
  What does the "structure" of a rock include? Remember its elements. Understand why a rock may resist one process but give way to another, and how this keeps differences in relief alive.

4.Weathering

• Meaning of WeatheringImportance 4/5
  What is weathering? Remember the definition, and why it is described as an in-situ (on-site) process. Is the small movement that sometimes occurs during weathering the same as transportation?
• Factors Controlling Weathering and Depth of the Weathering MantleImportance 3/5
  Which geological, climatic, topographic and vegetative factors control weathering? Understand how climate affects both the kind of weathering and the depth of the weathering mantle across climatic regimes.
• Three Groups of Weathering Processes and Their InteractionImportance 3/5
  What are the three groups of weathering processes? Are they independent of each other? Understand, with examples, how they work together and when one of them dominates.
• Solution, Carbonation, Hydration, Oxidation and ReductionImportance 4/5UPSC 2024
  Be clear what each of these five processes does to rock minerals and which materials it typically affects. For example, what happens to iron compounds in oxidation and reduction? Which minerals and materials does hydration typically affect, and why does repeated hydration weaken rock?
• Conditions That Speed Up Chemical WeatheringImportance 3/5
  What must be present for chemical reactions in rock to speed up? Understand the role of the carbon dioxide and oxygen in rainwater, and why decaying plants and animals add to carbon dioxide underground.
• Applied Forces in Physical WeatheringImportance 2/5
  What are the three kinds of forces that drive physical weathering? Remember the examples that belong under each kind.
• Thermal Expansion, Pressure Release and Rock FatigueImportance 3/5
  Which two causes account for most physical weathering? Understand why such small and slow processes can still damage rocks badly over time (think of repeated expansion and contraction, called rock fatigue).
• Frost Wedging and Salt WeatheringImportance 3/5
  How does frost wedging work, and how does salt weathering (crystallisation) work? Understand the climate in which each is typical and how the two differ.
• Granular Disintegration, Block Separation and ShatteringImportance 2/5
  Remember what granular disintegration, block separation and shattering each mean, and how they differ in the way the rock breaks.

5.Biological Activity and Weathering

• Mechanical Role of Organisms and HumansImportance 2/5
  Remember the organisms and the human activities that break up rock mechanically. Understand how they expose new surfaces and let moisture and air into the rock.
• Chemical Role of Decaying Organic MatterImportance 3/5
  What is biological weathering? Understand how decaying plant and animal matter produces acids, and how these acids affect decay and the solubility of some elements. Remember which acids are involved.

6.Special Effects of Weathering

• Nature and Causes of ExfoliationImportance 3/5
  What is exfoliation? Be clear whether it is a process or a result of processes. Remember which weathering processes can cause it.
• Exfoliation Domes and TorsImportance 2/5
  What are exfoliation domes and tors? Understand how unloading helps form exfoliation domes. How do weathering along joints and the removal of weathered material leave tors standing?

7.Significance of Weathering

• Role of Weathering in Erosion, Soils and BiodiversityImportance 3/5
  How does weathering prepare the way for regolith, soil, mass movement and erosion? How does it link to forests and biodiversity? Is weathering essential for erosion, or does it only help it?
• Enrichment of Ores Through WeatheringImportance 2/5
  What is enrichment of ores? Understand how the removal of some materials raises the concentration of valuable ones, and remember the main metals that benefit.

8.Mass Movements

• Meaning and Range of Mass MovementsImportance 3/5
  Learn the definition of mass movements, and their range of movement from slow to rapid and shallow to deep (creep, flow, slide and fall). Is weathering a pre-requisite for them?
• Mass Movements and Erosion DistinguishedImportance 3/5
  Both shift material from one place to another, so why are they treated differently? Understand the role of a geomorphic agent in each, and the idea of shearing resistance. Which is the more suitable term, mass wasting or mass movement?
• Favourable Conditions and Activating Causes of Mass MovementsImportance 3/5
  What natural conditions favour mass movements? Remember the nine activating causes that come before them, including both natural and human ones.
• Heave, Flow and SlideImportance 2/5
  Be clear about heave, flow and slide as the three forms of movement, and what heave means. Which of creep, solifluction, earthflow, mudflow and debris avalanche are slow movements and which are rapid? What is subsidence?
• Nature of LandslidesImportance 3/5
  How do landslides differ from slow mass movements in speed, and from wet flow movements in moisture content? Remember what decides the size and shape of the detached mass.
• Slump, Debris Slide and Debris FallImportance 3/5
  What are slump, debris slide and debris fall? Distinguish slump from debris slide: which one involves backward rotation? Understand what makes debris fall nearly a free fall.
• Rockslide and Rock Fall DistinguishedImportance 2/5
  How do rockslide and rock fall differ? Understand the kind of surface each involves and how deep into the rock each acts.
• Landslides in the Himalayas and the Western GhatsImportance 4/5
  Why do landslides and debris avalanches occur so often in the Himalayas? Why do they still occur, though less often, in the Western Ghats and the Nilgiris, which are more stable and made of very hard rocks? Understand the role of tectonics, rock type, slope, weathering and rainfall in each region.

9.Erosion and Deposition

• Meaning of ErosionImportance 3/5
  What does erosion involve? Understand the role of abrasion and of kinetic energy. Is weathering a pre-condition for erosion? Which processes are called degradational?
• Climatically Controlled and Other Agents of ErosionImportance 3/5
  Which agents of erosion are controlled by climate, and which are not? Understand how the climate-controlled agents represent the three states of matter, what decides the work of waves and groundwater, and what conditions karst topography needs.
• DepositionImportance 3/5
  Why does deposition take place? Is it the work of an agent, or a consequence of erosion? Understand in what order materials settle, and how the same agents also fill up depressions.

10.Soil Formation

• Soil as a Dynamic Medium and PedologyImportance 2/5
  Why is soil called a dynamic medium? Understand how it changes with the seasons and with organic matter. Remember the terms pedology and pedologist.
• Stages of PedogenesisImportance 3/5
  What is pedogenesis? Understand the sequence from weathered material to mature soil, including colonisation by organisms and the build-up of humus. Is weathering alone responsible for soil formation?
• Five Soil-Forming Factors and Their Active or Passive RoleImportance 4/5
  Which five factors control soil formation? Which are passive, and why are they called passive? How does the process of soil formation differ from the factors that control it?
• Parent MaterialImportance 4/5
  How do residual and transported soils differ? Understand which properties of the parent material matter (texture, structure, mineral and chemical composition). Why do young soils and soils in limestone areas show a strong link with their parent rock?
• TopographyImportance 3/5
  How does topography affect soil? Understand the role of exposure to sunlight and of drainage, and how soil depth differs on steep slopes, gentle slopes and flat upland areas.
• Climate: Moisture, Leaching and Salt AccumulationImportance 4/5
  How does moisture shape soil? Understand eluviation and illuviation as processes. What are desilication, hardpans and kanker, and in which climate does each form? Note that a hardpan can be any hardened layer in the soil; salt crusts in dry climates are one kind.
• Climate: Temperature and Soil DevelopmentImportance 3/5
  How does temperature affect chemical and biological activity in soil? Why do tropical soils show deeper profiles than tundra soils? Which chemical process is an exception to the effect of cooler temperatures?
• Biological Activity: Humus and Bacterial ActivityImportance 4/5
  What is humus, and how do organic acids formed during humification affect soil minerals? Why does humus build up in cold climates but stay very low in humid tropical ones? Understand where peat forms and why.
• Nitrogen Fixation and Soil FaunaImportance 3/5
  What is nitrogen fixation? Remember the role of Rhizobium and the plants it lives with. How do ants, termites, earthworms and rodents affect soil, and what do earthworms do to its texture and chemistry?
• Time and Soil MaturityImportance 3/5
  How does time decide soil maturity and profile development? Understand what makes a soil young or mature, which soils are treated as young, and why no fixed span of time can be given.

1. 1.

   Consider the following statements:
   1. Diastrophism and volcanism are endogenic geomorphic processes.
   2. Weathering is an exogenic geomorphic process.
   3. Deposition is an endogenic geomorphic process.
   Which of the statements given above is/are correct?

   1. A1 only
   2. B1 and 2 only
   3. C2 and 3 only
   4. D1, 2 and 3
2. 2.

   Match List I with List II:

   List I (Diastrophic process)	List II (Involves)
   A. Orogenic processes	1. Horizontal movements of crustal plates
   B. Epeirogenic processes	2. Mountain building through severe folding of long, narrow belts
   C. Earthquakes	3. Local, relatively minor movements
   D. Plate tectonics	4. Uplift or warping of large parts of the earth's crust

   Select the correct answer using the code given below:

   1. AA-4, B-2, C-3, D-1
   2. BA-2, B-4, C-1, D-3
   3. CA-4, B-2, C-1, D-3
   4. DA-2, B-4, C-3, D-1
3. 3.

   Consider the following statements:
   Statement-I: Exogenic processes fail to even out the relief variations of the earth's surface.
   Statement-II: Endogenic forces continuously elevate or build up parts of the earth's surface.
   Which one of the following is correct in respect of the above statements?

   1. ABoth Statement-I and Statement-II are correct and Statement-II explains Statement-I
   2. BBoth Statement-I and Statement-II are correct and Statement-II does not explain Statement-I
   3. CStatement-I is correct but Statement-II is incorrect
   4. DStatement-I is incorrect but Statement-II is correct
4. 4.

   Consider the following statements about weathering:
   1. It is an in-situ or on-site process, as very little or no motion of materials takes place.
   2. It is a pre-requisite for mass movements.
   3. It helps in the enrichment and concentration of ores of iron, manganese, aluminium and copper.
   4. Most physical weathering processes are caused by thermal expansion and pressure release.
   How many of the above statements are correct?

   1. AOnly one
   2. BOnly two
   3. COnly three
   4. DAll four
5. 5.

   With reference to biological weathering, consider the following statements:
   1. Burrowing by earthworms, termites and rodents exposes new surfaces to chemical attack.
   2. Decaying plant and animal matter helps produce humic, carbonic and other acids that enhance decay.
   Which of the statements given above is/are correct?

   1. A1 only
   2. B2 only
   3. CBoth 1 and 2
   4. DNeither 1 nor 2
6. 6.

   With reference to mass movements, consider the following statements:
   1. Geomorphic agents like running water and glaciers participate in mass movements.
   2. Mass movements come under erosion.
   Which of the statements given above is/are correct?

   1. A1 only
   2. B2 only
   3. CBoth 1 and 2
   4. DNeither 1 nor 2
7. 7.

   Consider the following pairs:

   Mass movement	Description
   1. Slump	Slipping of rock debris with a backward rotation with respect to the slope
   2. Debris slide	Rapid rolling or sliding of earth debris without backward rotation
   3. Rock fall	Sliding of individual rock masses down bedding, joint or fault surfaces

   How many of the pairs given above are correctly matched?

   1. AOnly one
   2. BOnly two
   3. CAll three
   4. DNone
8. 8.

   Consider the following statements:
   Statement-I: Debris avalanches and landslides occur very frequently in the Himalayas.
   Statement-II: The Himalayas are tectonically stable and mostly made up of very hard rocks.
   Which one of the following is correct in respect of the above statements?

   1. ABoth Statement-I and Statement-II are correct and Statement-II explains Statement-I
   2. BBoth Statement-I and Statement-II are correct and Statement-II does not explain Statement-I
   3. CStatement-I is correct but Statement-II is incorrect
   4. DStatement-I is incorrect but Statement-II is correct
9. 9.

   Consider the following:
   1. Many steep slopes with almost vertical cliffs and escarpments
   2. Pronounced mechanical weathering due to temperature changes
   3. Heavy rainfall over short periods
   4. Intense tectonic activity
   How many of the above are reasons why landslides and debris avalanches occur in the Western Ghats and Nilgiris?

   1. AOnly one
   2. BOnly two
   3. COnly three
   4. DAll four
10. 10.

    The work of which one of the following agents of erosion is NOT controlled by climatic conditions?

    1. AWind
    2. BRunning water
    3. CGlaciers
    4. DGroundwater
11. 11.

    With reference to deposition, consider the following statements:
    1. Deposition is the work of a particular geomorphic agent.
    2. Coarser materials get deposited first and finer ones later.
    Which of the statements given above is/are correct?

    1. A1 only
    2. B2 only
    3. CBoth 1 and 2
    4. DNeither 1 nor 2
12. 12.

    Match List I with List II:

    List I (Term)	List II (Meaning)
    A. Eluviation	1. Removal of silica from the soil in wet equatorial areas
    B. Illuviation	2. Deposition of transported soil components down below
    C. Desilication	3. Calcium carbonate nodules formed in tropical areas of intermediate precipitation
    D. Kanker	4. Downward transportation of soil components by excess water

    Select the correct answer using the code given below:

    1. AA-4, B-2, C-1, D-3
    2. BA-2, B-4, C-1, D-3
    3. CA-4, B-2, C-3, D-1
    4. DA-2, B-4, C-3, D-1
13. 13.

    Consider the following soil-forming factors:
    1. Parent material
    2. Topography
    3. Climate
    4. Time
    5. Biological activity
    How many of the above are considered passive control factors in soil formation?

    1. AOnly two
    2. BOnly three
    3. COnly four
    4. DAll five
14. 14.

    With reference to temperature as a factor in soil formation, consider the following statements:
    1. Chemical activity increases at higher temperatures and decreases in cooler temperatures, carbonation being an exception.
    2. Tropical soils show shallower profiles than soils in cooler regions.
    Which of the statements given above is/are correct?

    1. A1 only
    2. B2 only
    3. CBoth 1 and 2
    4. DNeither 1 nor 2
15. 15.

    With reference to biological activity in soils, consider the following statements:
    1. Humus accumulates in cold climates because bacterial growth is slow.
    2. Soils of humid tropical and equatorial climates have a very high humus content because of intense bacterial action.
    Which of the statements given above is/are correct?

    1. A1 only
    2. B2 only
    3. CBoth 1 and 2
    4. DNeither 1 nor 2

1. 1.

   UPSC 2024

   Consider the following statements :
   Statement-I : Rainfall is one of the reasons for weathering of rocks.
   Statement-II : Rain water contains carbon dioxide in solution.
   Statement-III : Rain water contains atmospheric oxygen.
   Which one of the following is correct in respect of the above statements ?

   1. ABoth Statement-II and Statement-III are correct and both of them explain Statement-I
   2. BBoth Statement-II and Statement-III are correct, but only one of them explains Statement-I
   3. COnly one of the Statements II and III is correct and that explains Statement-I
   4. DNeither Statement-II nor Statement-III is correct
2. 2.

   UPSC 2024

   Consider the following information :

   	Region	Name of the mountain range	Type of mountain
   1	Central Asia	Vosges	Fold mountain
   2	Europe	Alps	Block mountain
   3	North America	Appalachians	Fold mountain
   4	South America	Andes	Fold mountain

   In how many of the above rows is the given information correctly matched ?

   1. AOnly one
   2. BOnly two
   3. COnly three
   4. DAll four
3. 3.

   UPSC 2013

   Consider the following:
   1. Electromagnetic radiation
   2. Geothermal energy
   3. Gravitational force
   4. Plate movements
   5. Rotation of the earth
   6. Revolution of the earth
   Which of the above are responsible for bringing dynamic changes on the surface of the earth?

   1. A1, 2, 3 and 4 only
   2. B1, 3, 5 and 6 only
   3. C2, 4, 5 and 6 only
   4. D1, 2, 3, 4, 5 and 6
4. 4.

   UPSC 2001

   Consider the following statements made about the sedimentary rocks:
   I. Sedimentary rocks are formed at Earth’s surface by the hydrological system.
   II. The formation of sedimentary rocks involves the weathering of pre-existing rocks.
   III. Sedimentary rocks contain fossils.
   IV. Sedimentary rocks typically occur in layers.
   Which of these statements are correct?

   1. AI and II
   2. BI and IV
   3. CII, III and IV
   4. DI, II, III and IV
5. 5.

   UPSC 2001

   Quartzite is metamorphosed from

   1. ALimestone
   2. BObsidian
   3. CSandstone
   4. DShale