Various landforms observed on the surface of the earth are due to the: 1. differences in the type and structure of the crustal material 2. differences in the land forming processes 3. differential rates of the processes at different places on the Earth’s surface Select the correct answer using the code given below:

1. Introduction to Geomorphic Processes (basic)

The Earth’s surface is not a static canvas; it is a dynamic landscape constantly being reshaped by a "tug-of-war" between two massive sets of forces. We call these Geomorphic Processes—the physical and chemical actions that change the configuration of the Earth's surface FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI, Chapter 5, p.38. These processes are categorized into two types based on where their energy comes from: Endogenic (internal) and Exogenic (external) forces.

Endogenic forces act like the Earth's internal construction crew. Driven by the Earth’s internal heat—generated largely by radioactive decay and gravitational pressure—these forces create convection currents in the mantle that move tectonic plates Physical Geography by PMF IAS, Chapter 6, p.79. This results in diastrophism (slow movements like mountain building) and volcanism (sudden movements). Their primary job is to build up relief, creating mountains, plateaus, and new crust.

In contrast, Exogenic forces act as the Earth’s external sculpting tools. They derive their energy from the Sun (which drives climate/weather) and gravity. These forces—including weathering, erosion, and mass wasting—work to level the land through a process called gradation FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI, Chapter 5, p.37. Gradation has two sides: degradation, which wears down high points (mountains), and aggradation, which fills up low points (basins) with sediment.

Feature	Endogenic Forces	Exogenic Forces
Source of Energy	Earth's internal heat (Radioactivity/Gravity)	Sun (Atmosphere) and Gravity
Primary Effect	Builds up relief (Constructional)	Levels down relief (Destructional/Gradational)
Key Examples	Folding, Faulting, Volcanism	Weathering, Erosion, Deposition

Finally, we must distinguish between a process and an agent. A geomorphic process is the physical or chemical action itself (e.g., erosion), while a geomorphic agent is the mobile medium—like running water, wind, or glaciers—that actually carries out the work of moving material across the landscape Physical Geography by PMF IAS, Chapter 6, p.78.

Sources: FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI, Chapter 5: Geomorphic Processes, p.37-38; Physical Geography by PMF IAS, Chapter 6: Geomorphic Movements, p.78-79

2. Endogenic Forces: Diastrophism and Volcanism (basic)

To understand why our Earth looks the way it does, we must first look deep beneath our feet. The Earth’s surface is constantly being reshaped by endogenic forces—internal energies originating from within the Earth due to radioactivity, primordial heat, and tidal friction. These forces are the "builders" of the landscape, creating the initial inequalities in elevation that external forces (like wind and water) later try to level out. Endogenic movements are generally classified into two types: diastrophic movements, which are slow and gradual, and sudden movements, such as earthquakes and volcanic eruptions Physical Geography by PMF IAS, Geomorphic Movements, p.79.

Diastrophism is a broad term that includes all processes that move, elevate, or build up portions of the Earth's crust FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI, p.38. It is primarily driven by Plate Tectonics. We categorize these movements based on the direction of the force and the scale of the impact:

Feature	Orogenic Movements	Epeirogenic Movements
Meaning	Mountain building (Oros = Mountain).	Continent building (Epeiros = Mainland).
Direction	Horizontal/Tangential forces acting on the crust.	Vertical forces causing uplift or subsidence.
Result	Severe folding (from compression) or faulting (from tension) in narrow belts Physical Geography by PMF IAS, Geomorphic Movements, p.81.	Simple deformation, uplift, or warping of large parts of the crust FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI, p.38.

While diastrophism works slowly over millions of years, Volcanism represents a more direct and often sudden transfer of internal energy to the surface. It involves the movement of molten rock (magma) toward or onto the Earth's surface. This occurs because radioactive decay deep within the Earth generates immense heat, melting rocks into magma. When pressure is reduced—often due to tectonic plates pulling apart—this magma rises, forming both intrusive features (cooling underground) and extrusive features like volcanoes Environment and Ecology, Majid Hussain, Natural Hazards and Disaster Management, p.10. Together, diastrophism and volcanism provide the raw material (mountains, plateaus, and new rock) that the processes of weathering and erosion will eventually act upon.

Sources: Physical Geography by PMF IAS, Geomorphic Movements, p.79; Physical Geography by PMF IAS, Geomorphic Movements, p.81; FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI, Geomorphic Processes, p.38; Environment and Ecology, Majid Hussain, Natural Hazards and Disaster Management, p.10

3. Exogenic Forces: Denudation and Gradation (basic)

To understand how our planet’s surface is sculpted, we must look at Exogenic Forces. While internal (endogenic) forces like volcanoes and earthquakes build up the Earth's crust, exogenic forces work tirelessly from the outside to level it down. These processes derive their primary energy from the Sun (driving climate/weather) and Gravity. The ultimate goal of these forces is Gradation—the process of bringing the Earth’s surface to a common 'grade' or level.

Gradation works through two distinct actions:

• Degradation: The wearing down of high reliefs (mountains/hills) through erosion.
• Aggradation: The filling up of low-lying areas (valleys/basins) through deposition.

Together, these ensure that the Earth's surface remains dynamic. This continuous 'uncovering' and leveling of the landscape is captured by the umbrella term Denudation, which comes from the word 'denude,' meaning to strip off or uncover Fundamentals of Physical Geography, Geography Class XI (NCERT 2025 ed.), Chapter 5, p. 39.

Denudation is not a single act but a sequence of four major processes: Weathering (breaking rocks in-situ), Mass Wasting (bulk movement due to gravity), Erosion (acquisition and transportation of debris), and Transportation. While weathering prepares the material by weakening the rock, erosion is largely responsible for the continuous change in landforms Fundamentals of Physical Geography, Geography Class XI (NCERT 2025 ed.), Chapter 5, p. 43. Crucially, these processes do not work at the same speed everywhere. Their intensity depends on thermal gradients, moisture levels, and the physical properties of the rocks, such as joints, faults, or mineral hardness Physical Geography by PMF IAS, Chapter 6, p. 82.

Process	Primary Characteristic	Nature
Weathering	Breaking down rocks where they stand.	In-situ (on-site)
Erosion	Picking up and moving rock debris.	Ex-situ (mobile)
Aggradation	Depositing materials in lowlands.	Constructive/Leveling

Sources: Fundamentals of Physical Geography, Geography Class XI (NCERT 2025 ed.), Chapter 5: Geomorphic Processes, p.39, 43; Physical Geography by PMF IAS, Chapter 6: Geomorphic Movements, p.82, 83

4. Plate Tectonics and Macro-Landforms (intermediate)

Concept: Plate Tectonics and Macro-Landforms

5. Soil Formation (Pedogenesis) and Lithology (intermediate)

Pedogenesis, or the process of soil formation, is the transformative journey of solid rock (lithology) into a fertile mantle capable of supporting life. This process begins with weathering, an in-situ or on-site disintegration and decomposition of rocks FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Geomorphic Processes, p.40. The nature of the parent material (the lithology) acts as the genetic blueprint; it determines the mineral composition, texture, and chemical properties of the nascent soil. For instance, rocks with many joints and cracks are more susceptible to the entry of water and chemical solutions, accelerating the breakdown process Certificate Physical and Human Geography, GC Leong (Oxford University press 3rd ed.), Weathering, Mass Movement and Groundwater, p.37.

Soil formation is not the result of a single force but an interplay of five fundamental factors: Parent Material, Topography, Climate, Biological Activity, and Time FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Geomorphic Processes, p.44. These factors do not act in isolation but are deeply interconnected Geography of India, Majid Husain, Soils, p.1. Geographers typically categorize these into Active and Passive factors based on how they drive the soil-forming environment:

Category	Factors	Role in Pedogenesis
Active Factors	Climate, Biological Activity	They supply the energy (heat) and moisture (precipitation) that drive chemical reactions and organic decomposition.
Passive Factors	Parent Material, Topography, Time	They provide the physical template, the setting, and the duration required for the active factors to work.

Finally, Time is the silent architect of soil maturity. A soil is considered "mature" only after these processes have operated for a sufficiently long period to develop a distinct soil profile or layers (horizons) FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Geomorphic Processes, p.45. Soils derived from recent deposits, such as new river alluvium, are considered "young" because they lack these well-defined horizons, proving that lithology provides the material, but time provides the structure.

Sources: FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Geomorphic Processes, p.40, 44, 45; Certificate Physical and Human Geography, GC Leong (Oxford University press 3rd ed.), Weathering, Mass Movement and Groundwater, p.37; Geography of India, Majid Husain (McGrawHill 9th ed.), Soils, p.1

6. The Geomorphic Triad: Structure, Process, and Stage (intermediate)

In the study of geomorphology, we often look for a 'formula' to explain why the Earth looks the way it does. The most famous answer came from the American geographer William Morris Davis, who proposed that every landscape is a product of three factors: Structure, Process, and Stage. Known as the Geomorphic Triad, this principle suggests that landforms are not random occurrences but the logical outcome of specific materials being acted upon by specific forces over a specific period of time.

Structure refers to the 'raw material' of the landscape. It includes the lithology (rock type, mineral composition, and hardness) and the structural features (such as folds, faults, joints, and the dip of the rock layers). For instance, a hard granite mountain will resist erosion differently than a soft limestone plateau. Similarly, the presence of joints or cracks determines how easily water can penetrate and weather the rock from within Physical Geography by PMF IAS, Geomorphic Movements, p. 78. Process represents the 'tools' or 'agents' of change. These include endogenic forces (like volcanism and diastrophism that build land up) and exogenic forces (like weathering, erosion, and deposition that wear land down). These processes, such as wind-driven deflation or water-driven abrasion, operate at varying rates depending on the environment Physical Geography by PMF IAS, Major Landforms and Cycle of Erosion, p. 235.

Finally, Stage (often synonymous with Time) acknowledges that landforms have a history. Much like a living organism, a landscape passes through an evolutionary cycle—from youth (where features are sharp and rugged) to maturity and eventually old age (where the land is worn down into a near-flat plain). Evolution here implies the gradual transformation of one landform into another as time passes Fundamentals of Physical Geography, Landforms and their Evolution, p. 47. By understanding this triad, geologists can look at a hill or a valley and 'read' its history, knowing exactly which forces shaped its current structure over the ages.

Factor	Simple Definition	Example Components
Structure	The 'What' (The Material)	Rock hardness, faults, folds, mineral density.
Process	The 'How' (The Action)	Weathering, erosion, glaciation, volcanism.
Stage	The 'When' (The Time)	Youthful vigor, mature balance, old age stability.

Sources: Physical Geography by PMF IAS, Geomorphic Movements, p.78; Physical Geography by PMF IAS, Major Landforms and Cycle of Erosion, p.235; Fundamentals of Physical Geography, Landforms and their Evolution, p.47

7. Differential Rates of Geomorphic Processes (exam-level)

If you look at the Earth's surface, you’ll notice it is far from a uniform slab. It is a masterpiece of complexity, shaped by a constant tug-of-war between internal (endogenic) forces that build up the crust and external (exogenic) forces that wear it down. However, the most fascinating part of geomorphology is not just that these processes happen, but that they happen at differential rates. This means that even if the same wind blows or the same rain falls, two different landscapes will react in completely different ways. These variations are primarily driven by three factors: the nature of the material, the climatic regime, and the gravitational gradient FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Chapter 5, p.38.

The first reason for these differential rates is lithology and structure. Different types of rocks offer varying levels of resistance. A rock might be incredibly tough and resistant to physical abrasion (like wind-blown sand) but might crumble quickly when exposed to chemical weathering (like acid rain). For instance, limestone might remain sturdy in a dry desert but dissolve rapidly in a humid, rainy tropical environment. Over long periods, these processes cause what we call continued fatigue in the rock structure—small, imperceptible changes that eventually lead to significant topographical shifts FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Chapter 5, p.40.

Climate acts as the master regulator of these rates. Within different climatic regions, factors like temperature ranges, the frequency of freezing and thawing, and the amount of precipitation dictate which geomorphic process dominates. Even on a single mountain, the aspect (the direction a slope faces) can create a micro-climate. A north-facing slope might stay frozen and undergo frost wedging, while a south-facing slope receives more sunlight and experiences different thermal stresses FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Chapter 5, p.39. This leads to variations in the depth of the weathering mantle (the layer of loose debris), which is much deeper in hot, humid tropics than in cold, arid poles FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Chapter 5, p.40.

Finally, we cannot ignore gravity and gradients. Gravity is the "master switch" that provides the energy for movement. Without a gradient (a slope or a pressure difference), there would be no mobility, meaning no erosion, transportation, or deposition would occur FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Chapter 5, p.38. The combination of these forces ensures that our Earth is never static; it is a landscape in a perpetual state of varied transformation.

Factor	Impact on Geomorphic Rates
Rock Structure	Determines resistance; folds, faults, and mineral composition dictate how easily a rock breaks.
Climate	Controls the 'intensity' of the process (e.g., high heat/moisture speeds up chemical reactions).
Topography	Determines the 'energy' available via gravity (steeper slopes = faster erosion).

Sources: FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Chapter 5: Geomorphic Processes, p.38-40

8. Solving the Original PYQ (exam-level)

Now that you have mastered the individual components of Geomorphology, this question brings those building blocks together to test your understanding of the integrated nature of landscape evolution. As we discussed in our concept sessions, landforms are not static features; they are the result of a dynamic equation. Statement 1 refers to lithology and structure—how hard or soft the rock is and whether it is folded or faulted—which dictates how resistant it is to change. Statement 2 highlights the Geomorphic Processes, specifically the tug-of-war between endogenic forces (building up) and exogenic forces (wearing down). Finally, Statement 3 addresses the differential rates of these processes, which explains why a desert landscape looks vastly different from a tropical one even if the rock types are similar, due to variations in climate and energy gradients as detailed in NCERT Class XI: Fundamentals of Physical Geography.

To arrive at the correct answer, you must apply the logic of process-response systems. If you only consider the material (Statement 1), you ignore the forces acting upon it. If you only consider the processes (Statement 2), you ignore why those processes create different shapes in different regions (Statement 3). Because the Earth’s surface is a product of material, process, and time/rate—often referred to as the Davisian trio in classical geomorphology—all three factors are indispensable. Therefore, the reasoning leads us directly to Option (D) 1, 2 and 3 as the only comprehensive choice.

In UPSC exams, options like (A), (B), and (C) are common traps designed to catch students who have a partial understanding. A student might focus only on tectonics (internal processes) and settle for (B), forgetting that the rate of erosion is equally vital in carving the final landform. UPSC often uses "all of the above" scenarios in geomorphology because the subject emphasizes the interconnectivity of Earth systems. To avoid these traps, always ask yourself: "If I removed this factor, would the landform still look the same?" If the answer is no, that factor must be part of your final selection.