Which among the following pairs are correct ? 1. Cirque and Col : Glacial topography 2. Barkhans and Yardangs : Desert topography 3. Eddies and potholes : Fluvial topography Select the correct answer using the code given below:

1. Geomorphic Processes: Endogenic and Exogenic Forces (basic)

To understand the beauty of our landscape, we must first recognize that the Earth’s surface is not static; it is a dynamic stage shaped by a constant tug-of-war between two massive forces. These are the geomorphic processes — physical and chemical actions that result in the configuration of the Earth’s surface. Broadly, we categorize these into Endogenic (internal) and Exogenic (external) forces. Think of endogenic forces as the 'builders' that create the raw material of mountains and plateaus, while exogenic forces act as the 'sculptors' that carve, wear down, and reshape that material over millions of years FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI, Chapter 6, p.38. Endogenic forces originate from deep within the Earth’s interior, fueled by primordial heat and radioactivity. These internal movements can be sudden, like volcanism and earthquakes, or slow and steady, like diastrophism (the process that builds mountain ranges through crustal warping). Their primary role is to create 'relief' — basically, they push the land up, creating height and unevenness Physical Geography by PMF IAS, Geomorphic Movements, p.78. On the other hand, Exogenic forces derive their energy from the Sun and gravity. They perform the work of weathering, mass wasting, erosion, and deposition. These processes are constantly trying to flatten the high points and fill in the low points, a process known as degradation and aggradation. To carry out this sculpting, exogenic forces use geomorphic agents. These are mobile elements of nature—like running water (rivers), moving ice (glaciers), wind, and waves—that acquire, transport, and deposit earth materials FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI, Chapter 6, p.38. The final shape of any landform depends on how these agents interact with the rocks over time. This continuous cycle ensures that every landform has a 'life history,' moving through stages comparable to youth, maturity, and old age FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI, Chapter 6, p.47.

Feature	Endogenic Forces	Exogenic Forces
Origin	Internal (Earth's Interior)	External (Atmosphere/Surface)
Energy Source	Radioactivity, Primordial Heat	Sun's Heat, Gravity
Action	Building up (Constructional)	Wearing down (Destructional)
Examples	Volcanism, Mountain Building	Weathering, Erosion, Deposition

Sources: FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI, Chapter 6: Geomorphic Processes, p.38; Physical Geography by PMF IAS, Geomorphic Movements, p.78; FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI, Chapter 6: Landforms and their Evolution, p.47

2. Weathering, Erosion, and Mass Movement (basic)

Concept: Weathering, Erosion, and Mass Movement

3. Agents of Gradation and Landform Cycles (basic)

To understand the face of our Earth, we must look at it as a constant battleground between forces that build land up and forces that wear it down. This process of leveling the Earth’s surface is called Gradation. It works in two directions: Degradation (wearing down high lands through erosion) and Aggradation (filling up lowlands through deposition). Together, these processes strive to reach a state of equilibrium called a grade.

The work of gradation is carried out by mobile agents. Interestingly, the most dominant agents represent the three states of matter: Wind (gaseous), Running Water (liquid), and Glaciers (solid). These three are primarily controlled by climatic conditions, such as temperature and precipitation Fundamentals of Physical Geography, Chapter 6, p.43. However, other agents like Sea Waves and Groundwater operate based on different factors. For instance, the work of waves is determined by the coastal interface, while groundwater depends heavily on the lithological character (rock type) of the region, such as the presence of soluble limestone Fundamentals of Physical Geography, Chapter 6, p.43.

Agent	Primary Control	Nature of Work
Running Water	Climate / Gravity	Most powerful agent; creates valleys, rills, and gullies Geography of India, Chapter 6, p.15.
Glaciers	Climate (Cold)	Massive ice sheets that pluck and abrade rocks into U-shaped valleys.
Wind	Climate (Arid)	Erodes and transports loose particles in dry regions to form dunes.
Groundwater	Lithology (Solubility)	Chemical action that dissolves rocks like limestone to create caves.

Every agent follows a similar cycle. First, they use kinetic energy to erode and transport materials. As the slope becomes gentler or the agent loses its velocity, it loses energy. This leads to deposition, where the heavier, coarser materials settle first, followed by finer particles Fundamentals of Physical Geography, Chapter 6, p.43. Therefore, landforms are never permanent; they are simply stages in a continuous cycle of being carved out and filled back in.

Sources: Fundamentals of Physical Geography, Geomorphic Processes, p.43; Geography of India, Soils, p.15

4. Adjacent Landforms: Karst and Coastal Topography (intermediate)

In this step, we explore how water—working through chemical and physical means—sculpts two of the most distinct terrains on Earth: Karst (limestone) and Coastal landscapes. While Karst is primarily a story of dissolving rock, Coastal topography is a story of relentless energy and impact.

Karst Topography occurs in regions with thick limestone or dolomite. Because limestone is mainly calcium carbonate (CaCO₃), it reacts with rainwater that has absorbed CO₂ from the atmosphere to form a weak carbonic acid. This process, known as carbonation, dissolves the rock along joints. On the surface, you’ll see small depressions called swallow holes. As these grow through continuous solution, they form larger, funnel-shaped sinkholes FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI, p.52. When several sinkholes merge, they form massive depressions called dolinas or even larger uvalas Certificate Physical and Human Geography, GC Leong, p.79.

Inside limestone caves, the dissolved minerals are redeposited as the water evaporates, creating spectacular "dripstones." The differences between these features are often tested in exams:

Feature	Formation Direction	Description
Stalactites	Hanging down from the ceiling	Broad at the base, tapering like icicles FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI, p.53.
Stalagmites	Rising up from the floor	Formed by dripping water from above; often take the shape of columns or discs.

Coastal Topography is shaped by the destructive and constructive power of waves. On high, rocky coasts, waves attack the base of cliffs through hydraulic action (compressing air in cracks) and abrasion. Over time, a sea cave may be hollowed out. If the waves erode through a headland, a sea arch is formed. When the arch collapses, a lonely pillar of rock called a stack is left standing in the water—such as the famous Old Man of Hoy Certificate Physical and Human Geography, GC Leong, p.91. Conversely, constructive waves deposit sediment to form spits (ridges of sand attached to land at one end) and bars (which can cut off a lagoon from the sea) Certificate Physical and Human Geography, GC Leong, p.95.

Sources: FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI, Chapter 6: Landforms and their Evolution, p.52-53; Certificate Physical and Human Geography, GC Leong, Limestone and Chalk Landforms, p.79; Certificate Physical and Human Geography, GC Leong, Coastal Landforms, p.91-95

5. Fluvial Dynamics: The Work of Running Water (intermediate)

Concept: Fluvial Dynamics: The Work of Running Water

6. Glacial Landscapes: The Power of Ice (exam-level)

When we think of ice, we often imagine a static, frozen block. However, in the context of geomorphology, glaciers are dynamic, massive bodies of ice that flow slowly under the influence of gravity. As they move, they act like giant natural bulldozers, carving the landscape through two primary processes: abrasion (grinding the bedrock like sandpaper) and plucking (lifting large chunks of rock frozen into the ice). Glacial landscapes are a testament to this immense power, characterized by distinct erosional features in high altitudes and depositional features in the lowlands.

The most fundamental erosional landform is the Cirque. Imagine a massive, bowl-shaped armchair carved into the side of a mountain. These depressions are found at the heads of glacial valleys where ice accumulates. As the glacier moves down, it deepens these basins, creating steep, near-vertical backwalls. When the ice eventually melts, these depressions often fill with water to form beautiful alpine lakes known as tarns FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Chapter 6, p.54. When two cirques erode toward each other from opposite sides of a ridge, they leave behind a narrow, knife-like ridge called an Arête Physical Geography by PMF IAS, Major Landforms and Cycle of Erosion, p.231. If three or more cirques meet, the result is a sharp, pyramidal peak known as a Horn (like the famous Matterhorn in the Alps).

As the glacier descends from the peaks, it transforms narrow V-shaped river valleys into wide, flat-bottomed U-shaped valleys or glacial troughs. A fascinating byproduct of this is the Hanging Valley. This occurs when a smaller "tributary" glacier joins a much deeper main glacier; after the ice melts, the floor of the tributary valley is left "hanging" high above the main valley floor, often resulting in spectacular waterfalls Certificate Physical and Human Geography, Chapter 7, p.66.

Once the glacier reaches warmer altitudes and begins to melt, it can no longer carry its heavy load of debris (known as till). This material is deposited to form Moraines. These are long ridges of unsorted rocky debris that tell the story of the glacier's path. Depending on where they are deposited, we classify them into several types:

Moraine Type	Location/Formation
Terminal Moraine	Deposited at the very end (toe) of the glacier, marking its furthest advance FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Chapter 6, p.55.
Lateral Moraine	Forms along the sides of the glacial valley, parallel to the ice flow.
Medial Moraine	Formed when two glaciers join and their internal lateral moraines merge into one central ridge FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Chapter 6, p.56.
Ground Moraine	An irregular sheet of till left over the valley floor as a glacier rapidly retreats.

Sources: FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Landforms and their Evolution, p.54; Physical Geography by PMF IAS, Major Landforms and Cycle of Erosion, p.231; Certificate Physical and Human Geography, Landforms of Glaciation, p.66; FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Landforms and their Evolution, p.55; FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Landforms and their Evolution, p.56

7. Aeolian Processes: Desert Landforms (exam-level)

In arid and semi-arid regions, wind acts as a powerful agent of erosion, transportation, and deposition. These are known as Aeolian processes (named after Aeolus, the Greek god of wind). While water still plays a role via flash floods, the absence of vegetation and moisture allows the wind to sculpt the landscape through abrasion (sandblasting effect), deflation (lifting loose particles), and attrition (particles bumping into each other).

Erosional landforms are created when wind-blown sand carves existing rock structures. Two common features often confused are Zeugen and Yardangs. A Zeugen is a 'ridge and furrow' landscape where a layer of hard rock sits horizontally over a layer of softer rock. Mechanical weathering opens joints in the hard rock, and wind abrasion 'eats' into the underlying soft layer, creating deep furrows GC Leong, Arid or Desert Landforms, p.70. In contrast, Yardangs are formed when the hard and soft rocks are arranged in vertical bands aligned with the prevailing wind direction PMF IAS, Major Landforms and Cycle of Erosion, p.237. The wind carves out the softer vertical bands into long, streamlined grooves, leaving the harder bands as steep-sided ridges.

Feature	Rock Stratification	Appearance
Zeugen	Horizontal layers (Hard over Soft)	Tabular blocks or 'mushrooms' with flat tops.
Yardang	Vertical bands (Hard side-by-side with Soft)	Streamlined, boat-shaped ridges parallel to wind.

On the depositional side, sand dunes are the most iconic features. Barchans are crescent-shaped dunes where the 'horns' or wings point downwind (away from the wind direction). They form in areas with a constant wind direction and a limited sand supply NCERT Class XI, Landforms and their Evolution, p.61. If the wind direction shifts slightly, a barchan may lose one wing and transform into a Seif (a longitudinal dune). Interestingly, Parabolic dunes look like reversed barchans; their wings point upwind because they are often anchored by vegetation NCERT Class XI, Landforms and their Evolution, p.61.

Sources: Certificate Physical and Human Geography, GC Leong, Arid or Desert Landforms, p.70-74; Physical Geography by PMF IAS, Major Landforms and Cycle of Erosion, p.237; FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT), Landforms and their Evolution, p.61

8. Solving the Original PYQ (exam-level)

Now that you have mastered the erosional and depositional processes of various geomorphic agents, this question serves as a perfect synthesis of those building blocks. In Pair 1, we look at Glacial topography where Cirques (amphitheater-like depressions) and Cols (mountain passes) are classic erosional features formed by moving ice. Moving to Pair 2, the question tests your knowledge of Desert (Aeolian) topography. Here, Barkhans represent the depositional side as crescent-shaped dunes, while Yardangs showcase the erosional power of wind carving through rock. Finally, Pair 3 connects Fluvial topography to the mechanical action of water, where Eddies—turbulent swirling currents—act as the primary mechanism for drilling Potholes into the rocky riverbed.

To arrive at the correct answer, (A) 1, 2 and 3, you must evaluate each agent's signature landform. Ask yourself: Is the primary force behind this shape ice, wind, or water? Since all three pairs correctly align the feature with its specific environment as detailed in FUNDAMENTALS OF PHYSICAL GEOGRAPHY (NCERT Class XI), the comprehensive option is the only logical choice. In the UPSC exam, the challenge often lies in not getting distracted by technical terms; once you recognize that Eddies are the cause and Potholes are the effect in a river system, the third pair becomes as clear as the first two.

A common trap in such matching questions is the selective exclusion found in options (B), (C), and (D). UPSC frequently swaps landforms between categories—for instance, placing Yardangs under Glacial or Cirques under Fluvial—to test if your conceptual clarity is solid. Students often doubt Pair 3 because Eddies are a fluid dynamic process rather than a static landform, but because they are the fundamental driver of pothole formation in fluvial systems, the match is entirely accurate. Do not let the 'only' in the other options sway you if you have verified the validity of all three statements through your conceptual framework.