Match List-I with List-II and select the answer using the code given below the Lists : List-I List-II (Island / Nation) (Tectonic Plate) A. Comoros 1. North American Plate B. Baffin Island 2. African Plate C. Sri Lanka 3. Eurasian Plate D. Andaman Islands 4. Indo-Australian Plate Code : A B C D

1. Fundamentals of Plate Tectonics Theory (basic)

Welcome to your first step in mastering Plate Tectonics! To understand why our mountains rise and oceans widen, we must first look at the Earth not as a solid, static rock, but as a giant, dynamic machine. At its core, Plate Tectonics Theory suggests that the Earth's rigid outer shell, known as the Lithosphere, is not a single piece but is broken into several large and small "plates" that move relative to one another. Physical Geography by PMF IAS, Earths Interior, p.54

The secret to this movement lies in the layering of the Earth. Imagine a rigid cracked shell of a hard-boiled egg sliding over a slippery, jam-like interior. The "shell" is the Lithosphere, which includes the crust and the very topmost part of the mantle. It is strong and rigid, but it sits directly on top of the Asthenosphere—a hot, semi-fluid (ductile) layer of the upper mantle. Because the asthenosphere is mechanically weak and plastic-like, it allows the heavy lithospheric plates to "float" and glide over it. Physical Geography by PMF IAS, Earths Interior, p.55

Feature	Lithosphere	Asthenosphere
State	Rigid and Brittle	Plastic, Ductile, and Viscous
Composition	Crust + Topmost Mantle	Upper Mantle (below Lithosphere)
Function	Breaks into tectonic plates	The "lubricant" that allows movement

But what actually pushes these massive plates? The engine is Convectional Currents. Deep within the Earth, heat is generated by the radioactive decay of elements like Uranium and Thorium, as well as residual primordial heat from the Earth's formation. Physical Geography by PMF IAS, Tectonics, p.98. This heat creates a cycle where hot mantle material rises, cools near the surface, and then sinks back down. Geologist Arthur Holmes first proposed that these currents act like a conveyor belt, dragging the plates along the surface at speeds ranging from less than 2.5 cm/year (Arctic Ridge) to over 15 cm/year (East Pacific Rise). Physical Geography by PMF IAS, Tectonics, p.102

Sources: Physical Geography by PMF IAS, Earths Interior, p.54-55; Physical Geography by PMF IAS, Tectonics, p.98, 102; Environment and Ecology, Majid Hussain, BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY, p.10

2. Classification of Major and Minor Plates (basic)

Think of the Earth's lithosphere (the crust and the uppermost solid mantle) not as a continuous shell, but as a giant jigsaw puzzle. These puzzle pieces are what we call Tectonic Plates. Geologists classify these plates into two main categories—Major and Minor—primarily based on their massive surface area and their role in global tectonics. While they vary in size, every plate, whether huge or small, is constantly in motion, floating atop the semi-fluid asthenosphere.

According to the theory of plate tectonics, there are seven major plates that cover the vast majority of the Earth's surface. These plates are often a mix of both continental and oceanic crust. For example, the North American Plate includes not just the continent but also the floor of the western Atlantic Ocean Fundamentals of Physical Geography, Geography Class XI (NCERT 2025 ed.), Distribution of Oceans and Continents, p.32. Interestingly, the Pacific Plate is the only major plate that is almost entirely oceanic.

Type of Plate	Characteristics	Primary Examples
Major Plates	Vast surface area; define the primary global tectonic framework.	Antarctica, North American, South American, Pacific, India-Australia-New Zealand, Africa, and Eurasia.
Minor Plates	Smaller fragments, often formed due to stress between converging major plates.	Cocos, Nazca, Arabian, Philippine, Caribbean, and Juan de Fuca.

Minor plates, though smaller, are incredibly active and responsible for significant geological features. For instance, the Nazca Plate (located between South America and the Pacific Plate) is famous for subducting under the South American Plate to form the Andes Mountains Physical Geography by PMF IAS, Tectonics, p.105. Similarly, the Arabian Plate consists mostly of the Saudi Arabian landmass. In recent years, researchers have even identified smaller microplates, such as the Capricorn microplate, which sits between the Indian and Australian portions of their larger shared plate Physical Geography by PMF IAS, Tectonics, p.106.

Sources: Fundamentals of Physical Geography, Geography Class XI (NCERT 2025 ed.), Distribution of Oceans and Continents, p.32; Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.), Tectonics, p.102-106

3. Types of Plate Boundaries and Landforms (intermediate)

To understand the Earth's surface, we must look at the margins where tectonic plates meet. These boundaries are the "weak zones" of the lithosphere where internal heat from mantle convection currents finds an escape, leading to the creation and destruction of landforms Physical Geography by PMF IAS, Volcanism, p.139. Depending on the direction of plate movement, we classify these interactions into three main types: Divergent, Convergent, and Transform.

1. Divergent Boundaries (Constructive): Here, plates pull away from each other. As they separate, magma rises from the mantle to fill the gap, cooling to form new crust. This process is the engine behind the creation of new seas and oceans Physical Geography by PMF IAS, Divergent Boundary, p.126. While most commonly found on the ocean floor as mid-ocean ridges, they can also occur on land, creating rift valleys.

2. Convergent Boundaries (Destructive): This occurs when two plates collide. The outcome depends on the nature of the plates involved. In all cases, the denser plate subducts (sinks) beneath the less dense plate Physical Geography by PMF IAS, Convergent Boundary, p.111.

• Ocean-Ocean (O-O) Convergence: This results in the formation of Island Arcs—narrow, curved chains of volcanic islands like the Ryukyu Islands of Japan—and deep-sea trenches like the Japan Trench Physical Geography by PMF IAS, Convergent Boundary, p.114.
• Ocean-Continent (O-C) Convergence: The denser oceanic plate subducts, creating massive volcanic mountain ranges (like the Andes) on the continental edge.
• Continent-Continent (C-C) Convergence: Since both plates are relatively light, neither subducts easily; instead, they crumple to form massive fold mountains like the Himalayas.

3. Transform Boundaries (Conservative): Here, plates slide past each other horizontally along a transform fault. No new crust is created, and none is destroyed. These boundaries are often hidden in the deep ocean, where they offset divergent ridges in a zigzag pattern, though they can occasionally be found on land, such as the Dead Sea transform fault Physical Geography by PMF IAS, Types of Mountains, p.138.

Boundary Type	Action	Key Landforms
Divergent	Spreading	Mid-ocean ridges, Rift valleys, New ocean basins
Convergent	Subduction/Collision	Trenches, Island arcs, Fold mountains, Volcanic arcs
Transform	Lateral Sliding	Fault lines, Offset ridges

Sources: Physical Geography by PMF IAS, Divergent Boundary, p.126; Physical Geography by PMF IAS, Types of Mountains, p.138; Physical Geography by PMF IAS, Volcanism, p.139; Physical Geography by PMF IAS, Convergent Boundary, p.111, 114

4. Geological Evolution of the Indian Plate (intermediate)

To understand why India looks the way it does today, we must view it as a tectonic traveler. Millions of years ago, the landmass we call India was located in the Southern Hemisphere, near the South Pole, as part of the massive supercontinent Gondwanaland Physical Geography by PMF IAS, Convergent Boundary, p.121. This southern landmass included present-day South America, Africa, Antarctica, and Australia. Between India and the northern supercontinent (Laurasia) lay the Tethys Sea, a shallow sea that would eventually vanish to give birth to the Himalayas Physical Geography by PMF IAS, Convergent Boundary, p.121.

The evolution of the Indian Plate is characterized by its remarkable northward drift. After breaking away from the Australia-Antarctica assembly about 140 million years ago, the Indian plate began moving toward the Eurasian plate at a relatively high speed of about 5-6 cm per year. During this journey, two transformative geological events occurred:

• The Deccan Traps: As the plate moved north, it passed over the Reunion Hotspot around 60 million years ago. This caused massive outpourings of basaltic lava, creating the vast Deccan Plateau (shield volcanism) in western and central India Physical Geography by PMF IAS, Convergent Boundary, p.121.
• The Himalayan Orogeny: Around 40-50 million years ago, India finally collided with the Eurasian Plate. Because both plates were continental (though the Tethys oceanic crust subducted first), the sediments of the Tethys were squeezed and folded into the Himalayan mountain ranges Geography of India, Majid Husain, Physiography, p.5.

Interestingly, the Peninsular Block of India is one of the oldest and most stable landmasses on Earth, with some rocks dating back over 3,600 million years Geography of India, Majid Husain, Physiography, p.48. While it remained largely rigid during the Himalayan collision, the intense pressure caused internal block faulting, creating the rift valleys where the Narmada and Tapi rivers flow today. Even now, the Indian plate continues to move northward, causing a crustal shortening of about 500 km and ensuring that the Himalayas continue to grow in height Geography of India, Majid Husain, Physiography, p.5.

Sources: Physical Geography by PMF IAS, Convergent Boundary, p.121; Geography of India by Majid Husain, Physiography, p.5, 48; INDIA PHYSICAL ENVIRONMENT, NCERT Class XI, Structure and Physiography, p.8

5. The East African Rift and Indian Ocean Islands (intermediate)

Concept: The East African Rift and Indian Ocean Islands

6. Regional Tectonics: Arctic and SE Asia (exam-level)

When we apply plate tectonics to specific regions like the Arctic and Southeast Asia, we look beyond the seven major plates to see how specific islands and archipelagos are positioned relative to plate boundaries. In the Arctic, Baffin Island is a prime example of a landmass that is geologically part of the stable North American Plate Physical Geography by PMF IAS, Tectonics, p.102. While it is surrounded by icy waters, its basement rock is a continuation of the North American continental crust, illustrating that plate boundaries often lie far offshore in the oceanic crust rather than at the coastline. Moving to Southeast Asia, the tectonic setting becomes much more complex due to Ocean-Ocean convergence. This region is a jigsaw puzzle of major plates and microplates. The Indonesian and Philippine archipelagos were formed by the subduction of denser oceanic crust, which melts at depth to create volcanic island arcs Physical Geography by PMF IAS, Convergent Boundary, p.113. A critical example for your exams is the Andaman Islands. While they are geographically close to India, they sit on the edge of the Eurasian Plate (specifically the Burma microplate). This is because the Indo-Australian Plate is subducting underneath the Eurasian Plate at this boundary; the islands themselves sit on the "overriding" plate side of the trench Physical Geography by PMF IAS, Minor Tectonic Plates, p.106. In the Indian Ocean, we see further distinctions: Sri Lanka is a detached fragment of the Indo-Australian Plate Physical Geography by PMF IAS, The Indo-Australian Plate, p.104, sharing the same tectonic foundation as the Indian subcontinent. Conversely, the Comoros Islands near East Africa sit on the African Plate. Understanding these associations is vital because it explains why some islands experience intense volcanic and seismic activity (like the Andamans or Indonesia) while others (like Baffin Island) remain tectonically quiet.

Region	Island/Landmass	Tectonic Plate Membership
Arctic	Baffin Island	North American Plate
South Asia	Sri Lanka	Indo-Australian Plate
Southeast Asia	Andaman Islands	Eurasian Plate (Burma Microplate)
East Africa	Comoros	African Plate

Sources: Physical Geography by PMF IAS, Tectonics, p.102; Physical Geography by PMF IAS, Convergent Boundary, p.113; Physical Geography by PMF IAS, Minor Tectonic Plates, p.106; Physical Geography by PMF IAS, The Indo-Australian Plate, p.104

7. Solving the Original PYQ (exam-level)

Now that you have mastered the fundamental distribution of major and minor tectonic plates, this question requires you to apply that spatial awareness to specific landmasses. The core concept here is the distinction between continental margins and plate boundaries. As we discussed in our study of Physical Geography by PMF IAS, islands are rarely independent plates; they are usually fragments of larger lithospheric blocks or products of volcanic activity at the edges of those blocks.

Let’s walk through the logic: start with the most geographically certain links to narrow your choices. Baffin Island is deep within the Canadian Arctic, making it a clear match for the North American Plate (B-1). Similarly, Comoros is located in the Mozambique Channel off the coast of East Africa, placing it on the African Plate (A-2). This immediately narrows your options down significantly. For the remaining two, remember that Sri Lanka is geologically an extension of the Indian peninsula, sitting on the Indo-Australian Plate (C-4). The Andaman Islands present the trickiest part of the puzzle; they are located at a convergent boundary where the Indo-Australian plate subducts. Because they sit on the overriding side of the arc (the Burma microplate), they are categorized under the Eurasian Plate (D-3).

UPSC frequently uses "boundary islands" like the Andamans as distractors. In options (A) and (B), the sequence is designed to trip up students who associate the Andamans with the Indo-Australian Plate simply because of their proximity to India. However, the tectonic identity of a landmass is determined by which plate it rests upon, not which country it belongs to politically. By carefully identifying the overriding plate in subduction zones and the shared lithospheric blocks of continental islands, you can confidently arrive at the correct answer: (D) 2 1 4 3.