Which of the following hills is the southernmost hill range in India ?

1. Physiography of the Peninsular Plateau (basic)

The Peninsular Plateau is the oldest and most stable landmass of India. Unlike the youthful and restless Himalayas, this region is a massive tableland composed of ancient crystalline, igneous, and metamorphic rocks. It was formed due to the breaking and drifting of the Gondwanaland supercontinent, making it one of the most stable geological blocks on Earth. Geographically, it is triangular in shape, with its base coinciding with the southern edge of the Great Northern Plains and its apex at Kanyakumari CONTEMPORARY INDIA-I, Geography, Class IX, p.10.

The plateau is broadly divided into two main sections by the Narmada River: the Central Highlands to the north and the Deccan Plateau to the south. One of its most defining features is its west-to-east slope. While the Western Ghats are higher and more continuous, the land gradually tilts toward the east, which is why most major peninsular rivers—like the Godavari, Krishna, and Kaveri—flow into the Bay of Bengal CONTEMPORARY INDIA-I, Geography, Class IX, p.12. Interestingly, this plateau isn't just limited to the south; it has a hidden extension in the Northeast, forming the Meghalaya Plateau (Garo, Khasi, and Jaintia Hills), which is separated from the main block by a geological fault Geography of India, Majid Husain, Physiography, p.57.

Feature	Peninsular Plateau	Himalayan Mountains
Geological Age	Ancient, stable landmass (Gondwanaland).	Young, weak, and flexible.
Rock Type	Igneous and Metamorphic rocks.	Sedimentary rocks.
Topography	Rounded hills and shallow valleys.	High peaks and deep valleys.

Sources: CONTEMPORARY INDIA-I, Geography, Class IX, Physical Features of India, p.10-12; Geography of India, Majid Husain, Physiography, p.57

2. Western Ghats vs. Eastern Ghats (intermediate)

The Western Ghats and Eastern Ghats constitute the structural edges of the Deccan Plateau, but they are vastly different in personality. Think of the Western Ghats as a continuous wall and the Eastern Ghats as a series of broken stepping stones. The Western Ghats (locally known as Sahyadri in Maharashtra) are significantly higher and more continuous, meaning they can only be crossed through specific passes like the Thal, Bhor, and Pal Ghats Contemporary India-I, Physical Features of India, p.12. In contrast, the Eastern Ghats are lower and have been heavily eroded and dissected by the great east-flowing rivers like the Mahanadi, Godavari, Krishna, and Kaveri, making them discontinuous and irregular Contemporary India-I, Physical Features of India, p.12.

One of the most critical geographical features is where these two giants meet: the Nilgiri Hills. This area acts as a 'mountain knot' connecting the two systems Geography of India, Physiography, p.58. If we travel further south from the Nilgiris, we encounter a major break called the Palghat Gap. South of this gap, the mountains rise again as the Anaimalai Hills (home to Anaimudi, the highest peak in South India) and eventually taper off into the Cardamom Hills, which are the southernmost major range of the Indian mainland India Physical Environment, Structure and Physiography, p.12.

Feature	Western Ghats (Sahyadris)	Eastern Ghats
Continuity	Continuous; can be crossed only through passes.	Discontinuous; dissected by rivers.
Average Elevation	Higher (900–1600 meters).	Lower (Average ~600 meters).
Rainfall Type	Causes Orographic Rain by intercepting moist monsoon winds.	Lower rainfall; parallel to the monsoon track in many areas.

Sources: Contemporary India-I, Physical Features of India, p.12; Geography of India, Physiography, p.58; India Physical Environment, Structure and Physiography, p.12

3. The Junction: Nilgiri Hills (intermediate)

The Nilgiri Hills, often referred to as the "Blue Mountains," serve as the majestic mountain knot where the Western Ghats and the Eastern Ghats converge in Southern India. This junction is a critical geographical feature located at the tri-junction of Tamil Nadu, Kerala, and Karnataka. While the Western Ghats are generally higher (average 900–1600m) and form a continuous wall, the Eastern Ghats are lower (average 600m) and have been eroded into discontinuous blocks by major rivers draining into the Bay of Bengal CONTEMPORARY INDIA-I, Physical Features of India, p.12. In this region, the Western Ghats are locally known as the Nilgiris, transitioning from the Sahyadri in the north INDIA PHYSICAL ENVIRONMENT, Structure and Physiography, p.12.

Physiographically, the Nilgiris are separated from the southern reaches of the peninsula by the Palghat Gap (or Palakkad Gap). This significant low mountain pass acts as a vital break in the otherwise continuous Western Ghats, allowing for climatic and cultural exchange between the coastal plains of Kerala and the interior of Tamil Nadu. To the south of this gap, the mountains rise again as the Anaimalai Hills, which house Anaimudi—the highest peak in the Peninsular plateau at 2,695 meters Geography of India, Majid Husain, Physiography, p.58.

Beyond its physical stature, the Nilgiri region holds immense ecological value. It is the heart of the Nilgiri Biosphere Reserve, which was the first biosphere reserve established in India. It is globally recognized for its biodiversity and is included in the UNESCO World Network of Biosphere Reserves, alongside other critical sites like the Gulf of Mannar and Nokrek Geography of India, Majid Husain, Natural Vegetation and National Parks, p.49.

Feature	Western Ghats	Eastern Ghats
Continuity	Continuous (crossed via passes like Thal/Bhor)	Discontinuous and irregular
Average Elevation	900 – 1600 meters	~600 meters
Interaction	Both meet at the Nilgiri Mountain Knot

Sources: CONTEMPORARY INDIA-I, Physical Features of India, p.12; INDIA PHYSICAL ENVIRONMENT, Structure and Physiography, p.12; Geography of India (Majid Husain), Physiography, p.58; Geography of India (Majid Husain), Natural Vegetation and National Parks, p.49

4. Gaps and Passes of the Western Ghats (exam-level)

Unlike the Eastern Ghats, which are highly dissected and irregular, the Western Ghats (Sahyadris) form a near-continuous mountain wall running parallel to the Arabian Sea coast. This continuity is a defining geographic feature, but it creates a challenge for transport between the coastal plains and the interior Deccan Plateau. To overcome this, human civilization has relied on a few natural depressions or "Gaps" (Passes) that pierce through the range.

In the northern section of the Western Ghats (Maharashtra region), two primary passes facilitate movement from the Konkan coast to the plateau. The Thalghat (also known as Kasara Ghat) serves as the vital link between Mumbai and Nashik, while the Bhorghat connects Mumbai to Pune. These passes are historical gateways that now host some of India's busiest railway lines and highways Majid Husain, Geography of India, Chapter 2, p.65. As we move south, the mountains gain elevation, reaching their highest point at Anaimudi (2,695 m), located in the Anaimalai Hills Majid Husain, Geography of India, Chapter 2, p.58.

The most significant break in the entire Western Ghats is the Palghat Gap (or Palakkad Gap). Unlike the narrow northern passes, this is a broad corridor about 30 km wide that separates the Nilgiri Hills in the north from the Anaimalai Hills in the south Majid Husain, Geography of India, Chapter 2, p.58. It acts as a major climatic and cultural conduit between Kerala and Tamil Nadu. Further south, near the tip of the peninsula, lies the Shencottah Gap, which cuts through the mountains to connect the Kollam district of Kerala with Madurai in Tamil Nadu.

Pass/Gap	Location/Connection	Key Geographic Context
Thalghat	Mumbai to Nashik	Located in the northern Sahyadris.
Bhorghat	Mumbai to Pune	Essential link for the Mumbai-Chennai route.
Palghat Gap	Kochi/Palakkad to Coimbatore	Divides the Nilgiris from the Anaimalai Hills.
Shencottah Gap	Kollam to Madurai	Southernmost major gap of the Western Ghats.

Sources: Geography of India (Majid Husain), Chapter 2: Physiography, p.58; Geography of India (Majid Husain), Chapter 2: Physiography, p.65

5. River Systems of the Southern Hills (intermediate)

The southern hills of India—comprising the Nilgiri, Anaimalai, and Cardamom Hills—act as a massive 'water tower' for the peninsula. Unlike the young, turbulent rivers of the Himalayas, the rivers originating here are mostly in their senile stage. This means they have already spent millions of years eroding their valleys, resulting in broad, shallow channels with very little vertical erosion Geography of India, The Drainage System of India, p.22. Because these hills are part of the Western Ghats, they create a major water divide: the vast majority of large rivers flow eastward into the Bay of Bengal, while short, swift-moving streams rush westward into the Arabian Sea.

The Kaveri River is the undisputed crown jewel of this system. Rising in the Brahmagiri hills of Karnataka, it is unique among Peninsular rivers. While most southern rivers are purely seasonal and rain-fed, the Kaveri remains almost perennial. This is because its upper catchment receives rainfall from the Southwest Monsoon (summer), while its lower reaches in Tamil Nadu are fed by the Northeast Monsoon (winter) INDIA PHYSICAL ENVIRONMENT, Drainage System, p.24. This dual-monsoon regime ensures a relatively steady flow of water throughout the year, supporting vast agricultural belts.

Further south, the Cardamom Hills give rise to the Periyar River, the longest and most important river in Kerala. Classified as a 'medium' river basin (catchment area between 2,000-20,000 sq. km), the Periyar is a lifeline for the region, supporting major hydroelectric projects like the Idukki dam and providing water for industrial hubs like Kochi INDIA PHYSICAL ENVIRONMENT, Drainage System, p.19.

Feature	Peninsular Rivers (Southern Hills)	Extra-Peninsular Rivers (Himalayas)
Age	Older, mature/senile stage	Young, youthful stage
Nature of Flow	Mostly seasonal (Rain-fed)	Perennial (Glacier & Rain-fed)
Erosion	Mainly lateral (broad valleys)	Vigorous vertical (deep gorges)

Sources: Geography of India, The Drainage System of India, p.22; INDIA PHYSICAL ENVIRONMENT, Drainage System, p.19, 24

6. North-to-South Mapping of Southern Hills (exam-level)

Understanding the spatial arrangement of the southern hills is crucial for UPSC mapping questions. As the Indian peninsula tapers toward the Indian Ocean, the Western Ghats and Eastern Ghats converge, creating a complex knot of highland ranges. The sequence generally begins in the north with the Nallamalai Hills (part of the Eastern Ghats in Andhra Pradesh) and moves down toward the Nilgiri Hills. The Nilgiris serve as the grand junction where the Eastern and Western Ghats finally meet Geography of India, Majid Husain, Physiography, p.58. Interestingly, the Western Ghats are known by various local names as you move south: Sahyadri in Maharashtra, Nilgiris in Karnataka/Tamil Nadu, and the Anaimalai and Cardamom Hills in Kerala INDIA PHYSICAL ENVIRONMENT, NCERT Class XI, Structure and Physiography, p.12. Moving further south from the Nilgiris, we encounter a distinct break in the mountain wall known as the Palghat Gap (or Palakkad Gap). This 25 km wide gap is a vital corridor connecting the plains of Tamil Nadu with the Kerala coast Geography of India, Majid Husain, Physiography, p.58. South of this gap, the mountains rise again as the Anaimalai Hills (home to Anai Mudi, the highest peak of South India), followed by the Cardamom Hills. The Cardamom Hills are the southernmost major range of the Indian mainland, though they taper further into the Agasthyamalai range before reaching Cape Comorin.

Region (North to South)	Key Mountain/Hill Range	Notable Feature
North (Eastern Ghats)	Nallamalai Hills	Part of the Cuddapah formations.
Central Junction	Nilgiri Hills	The meeting point of Eastern and Western Ghats.
South of Palghat Gap	Anaimalai Hills	Highest elevation in the Peninsula (Anai Mudi).
Deep South	Cardamom Hills	Southernmost major range; famous for spice plantations.

Sources: Geography of India, Majid Husain, Physiography, p.58; INDIA PHYSICAL ENVIRONMENT, NCERT Class XI, Structure and Physiography, p.12

7. Solving the Original PYQ (exam-level)

Having mastered the North-to-South alignment of the Indian Peninsula, you can now see how these individual building blocks fit into a larger geographical puzzle. This question tests your ability to visualize the Western Ghats as they taper toward the tip of the Indian subcontinent. While the Nallamalai Hills are situated much further North in the Eastern Ghats (Andhra Pradesh/Telangana), the real challenge lies in distinguishing the sequence of the southern ranges where the Western and Eastern Ghats converge. According to INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.), the sequence follows a clear southward progression: the Nilgiri Hills act as the junction, followed by the Palghat Gap, then the Annamalai Hills, and finally the Cardamom Hills.

To arrive at the correct answer, (D) The Cardamom Hills, you must apply the logic of relative spatial positioning. Start by identifying the Nilgiri Hills as the "meeting point" or the middle anchor. Moving south, you cross the Anaimalai range—famous for Anai Mudi, the highest peak of South India. However, the range that extends furthest toward Cape Comorin (Kanyakumari) is the Cardamom range. As noted in Geography of India, Majid Husain, these hills are the final major physiographic feature of the Indian mainland. UPSC often uses the Nilgiri Hills or Annamalai Hills as distractors because they are more prominent in common discourse, but the Cardamom Hills represent the true geographical terminus of the mainland's major relief.