Himalayas: Three Parallel Ranges

🟢 Lite — Quick Review (1h–1d)

Physical features of India are the natural landforms — mountains, plateaus, plains, and coastal strips — that shape drainage, agriculture, and settlement across the subcontinent. For TNPSC Group 1, three elements dominate every cycle:

The Himalayan System splits into three ranges: Greater Himalayas (Himadri) above 6,000 m, Middle Himalayas (Himachal) at 3,000–4,500 m, and Outer Himalayas (Shivalik) below 3,000 m. They rose during the Tertiary period (50 Ma) when the Indian Plate collided with the Eurasian Plate.
The Indo-Gangetic-Brahmaputra Plain covers ~7 lakh sq km — the world’s largest alluvial plain — built by the Indus, Ganga, and Brahmaputra. Sub-regions include Rajasthan desert, Punjab-Haryana plain, Ganga plain, and Brahmaputra valley.
The Peninsular Plateau divides into the Central Highlands (Malwa, Bundelkhand, Chota Nagpur) and the Deccan Plateau (Maharashtra, Karnataka, Tamil Nadu sections), composed of Archean granites, gneisses, and Dharwar schists.

Coastal features matter too: the Western Ghats (UNESCO, 2018; 1,600 km continuous) versus the Eastern Ghats (discontinuous, lower). The Western Coastal Plain (narrow, estuarine backwaters — Malabar Coast) contrasts with the wider Eastern Coastal Plain (Mahanadi–Cauvery deltas, Coromandel Coast).

TNPSC exam pointers: Expect match-the-following on mountain ranges and elevations, or description questions on the three Himalayan subdivisions. The Doab–Bhabar–Terai distinction and the Western vs Eastern Ghats contrast appear almost every cycle.

🟡 Standard — Regular Study (2d–2mo)

Himalayas: Three Parallel Ranges

The Himalayas formed from the Tertiary collision at roughly 40–50 mm/year — the fastest continental convergence on Earth. The Greater Himalayas (Himadri) contain peaks above 6,000 m including Mount Everest (8,586 m) and form a continuous barrier. The Middle Himalayas (Himachal) lie between 3,000–4,500 m, are heavily forested, and include popular hill stations (Shimla, Nainital). The Outer Himalayas (Shivalik) stand below 3,000 m, composed of unconsolidated gravel and sand (siwalik sediments), and are prone to landslides.

The Siwalik Range is the newest section of the Himalayan foothills, running from Jammu & Kashmir to Assam. The Purvanchal Hills extend the Himalayan system eastward along India’s northeastern border, comprising the Patkai, Naga, and Lushai hills. The Trans-Himalaya includes the Ladakh Plateau and the Karakoram — the syntaxial bend at the western extremity marks where the range curves sharply south.

Indo-Gangetic-Brahmaputra Plain

This plain’s four subdivisions reflect different depositional environments. The Rajasthan desert section in the west is arid with sand dunes. The Punjab-Haryana plain is the dissected alluvial plain of the five rivers (Punjab = “five rivers”). The Ganga plain is the most extensive, fertile, and densely populated. The Brahmaputra valley in Assam is marshy (terai-like) and prone to annual flooding.

Three terrace levels matter: Bhabar (porous pebble belt at the foothills, 8–16 km wide, where streams disappear underground), Terai (damp, marshy zone south of Bhabar, reclaimed for agriculture), Bhangar (older Pleistocene alluvium with calcareous kankar nodules), and Khadar (newer floodplain alluvium, sandy, renewed annually).

Peninsular Plateau

The Central Highlands include the Malwa Plateau (Madhya Pradesh, volcanic soils), Bundelkhand (P.State, granite domes), Chota Nagpur Plateau (Jharkhand, rich in mica and coal), and Meghalaya Plateau (northeastern extension). The Deccan Plateau — a vast basaltic lava flow region called the Deccan Traps (Cretaceous period, 65 Ma) — covers Maharashtra, Karnataka, Telangana, Andhra Pradesh, and Tamil Nadu. These traps thin eastward and are overlaid by Laterite.

The Aravalli Range (Delhi to Gujarat, 692 km) is the oldest fold mountain in India, running northwest–southeast. The Vindhya Range and Satpura Range form the connecting link between the Central Highlands and the Deccan, with the Narmada and Tapti rivers flowing through their valleys.

Coastal Plains

Feature	Western Coastal Plain	Eastern Coastal Plain
Width	50–100 km	100–130 km
Key sections	Konkan (Mumbai–Goa), Malabar Coast (Kerala)	Mahanadi, Godavari, Krishna, Cauvery deltas; Coromandel Coast
Character	Estuarine backwaters, narrow beaches	Wide deltas, extensive beaches
Rivers	Narmada, Tapti (form estuaries)	Mahanadi, Godavari, Krishna, Cauvery (form deltas)

The Western Ghats (Sahyadri) run 1,600 km continuously from Tapi to Kanyakumari at 900–1,100 m average elevation; major passes include Palakkad Gap (Kerala–Tamil Nadu trade route), Bhor Ghat (Mumbai–Pune rail route), and Goa Gap. The Eastern Ghats are discontinuous, lower (average 450 m), and dissected by eastward-flowing rivers.

🔴 Extended — Deep Study (3mo+)

Geomorphological Mechanisms

The Himalayas continue to rise ~5 mm/year through seismic activity along the Main Central Thrust (MCT) and Main Boundary Fault (MBF). The syntaxial bend at the western extremity (Nanga Parbat–Kashmir syntaxis) represents the most intense crustal shortening. The Garo-Rajmahal Gap — a structural discontinuity in the Himalayan system — allows the Brahmaputra to breach the range and enter Bangladesh. TNPSC has previously asked about the Brahmaputra’s anomalous transverse course through this gap.

The Deccan Traps represent one of Earth’s largest continental flood basalt provinces, erupted over 5 million years during the Cretaceous–Paleogene boundary. Their weathering produced the rich black cotton soil (regur) of Maharashtra and Madhya Pradesh, ideal for cotton cultivation. The Laterite capping on Eastern Ghats and Deccan plateau edges formed through intense tropical weathering and is a key distinguishing feature.

Biodiversity and UNESCO Recognition

The Western Ghats were designated a UNESCO World Heritage Site in 2018 and rank among Earth’s eight “hottest biodiversity hotspots.” They host ~7,400 plant species (375 endemic), 139 endemic amphibian species, and 16 endemic bird species. The Silent Valley in Kerala, Mahabaleshwar–Koyna region, and Brahmagiri wildlife sanctuary are TNPSC-relevant micro-topics.

Common TNPSC Mistakes

Confusing Bhabar and Terai: Bhabar is the narrow pebble-zone at the foothills; Terai is the wide marshy belt south of it. Students often swap their descriptions.
Equating Western and Eastern Ghats: The Western Ghats are continuous, higher, and recognized by UNESCO; the Eastern Ghats are discontinuous, lower, and dissected. They are not equivalent features.
Forgetting the Deccan Traps’ age: The traps are Cretaceous (~65 Ma), not the same age as Himalayan uplift. They post-date the Gondwana sedimentation.

Practice Prompts

Describe with a sketch the three Himalayan ranges from north to south, indicating their average elevation, rock type, and two major peaks or hill stations found in each.
Compare and contrast the Western Coastal Plain and Eastern Coastal Plain under the heads of width, drainage pattern, agricultural significance, and major ports.

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Himalayas: Three Parallel Ranges