Physical Features of India

Revision Notes for (Class X NCERT Chapter 2)

1 Overview of India’s Physiographic Diversity

India is characterized by an extraordinary array of physical features, ranging from the towering folds of the north to the ancient stable blocks of the south. This varied terrain is a result of complex geological processes; while the Peninsular Plateau represents one of the oldest and most stable landmasses on Earth (part of the Gondwana landmass), the Himalayas and Northern Plains are recent formations. This diversity directly dictates the nation's climatic patterns, the distribution of fertile "granaries," and the availability of mineral wealth, providing India with significant strategic depth and resource self-sufficiency.

Major Physiographic Divisions

Based on physical features, India is divided into six distinct regions:

• The Himalayan Mountains
• The Northern Plains
• The Peninsular Plateau
• The Indian Desert
• The Coastal Plains
• The Islands

The Geological Contrast: Ancient Stability vs. Tectonic Vulnerability The transition from the Peninsular Plateau to the Himalayan Mountain system marks a shift from geological antiquity to youth. The Plateau, composed of stable igneous and metamorphic rocks with rounded hills, represents a stable land block. In contrast, the Himalayas form an "unstable zone" of recent origin. Their youthful topography—defined by high peaks, deep valleys, and fast-flowing rivers—continues to be shaped by structural folding, making the region highly susceptible to seismic activity compared to the stable crystalline basement of the south.

2 The Himalayan Mountain System: Longitudinal and Regional Analysis

The Himalayas serve as a massive physical and climatic barrier stretching 2,400 km from the Indus to the Brahmaputra. Structurally, they are young fold mountains representing one of the most rugged terrains in the world. Their "youthful" nature is evidenced by high-velocity rivers and deep gorges, with an altitudinal variation that is notably greater in the eastern half than in the western half.

Longitudinal Parallel Ranges

The system consists of three parallel ranges, each with distinct geological and physical characteristics:

Range Name	Average Altitude / Width	Distinctive Features
Great or Inner Himalayas (Himadri)	Alt: 6,000m / Width: Varied	Most continuous range; core composed of granite; perennially snow-bound with numerous glaciers.
Himachal (Lesser Himalayas)	Alt: 3,700–4,500m / Width: 50km	Composed of highly compressed and altered rocks; contains the Pir Panjal, Dhaula Dhar, and Mahabharat ranges; famous for hill stations.
Shiwaliks (Outer Himalayas)	Alt: 900–1,100m / Width: 10–50km	Composed of unconsolidated sediments; contains "Duns" (longitudinal valleys) like Dehra Dun, Kotli Dun, and Patli Dun.

Highest Peaks of the Himalayas

Peak Name	Country	Height (metres)
Mt. Everest	Nepal	8,848
Kanchenjunga	India	8,598
Makalu	Nepal	8,481
Dhaulagiri	Nepal	8,172
Nanga Parbat	India	8,126
Annapurna	Nepal	8,078
Nanda Devi	India	7,817
Kamet	India	7,756
Namcha Barwa	India	7,756
Gurla Mandhata	Nepal	7,728

Regional Divisions by River Valleys

• Punjab Himalayas: Lying between the Indus and Satluj rivers (regionally known as Kashmir and Himachal Himalaya).
• Kumaon Himalayas: Lying between the Satluj and Kali rivers.
• Nepal Himalayas: Lying between the Kali and Teesta rivers.
• Assam Himalayas: Lying between the Teesta and Dihang rivers.

The Purvachal (Eastern Hills)

Beyond the Dihang gorge, the Himalayas bend sharply southwards. These hills, known as the Purvachal, are primarily composed of strong sedimentary sandstones. They are characterized by dense forest cover and parallel ranges, including the Patkai, Naga, Manipur, and Mizo hills, creating a distinct geographical identity characterized by rugged forest terrain.

3 The Northern Plains: Formation and Relief Features

The Northern Plains are a product of millions of years of alluvial deposition at the foothills of the Himalayas. Covering 7 lakh sq. km, these plains are the "granaries of India," where rich soil and favorable climate support intensive agricultural production and high population densities.

Etymology and Major Sections

The plains are formed by the interplay of the Indus, Ganga, and Brahmaputra rivers.

• Etymology: "Doab" is derived from 'do' (two) and 'ab' (water). Similarly, "Punjab" comes from 'Punj' (five) and 'ab' (water).
• Punjab Plains: The western part dominated by "doabs."
• Ganga Plain: Extends between Ghaggar and Teesta rivers; covers Haryana, Delhi, U.P., Bihar, and West Bengal.
• Brahmaputra Plain: Lies mainly in Assam.

Relief Regions of the Northern Plains

Region Name	Physical Characteristics	Agricultural / Ecological Value
Bhabar	8–16 km wide belt of pebbles at the foot of Shiwaliks.	All streams disappear in this belt due to high porosity.
Terai	Wet, swampy, and marshy region south of Bhabar.	Streams re-emerge; high wildlife diversity; cleared for intensive agriculture.
Bhangar	Older alluvium; terrace-like features; contains kankar (calcareous deposits).	Largest part of the plain; lies above floodplains.
Khadar	Newer, younger deposits of the floodplains.	Renewed annually; highly fertile; ideal for intensive agriculture.

So What? Riverine Dynamics In the lower course, the gentle slope causes a decrease in river velocity, leading to depositional work. This results in the formation of riverine islands (e.g., Majuli, the world's largest inhabited riverine island). Additionally, the heavy silt load causes rivers to split into numerous channels known as distributaries.

4 The Peninsular Plateau: Ancient Landmasses and Ghats

The Peninsular Plateau is a tableland composed of old crystalline, igneous, and metamorphic rocks. As the oldest and most stable part of the Indian landmass, it serves as a critical mineral storehouse for industrialization.

Broad Divisions

• The Central Highlands: Lying north of the Narmada, covering the Malwa plateau.
  Slope and Drainage: The plateau is wider in the west and narrower in the east. The flow of rivers (Chambal, Sind, Betwa, and Ken) is from Southwest to Northeast, clearly indicating the regional slope.
• The Deccan Plateau: A triangular landmass south of the Narmada. It is higher in the west and slopes gently eastward.
• The Northeast Extension: Includes the Meghalaya, Karbi-Anglong Plateau, and North Cachar Hills.
  Strategic Detail: These extensions are separated by a fault (Malda Fault) from the Chotanagpur Plateau.
• Chotanagpur Plateau: Marks the further eastward extension of the Central Highlands, drained by the Damodar river.

Comparison: Western Ghats vs. Eastern Ghats

Feature	Western Ghats	Eastern Ghats
Continuity	Continuous; crossed only through passes (Thal, Bhor, Pal Ghats).	Discontinuous and irregular; dissected by rivers flowing into the Bay of Bengal.
Elevation	Higher; average 900–1,600 metres.	Lower; average 600 metres.
Highest Peak	Anai Mudi (2,695m).	Mahendragiri (1,501m).
Rainfall	Causes orographic rain on western slopes.	Rainfall is less intense; stretches from Mahanadi Valley to Nilgiris.

The Deccan Trap: A defining feature is the Deccan Trap, an area of volcanic origin. The igneous rocks here have denuded over time, resulting in the formation of fertile black soil, essential for cotton cultivation and specific crop types.

5 Arid Zones, Coasts, and Islands

The Indian Desert

Located on the western margins of the Aravali Hills, it is an undulating sandy plain covered with sand dunes.

• Climate: Low rainfall (below 150 mm/year) and arid conditions.
• Hydrology: Luni is the only large river.
• Features: Dominated by Barchans (crescent-shaped dunes).

The Coastal Plains

• Western Coast: Narrow plain between Western Ghats and Arabian Sea. Sections: Konkan (Mumbai-Goa), Kannad Plain, and Malabar Coast.
• Eastern Coast: Wide and level. Sections: Northern Circar and Coromandel Coast. Features extensive deltas and Lake Chilika (India's largest saltwater lake).

The Island Groups

• Lakshadweep Islands: Close to Malabar coast; total area 32 sq km. Origin: Composed of small coral islands. Specifically, they feature Atolls—circular or horse-shoe shaped coral reefs.
• Andaman & Nicobar Islands: Elongated chain in the Bay of Bengal; believed to be elevated portions of submarine mountains. Strategic Feature: Contains Barren Island, India's only active volcano. Experiences an equatorial climate with thick forest cover.

6 Final Summary: Resource Complementarity

The interplay of India's physiographic units ensures natural resource self-sufficiency, with each region providing a unique economic base that supports national development.

Economic and Resource Significance of Physiographic Units

Physiographic Unit	Primary Resource Contribution
Mountains	Major sources of water (perennial rivers) and forest wealth.
Northern Plains	The "granaries" of the country; base for early civilizations.
Plateau	Storehouse of minerals; crucial for industrialization.
Coasts / Islands	Provide essential sites for fishing and international port activities.