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| Class 9th Chapters | ||
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| 1. India – Size And Location | 2. Physical Features Of India | 3. Drainage |
| 4. Climate | 5. Natural Vegetation And Wildlife | 6. Population |
Chapter 2 Physical Features Of India
India is a vast country characterised by a remarkable diversity of landforms. Depending on where one lives, the terrain can range from the extensive flat stretches of plains to the rugged landscapes of mountains and valleys. India encompasses virtually all major physical features found on Earth, including mountains, plains, deserts, plateaus, and islands.
The land of India exhibits significant physical variations. Geologically, the **Peninsular Plateau** is one of the Earth's oldest landmasses and is considered a relatively stable block. In contrast, the **Himalayas** and the **Northern Plains** are much younger landforms. From a geological perspective, the Himalayan mountain system is considered an unstable zone, featuring a very youthful topography with towering peaks, deep valleys, and fast-flowing rivers. The northern plains are formed by alluvial deposits, while the Peninsular plateau is composed of older igneous and metamorphic rocks with gently sloping hills and broad valleys.
Figure 2.2 is a map illustrating the six major physiographic divisions of India: The Himalayan Mountains, The Northern Plains, The Peninsular Plateau, The Indian Desert, The Coastal Plains, and The Islands.
Major Physiographic Divisions
The diverse physical features of India can be broadly categorised into six major physiographic divisions:
- The Himalayan Mountains
- The Northern Plains
- The Peninsular Plateau
- The Indian Desert
- The Coastal Plains
- The Islands
The Himalayan Mountains
The **Himalayas** are geologically young and structurally fold mountains located along India's northern borders. They extend in a west-east direction, from the Indus River to the Brahmaputra River, forming a formidable mountain barrier. The Himalayas are among the loftiest and most rugged mountain ranges globally, covering an arc-like distance of approximately **2,400 km**.
The width of the Himalayas varies, being wider in Kashmir (400 km) and narrower in Arunachal Pradesh (150 km). The altitudinal variations are more pronounced in the eastern part compared to the western part.
Figure 2.1 is an illustrative photo of the Himalayas, showcasing their majestic and rugged peaks, representing the towering mountain range along India's northern border.
The Himalayas consist of three parallel ranges running longitudinally, with numerous valleys situated between them:
- **The Great or Inner Himalayas (Himadri):** This is the northernmost and most continuous range. It features the loftiest peaks with an average altitude of 6,000 metres and contains all the prominent Himalayan peaks. The core of this range is composed of granite, and it is perpetually covered in snow, with many glaciers originating here.
- **The Himachal or Lesser Himalaya:** Located to the south of the Himadri, this range is the most rugged mountain system. It is primarily composed of highly compressed and altered rocks. Altitudes range between 3,700 and 4,500 metres, with an average width of 50 km. Prominent ranges include the Pir Panjal (the longest and most important), Dhaula Dhar, and Mahabharat ranges. This region is known for its famous valleys like Kashmir, Kangra, and Kullu, popular for hill stations.
- **The Shiwaliks:** This is the outermost range of the Himalayas, with a width of 10-50 km and altitudes varying between 900 and 1100 metres. These ranges are formed of unconsolidated sediments carried down by rivers from the northern Himalayan ranges. The valleys lying between the Lesser Himalaya and the Shiwaliks are called **Duns** (e.g., Dehra Dun, Kotli Dun, Patli Dun), and they are covered with thick gravel and alluvium.
Some of the highest peaks of the Himalayas include:
Format 1 (Vertical)
| Peak | Country | Height in metres |
|---|---|---|
| Mt. Everest | Nepal | 8848 |
| Kanchenjunga | India | 8598 |
| Makalu | Nepal | 8481 |
| Dhaulagiri | Nepal | 8172 |
| Nanga Parbat | India | 8126 |
| Annapurna | Nepal | 8078 |
| Nanda Devi | India | 7817 |
| Kamet | India | 7756 |
| Namcha Barwa | India | 7756 |
| Gurla Mandhata | Nepal | 7728 |
Besides longitudinal divisions, the Himalayas are also divided regionally from west to east based on river valleys. Examples include:
- **Punjab Himalaya:** Between Indus and Satluj rivers (also known as Kashmir and Himachal Himalaya).
- **Kumaon Himalayas:** Between Satluj and Kali rivers.
- **Nepal Himalayas:** Between Kali and Teesta rivers.
- **Assam Himalayas:** Between Teesta and Dihang rivers.
The **Brahmaputra River** marks the easternmost boundary of the Himalayas. Beyond the Dihang gorge, the Himalayas take a sharp southward bend and extend along India's eastern border, forming the **Purvachal** or the Eastern hills and mountains. These hills, running through the north-eastern states, are composed mainly of strong sandstones (sedimentary rocks). They are covered with dense forests and primarily exist as parallel ranges and valleys. The Purvachal includes the Patkai hills, Naga hills, Manipur hills, and Mizo hills.
Figure 2.4 is a photo illustrating the Mizo Hills, which are part of the Purvachal or Eastern Hills in Northeast India. These hills, composed of sedimentary rocks and covered with dense forests, are a distinct physiographic feature.
The Northern Plain
The **Northern Plain** of India is an extensive and fertile region formed by the interaction of three major river systems: the **Indus, the Ganga, and the Brahmaputra**, along with their tributaries. This vast plain is composed of **alluvial soil**, deposited over millions of years in a basin at the foothills of the Himalayas. It spans an area of **7 lakh sq. km**.
The plain is approximately **2400 km long** and varies in width from **240 to 320 km**. Its fertile soil, combined with adequate water supply from rivers and a favourable climate, makes it an agriculturally highly productive region and one of the most densely populated physiographic divisions of India.
Figure 2.5 is a map focusing on the Northern Plains of India. It depicts the vast stretch of the plain and the major river systems (Indus, Ganga, Brahmaputra, and their tributaries) responsible for its formation through alluvial deposition.
The rivers originating from the northern mountains deposit sediments in the plains. In their lower courses, the reduced velocity due to gentle slopes leads to the formation of riverine islands, such as Majuli in the Brahmaputra River, which is the world's largest inhabited riverine island. Rivers in their lower courses also split into numerous channels called **distributaries** due to silt deposition.
The Northern Plain is broadly divided into three sections:
- **The Punjab Plains:** The western part, formed by the Indus and its tributaries (Jhelum, Chenab, Ravi, Beas, Satluj), which originate in the Himalayas. A significant portion of this plain lies in Pakistan. This area is characterised by **doabs**, fertile land between two rivers ('do' meaning two, 'ab' meaning water; similarly, 'Punjab' means land of five rivers).
- **The Ganga Plain:** Extends between the Ghaggar and Teesta rivers, covering states like Haryana, Delhi, Uttar Pradesh, Bihar, parts of Jharkhand, and West Bengal.
- **The Brahmaputra Plain:** Located in the east, particularly in Assam.
Contrary to the perception of being a uniformly flat land, the Northern Plains exhibit diverse relief features and can be divided into four regions based on these variations:
- **Bhabar:** A narrow belt (8-16 km wide) parallel to the Shiwaliks where rivers descending from the mountains deposit pebbles. Streams often disappear in this porous belt.
- **Terai:** South of the Bhabar belt, where streams and rivers re-emerge, creating a wet, swampy, and marshy region. Historically, it was a thickly forested area rich in wildlife, but forests have been cleared for agriculture and settlement (especially after Partition). Dudhwa National Park is located in this region.
- **Bhangar:** The largest part of the Northern Plain, formed of older alluvium. It lies above the floodplains and has a terrace-like structure. The soil contains calcareous deposits called kankar.
- **Khadar:** The newer, younger alluvial deposits of the floodplains. These are renewed almost annually by floods, making them highly fertile and ideal for intensive agriculture.
The Peninsular Plateau
The **Peninsular Plateau** is a stable **tableland** composed of ancient crystalline, igneous, and metamorphic rocks. It was formed from the breaking and drifting of the Gondwana supercontinent, making it one of the oldest landmasses. The plateau features broad and shallow valleys and gently rounded hills.
The Peninsular plateau is divided into two main sections:
- **The Central Highlands:** The part of the Peninsular plateau situated north of the Narmada River. It covers a major area of the Malwa plateau and is bounded by the Satpura range in the south and the Aravalis in the northwest. Its westward extension merges with the Rajasthan desert. Rivers in this region (Chambal, Sind, Betwa, Ken) flow from southwest to northeast, indicating the slope. The Central Highlands are wider in the west and narrower in the east. Eastward extensions are known locally as Bundelkhand and Baghelkhand. The **Chotanagpur plateau**, drained by the Damodar River, marks the further eastward extension.
- **The Deccan Plateau:** A triangular landmass located south of the Narmada River. Its broad base in the north is flanked by the Satpura range, and its eastern extensions include the Mahadev, Kaimur hills, and Maikal range. The Deccan Plateau is higher in the west and slopes gently towards the east. An extension is also found in the northeast (Meghalaya, Karbi-Anglong Plateau, North Cachar Hills), separated by a fault from the Chotanagpur Plateau. Prominent hill ranges from west to east in this northeastern extension are the Garo, Khasi, and Jaintia Hills.
The **Western Ghats** and the **Eastern Ghats** form the western and eastern boundaries of the Deccan Plateau. The Western Ghats run parallel to the western coast, are continuous, and can only be crossed via passes (Thal, Bhor, Pal Ghats). They are higher than the Eastern Ghats, with an average elevation of 900–1600 metres. The Western Ghats receive orographic rain from moist winds rising along their western slopes. They are known by various local names and their height increases from north to south, with the highest peaks being Anai Mudi (2,695 m) and Doda Betta (2,637 m).
The Eastern Ghats stretch from the Mahanadi Valley to the Nilgiris in the south, with an average height of 600 metres. They are discontinuous, irregular, and dissected by rivers flowing into the Bay of Bengal. Mahendragiri (1,501 m) is the highest peak in the Eastern Ghats. The Shevroy Hills and Javadi Hills are located southeast of the Eastern Ghats.
Figure 2.6 is a photograph of a waterfall in the Chotanagpur Plateau. Waterfalls are a feature found in plateau regions, often where rivers flow over escarpments or variations in the land surface, illustrating the ruggedness of plateau topography compared to plains.
A notable feature of the Peninsular plateau is the **Deccan Trap**, a region of **black soil** formed from volcanic origin. The rocks are igneous and have denuded over time, contributing to the formation of this fertile black soil. The **Aravali Hills**, highly eroded and existing as broken hills, lie on the western and northwestern edges of the Peninsular plateau, extending from Gujarat to Delhi.
The Indian Desert
The **Indian Desert**, also known as the Thar Desert, is located towards the western margins of the Aravali Hills. It is a sandy plain characterised by undulating terrain and covered with sand dunes.
This region receives very low rainfall, typically below 150 mm per year, resulting in an **arid climate** with sparse vegetation. Streams appear only during the rainy season and quickly disappear into the sand due to insufficient water to reach the sea. The **Luni River** is the only significant river in this region.
Barchans (crescent-shaped dunes) are a common feature in the Indian Desert, covering large areas. Longitudinal dunes become more noticeable near the Indo-Pakistan border.
Figure 2.7 shows a photo of the Indian Desert, featuring extensive sand dunes (barchans) which are characteristic landforms of this arid region, highlighting the dry and sandy nature of the terrain.
The Coastal Plains
The Peninsular plateau is flanked by narrow coastal strips running along the Arabian Sea in the west and the Bay of Bengal in the east, known as the **Coastal Plains**.
The **western coast**, situated between the Western Ghats and the Arabian Sea, is a narrow plain divided into three sections from north to south:
- **Konkan coast** (Mumbai – Goa)
- **Kannad Plain** (central stretch)
- **Malabar coast** (southern stretch)
The plains along the **Bay of Bengal** (eastern coast) are wider and more level. In the northern part, this plain is called the **Northern Circar**, while the southern part is known as the **Coromandel Coast**. Large rivers like the Mahanadi, Godavari, Krishna, and Kaveri have formed extensive and fertile **deltas** on this coast. **Lake Chilika**, located south of the Mahanadi delta in Odisha, is an important feature along the eastern coast and is the largest salt water lake in India.
Figure 2.8 is a map highlighting the Coastal Plains of India along both the Arabian Sea and the Bay of Bengal, showing the differences in width and the presence of deltas and lakes along these coastal stretches.
The Islands
Besides its vast mainland, India includes two major groups of islands.
1. **Lakshadweep Islands:** Located close to the Malabar coast of Kerala in the **Arabian Sea**. This group is composed of small **coral islands**. Formerly known as Laccadive, Minicoy, and Amindive, they were renamed Lakshadweep in 1973 and cover a small area of 32 sq km. Kavaratti island is the administrative headquarters. The islands are known for their diverse flora and fauna. Pitti island, which is uninhabited, hosts a bird sanctuary. **Corals** are microscopic organisms that live in colonies and form reefs by secreting calcium carbonate; types include barrier reefs, fringing reefs, and atolls (circular/horseshoe-shaped). Lakshadweep islands are of coral origin.
Figure 2.9 is an illustration of an island, representing the isolated landmass surrounded by water, like the Lakshadweep or Andaman and Nicobar islands that constitute significant parts of India's territory.
2. **Andaman and Nicobar Islands:** An elongated chain of islands situated in the **Bay of Bengal**, extending from north to south. These islands are larger, more numerous, and scattered compared to Lakshadweep. The group is divided into the Andaman in the north and the Nicobar in the south. They are believed to be the elevated portions of submarine mountains. These island groups hold significant strategic importance for India. They also boast rich diversity of flora and fauna. Located close to the Equator, they experience an equatorial climate and are covered with thick forest. India's only active volcano, **Barren island**, is found in this group.
A detailed study of India's physiographic units reveals that each region possesses unique characteristics and resources. These diverse regions **complement each other**, enhancing India's overall natural wealth. Mountains provide water and forest resources, the northern plains are the agricultural heartland, the plateau is rich in minerals vital for industry, and the coastal areas and islands are crucial for fishing and port activities. This diversity in physical features offers immense potential for future development.
The bhabar is a narrow belt (8-16 km wide) parallel to the Shiwalik foothills where rivers deposit pebbles after descending from the mountains. Streams often disappear into this porous belt.
The three major divisions of the Himalayas from north to south are the Great or Inner Himalayas (Himadri), the Lesser Himalaya (Himachal), and the Shiwaliks.
The plateau that lies between the Aravali and the Vindhyan ranges is the **Malwa Plateau**, part of the Central Highlands.
The island group of India having coral origin is the **Lakshadweep Islands**.
**Bhangar vs. Khadar:**
- Bhangar: Older alluvial deposits of the Northern Plain, lying above the floodplains, with a terrace-like structure and containing calcareous deposits (kankar). Less fertile than Khadar.
- Khadar: Newer, younger alluvial deposits of the floodplains, renewed annually by floods, highly fertile and ideal for intensive agriculture.
**Western Ghats vs. Eastern Ghats:**
- Western Ghats: Mark the western edge of the Deccan Plateau, parallel to the western coast. Continuous, higher elevation (900-1600m), cause orographic rain, known by local names, height increases north to south.
- Eastern Ghats: Mark the eastern edge of the Deccan Plateau, parallel to the eastern coast. Discontinuous, irregular, lower elevation (600m), dissected by rivers flowing into the Bay of Bengal, stretch from Mahanadi valley to Nilgiris.
**The Indian Desert:** Located west of the Aravali Hills, it's a sandy plain with undulating terrain and sand dunes. Characterised by arid climate, low rainfall (<150mm/year), and sparse vegetation. Luni is the only major river; streams are seasonal. Barchans are common dunes.
**The Central Highlands:** Part of the Peninsular Plateau north of the Narmada, covering the Malwa plateau. Bounded by Satpura (south) and Aravalis (northwest). Rivers drain southwest to northeast. Wider in the west, narrower in the east. Includes Bundelkhand, Baghelkhand, and Chotanagpur plateau.
**The Island groups of India:** Two main groups. Lakshadweep (Arabian Sea): small, coral islands, near Malabar coast, Kavaratti is HQ, known for flora/fauna/bird sanctuary. Andaman and Nicobar (Bay of Bengal): elongated chain, north-south, larger, more numerous, elevated submarine mountains, strategically important, equatorial climate, thick forests, rich flora/fauna, includes Barren island (active volcano).
The Himalayan region is geologically young, unstable, with high peaks, deep valleys, fast-flowing rivers, and prone to seismic activity, formed by fold mountains. The Peninsular plateau is geologically old, stable (mostly), composed of ancient crystalline rocks, with broad shallow valleys, rounded hills, and gentler slopes.
The Northern Plains are vast, fertile, flat lands formed by alluvial deposits of Indus, Ganga, Brahmaputra and tributaries. Highly productive agriculturally, densely populated. Divided into Punjab, Ganga, and Brahmaputra plains. Feature variations like Bhabar (pebbles), Terai (marshy), Bhangar (older alluvium, terraces), and Khadar (newer alluvium, floodplains).