Chapter Notes

Physical Features of India

India is a vast country with an incredible variety of landforms. If you live in a place like Delhi or Lucknow, you're used to seeing vast, flat plains. But if you live in a place like Shimla or Darjeeling, you're surrounded by rugged mountains and deep valleys. India is unique because it has almost every major physical feature you can find on Earth: towering mountains, expansive plains, dry deserts, high plateaus, and beautiful islands.

Geologically, India's landmasses have different origins and ages.

• The Peninsular Plateau (the large triangular part of southern India) is one of the most ancient and stable land blocks on the Earth's surface. It's made of very old igneous and metamorphic rocks.
• In contrast, the Himalayas and the Northern Plains are very recent landforms. The Himalayas are considered a geologically "youthful" and unstable mountain system, which is why they have such high peaks, deep valleys, and fast-flowing rivers.
• The Northern Plains were formed by the alluvial deposits (silt, sand, and clay) brought down by these rivers.

Major Physiographic Divisions

The physical features of India can be grouped into six major 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 that form a massive barrier along India's northern borders. They stretch in a west-to-east direction, from the Indus River to the Brahmaputra River, covering a distance of about 2,400 km in a massive arc.

Longitudinal Divisions of the Himalayas

The Himalayas consist of three main parallel ranges, running from north to south.

The Great or Inner Himalayas (The Himadri)

• This is the northernmost and highest range, with an average height of 6,000 metres.
• It is the most continuous range and contains all of the most prominent Himalayan peaks, including Mt. Everest (in Nepal), and Kanchenjunga (in India).
• The core of the Himadri is composed of granite.
• It is permanently snow-bound, and many glaciers, which are the source of major rivers, descend from this range.

The Lesser Himalaya (The Himachal)

• This range lies to the south of the Himadri and is the most rugged of the three.
• The ranges are mainly composed of highly compressed and altered rocks.
• The altitude varies between 3,700 and 4,500 metres, with an average width of 50 km.
• Important ranges here include the Pir Panjal (the longest), the Dhaula Dhar, and the Mahabharat ranges.
• This region is famous for its beautiful valleys, like the Kashmir Valley, and the Kangra and Kullu Valleys in Himachal Pradesh. It is also well-known for its hill stations.

The Outer Himalayas (The Shiwaliks)

• This is the outermost range of the Himalayas.
• It has a lower altitude, varying between 900 and 1100 metres, and a width of 10-50 km.
• These ranges are composed of unconsolidated sediments (like gravel and alluvium) brought down by rivers from the main Himalayan ranges to the north.
• The longitudinal valleys lying between the Lesser Himalaya and the Shiwaliks are known as Duns. Some well-known Duns are Dehra Dun, Kotli Dun, and Patli Dun.

West-to-East Divisions of the Himalayas

Besides the north-south divisions, the Himalayas are also divided based on regions from west to east, demarcated by river valleys.

• Punjab Himalaya: The part lying between the Indus and Satluj rivers. It is also known regionally as the Kashmir and Himachal Himalaya.
• Kumaon Himalayas: The part lying between the Satluj and Kali rivers.
• Nepal Himalayas: The part lying between the Kali and Teesta rivers.
• Assam Himalayas: The part lying between the Teesta and Dihang rivers.

The Purvachal or Eastern Hills

At the easternmost boundary, marked by the Brahmaputra River, the Himalayas bend sharply to the south. They spread along the eastern boundary of India and are known as the Purvachal or the Eastern hills and mountains.

• These hills run through the north-eastern states and are mostly composed of strong sandstones, which are sedimentary rocks.
• They are covered with dense forests and run as parallel ranges and valleys.
• The Purvachal includes the Patkai hills, the Naga hills, the Manipur hills, and the Mizo hills.

The Northern Plain

The vast Northern Plain was formed by the interplay of three major river systems: the Indus, the Ganga, and the Brahmaputra, along with their tributaries.

Formation and Features

• The plain is formed of alluvial soil, deposited over millions of years in a vast basin at the foothills of the Himalayas.
• This makes the plain incredibly fertile and agriculturally productive.
• It covers an area of 7 lakh sq. km, is about 2400 km long and 240 to 320 km broad.
• Because of its rich soil, adequate water supply, and favorable climate, it is a very densely populated region of India.
• In the lower course of the rivers, the gentle slope causes the river's velocity to decrease, leading to the formation of riverine islands. Majuli, in the Brahmaputra river, is the largest inhabited riverine island in the world.

Sections of the Northern Plain

The Northern Plain is broadly divided into three sections:

• The Punjab Plains: This is the western part of the Northern Plain, formed by the Indus and its five main tributaries (Jhelum, Chenab, Ravi, Beas, Satluj). A large part of this plain lies in Pakistan. This area is dominated by doabs (land between two rivers).
• The Ganga Plain: This vast plain extends between the Ghaggar and Teesta rivers. It covers the states of Haryana, Delhi, U.P., Bihar, and parts of Jharkhand and West Bengal.
• The Brahmaputra Plain: This is the easternmost part of the plain, located mainly in Assam.

Relief Features of the Northern Plain

The Northern Plain is not uniformly flat. It has diverse relief features and can be divided into four distinct regions based on these variations.

1. Bhabar: After descending from the mountains, rivers deposit pebbles in a narrow belt about 8 to 16 km wide, parallel to the slopes of the Shiwaliks. This belt is known as the bhabar. All streams disappear into this porous belt.
2. Terai: South of the bhabar belt, the streams and rivers re-emerge, creating a wet, swampy, and marshy region known as the terai. This area was once thickly forested and full of wildlife.
3. Bhangar: This is the largest part of the northern plain and is formed of older alluvium. It lies above the floodplains of the rivers and has a terrace-like feature. The soil in this region contains calcareous deposits locally known as kankar.
4. Khadar: The floodplains are formed of newer, younger deposits called khadar. This soil is renewed almost every year by floods, making it extremely fertile and ideal for intensive agriculture.

The Peninsular Plateau

The Peninsular Plateau is a tableland composed of old crystalline, igneous, and metamorphic rocks. It is the oldest landmass in India, formed from the breaking and drifting of the ancient Gondwana land. The plateau is characterized by broad, shallow valleys and rounded hills.

The plateau has two broad divisions: the Central Highlands and the Deccan Plateau.

The Central Highlands

• This is the part of the Peninsular plateau lying to the north of the Narmada river.
• The Vindhyan range bounds it on the south and the Aravali hills on the northwest.
• The rivers in this region, such as the Chambal, Sind, Betwa, and Ken, flow from southwest to northeast, indicating the slope of the land.
• The Central Highlands are wider in the west and narrower in the east. The eastward extensions are locally known as Bundelkhand and Baghelkhand.
• The Chotanagpur plateau marks the further eastward extension, drained by the Damodar river.

The Deccan Plateau

• This is a triangular landmass that lies south of the Narmada river.
• The Satpura range forms its broad base in the north, while the Mahadev, Kaimur, and Maikal ranges form its eastern extensions.
• The Deccan Plateau is higher in the west and slopes gently eastwards.
• An extension of the plateau is also visible in the northeast, known as the Meghalaya, Karbi-Anglong Plateau, and North Cachar Hills. It is separated from the Chotanagpur Plateau by a fault. The prominent hill ranges here are the Garo, the Khasi, and the Jaintia Hills.

The Western and Eastern Ghats

These two mountain ranges mark the western and eastern edges of the Deccan Plateau.

The Indian Desert

The Indian Desert, also known as the Thar Desert, lies towards the western margins of the Aravali Hills.

• It is an undulating sandy plain covered with sand dunes.
• This region receives very low rainfall, below 150 mm per year, resulting in an arid climate with sparse vegetation.
• Streams appear only during the rainy season and disappear into the sand soon after, as they don't have enough water to reach the sea. The Luni is the only large river in this region.
• Barchans, which are crescent-shaped dunes, cover large areas of the desert.

The Coastal Plains

The Peninsular plateau is flanked by narrow coastal strips on both its western and eastern sides.

The Western Coastal Plain

• This is a narrow plain sandwiched between the Western Ghats and the Arabian Sea.
• It consists of three sections:
  • Konkan: The northern part (Mumbai – Goa).
  • Kannad Plain: The central stretch.
  • Malabar Coast: The southern stretch.

The Eastern Coastal Plain

• These plains lie along the Bay of Bengal and are wide and level.
• It is divided into two parts:
  • Northern Circar: The northern part.
  • Coromandel Coast: The southern part.
• Large rivers like the Mahanadi, Godavari, Krishna, and Kaveri have formed extensive deltas on this coast. Lake Chilika, the largest salt water lake in India, is an important feature along the eastern coast.

The Islands

Besides its vast mainland, India also has two groups of islands.

Lakshadweep Islands

• This island group lies close to the Malabar coast of Kerala in the Arabian Sea.
• They are composed of small coral islands.
• In 1973, they were named Lakshadweep.
• It covers a small area of 32 sq. km. Kavaratti island is the administrative headquarters.
• This island group has a great diversity of flora and fauna. The uninhabited Pitti island has a bird sanctuary.

Andaman and Nicobar Islands

• These islands are located in the Bay of Bengal and form an elongated chain extending from north to south.
• They are bigger in size, more numerous, and more scattered than the Lakshadweep Islands.
• The entire group is divided into two categories: The Andaman in the north and The Nicobar in the south.
• It is believed that these islands are an elevated portion of submarine mountains.
• These islands lie close to the equator, experience an equatorial climate, and have thick forest cover. India's only active volcano is found on Barren island in this group.