Class 9 (Geography) Chapter 2 (Physical Features of India)

 

Class 9 (Geography)

Chapter 2 (Physical Features of India)

 

Notes

 

 

Physical Features of India:

Origins of Indian Landforms:

• The Peninsular Plateau region was once part of Gondwana Land millions of years ago.
• Landmass shifts and oceanic currents fragmented the land into pieces.
• The northward movement of the Indo-Australian plate led to its collision with the Eurasian plate, resulting in the formation of the Himalayas.

Key Physical Features of India:

• India's physical features can be broadly classified into six categories based on their physiographic structures.

The Himalayan Mountain Range:

• The Himalayas, located in the northernmost part of India, are renowned for being the world's tallest and most rugged mountains.
• Stretching over 2500 KM from Kashmir to Arunachal Pradesh, they form an arc.
• The width of the Himalayan range varies from 400 Km to 150 KM and is divided into three main sections:
• The Greater Himalayas with peaks towering up to 6000 meters.
• The Lesser Himalayas with peaks reaching heights of about 4000 meters.
• The Outer Himalayas, also known as the Shivalik Range.
• Additionally, the Eastern Hills or Purvanchal are situated in North Bengal and the northernmost parts of northeastern states.

The Northern Plains:

• These plains, situated at the foothills of the Himalayas, are irrigated by the major river systems of the Ganges, Indus, and Brahmaputra.
• The fertile plains owe their richness to the extensive alluvial deposits brought down by these rivers.
• The Northern Plains can be categorized into three sections:
• The region of the Indus River and its tributaries in Pakistan.
• The plains along the Ganges in states like Haryana, Bihar, Uttar Pradesh, and Jharkhand.
• The Brahmaputra Plains in Assam and other northeastern states.

The Peninsular Plateau:

• Formed from the geological movements of Gondwana Land, the Peninsular Plateau is the oldest landmass in India.
• It is divided into:
• The Central Highlands covering the Malwa Plateau north of the Narmada River.
• The Deccan Plateau, triangular in shape and bordered by the Eastern and Western Ghats.
• The Satpura mountain ranges in the northern part of the Deccan Plateau.
• The Western Ghats, with peaks rising to 1600 meters, and the Eastern Ghats, reaching heights of about 600 meters.

The Indian Desert:

• Located on the western edges of the Aravalli Hills, the Indian Desert comprises undulating sandy fields.
• With minimal precipitation (around 150 mm per annum), it is considered the driest region in the country.
• The desert region spans across Rajasthan and the northwestern parts of Gujarat.

The Coastal Plains:

• India's coastal plains lie along the Arabian Sea and the Bay of Bengal.
• The Western coast is divided into three segments: the Konkan (Mumbai – Goa), the Kannad Plain, and the Malabar coast.
• The Eastern coast comprises the Northern Circar and the Coromandel Coast.
• Large deltas, formed by rivers such as the Mahanadi, Godavari, Krishna, and Kaveri, are notable features.
• Lake Chilika is a prominent feature on the eastern coast.

The Islands:

• Two major groups of islands surround the Indian mainland.
• The Lakshadweep islands, consisting mainly of coral formations, lie closer to the Malabar Coast.
• The Andaman and Nicobar Islands, situated in the Bay of Bengal, are larger in size and renowned for their rich biodiversity.
• The Andaman and Nicobar Islands, being closer to the equator, experience a tropical climate.

 

 

Important Question Answers

 

Question 1. What defines tectonic plates?

Answer: Tectonic plates refer to large fragments of the Earth's crust that have been torn apart due to rising currents.

Question 2. Which landmasses were part of the ancient Gondwana land?

Answer: South America, portions of Africa (including South Africa and Madagascar), parts of Asia (such as India, Arabia, and Malaya), Australia, and Antarctica were all components of the Gondwana land.

Question 3. Define the term "bhabar."

Answer: The bhabar is a narrow belt of plain covered with pebbles that runs along the foothills of the Shiwaliks from the Indus to the Teesta.

Question 4. List the three main divisions of the Himalayas from north to south.

Answer: The three major divisions of the Himalayas from north to south are the Great Himalayas (Himadri), the Middle Himalayas (Himachal), and the Outer Himalayas (Shivaliks).

Question 5. Which plateau is situated between the Aravali and Vindhyan ranges?

Answer: The Malwa plateau is located between the Aravali and Vindhyan Ranges.

Question 6. Identify the Indian island group formed primarily from coral.

 Answer: The Lakshadweep Islands constitute the Indian island group primarily formed from coral.

Question 7. Distinguish between Converging and diverging tectonic plates

Answer: When tectonic plates converge, they move towards each other, resulting in a collision or one plate sliding under the other. This process leads to the formation of folds in the crust.

On the other hand, when tectonic plates diverge, they move away from each other without colliding or crumbling. This movement creates fractures in the crust.

Question 8. Distinguish between Bhangar and Khadar.

Answer:  Bhangar refers to the older alluvium or aged soil, constituting the majority of the Northern Plains. It lies above the flood plains of rivers and exhibits a terrace-like feature, often containing calcareous deposits known as Kankar. However, it is less fertile compared to Khadar.

Khadar, on the other hand, represents the newer and younger deposits of flood plains, renewed annually. It is situated below Bhangar and is characterized by its higher fertility, making it more suitable for agricultural purposes.

Question 9. Distinguish between Western Ghats and Eastern Ghats

Answer:  The Western Ghats delineate the western boundary of the Deccan Plateau, whereas the Eastern Ghats mark its eastern edge. The Western Ghats form a continuous range, traversable only through passes, while the Eastern Ghats are discontinuous, irregular, and intersected by rivers flowing into the Bay of Bengal.

With an average elevation ranging from 900 to 1600 meters, the Western Ghats stand taller compared to the Eastern Ghats, which have an average elevation of around 600 meters. The Western Ghats serve as a source for many major rivers, unlike the Eastern Ghats, from which no significant river originates.

The Western Ghats predominantly experience orographic rainfall during the summer monsoons, resulting in a hot and moist climate. In contrast, the Eastern Ghats receive rainfall both in summer and winter, particularly through winter monsoons, though the amount is generally lower than that received by the western strip.

The soil in the Western Ghats is highly fertile, conducive to the cultivation of rice, spices, rubber, and fruits like coconuts and cashew nuts. Conversely, the soil in the Eastern Ghats is not as fertile as that in the Western Ghats, but it still supports the cultivation of crops such as rice, groundnuts, cotton, tobacco, and coconuts.

Question 10. Contrast the relief of the Himalayan region with that of the Peninsular plateau.

Answer: The Himalayan Region, characterized by its young fold mountains resulting from the uplift of strata formed by sedimentary rocks, contrasts with the Peninsular Plateau, which originated from igneous and metamorphic rocks following the fragmentation of Gondwanaland.

In terms of topography, the Himalayan Region features the loftiest mountains and deep valleys, often with I-shaped and U-shaped valleys. On the other hand, the Peninsular Plateau consists of broad and shallow valleys, along with rounded hills, including horsts, rift valleys, and troughs.

The Himalayan Region serves as the origin of perennial rivers, while the Peninsular Plateau is characterized by rainfed, seasonal rivers.

Geologically, the Himalayan Region is considered an unstable zone, whereas the Peninsular Plateau forms a stable zone.

Question 11: Discuss the Northern Plains of India.

Answer: The Northern Plains of India have been shaped by the alluvium deposited by mountain rivers, rendering the surface soil fertile for diverse crop cultivation. This facilitated the rise of the Indus River Valley Civilization. The fertile soil, coupled with favorable climatic conditions and consistent water supply from rivers, contributed to agricultural prosperity. Stretching over a distance of 3200 km between the mouths of the Indus and the Ganga-Brahmaputra, these plains vary in width from 300 to 150 km. The region encompasses the Indus river system in the west and the Ganga-Brahmaputra river system in the east. Notably, the latter forms the world's largest and fastest-growing delta. The Northern Plains are divided into four zones based on relief: Bhabhar, Tarai, Bangar, and Khadar.

Question 12: Briefly explain the following.

(i) The Indian Desert

Answer: The Indian Desert lies along the western margins of the Aravali Hills, characterized by undulating sandy plains dotted with sand dunes known as barchans. With rainfall averaging below 150 mm per year, this region experiences an arid climate with minimal vegetation. Temporary streams emerge during the rainy season but vanish into the sand due to insufficient water to reach the sea, with the Luni River being the notable exception.

(ii) The Central Highlands

Answer: The Central Highlands, situated north of the Narmada River and covering a significant portion of the Malwa plateau, form part of the peninsular plateau. Bounded by the Vindhyan range to the south and the Aravali range to the northwest, this region is drained by rivers like the Chambal, Sind, Betwa, and Ken, flowing southwest to northeast. The Central Highlands are wider in the west but narrower in the east, extending further as Bundelkhand and Baghelkhand to the east, eventually merging into the Chotanagpur plateau drained by the Damodar River.

(iii) The Island groups of India

Answer: India comprises two main island groups, namely Lakshadweep and Andaman and Nicobar Islands. Lakshadweep, located opposite the Kerala coast in the Arabian Sea, consists of numerous small coral islands known as atolls, characterized by their ring or horseshoe shape. In contrast, the Andaman and Nicobar Islands are larger and more widely scattered, with about 200 islands in the Andaman group and 19 islands in the Nicobar group.