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.
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