Class IX
Geography
Unit II – Physical Features of India
Notes
Marble is a very hard rock. It is used in the construction
of the Taj Mahal.
Soap stone is a very soft rock. It is used in making talcum
powder.
Soil colour varies from one place to another because soil is
formed out of different types of rocks.
Geological formations, weathering, erosion and deposition
are the major factors that are responsible for India’s relief features as they
exist today.
“Theory of Plate Tectonics” explains how the physical
features of earth were formed and modified.
The crust of the earth is made of seven major plates (and a
few minor plates). The movement of the plates results in folding, faulting,
earthquakes, volcanic eruptions etc. The plates may move towards each other or
away from each other.
Earthquakes and volcanic eruptions occur mostly at plate
margins.
Once upon a time, India, Australia, South Africa and South
America existed together in as a single landmass. It was called the Gondwana Land.
It was the southern part of the super continent called Pangea.
The northern part of Pangea was called Angara Land.
The Indo-Australian plate broke up from the Gondwana Land,
drifted northwards and collided with the Eurasian plate. The collision caused the
sedimentary rocks in the Tethys Sea to fold, resulting in the formation of the
Himalayas and the mountain systems of western Asia.
The Peninsular Plateau in India is one of the oldest
landmasses on the earth’s surface. It was a part of the Gondwana Land. Later,
the Himalayas were formed. The Great Plains in northern India were formed much
later.
Major physiographic divisions of India
-
The Himalayas
-
The Northern Plains
-
The Peninsular Plateau
-
The Indian Desert
-
The Coastal Plains
-
The Islands
The Himalayas
-
Geologically young
-
Structurally fold mountains
-
Run in a west-east direction from
the Indus to the Brahmaputra
-
The loftiest mountain system in
the world
-
In the shape of an arc that is
about 2,400 km long
-
The Brahmaputra marks the
easternmost boundary
-
About 400 km wide in Kashmir
-
About 150 km wide in Arunachal
Pradesh
-
The altitudinal variations are
more in the eastern half than in the western half.
-
Consist of three parallel ranges
namely the Himadri or the Greater Himalayas or the Inner Himalayas, the
Himachal or the Lesser Himalayas and the Siwaliks or the Outer Himalayas
The Purvanchal or the Eastern hills
-
Himalayas in the north-eastern
states are known as the Purvanchal hills or the Eastern hills
-
Mostly composed of strong
sandstone, a sedimentary rock
-
Covered with dense forests
-
Comprise the Patkai hills, the
Naga hills, Manipur hills and the Mizo hills
The Himadri or the Greater Himalayas or the Inner Himalayas
-
The most continuous range
-
Consists of the world’s highest
and famous peaks
-
Average altitude 6,000 m
-
Kanchenjunga (8,598 m) is the
highest peak in India and the third highest peak in the world. It is in Sikkim,
along the border of India and Nepal. If Pakistan-occupied-Kashmir is also
considered, the highest peak is K2 or Godwin Austin (8,611 m). K2,
in the Karakoram range, is the second highest peak after Mount Everest.
-
Nanga Parbat, Nanda Devi, Kamet
and Namcha Barwa are the other important Himalayan peaks in India.
-
Everest, Makalu, Dhaulagiri,
Annapurna and Gurla Mandhata are the important Himalayan peaks in Nepal.
-
Snow-bound throughout the year
-
A number of glaciers originate
from the Himadri
-
The core of the Himadri is
composed of granite rock.
The Himachal or the Lesser Himalayas
-
The most rugged mountain system in
the world
-
Composed of highly compressed and
altered rocks
-
Altitude between 3,700 m and 4,500
m
-
Average width 50 km
-
Comprises the Pir Panjal, the
Dhaula Dhar and the Mahabharat ranges
-
The Pir Panjal is the longest and
the most important range
-
Includes the Kangra valley and the
Kulu valley in Himachal Pradesh and the Kashmir valley
-
Well known for hill stations like
Mussoorie (Uttarakhand), Nainital (Uttarakhand), Ranikhet (Uttarakhand) etc.
The Siwaliks or the Outer Himalayas
-
The outermost range of the Himalayas
-
Width 10 – 50 km
-
Altitude 900 – 1100 m
-
Composed of unconsolidated
sediments brought down by the rivers from the northern ranges
-
Covered with gravel and alluvium
-
Comprise duns like Dehra Dun,
Patli Dun and Kotli Dun
Duns: Longitudinal valleys between the Lesser Himalayas and
the Siwaliks
Punjab Himalayas / Kashmir Himalayas / Himachal Himalayas:
They are between the Indus and the Satluj rivers.
Kumaon Himalayas: They are between the Satluj and the Kali
rivers.
Nepal Himalayas: They are between the Kali and the Tista
rivers.
Assam Himalayas: They are between the Tista and the Dihang
(Brahmaputra) rivers.
The Great Plain or the Northern Plain or the Indo-Gangetic
Plain
-
Granaries of the country, base for
early civilizations
-
Comprises the Indus, the Ganga and
the Brahmaputra and their tributaries
-
Formed of alluvial soil deposits
for millions of years
-
About 2400 km long; 240 – 320 km
broad; area 7 lakh km2
-
Densely populated
-
Agriculturally very productive
because of fertile soil, abundant water availability and favourable climate
-
Divisions: the Punjab Plains, the
Ganga Plain and the Brahmaputra Plain
The Punjab Plains
-
The western part of the Northern
Plain
-
Formed by the Indus and its
tributaries (the Ravi, the Beas, the Jhelum, the Satluj and the Chenab)
-
Mostly in Pakistan
-
Dominated by the doabs
The Ganga Plain
-
The central part of the Northern
Plain
-
Between the Ghaggar and the Tista
rivers
-
Spread over Haryana, Delhi, UP,
Bihar, a part of Jharkhand and West Bengal
The Brahmaputra Plain
-
The easternmost part of the
Northern Plain
-
Mostly in Assam
Riverine islands: These are formed in the lower course of
the river because the slope is gentle and the velocity of the river decreases.
Majuli, in the Brahmaputra river, is the largest inhabited
riverine island in the world.
Distributaries: The channels into which a river splits in
its lower course
Doab: Do + ab (two rivers)
Punjab: Panch + ab (five rivers)
It is incorrect to think that the Northern Plain is a flat
land without any variations in relief.
Divisions of Northern Plain on the basis of relief features
-
Bhabar
-
Terai
-
Bhangar
-
Khadar
Bhabar
-
Located at the foot of the
Siwaliks
-
A narrow belt (8 – 16 km wide)
-
Composed of deposits of pebbles
and stones
-
Streams disappear in this region
Terai
-
Streams and rivers reemerge in
this region
-
wet, swampy and marshy
-
thickly forested; full of wildlife
-
Dudhwa National Park, a tiger
reserve in Uttar Pradesh, is located in the terai belt of the Northern Plain
Bhangar
-
Older alluvium
-
Occupies the largest part of the
Northern Plain
-
Lie above the floodplains;
terrace-like
-
Contains calcareous (calcium
carbonate) deposits
Kankar: Local name of calcareous deposits in bhangar
Khadar
-
Newer, younger alluvium
-
Renewed every year
-
Very fertile
-
Ideal for intensive agriculture
The Peninsular Plateau
-
A tableland
-
Composed of old crystalline,
igneous and metamorphic rocks
-
Storehouse of minerals; has a
crucial role in the industrialization of India
-
Broad divisions: Central
Highlands, Deccan Plateau
-
The Narmada river demarcates the
two divisions
The Central Highlands
-
Central Highlands lie north of
Narmada. This part is called Malwa Plateau.
-
Wider in the west, narrower in the
east
-
The Vindhyas lie south of the
Central Highlands and the Aravallis lie northwest of the Central Highlands.
-
The western part of the Malwa
Plateau merges with the desert in Rajastan
-
The Malwa Plateau is drained by the
Chambal, the Sind, the Betwa and the Ken rivers. They flow from southwest to
northeast. (It gives you an idea of the direction of the slope.)
-
The eastern part of the Central
Highlands consist of Bundelkhand and Bagelkhand
-
The Chota Nagpur Plateau, drained
by the Damodar, is the easternmost part of the Central Highlands.
The Deccan Plateau
-
A triangular landmass
-
Lies south of the Narmada
-
The Satpura range is the northern
boundary
-
Western Ghats mark the western
edge
-
Eastern Ghats mark the eastern
edge
-
The Mahadev hills, the Kaimur
hills and the Maikala hills lie northeast of the Deccan Plateau; Also lying in
the northeast are Meghalaya and Karbi-Anglong Plateau and Garo hills, Khasi
hills and Jaintia hills
-
Slopes from west to east
-
Separated by a fault from the
Chota Nagpur Plateau
-
The part of the Deccan Plateau containing
black soil is known as the Deccan Trap, of volcanic origin.
The Aravallis
-
Highly eroded, broken hills
-
Run in a southwest – northeast
direction
-
Extend from Gujarat to Delhi
Western Ghats
-
Western edge of Deccan Plateau
-
Parallel to west coast
-
Continuous hills
-
Can be crossed only through passes
like Thal Ghat, Pal Ghat, Bhor Ghat etc.
-
Higher than the Eastern Ghats
-
Average elevation 900 – 1600
meters; height increases from north to south
-
Anai Mudi (2,695 m) and Doda Betta
(2,637 m) are the highest peaks
-
Cause orographic rain
Eastern Ghats
-
Average elevation 600 m
-
Mahendra Giri (1,501 m) is the
highest peak
-
Stretch from the Mahanadi valley
to the Nilgiris
-
Discontinuous, irregular
-
Dissected by rivers draining into
the Bay of Bengal
-
Ooty (or Udagamandalam) in the
Nilgiris and Kodaikanal in the Palani hills are famous hill stations in Tamil
Nadu.
-
Shevroy hills and Javadi hills lie
southeast of Eastern Ghats
The Indian Desert
-
A large, arid region in the
northwestern part of India, mostly in India and partly in Pakistan
-
An undulating sandy plain with a
poor vegetation cover
-
Covered with sand dunes (some
longitudinal; some crescent-shaped called barchans)
-
Area 2,00,000 km2
-
9th largest
sub-tropical desert
-
Has the Aravallis on the east, the
Rann of Kutch (a salt marsh) in the south and the Indus river on the west
-
Very low rainfall (below 15 cm per
year)
-
Streams appear during the rainy
season
-
The only large river is the Luni
Coastal Plains: Narrow coastal strips on either side of the
peninsular plateau; sites for fishing and port activities
The Western Coast
-
Lies between the Arabian Sea and
the Western Ghats
-
A narrow plain
-
The 3 sections: The Konkan coast
(the northern part of the west coast from Mumbai to Goa), the Kannad Plain (the
central part) and the Malabar coast (the southern part, in Kerala)
The Eastern Coast
-
Lies between the Bay of Bengal and
the Eastern Ghats
-
A wider plain
-
The northern part of the eastern
coast is called Northern Circar
-
The southern part is called the
Coromandel Coast
-
Comprises deltas of the Mahanadi,
the Godavari, the Krishna and the Kaveri
-
Lake Chilika on the east coast is
India’s largest salt water lake. It is in Orissa, south of the Mahanadi delta
The Islands – Lakshadweep
-
Lie close to the Malabar coast of
Kerala
-
Small coral islands
-
Earlier known as Laccadive, Minicoy
and Amindive; renamed Lakshadweep in 1973
-
Area 32 km2
-
Administrative headquarters at
Kavaratti
-
The Pitli island has a bird
sanctuary
Coral polyps: Short-lived microscopic organisms which
secrete a hard rock-like substance
Reef: A ridge of jagged rock formed from coral secretions
and skeletons
Types of reefs: Barrier reef, fringing reef, atoll
Barrier reef: A coral reef running parallel to the shore
Fringing reef: A coral reef very close to the land
Atoll: A circular or horse-shoe shaped coral reef
The Great Barrier Reef: It is in Australia
Andaman and Nicobar Islands
-
Bigger in size than Lakshadweep
-
The northern part of the island
group is called the Andamans and the southern part Nicobar
-
An elevated portion of submarine
mountains
-
Some are of volcanic origin
-
Of great strategic importance
-
Close to the equator; have
equatorial climate and thick forest cover
-
An active volcano exists on the
Barren island in the Andamans
Lifesavers like you are rare (PS...2 days before the midterms)
ReplyDelete