2) The Peninsular Plateau
1.
Rising from the height of 150 m
above the river plains up to an elevation of 600-900 m is the irregular
triangle known as the peninsular plateau.
2.
Delhi ridge in the northwest,
(extension of Aravalis), the Rajmahal hills in the east, Gir
range in the west and the Cardamom hills in the south constitute the
outer extent
3.
An extension of this is
also seen in the northeast, in the form of Shillong and Karbi-Anglong plateau
4.
This is one of the oldest and
the most stable landmass of India.
5.
The general elevation of the
plateau is from the west to the east
6.
This is also proved by the
pattern of the flow of rivers.
7.
Some of the important
physiographic features of this region are tors, block mountains rift valleys, spurs, bare rocky structures,
series of hummocky hills and wall-like quartzite dykes
On
the basis of the prominent relief features, the peninsular plateau can be
divided into three broad groups:
(i) The Deccan Plateau
(ii) The Central Highlands
(iii) The Northeastern Plateau
The Deccan
Plateau
1.
This is bordered by the Western
Ghats in the west.
2.
Eastern Ghats in the east and
the Satpura.
3.
Maikal range and Mahadeo hills
in the north.
4.
Western Ghats are locally known
by different names such as Sahyadri in Maharashtra, Nilgiri
hills in Karnataka and Tamil Nadu and Anaimalai hills and Cardamom
hills in Kerala.
5.
Western Ghats are comparatively
higher in elevation and more continuous than the Eastern Ghats.
6.
Their average elevation is
about 1,500 m with the height increasing from north to south.
7.
‘Anaimudi’ (2,695 m), the highest
peak of Peninsular plateau is located on the Anaimalai hills of the
Western Ghats.
8.
Most of the Peninsular rivers
have their origin in the Western Ghats.
9.
Eastern Ghats comprising the discontinuous and low hills are
highly eroded by the rivers such as the Mahanadi, the Godavari, the Krishna, and the
Kaveri.
10.
Some of the important
ranges include the Javadi hills, the Palconda range, the
Nallamala hills, the Mahendragiri hills
11.
The Eastern and the Western
Ghats meet each other at the Nilgiri hills.
The Central
Highlands
1.
They are bounded to the west by
the Aravali range.
2.
The Satpura range is formed by
a series of scarped plateaus on the south.
3.
Generally at an elevation
varying between 600-900 m above the mean sea level.
4.
It is a classic example of the
relict mountains which are highly denuded and form discontinuous ranges.
5.
The extension of the peninsular
plateau can be seen as far as Jaisalmer in the West.
6.
The general elevation of the
Central Highlands ranges between 700-1,000 m above the mean sea level.
7.
It slopes towards the north and
north-eastern directions.
8.
Most of the tributaries of the
river Yamuna have their origin in the Vindhyan and Kaimur ranges.
9.
Banas is the only
significant tributary of the river Chambal that
originates from the Aravalli in the west.
The North-eastern
Plateau
1.
It is an extension of the main peninsular
plateau.
2.
Due to the force exerted by the
north-eastward movement of the
Indian plate at the time of the Himalayan origin, a huge fault was created
between the Rajmahal hills and the Meghalaya plateau.
3.
Later, this depression got
filled up by the deposition activity of the numerous rivers.
4.
Today, the Meghalaya and Karbi
Anglong plateau stand detached from the main Peninsular Block.
5.
The Meghalaya plateau is further
sub-divided into three: Named after the tribal groups inhabiting this
region.
(i)
The Garo Hills
(ii)
The Khasi Hills
(iii)
The Jaintia Hills
6.
An extension of this is also
seen in the Karbi Anglong hills of Assam.
7.
The Meghalaya plateau is also rich
in mineral resources like coal, iron ore, sillimanite, limestone and uranium.
8.
This area receives maximum
rainfall from the south west monsoon.
9.
The Meghalaya plateau has a highly
eroded surface.
10.
Cherrapunji displays a bare
rocky surface devoid of any permanent vegetation cover.
Some quick facts
1.
The northern boundary of the Peninsular Block may be taken as an irregular line running from Kachchh along the
western flank of the Aravali Range near Delhi and then roughly parallel to the Yamuna and the Ganga as far as
the Rajmahal Hills and the Ganga delta.
2.
The north-eastern parts are
separated by the Malda fault in West Bengal from the Chotanagpur plateau.
3.
The Peninsula is formed essentially by
a great complex of very ancient gneisses and granites,
4.
Since the Cambrian period, the Peninsula has been standing like a rigid block
5.
As a part of the Indo-Australian Plate,
it has been subjected to various vertical movements and block faulting.
6.
The rift valleys of the
Narmada, the Tapi and the Mahanadi and the Satpura block mountains are some
examples of it.
7.
The river valleys here are
shallow with low gradients
8. Aravali hills, one of
the oldest ranges of the world
9.
The Vindhyas and the Satpuras are the important ranges.
10.
The rivers Narmada and Tapi flow through
these ranges.
11.
These are west-flowing rivers that drain into the Arabian Sea.
12.
Western Ghats are almost
continuous,
13.
The Eastern Ghats are broken
and uneven
14.
The plateau is rich in minerals
like coal and iron-ore.
15.
The western coastal plains are
very narrow
16.
The eastern Coastal plains are
much broader
17.
There are a number
of east flowing rivers. The rivers
Mahanadi, Godavari, Krishna and Kaveri drain into the Bay of Bengal.
18.
These rivers have formed
fertile deltas at their mouth.
The Peninsula mostly consists of
relict and residual mountains like
1.
The Aravali hills
2.
The Nallamala hills
3.
The Javadi hills
4.
The Veliconda hills
5.
Palkonda range
6.
The Mahendragiri hills
3) INDO GANGETIC PLAINS
1.
The third geological division of India comprises the plains formed by the river Indus, the
Ganga and the Brahmaputra.
2.
It was a geo-synclinal
depression which attained its maximum development
3.
During the third phase of the
Himalayan mountain formation approximately about 64 million years ago.
4.
Since then, it has been
gradually filled by the sediments brought by the Himalayan and Peninsular
rivers.
5.
Average depth of alluvial
deposits in these plains ranges from 1,000-2,000 m.
The
Northern Plain
1.
Formed by the interplay of the
three major river systems, namely– the Indus, the Ganga and the Brahmaputra
2.
Formed of alluvial soil
3.
It spreads over an area of 7
lakh sq. km.
4.
The plain being about 2400 Km
long and 240 to 320 Km broad, is a densely populated physiographic division
5.
The velocity of the river
decreases which results in the formation of riverine islands
6.
Majuli, in the Brahmaputra
River is the largest inhabited riverine island in the world.
7.
The rivers in their lower
course split into numerous channels due to the deposition of silt
8.
These channels are known as
distributaries
9.
The Northern Plain is broadly
divided into three sections.
10.
The Western part of the
Northern Plain is referred to as the Punjab Plains. Formed by the Indus and its
tributaries, the larger part of this plain lies in Pakistan.
11.
The Indus and its
tributaries–the Jhelum, the Chenab, the Ravi, the Beas and the Satluj originate
in the Himalaya. This section of the plain is dominated by the doabs.
12.
‘Doab’ is made up of two words-
‘do’ meaning two and ‘ab’ meaning water
13.
‘Punjab’ is also made up two
words- ‘Punj’ meaning five and ‘ab’ meaning water.
14.
The Ganga plain extends between
Ghaggar and Teesta rivers.
15.
It is spread over the states of
North India, Haryana, Delhi, U.P., Bihar, partly Jharkhand and West Bengal to
its East, particularly in Assam lies the Brahmaputra plain
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