Physiography Of INDIA
This post will cover
1.Structure and location
2.Relief features
3.Formation of Himalayas
|
India- Subcontinent and Location
Subcontinent: A subcontinent is a large, relatively self-contained landmass forming a subdivision
of
a continent. The term subcontinent signifies "having a certain geographical or political
independence"
from
the rest of the continent, or
"a vast and more or less self-contained subdivision of
a continent."
Used on its own in English, the phrase "the Subcontinent" commonly refers to the Indian subcontinent. The region largely comprises a peninsula of Asia south of the Himalayas and constitutes a geo-culturally distinct region within Asia. The region contains desert, plateau, rain forest, mountains and a myriad of languages, races, and religions. According to some pundits the concept was evolved during the British rule, who wanted to project India as culturally and geographically diverse, in order to rule it and avoid its unification.
Locational Features of India
· Area of India: 3.28 million sq. km.
· It is 7th largest country in
the world. It has 2.4% of
the total world’s
area.
· Latitudinal and Longitudinal
extent:
Latitudinal
and longitudinal extent of India are
roughly about 30 degrees.
o Longitudinal extension:68 Degrees 7’
East
to 97 Degrees
25' East
o Latitudinal extension: 8 Degrees 4'North to 37 Degree 6' North.
The southern boundary has two values. Main land boundary - 8° 4’ N and Southern most point of India is the lower point of Nicobar Islands which is 6°45’N. This point is called the ‘Indira Point’
which was previously known as ‘Pygmalion point’
· Coastline has two different longitudinal values.
o Total length of the
coastline contained within
the mainland-6100kms
o Total coastline contained within
the Indian territory-7517kms
Indian Standard Time Longitude (IST)
· The longitudinal value is 82 1/2°
E and this longitude passes through Allahabad.
Q: What
are
the implications
of India
having a long coastline?
· Moderating effect caused because of proximity to sea which is dominating in the peninsular
region and determines a maritime type of
climate.
· Vulnerability to calamities like cyclones and tsunamis and rise in the sea level due to climate change.
·
Social and Economic
implications:
o A greater number of ports leading to a higher trade.
o Large amount of marine resources owing
to large EEZ(Exclusive Economic Zone)
o Cultural affinity to the West and East in
previous centuries.
o Forces the
Indian
government to maintain a large Navy in order to
protect its sea territory
STRUCTURE AND PHYSIOGRAPHY OF INDIA
Based on the variations in its geological structure and formations, India can be divided
into three geological divisions. These geological regions
broadly follow the physical features:
1. The Peninsular Block
2. The Himalayas and other Peninsular Mountains
3.
Indo-Ganga-Brahmaputra Plain.
THE PENINSULAR BLOCK:
· The northern boundary of the Peninsular Block is 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.
Apart from these, the Karbi Anglong
and
the Meghalaya Plateau in the northeast and Rajasthan
in the west are also extensions of this block. The northeastern parts are separated by the
Malda fault in West Bengal from the
Chotanagpur plateau.
In Rajasthan, the desert and other desert–like features overlay this
block.
· Formed by a great complex of
very ancient gneisses and granites, which constitutes a major part of
it.
·
Since the Cambrian period, the Peninsula has been standing like a rigid block and never been
submerged, with the exception of some of its western coast which is submerged beneath the
sea
·
Part of the Indo-Australian Plate, it has been subjected to various vertical movements and block
faulting. The rift valleys of the Narmada, the Tapi and the Mahanadi and the Satpura block mountains are some examples
of
it.
· The Peninsula mostly consists of
relict and residual mountains
· The river valleys
here
are shallow with
low gradients.
THE HIMALAYAS
AND
OTHER PENINSULAR MOUNTAINS:
· Young, weak and flexible in their geological structure unlike the rigid and stable Peninsular
Block.
· Still subjected to the interplay of exogenic and endogenic forces, resulting in the development of
faults, folds and thrust plains.
· These mountains
are tectonic in origin,
dissected
by fast-flowing rivers
which
are
in
their
youthful stage.
Various landforms like gorges, V-shaped valleys, rapids, waterfalls, etc. are
indicative of this stage.
INDO-GANGA-BRAHMAPUTRA PLAIN:
· These plains
are formed mainly
by sediments brought by
the Indus,
the
Ganga and
the
Brahmaputra river systems.
· Originally, it was a geo-synclinal depression which attained its maximum development during
the third phase of the Himalayan mountain
formation.
· Average depth of
alluvial deposits in
these plains ranges from 1,000-2,000 m.
PHYSIOGRAPHY:
Physiography of an area is the outcome of structure, process and the stage of development. The land
of India is characterized by great diversity in its physical features. Based on these macro variations, India can
be divided into the following physiographic
divisions:
(1) The Northern and North-eastern Mountains
(2) The Northern Plain
(3) The Peninsular Plateau
(4) The Indian Desert
(5) The Coastal Plains
(6) The Islands
The North and Northeastern Mountains:
· The North and Northeastern Mountains consist of the Himalayas and the Northeastern hills.
· The Himalayas consist of a series of parallel mountain ranges. Some of the important ranges are
the Greater Himalayan range, which includes the Great Himalayas and the
Trans-Himalayan range, the Middle
Himalayas
and the Shiwalik.
· Orientation:
o Northwest to the
Southeast direction in the Northwestern part of
India.
o In the Darjeeling and Sikkim regions
lie
in an east west direction,
o In Arunachal
Pradesh they are
from southwest to the northwest direction.
o In Nagaland,
Manipur and Mizoram, they are in the north-south direction.
· The approximate length of the Great Himalayan range, also known as the central axial range, is
2,500 km from east to west, and their width
varies between 160-400 km from north
to south.
On the basis of relief, alignment of ranges and other geomorphological features, the Himalayas can be divided
into the following sub-divisions:
1. Kashmir or Northwestern Himalayas
2. Himachal
and
Uttaranchal Himalayas
3. Darjeeling
and
Sikkim Himalayas
4. Arunachal Himalayas
5. Eastern Hills and Mountains.
Typical features of Himalayas and
its importance:
· Protects India from the cold North-Eastern
trade winds from Tibet
· They help in directing the monsoon winds or channeling effect on Monsoon
· Store house of various
resources
· Great source of
biodiversity
· They are a major tourist attraction
· Transhumance is practiced. (i.e. This is practiced by nomadic groups who migrate to ‘Bugyals’ (the summer glasslands in
the higher reaches) during summer months and return to the valleys during winters)
· Doon or Dun: It is a local word for longitudinal valley, particularly an open valley, in the Siwaliks or between the Siwaliks and higher Himalayan foothills. E.g.: Dehradun, Nalgarh Dun, Harike Dun
· Karewas- Karewas are the thick deposits of glacial clay and other materials
embedded with moraines. These are found in Jammu & Kashmir Region (Kashmir Valley). They are very fertile and specifically use to cultivate saffron in India.
Theories of Formation of
Himalayas:
1. Continental Drift Theory - Alfred Wegener (1912)
· The super
continent
was called PANGAEA which
further broke into Lauransia and
Gondwanaland.
· The water body surrounding the Pangaea was called PANTHALASSA
2. Plate Tectonic
Theory:
· According to this theory, Himalayas were created due to collision of Indo-Australian plate and Eurasian plate in successive phases
·
This is the most acceptable theory which explains the origin of Himalayas.
No comments:
Post a Comment