Structure and Physiography Notes in English Class 11 Geography Chapter-2 Book-India Physical Environment
0Team Eklavyaजून 12, 2025
Physiographic divisions of India
1. Northern and north-eastern mountain ranges
2. Plains of Northern India
3. Peninsular Plateau
4. Indian desert
5. Coastal plains
6. Islands
surface features
Rocks and soils are related because unconsolidated rocks are actually soils.
Differences between rocks and soils are found on the surface of the earth according to the topographic features.
The age of the earth is approximately 4.6 billion years.
In such a long time, many changes have taken place due to endogenous and exogenous forces.
Millions of years ago, the 'Indian Plate' was located south of the equator.
Over millions of years, this plate broke into several pieces, and the Australian Plate began to move southeast and the Indian Plate began to move north.
The movement of the Indian Plate continues and has significant effects on the physical environment of the Indian subcontinent.
Division of India on the basis of structure
1. Peninsular section
The northern boundary of the peninsular block is fragmented, starting from Kutch, passing west of the Aravalli Hills to Delhi and then parallel to the Yamuna and Ganga rivers up to the Rajmahal Hills and the Ganga Delta.
The plateau of Karbi Anglong and Meghalaya in the north-east and Rajasthan in the west are its extensions.
The peninsular section in Rajasthan is covered with desert topography.
The peninsula is made up of ancient gneiss and granite.
This plot of land stands as a rigid block.
The peninsula mainly consists of residual hills, such as the Aravalli and Mahendragiri hills, etc.
The river valleys here are shallow and their gradient is low.
The rivers here form deltas before falling into the Bay of Bengal.
The deltas formed by Mahanadi, Godavari and Krishna are examples of this.
The Himalayas and the extra peninsular mountain ranges
The geological structure of the mountain ranges is weak and flexible.
Even at present they are influenced by exogenous and endogenous forces
The origin of these mountains is associated with tectonic movements.
These mountains are still in their youthful stage.
Indus-Ganga-Brahmaputra Plain
It is a geosynclinal trough which was formed mainly in the third phase of the Himalayan mountain formation process about 64 million years ago.
Since then, the rivers originating from the Himalayas and the Peninsula have been filling it with the sediments they bring with them.
The average depth of alluvium in these plains is 1000 to 2000 meters.
Physiographic divisions of India
1. Northern and north-eastern mountain ranges
2. Plains of Northern India
3. Peninsular Plateau
4. Indian desert
5. Coastal plains
6. Islands
1. Northern and north-eastern mountain ranges
The northern and north-eastern mountain ranges include the Himalayan Mountains and the North-Eastern Hills.
The Himalayas consist of several parallel mountain ranges.
1. Transcend Himalayan Ranges
2. Great Himalayas
3. Central Himalayas
4. Shivalik
The Himalayas stand as a strong long wall between the Indian subcontinent and the countries of Central and East Asia.
The Himalayas are not only a natural barrier but also a climatic drain and cultural divider.
2. Plains of Northern India
It is made up of alluvial deposits brought by the Indus, Ganga and Brahmaputra rivers.
The length from east to west is approximately 3200 km.
The average width is 150 to 300 kilometers.
The maximum depth of alluvial deposits is 1000 to 2000 meters
3. Plains of Northern India
The plains of northern India are of three types
i. Bhabhar
It is a thin strip of 8 to 10 kilometers width which extends parallel to the Shivalik foothills.
Rivers deposit heavy water loads here, such as large rocks and pebbles
Sometimes the rivers themselves get lost in it.
ii. Terai
The width is 10 to 20 kilometers.
The rivers which are lost in the Bhabhar region appear on the surface in this region
The area is covered with natural vegetation and is home to a variety of wild animals.
iii. Alluvial
The alluvium is divided into parts
1. Bangar
2. Khadar
Most of the area here is flooded from time to time and the rivers change their course, forming braided channels.
The Brahmaputra Valley plain is known for the presence of riverine islands and sandbars.
4. Peninsular Plateau
It is one of the oldest and most stable landmass of India.
The peninsular plateau is a triangular shaped fragmented landmass
Delhi in the North West (Aravalli extension),
Rajmahal Hills in the east,
Gir Hills in the West
Cardamom Hills in the south
Shillong and Karbi-Anglong plateau in the north-east are extensions of this landmass.
Division of Peninsular Plateau
1. Deccan Plateau
Limitations:
In the north: Satpura, Maikal and Mahadeo hills.
In the west: Western Ghats.
In the east: Eastern Ghats.
In the south: the Nilgiri and Cardamom Hills.
i. Highest peak – Anaimudi 2695m.
ii. Second highest peak – Doddabetta
2. Central Highlands
Limitations:
In the west: Aravalli Mountains.
In the east: Rajmahal Hills.
In the south: Satpura Mountains.
3. North-eastern plateau
It is an extended part of the peninsular plateau.
At the time of origin of the Himalayas, due to the movement of the Indian plate in the north-east direction, it got separated due to the formation of a rift valley between the Rajmahal Hills and the Meghalaya Plateau.
Later it was filled in by alluvium deposited by the river.
Today the Meghalaya and Karbi Anglong plateaus are isolated from the main peninsular plateau due to this reason.
Meghalaya Plateau
i. Garo Hills
ii. Khasi Hills
iii.Jubilee Hill
The Meghalaya plateau is also a rich source of minerals such as coal, iron, sillimanite, limestone and uranium.
This region receives most of its rainfall from the south-west monsoon.
5. Indian desert
It is situated to the north-east of the Aravalli Hills.
It has a rugged surface on which many sand dunes and barkhans are found.
The annual rainfall is less than 150 mm.
This is a dry and vegetation-less area.
This area was part of the sea. This is confirmed by the evidence available in the Wood Fossil Park located in Akal and the marine deposits around Brahmsar near Jaisalmer.
On the basis of slope, the desert can be divided into two parts- the northern part sloping towards Sindh and the southern part sloping towards the Rann of Kutch. Most of the rivers here are short-lived. The Luni river flowing in the southern part of the desert is important.
Here the rivers merge into the lake or playa.
The water of these playa lakes is salty from which salt is made.
6. Coastal plains
1. West Coast
The Arabian Sea is situated on the western coast of India.
Its major coastlines fall in the states of Gujarat, Maharashtra, Goa, and Karnataka.
Major cities such as Mumbai, Goa, and Cochin are on the west coast.
2. East Coast
The Bay of Bengal is situated on the eastern coast of India.
The major coastlines here fall in Odisha, West Bengal, Andhra Pradesh, and Tamil Nadu.
Major cities such as Chennai, Kakinada, and Visakhapatnam are on the east coast.
👉 Every year the famous 'Nehru Trophy Valamkali' (boat race) is organised at 'Punnamada Kayal' in Kerala.
Islands
1. Andaman and Nicobar
A group of 572 islands
6 degree north to 14 degree north
92 degrees east to 94 degrees east
Two major islands - Ritchie and Labyrinth Islands
Division into two parts – North Andaman and South Nicobar
India's only active volcano - Bering Island
Lakshadweep group
A group of 36 islands and 11 inhabited by humans
8 degree north to 12 degree north
71 degree east to 74 degree east
Minicoy is the largest island
The entire island group is made up of coral deposits
