Structure and Physiology Class 11 Geography Chapter 2 - Competency Based Question and answer
Question: Explain the geological divisions of India.
Answer:
India is divided into three categories based on geological structure and formation. These divisions are as follows:
- The peninsular block
- The Himalayas and other peninsular mountains
- Indus-Ganga-Brahmaputra plain
1. The peninsular block:
- The peninsular block is mainly made up of ancient granite and gneiss type of rocks.
- This is the oldest rigid landmass of India.
- This peninsular block extends from Kachchh to the Aravalli in the northwest, and from the Ganga delta in the east, covering the whole of south India.
- This plateau also extended towards the north-east India, covering the Meghalaya and Karbi Anglong plateau of Assam.
- This region is full of mineral resources.
2. The Himalayas and other peninsular mountains:
- The Himalaya is a young folded mountain covering the whole northwestern to northeastern states.
- This mountain is very important for the whole country as this is act as the natural barrier of India and controls the climatic phenomenon of the country.
- Among the other peninsular mountains - the Aravalli, Vindyas, Satpura, Westernghat, Easternghat, etc., are important.
- All the mountains are the main source of numerous rivers.
3. Indus-Ganga-Brahmaputra plain:
- The great Indian plain is mainly formed by the deposition of alluvial materials carried by the Indus, Ganga, and Brahmaputra rivers and their tributaries, and makes the region more prosperous.
- This region is rich due to the presence of very fertile alluvial soil.
- Maximum populous states are located in this plain area.
Question: Briefly discuss the physiographic divisions of India.
Answer:
There are six physiographic divisions of India based on landform variations. These are -
- The northern and northeastern mountains.
- The northern plain.
- The peninsular plateau
- The India desert
- The coastal plains
- The islands.
1. The northern and northeastern mountains:
- Includes the Himalayas and the mountains of northeast India.
- These are the young fold mountains.
- Very high mountain peaks and deep valleys are common in this area.
2. The northern plain:
- This plain is made up of alluvial materials carried by the Himalayan rivers.
- The Indus, Ganga, and Brahmaputra river and their tributaries are the main creators of the northern plain.
- This plain is very fertile and famous for the cultivation of several crops.
3. The peninsular plateau:
- This is the oldest landmass of India, mainly made up of igneous and metamorphic rocks.
- The peninsular plateau includes the Deccan plateau, Meghalaya plateau, Karbi Anglong plateau of Assam, and the central highland.
- Plateaus are very rich in mineral deposits.
4. The Indian deserts:
- This desert is located in the northwest of the Aravalli range.
- Different types of sanddunes are found in this area.
- This area receives a very small amount of rainfall (less than 150mm).
5. The coastal plains:
- The coastal plain of India is divided into two major types: eastern and western coastal plains.
- The eastern coastal plains are created by the Mahanadi, Godavari, Krishna, and Kaveri rivers and their tributaries.
- The western coastal plain is very narrow, with very few short rivers except the Narmada and Tapi.
6. The islands:
- Two island groups are there: the Islands in the Bay of Bengal and in the Arabian Sea.
- The Andaman and Nicober island in the Bay of Bengal.
- The Lakshadweep and Minicoy are in the Arabian Sea.
Question: Explain the divisions of the peninsular plateau.
Answer:
The peninsular plateau is divided into three parts:
- The Deccan Plateau
- The Central Highlands
- The Northeastern Plateau.
1. The Deccan Plateau:
- This plateau is located in the south of the Narmada River.
- It is triangular shaped plateau.
- The Western Ghats in the west and the Easternghat in the east form the boundary of this plateau.
- Godavari, Krishna, and Kaveri are the main rivers in this area.
- The Nilgiri is the southernmost boundary of the Deccan plateau, where the Western Ghats and the Eastern Ghats meet together.
2. The Central Highlands:
- The central highland is located in the east of the Aravalli range, the Narmada River is the southernmost boundary, and the Rajmahal hill is the eastern boundary of this central highland.
- The slope of the central highland is sloping towards the north and northeast, from where many tributaries of the Ganga are flowing.
- The average elevation of this central highland is 700-1000 m.
3. The Northeastern Plateau:
- This plateau is the extension of the Peninsular plateau, which spreads over the northeastern states.
- The Meghalaya Plateau and the Karbi Anglong Plateau are part of this Northeastern Plateau.
- The Garo Hills, Khasi Hills, and Jaintia Hills are part of the Meghalaya plateau.
Question: Explain the formation of the Indian Desert.
Answer:
The Indian desert is located in the northwest part of the Aravalli range. It is believed that this part was under the ocean during the Mesozoic era, and this is proved by the wood fossils deposition found near Jaisalmer.
This Indian desert formed due to the following reasons:
1. Low rainfall:
This area receives a very small amount of rainfall (less than 150 mm per year) due to the presence of the Aravalli range parallel to the south-west monsoon wind direction.
2. Monsoon effect:
When the monsoon winds arrive in this region, it becomes dry, which is not capable to do rainfall.
3. Location:
This Indian desert part is located comparatively far from the ocean area, and it leads to an extreme type of climate.
4. Geological History:
As the evidence proves that this region was under the sea and then gradually changed to a dry region due to the climatic changes, over a long time, wind action forms sand dunes over this vast area.
Question: Differentiate between the eastern coastal plain and the western coastal plain in India.
Answer:
1. Location:
The western coastal plain lies between the Western Ghats and the Arabian Sea, but the eastern coastal plain lies between the Eastern Ghats and the Bay of Bengal.
2. Formation:
The western coastal plain is mainly formed by the submergence of the coastal area, and on the other hand, the eastern coastal plain is formed by the deposition of erosional materials carried by the eastern-flowing rivers of the Deccan plateau.
3. Width:
Being the submergence coast, the western coast is narrow, whereas the eastern coastal plain is wide.
4. Delta formation:
The deltas are not common in the western coastal plain, like in the eastern coastal plain.
But, KAYALS are more common in the western coastal plain. One famous KAYAL - 'Punnamada' in Kerala is famous for the Nehru Trophy Vallamkali (boat race).
5. Rivers:
The Narmada and the Tapi are the main rivers in the western coastal plain, but in the eastern coastal plain, numerous rivers are present, like the Mahanadi, Godavari, Krishna, and Kaveri.