Class 9 Geography: Physical Features of India–Extra Questions: it is a very important chapter in the geography for class IX as it explains the different important topics like how the Himalayas performed, formation of northern plains, the major six physical features of India namely the Himalaya mountain ranges, the Northern Plains, the Deccan Plateau, Indian coasts, Indian dessert and Islands of India. You can also find solutions and notes to the chapter the physical features of India class IX. Here we are giving only some extra questions that need to be attempted to have a practice of writing answers to the questions asked in the examination as well as to grasp and comprehend the matter given in the textbook.
The Physical Features of India class IX- Chapter extra questions for revision
Q.1. What is the plate tectonics theory?
Ans: The plate tectonic theory states that the earth’s crust is divided into some major and minor plates which keep floating on Asthenosphere (the molten part of Mantle) it is because of the tectonic forces of the earth that these plates move and such movements bring changes in the shape and size of continents and formation of landforms or change an existing landform. For example – formation of Himalayas and northern plains because of the collision of Indian peninsula plate with the Eurasian plate.
Q.2. What are the classifications of the different plate boundaries or margins?
- Convergent boundary – as to plates move towards each other, like plate overwrites the heavier plate. This collision creates massively formation of the crust and folding takes place
- Divergent boundary – along the June obi wan to the plates separate and in this process of moving apart, molten rock material couples to form new to the sphere. It creates false
- Transform boundary – along with John plates glide past each other, neither created nor destroying the Earth’s crust.
The slow movements of the lithospheric plates along the plate boundaries causes building formation or mountain belts, new seafloor, chain of volcanoes, earthquakes zones and many other features on the surface. Thus, these plates are also got tectonic plates.
Q.3. How were the Himalayas formed?
The formation of Himalayas while the result of plate tectonics convergent boundary that was formed due to the collision of Indo Australian plate containing the peninsular Indian plate and the bigger Eurasian plate.
- About 165 million years ago, the Indo Australian plate broke away from the assembly of continents drift slowly northwards.
- The Tethys Sea separated the Indo Australian plate from Eurasian plate and Indo Australian plate comprised continental crust as well as ocean crust of the Tethys Sea.
- About 65 million years ago industrial and plate collided with the much larger rotation plate in the northern hemisphere. The industrial bed subducted under Eurasian Plate.
- As the continental Indian plate ultimately collided with the continental Eurasian plate., The two continental plates got to build it together along the old site of subduction. It led to folding that led to the formation of the present Himalayan mountain belt.
- India is still moving into Asia at the rate of about 5 cm per year as a result of this continued convergence, the Himalayan ranges are gaining height even today.
Q.4. How were the Nothern Plains formed?
- The formation of Northern Plains is associated with the formation of the Himalayas. A geosyncline or the basing of depression was formed to the south of the northern mountain chains of Himalayas.
- This depression was gradually filled with the fine silt, called alluvium. The deposition of album has been carried out by the river from the Himalayas in the North and the potential for doing the south.
- The Northern Indian plane was thus born between the Himalayas region and the Indian Peninsular Plateau.
Q. 5. Give the longitudinal classification of Himalayas.
Longitudinally, the Himalayan mountains are divided into three parallel ranges – Himadri, Himachal and Shivalik.
- It is also called Greater Himalayas or inner Himalayas.
- It is most continuous range with an average height of 6000 m and contains all the prominent peaks.
- Its width is 120 – 190 km.
- it remains a snowbound throughout the year and number of glaciers are found. It is composed of granite.
- It is also known as Lesser Himalayas or middle Himalayas.
- It is mostly a rugged mountain chain
- it is composed of highly compressed and altered rocks.
- Altitude is between 3700 and 4500 m.
- Average width is 50 km
- Pir Panjal (Kashmir), Dhaula Dhar Himachal Pradesh) and Mahabharat (Nepal)ranges are also prominent ones.
- It is famous for its valleys like – Kashmir, Kangra, Kulu valley.
- This region is also known for hill stations – Mussoorie, Nainital, Shimla, Ranikhet etc.
- The outermost range of the Himalayas is known as Shiwaliks, also known as Manak Parbat in ancient times.
- The altitude varies between 900 and 1100 meters in this range.
- The width varies between 10 to 50 km.
- These ranges are composed of unconsolidated sediments brought down by the rivers.
- The longitudinal valleys lying between the Himachal and Shiwaliks are called ‘Dun’.
- Unlike typical river valleys, duns have a structural origin and are covered with boulders and gravel originating from the erosion of the Himalayas and the Shiwalik uplands. Major duns found in the region are Dehra, Kothri, Chaukham, Patli and Kotla. The dun of Dehra is the biggest with a length of 35 km and width of 25 km.