NCERT CLASS-9 GEOGRAPHY CHAPTER-2 NOTES

 NCERT CLASS-9 GEOGRAPHY

CHAPTER-2 [PHYSICAL FEATURES OF INDIA]

 

• India has all major physical features of the earth i.e, mountains, plains, deserts, plateaus and islands.
• Theory of plate tectonics- The crust (upper part) of the earth has been formed out of 7 major and some minor plates.
• Movement of these plates results in building up of stresses within the plates and the continental rocks above leading to folding, faulting and volcanic activity.
• Plate movements- 3 types- 

                = some plates come towards each other and form convergent boundary.

                = some plates move away from each and form divergent boundary.

                = some plates move horizontally past each other and form transform boundary.

• Oldest landmass (the peninsular part), was part of the Gondwana land.
• Gondwana land includes India, Australia, South Africa, South America and Antarctica as one single land mass.
• Gondwana land- southern part of ancient super continent Pangea with Angara land int eh northern part.
• The Himalayan uplift out of the Tethys sea and subsidence of the northern flank of the peninsular plateau resulted in the formation of a large basin.
• Peninsular plateau one of the most stable land blocks.
• Himalayan mountains form an unstable zone.
• The peninsular plateau, composed of igneous & metamorphic rocks with gently rising hills and wide valleys.
• Major physiographic divisions of India- 

               1. The Himalayan mountains

               2. The Northern Plains

               3. The Peninsular Plateau

               4. The Indian Desert

               5. The Coastal Plains

               6. The Islands

 

         THE HIMALAYAN MOUNTAINS-

• Geologically young, structurally fold mountains.
• Mountains ranges run Ina west-east direction of about 2400 km.
• Width varies from 400 km in Kashmir to 150 km in Arunachal Pradesh.
• Altitudinal variation greater in eastern half than those in the western half.
• Consists of 3 parallel ranges, a no. Of valleys lies between these ranges.
• Northernmost range, know as the Great or Inner Himalayas or the Himadri.

                = most continuous range consisting of the loftiest peak with an average height of 6000m.

                = folds of great Himalayas are asymmetrical in nature.  

                = core composed of granite.

                = perennially snow bound, and glaciers descend from this range.

• Range lying to the south of Himadri, Himachal or lesser Himalayas.

                = composed of highly compressed and altered rocks.

                = Altitude varies between 3700 and 4500m, average width of 50km.

                = The Pir Panjal range forms the longest and the most important ranges, the Dhaula Dhar and

                   the Mahabharat ranges are prominent ones.

                = consists of the famous valley of Kashmir, the Kangra and Kullu valley in Himachal Pradesh.

                = well known for hill stations.