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Class 9th

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  • April 21, 2013
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Answer the following questions briefly.
(i) What are tectonic plates?
(ii) Which continents of today were part of the Gondwana land? (iii) What is the bhabar?
(iv) Name the three major divisions of the Himalayas from north to south. (v) Which plateau lies between the Aravali and the Vindhyan ranges? (vi) Name the island group of India having coral origin.

Answer 2:
(i) The convectional currents present below the solid layer of Earth’s crust split the crust or the lithosphere into a number of large fragments. These fragments are called tectonic or lithospheric plates. (ii) The continents that were part of Gondwana land are Australia, Antarctica and South America. (iii) The bhabhar is that part of the Northern Plains where the rivers, after descending from the mountains, deposit pebbles. It is a narrow belt, having a width of about 8 to 16 km and lying parallel to the slopes of the Shiwaliks. (iv) The three major divisions of the Himalayas from north to south are the Great Himalayas/Inner Himalayas/Himadri (Northernmost division), the Lesser Himalayas/Himachal and the Shiwaliks(Southernmost division). (v) Malwa plateau lies between the Aravali and the Vindhyan ranges. (vi) Lakshadweep Islands are composed of small coral islands.

Distinguish between
(i) Converging and diverging tectonic plates
(ii) Bhangar and Khadar
(iii) Western Ghats and Eastern Ghats
Answer 3:
(i)The Earth’s crust is broken up into several lithospheric or tectonic plates. These plates are constantly moving atop the Earth’s mantle (semi-solid layer of molten rocks). Based upon their motion, tectonic plates are referred to as converging or diverging. Converging tectonic plates move towards each other and form convergent boundary. Diverging tectonic plates move away from each other and form divergent boundary. (ii) Bhangar is the terrace-like feature present above the flood plains of the rivers. It is composed of older alluvium. It is the largest part of the Northern Plain. The soil of...