2.
Answer the following questions in about 30 words.
(1) What were the forces suggested by Wegener for the movement of the
continents?
(ii) How are the convectional currents in the mantle initiated and maintained?
(111) What is the major difference between the transform boundary and the
convergent or divergent boundaries of plates?
(iv) What was the location of the Indian landmass during the formation of the
Deccan Traps?
Answer the following questions in about 150 words,
(1) What are the evidences in support of the continental drift theory?
(ii) Bring about the basic difference between the drift theory and Plate
tectonics.
3.
What were the major post-drift discoveries that rejuvenated the interest
of scientists in the study of distribution of oceans and continents?
Answers
Answer:
Explanation:
(i) Wegener suggested that two forces were responsible for continental drift. These are Polar fleeing force and Tidal force. The Polar fleeing force is related to the rotation of the earth. The Tidal force is due to the attraction of the moon and the sun, which causes tides in the oceans.
(ii) The convectional currents in the mantle of the earth are initiated and maintained by temperature differences within the earth. Hot magma from greater depths comes up and comparatively cold lava from above goes down giving birth to convectional currents.
(iii) Convergent boundaries -- where crust is destroyed as one plate dives under another. Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other
(iv) The Deccan Traps were formed during the movement of the Indian plate towards the Asiatic plate. This started somewhere around 60 million years ago and continued for a long period of time. At that time, Indian landmass was located in the south of the equator.
For Question
(1) Wegener knew that fossil plants and animals such as mesosaurs, a freshwater reptile found only South America and Africa during the Permian period, could be found on many continents. He also matched up rocks on either side of the Atlantic Ocean like puzzle pieces.
(ii)The theory of continental drift suggests that all the land masses on earth were once part of one supercontinent. Plate tectonics is the ability to measure the movement of land masses.
(iii) The matching of continents : The shorelines of Africa and Sout America facing each other have a remarkable and unmistakable match. (ii)Rocks of same age across the oceans :The belt of ancient rocks of 2000 millions years ages from Brazil coast matches with those from western Africa.
Answer:
( 2 )1. Wegener suggested that two forces were responsible for continental drift. These are Polar fleeing force and Tidal force. The Polar fleeing force is related to the rotation of the earth. The Tidal force is due to the attraction of the moon and the sun, which causes tides in the oceans.
2 . The convectional currents in the mantle of the earth are initiated and maintained by temperature differences within the earth. Hot magma from greater depths comes up and comparatively cold lava from above goes down giving birth to convectional currents.
3 . Divergent boundaries -- where new crust is generated as the plates pull away from each other. Convergent boundaries -- where crust is destroyed as one plate dives under another. Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other.