The evolutions of the continents

The shape of the earth’s surface has been charging over the time. The different continents of the earth had a single landmass in the beginning. The single landmass was called pangaea and surrounding ocean called panthalassa. The pangaea split into two major continental groups- laurasia and gondwanaland about 180 million years ago.

The southern landmass, gondwanaland, further broke up isolating india and antarctica-australia. South america similarly drifted away from africa. The sediments of the shallow sea ‘tethys sea’ between India and africa northwars. the himalayas emerged as a result of this process.

However, plate tectonics theory argues that earth’s crust is made up of a series of rigid plates that float on a soft layer of the mantle and are moved about by convection currents in the earth’s interior. These plates converge and diverge along margins naked by earthquakes, volcanoes and other seismic activities. Plates diverge from mid-ocean ridge where molten lava pushes upward and forces the plates apart a rate of about 30 mm per year. While converging, the oceanic plates below the lighter continetal rock.

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