YOUNG WORLD

Moving continents

Dr. T. V. PADMA

Indians travel, but India itself can't travel, can it? Who ever heard of a travelling continent? Surely a great big land mass can't sail across the oceans?

Oh, yes it can!

Have you ever wondered why the world looks the way it does? How did the Himalayas get so much higher than the rest of India? Why aren't mountains found everywhere? Why is black soil strewn along the Deccan plateau? Why do earthquakes concentrate on some corners of the earth? In a few weeks, you'll know the answers to more than just these questions.

When the earth was formed, it looked very different from the way it does now. The continents and seas did not have the same shape or location that they do today. Geologists break up the time between the earth's formation and the present into periods, which they call "eras". There are four geological eras, counting in millions of years, backwards from the present, the way historians use B.C.

Let's start at the beginning. The oldest era is the Precambrian, which stretches all the way back to the time of earth's formation, about 4600 million years ago (Mya). The Paleozoic comes next, beginning 570 Mya. The Mesozoic began 225 Mya. The Cenozoic, which includes the present, started 65 million years ago.

Two hundred million years back, all the continents (Asia, Europe, North America, South America, Africa, Australia and Antarctica) were all stuck together. There was just one huge super continent, called Pangea. Naturally there was also only just one ocean. This was called Panthalassa.

Pangea began to break up with a rift between what became Africa and what became Antarctica. Antarctica and India were stuck together at first. Then, about 190 million years ago, India broke free!

About 65 million years ago, the earth began to look more like it does now. Where was India at that time? India was out in the middle of the ocean! It was not yet part of Asia. India travelled slowly for millions of years before finally ramming into Asia.

Get an atlas or a globe. Look at the east coast of South America and the west coast of Africa. Don't they look as if they could fit together like two pieces of a jigsaw puzzle that almost fit? They were stuck together, as you now know, more than 200 Mya. It's harder to see how the other continents fitted together because their coastlines have altered more, over all this time.

By now, you are probably wondering how continents move and if they are still moving. More about this, including why the Himalayas grew so high, in the coming weeks.

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