Of Shakes And Quakes – The Incredible History of India’s Geography
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Of Shakes And Quakes – The Incredible History Of India’s Geography – If someone asked you to point out where India is on the world map, you’d probably do it in a jiffy. There it is, jutting into the Indian Ocean with Sri Lanka forming a teardrop beneath its landmass. The image is a very familiar one. But what if you were told that the Indian
subcontinent was not always located where it is today? That it was once attached to Africa and Madagascar?
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This is a fairly new discovery. For a long time, till the early twentieth century, people
thought that continents were fixed landmasses. But in 1912, a geologist called Alfred
Wegener came up with the theory of continental drift.
Wegener expanded on this idea in his book The Origin of Continents and Oceans, which was
published in 1915. He argued that the present continents all came from one single landmass that later drifted apart. While this sounded strange to people at that time, it explained why the world map looks like a jigsaw puzzle with different countries and continents appearing as they could fit into each other. These countries are far apart but their outlines seem like they could be joined together.
It took nearly fifty years for Wegener’s arguments to be scientifically proved! In the late
fifties and sixties, a great deal of new geological data established what Wegener had
suspected: the earth’s crust is a patchwork of plates and these plates are moving relative to each other. This led to the modern theory of plate tectonics.
Here is how scientists believe it all happened…
A billion years ago, there was a supercontinent called Rodinia. It was probably located south of the equator but we are still not sure about its exact shape or size. This supercontinent broke up around 750 million years ago and the various pieces, i.e. continents began to drift apart. This period is loosely called the Pre-Cambrian period. There were only single-cell organisms like bacteria alive then.
|Did You Know?|
The Aravalli Range in India is thought to be the oldest surviving geological feature
anywhere in the world! These mountains were once very tall, maybe as tall as the
The Himalayas, but over hundreds of millions of years, they have been eroded down to low hills and ridges. The northernmost point of the Aravallis is the North Ridge near Delhi University. Farther south, near the Gujarat-Rajasthan border, these short hills turn into mountains again. The Guru Shikhar peak at Mount Abu rises to 1722 meters above sea level and is considered to be a sacred place. The Rajput warrior clans claim that their ancestors arose from a great sacrificial fire on this mountain! Despite the significance of the Aravallis, they are under threat today because of reckless mining and quarrying.
Fossil records show that around 530 million years ago, there was a sudden appearance of a
large number of complex organisms on the earth. This is called the Cambrian Explosion—but
remember that we’re talking in geological terms. This ‘explosion’ took millions of years to
happen. Over the next 70–80 million years, a whole new array of life forms evolved. While all
of this was happening, the continental landmasses began to reassemble and, about 270
million years ago, fused into a new supercontinent called Pangea.
How did the new world look? As you can see, the Indian craton is wedged between Africa, Madagascar, Antarctica, and Australia.
It was on Pangea that the dinosaurs appeared 230 million years ago. But the earth was still
restless and Pangea began to break up around 175 million years ago, during the Jurassic era.
It first split into a northern continent called Laurasia (consisting of North America, Europe, and Asia) and a southern continent called Gondwana (Africa, South America, Antarctica,
Australia and India). You might have heard of the Gond tribe of central India—well, this is
where the name comes from!
A large number of dinosaur remains have been found in Raioli village of Balasinor Taluka,
Gujarat. The site was identified in 1981, and going by the thousands of fossilized eggs found
there, it appears to have been a popular hatchery for dinosaur mothers. The fossilized bones
of a previously unknown dinosaur, 25–30 feet long and two-thirds the size of the
Tyrannosaurus Rex was also discovered. This dinosaur has been named Rajasaurus
Narmadsensis—the Lizard King of the Narmada!
It is believed that, first, India, Antarctica, and Madagascar separated from Africa around 158
million years ago and then, 130 million years ago, India and Madagascar separated from
Antarctica. Around 90 million years ago, India separated from Madagascar and drifted
steadily northwards, towards Asia. As this happened, the landmass passed over the Reunion
‘hotspot’, causing an outburst of volcanic activity. This hotspot is currently under the island of
Reunion in the Indian Ocean and the eruptions it caused then, mostly in the Western Ghats
near Mumbai, created the Deccan Traps. When we say ‘eruptions’, it’s not the conical sort of eruption that you may associate with
volcanoes. These eruptions are more like a layer-by-layer oozing that created the stepped, flat-topped outcrops that geologists call Traps. (In the late seventeenth century, Shivaji and his
band of Maratha guerrillas used this unique terrain to wear down the armies of the Mughal
emperor Aurangzeb. The Traps lived up to their name on that occasion!) In geological terms,
this volcanic episode did not last very long—just 30,000 years. But it was a dramatic
phenomenon and might well have led to the extinction of the dinosaurs.
As India continued its northward journey, it collided with the Eurasian plate 55–60 million
years ago. This collision pushed up the Himalayas and the Tibetan Plateau. And the process is
still not over! The Himalayas are rising even now by around 5 mm every year, although
erosion reduces the actual increase in height. This region is considered to be seismically
unstable, meaning that it is prone to frequent and powerful earthquakes.