By Priya Ranganathan
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Many millions of years ago, during the time of the dinosaurs, the supercontinent of Gondwana was stirring. It was a restless land made up of plates that rubbed against each other and shaped by forces much larger than anything you or I have ever known. Volcanoes erupted, pieces of land broke apart and created seas, and dinosaurs ruled the earth in those days.
The name Gondwana comes from our India, when a geologist named Eduard Suess, who found ancient rocks from this supercontinent in the forests of the Gond tribe in India. Thus came the name “Gond-wana,” or the forest of the Gonds. This large supercontinent included most of the continents and countries as we know them today, including India.
Nearly 180 million years ago, in the Jurassic period, Gondwana began its first great divide. The western half of the supercontinent, made up of Africa and South America, split from the eastern half, which had Madagascar, India, Australia, and Antarctica. For a while, all was calm. But 140 million years ago, a hot plume of magma from the depths of the earth caused the delicate landmass to fracture, splitting once again. India and Madagascar split from Australia and Antarctica, creating the majestic Indian Ocean!
While all this splitting was happening, however, let’s take a look at what early India was composed of, even before it came to be known as India. The first clues to India’s ancient past lie in the Aravalli Hills of Rajasthan, Madhya Pradesh, and up to Delhi. Here lie rocks so old that we can barely think back to the time they were deposited, a time nearly 2.5 billion years ago, long before the dinosaurs ever existed. The Aravalli Hills rose out of the earth during this ancient time. These are some of the first rocks that created the land of India, and since then, many more have been layered on top of them, stone by stone building the land we know today. During the late Proterozoic period, right after the Aravalli rocks were laid down, the rocks of the Vindhya Hills and the Cudappah formation of modern Andhra Pradesh were deposited, where the Eastern Ghats stand today. Some say the Vindhyas were formed from the waste remnants of the Aravallis, nearly 500 million years ago!
We return to the time of the dinosaurs, when India and Madagascar were bobbing alone, newly separated from Gondwana and drifting northwards. It was the time of the great dinosaurs, where giants like the Rajasaurus and Tyrannosaurus Rex stomped about and gentle giants like the Apatosaurus grazed on the treetops. It was a time of flowering plants and a hot, humid climate with giant dragonflies and ancient swamps. And then finally, chaos broke loose.
The floating landmass of India and Madagascar drifted right over the Deccan volcanoes, which were a series of hotspots, or underwater volcanoes that heated the land above them. When India floated over this hotspot, the Deccan volcanoes erupted, creating such a massive disturbance around the planet that it sparked the extinction of the dinosaurs. Dense plumes of volcanic ash and smoke clogged the air, killing off many living creatures and changing the climate. Hot lava flowed over India, depositing layers of igneous (volcanic) rocks on the landmass and creating a rift between India and Madagascar. India, now completely isolated from other pieces of land, continued its northward journey, travelling far faster than any of the other landmasses on the planet due to its very thin crust. It was around this time that the Western Ghats or Sahyadri mountain range lining the western edge of the Indian peninsula were formed, this early range appearing as a cliff of nearly 1,000 metres in height. Most of the rock here is basalt, a volcanic rock known to be deposited by the Deccan volcano eruption.
The Indian plate continued to journey north until it encountered the larger Eurasian plate nearly 40 million years ago. With a mighty push, the Indian plate slid beneath the Eurasian plate, sending a powerful jolt through the land. As the plates fused over time, they gave birth to the tallest mountain range in the world – the Himalayas. Even today, the Himalayas continue to grow as the Indian plate slowly slides northward at a rate of 5 cm/yr, burying itself further under the Eurasian plate, which moves at only 2 cm/yr. This phenomenon is the reason why the Himalayas are still growing at a rate of more than 1 cm/yr and have not yet given up their title as the tallest mountains on earth!
Where the Indian Plate now stands was once a deep ocean. This ocean is now the fertile Gangetic Plain, formed by the mighty Ganga and Yamuna Rivers and their many tributaries as they pour down from the Himalayas. These rivers originate in glaciers – frozen rivers of ice – deep in the snowy peaks. Their waters shape the rocks and the land where they flow, all the way to the Sundarbans delta in the Bay of Bengal. The rice belt of India and some of the country’s most fertile land comes from this region.
Let’s talk quickly about the Gangotri glacier, shall we? This river of ice originates in the Garhwal Himalayas, born from the extreme cold and giving rise to the Ganga. Glaciers are known to expand – or move forward – and retreat over the years. The Gangotri glacier has been retreating slowly due to climate change, the warming temperatures heating up and melting this massive block of ice, despite its placement in the high Himalayas. If this glacier should melt much further, the mighty Ganga will turn into a tiny stream, and one day, it will vanish into the earth.
Our country is made from ancient rocks and rocked by powerful forces that we can barely begin to imagine. It existed far before it received its name, and the land that we walk upon holds imprints of dinosaurs and strange creatures that lived and died here. Oceans have been sealed by floating landmasses and volcanoes have erupted, changing the climate and shaping this land into the India we know and love today.
There are endless stories buried in the earth beneath our feet, stories that remain to be explored, one layer at a time!
About the Author:
Priya Ranganathan is a wetland ecologist and geologist by training who works in the wild Western Ghats. When she isn’t out wading through swamp forests, she can be found scribbling away in her notebook or practicing Bharatanatyam.
Youth for Nature 